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Nirmala J, Perez A, Culhane MR, Allerson MW, Sreevatsan S, Torremorell M. Genetic variability of influenza A virus in pigs at weaning in Midwestern United States swine farms. Transbound Emerg Dis 2020; 68:62-75. [PMID: 32187882 DOI: 10.1111/tbed.13529] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 02/04/2020] [Accepted: 02/13/2020] [Indexed: 01/15/2023]
Abstract
Suckling piglets play an important role at maintaining influenza A virus (IAV) infections in breeding herds and disseminating them to other farms at weaning. However, the role they play at weaning to support and promote genetic variability of IAV is not fully understood. The objective here was to evaluate the genetic diversity of IAV in pigs at weaning in farms located in the Midwestern USA. Nasal swabs (n = 9,090) collected from piglets in breed-to-wean farms (n = 52) over a six-month period across seasons were evaluated for the presence of IAV. Nasal swabs (n = 391) from 23 IAV-positive farms were whole-genome sequenced. Multiple lineages of HA (n = 7) and NA (n = 3) were identified in 96% (22/23) and 61% (237/391) of the investigated farms and individual piglets, respectively. Co-circulation of multiple types of functional HA and NA was identified in most (83%) farms. Whole IAV genomes were completed for 126 individual piglet samples and 25 distinct and 23 mixed genotypes were identified, highlighting significant genetic variability of IAV in piglets. Co-circulation of IAV in the farms and co-infection of individual piglets at weaning was observed at multiple time points over the investigation period and appears to be common in the investigated farms. Statistically significant genetic variability was estimated within and between farms by AMOVA, and varying levels of diversity between farms were detected using the Shannon-Weiner Index. Results reported here demonstrate previously unreported levels of molecular complexity and genetic variability among IAV at the farm and piglet levels at weaning. Movement of such piglets infected at weaning may result in emergence of new strains and maintenance of endemic IAV infection in the US swine herds. Results presented here highlight the need for developing and implementing novel, effective strategies to prevent or control the introduction and transmission of IAV within and between farms in the country.
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Affiliation(s)
| | - Andres Perez
- College of Veterinary Medicine, University of Minnesota, St. Paul, MN, USA
| | - Marie R Culhane
- College of Veterinary Medicine, University of Minnesota, St. Paul, MN, USA
| | - Matthew W Allerson
- College of Veterinary Medicine, University of Minnesota, St. Paul, MN, USA
| | - Srinand Sreevatsan
- Department of Pathobiology and Diagnostic Investigation, Michigan State University, East Lansing, MI, USA
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2
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Complete Coding Sequence of a Swine Influenza A Variant (H3N2) Virus Isolated in the Republic of Korea in 2017. Microbiol Resour Announc 2020; 9:9/7/e01355-19. [PMID: 32054707 PMCID: PMC7019062 DOI: 10.1128/mra.01355-19] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Cases of human infection with a swine influenza A virus variant have been reported in the United States, and since 2011, H3N2 variant viruses have also been regularly isolated from swine in the Republic of Korea. Here, we genetically characterized an influenza A H3N2 isolate (A/swine/P17-4/2017). BLASTN analysis of the 8 gene sequences revealed a high degree of nucleotide similarity (97.0 to 99.0%) to porcine strains circulating in the Republic of Korea and the United States. Specifically, we found a high degree of similarity in the nucleotide matrix gene to those of recent isolates from North Carolina. Cases of human infection with a swine influenza A virus variant have been reported in the United States, and since 2011, H3N2 variant viruses have also been regularly isolated from swine in the Republic of Korea. Here, we genetically characterized an influenza A H3N2 isolate (A/swine/P17-4/2017). BLASTN analysis of the 8 gene sequences revealed a high degree of nucleotide similarity (97.0 to 99.0%) to porcine strains circulating in the Republic of Korea and the United States. Specifically, we found a high degree of similarity in the nucleotide matrix gene to those of recent isolates from North Carolina. Therefore, continuous epidemiological surveillance is necessary to monitor the variation and evolution of influenza A viruses.
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3
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Nirmala J, Bender JB, Lynfield R, Yang M, Rene Culhane M, Nelson MI, Sreevatsan S, Torremorell M. Genetic diversity of influenza A viruses circulating in pigs between winter and summer in a Minnesota live animal market. Zoonoses Public Health 2019; 67:243-250. [PMID: 31868300 DOI: 10.1111/zph.12679] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 10/07/2019] [Accepted: 11/19/2019] [Indexed: 11/26/2022]
Abstract
There has been little surveillance of influenza A viruses (IAVs) circulating in swine at live animal markets, particularly in the United States. To address this gap, we conducted active surveillance of IAVs in pigs, the air, and the environment during a summer and winter season in a live animal market in St. Paul, Minnesota, that had been epidemiologically associated with swine-origin influenza cases in humans previously. High rates of IAV were detected by PCR in swine lungs and oral fluids during both summer and winter seasons. Rates of IAV detection by PCR in the air were similar during summer and winter, although rates of successful virus isolation in the air were lower during summer than in winter (26% and 67%, respectively). H3N2 was the most prevalent subtype in both seasons, followed by H1N2. Genetically diverse viruses with multiple gene constellations were isolated from both winter and summer, with a total of 19 distinct genotypes identified. Comparative phylogenetic analysis of all eight segments of 40 virus isolates from summer and 122 isolates from winter revealed that the summer and winter isolates were genetically distinct, indicating IAVs are not maintained in the market, but rather are re-introduced, likely from commercial swine. These findings highlight the extent of IAV genetic diversity circulating in swine in live animal markets, even during summer months, and the ongoing risk to humans.
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Affiliation(s)
- Jayaveeramuthu Nirmala
- Veterinary Population Medicine Department, College of Veterinary Medicine, University of Minnesota, St. Paul, MN, USA
| | - Jeff B Bender
- Veterinary Population Medicine Department, College of Veterinary Medicine, University of Minnesota, St. Paul, MN, USA.,School of Public Health, Environmental Health Sciences, University of Minnesota, Minneapolis, MN, USA
| | - Ruth Lynfield
- Minnesota State Health Department, St. Paul, MN, USA
| | - My Yang
- Veterinary Population Medicine Department, College of Veterinary Medicine, University of Minnesota, St. Paul, MN, USA
| | - Marie Rene Culhane
- Veterinary Population Medicine Department, College of Veterinary Medicine, University of Minnesota, St. Paul, MN, USA
| | - Martha Irene Nelson
- Fogarty International Center, National Institutes of Health, Bethesda, MD, USA
| | - Srinand Sreevatsan
- Department of Pathobiology and Diagnostic Investigation, Michigan State University, East Lansing, MI, USA
| | - Montserrat Torremorell
- Veterinary Population Medicine Department, College of Veterinary Medicine, University of Minnesota, St. Paul, MN, USA
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4
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Smith DW, Barr IG, Loh R, Levy A, Tempone S, O'Dea M, Watson J, Wong FYK, Effler PV. Respiratory Illness in a Piggery Associated with the First Identified Outbreak of Swine Influenza in Australia: Assessing the Risk to Human Health and Zoonotic Potential. Trop Med Infect Dis 2019; 4:tropicalmed4020096. [PMID: 31242646 PMCID: PMC6632059 DOI: 10.3390/tropicalmed4020096] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 06/19/2019] [Accepted: 06/24/2019] [Indexed: 12/15/2022] Open
Abstract
Australia was previously believed to be free of enzootic swine influenza viruses due strict quarantine practices and use of biosecure breeding facilities. The first proven Australian outbreak of swine influenza occurred in Western Australian in 2012, revealing an unrecognized zoonotic risk, and a potential future pandemic threat. A public health investigation was undertaken to determine whether zoonotic infections had occurred and to reduce the risk of further transmission between humans and swine. A program of monitoring, testing, treatment, and vaccination was commenced, and a serosurvey of workers was also undertaken. No acute infections with the swine influenza viruses were detected. Serosurvey results were difficult to interpret due to previous influenza infections and past and current vaccinations. However, several workers had elevated haemagglutination inhibition (HI) antibody levels to the swine influenza viruses that could not be attributed to vaccination or infection with contemporaneous seasonal influenza A viruses. However, we lacked a suitable control population, so this was inconclusive. The experience was valuable in developing better protocols for managing outbreaks at the human–animal interface. Strict adherence to biosecurity practices, and ongoing monitoring of swine and their human contacts is important to mitigate pandemic risk. Strain specific serological assays would greatly assist in identifying zoonotic transmission.
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Affiliation(s)
- David W Smith
- Department of Microbiology, PathWest Laboratory Medicine WA, Nedlands, WA 6009, Australia.
- Faculty of Health and Medical Sciences, University of Western Australia, Nedlands, WA 6009, Australia.
| | - Ian G Barr
- World Health Organization (WHO) Collaborating Centre for Reference and Research on Influenza, at The Peter Doherty Institute for Infection and Immunity, Melbourne, VIC 3000, Australia.
- Department of Microbiology and Immunology, University of Melbourne, at the Peter Doherty Institute for Infection and Immunity, Melbourne, VIC 3000, Australia.
| | - Richmond Loh
- Sustainability and Biosecurity, Department of Primary Industries and Regional Development, Perth, WA 6151, Australia.
| | - Avram Levy
- Department of Microbiology, PathWest Laboratory Medicine WA, Nedlands, WA 6009, Australia.
| | - Simone Tempone
- Communicable Disease Control Directorate, Department of Health Western Australia, Perth, WA 6004, Australia.
| | - Mark O'Dea
- School of Veterinary Medicine, Murdoch University, Perth, WA 6150, Australia.
| | - James Watson
- CSIRO Australian Animal Health Laboratory, Geelong, VIC 3219, Australia.
| | - Frank Y K Wong
- CSIRO Australian Animal Health Laboratory, Geelong, VIC 3219, Australia.
| | - Paul V Effler
- Faculty of Health and Medical Sciences, University of Western Australia, Nedlands, WA 6009, Australia.
- Communicable Disease Control Directorate, Department of Health Western Australia, Perth, WA 6004, Australia.
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5
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Virus survival and fitness when multiple genotypes and subtypes of influenza A viruses exist and circulate in swine. Virology 2019; 532:30-38. [PMID: 31003122 DOI: 10.1016/j.virol.2019.03.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Revised: 03/21/2019] [Accepted: 03/26/2019] [Indexed: 01/07/2023]
Abstract
We performed swine influenza virus (SIV) surveillance in Midwest USA and isolated 100 SIVs including endemic and reassortant H1 and H3 viruses with 2009 pandemic H1N1 genes. To determine virus evolution when different genotypes and subtypes of influenza A viruses circulating in the same swine herd, a virus survival experiment was conducted in pigs mimicking field situations. Five different SIVs were used to infect five pigs individually, then two groups of sentinel pigs were introduced to investigate virus transmission. Results showed that each virus replicated efficiently in lungs of each infected pig, but only reassortant H3N2 and H1N2v viruses transmitted to the primary contact pigs. Interestingly, the parental H1N2v was the majority of virus detected in the second group of sentinel pigs. These data indicate that the H1N2v seems to be more viable in swine herds than other SIV genotypes, and reassortment can enhance viral fitness and transmission.
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6
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Nuñez IA, Ross TM. A review of H5Nx avian influenza viruses. Ther Adv Vaccines Immunother 2019; 7:2515135518821625. [PMID: 30834359 PMCID: PMC6391539 DOI: 10.1177/2515135518821625] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Accepted: 11/09/2018] [Indexed: 12/12/2022] Open
Abstract
Highly pathogenic avian influenza viruses (HPAIVs), originating from the A/goose/Guangdong/1/1996 H5 subtype, naturally circulate in wild-bird populations, particularly waterfowl, and often spill over to infect domestic poultry. Occasionally, humans are infected with HPAVI H5N1 resulting in high mortality, but no sustained human-to-human transmission. In this review, the replication cycle, pathogenicity, evolution, spread, and transmission of HPAIVs of H5Nx subtypes, along with the host immune responses to Highly Pathogenic Avian Influenza Virus (HPAIV) infection and potential vaccination, are discussed. In addition, the potential mechanisms for Highly Pathogenic Avian Influenza Virus (HPAIV) H5 Reassorted Viruses H5N1, H5N2, H5N6, H5N8 (H5Nx) viruses to transmit, infect, and adapt to the human host are reviewed.
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Affiliation(s)
- Ivette A. Nuñez
- Center for Vaccines and Immunology, University of Georgia, Athens, Georgia, USA
| | - Ted M. Ross
- Center for Vaccines and Immunology, University of Georgia, 501 D.W. Brooks Drive, CVI Room 1504, Athens, GA 30602, USA
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7
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Chamba Pardo FO, Wayne S, Culhane MR, Perez A, Allerson M, Torremorell M. Effect of strain-specific maternally-derived antibodies on influenza A virus infection dynamics in nursery pigs. PLoS One 2019; 14:e0210700. [PMID: 30640929 PMCID: PMC6331129 DOI: 10.1371/journal.pone.0210700] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Accepted: 12/31/2018] [Indexed: 12/25/2022] Open
Abstract
Reducing the number of influenza A virus (IAV) infected pigs at weaning is critical to minimize IAV spread to other farms. Sow vaccination is a common measure to reduce influenza levels at weaning. However, the impact of maternally-derived antibodies on IAV infection dynamics in growing pigs is poorly understood. We evaluated the effect of maternally-derived antibodies at weaning on IAV prevalence at weaning, time of influenza infection, number of weeks that pigs tested IAV positive, and estimated quantity of IAV in nursery pigs. We evaluated 301 pigs within 10 cohorts for their influenza serological (seroprevalence estimated by hemagglutination inhibition (HI) test) and virological (prevalence) status. Nasal swabs were collected weekly and pigs were bled 3 times throughout the nursery period. There was significant variability in influenza seroprevalence, HI titers and influenza prevalence after weaning. Increase in influenza seroprevalence at weaning was associated with low influenza prevalence at weaning and delayed time to IAV infection throughout the nursery. Piglets with IAV HI titers of 40 or higher at weaning were also less likely to test IAV positive at weaning, took longer to become infected, tested IAV RT-PCR positive for fewer weeks, and had higher IAV RT-PCR cycle threshold values compared to piglets with HI titers less than 40. Our findings suggest that sow vaccination or infection status that results in high levels of IAV strain-specific maternally-derived antibodies may help to reduce IAV circulation in both suckling and nursery pigs.
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Affiliation(s)
| | - Spencer Wayne
- Health Services, Pipestone Veterinary Services, Pipestone, MN, United States of America
| | - Marie Rene Culhane
- Veterinary Population Medicine Department, University of Minnesota, St. Paul, MN, United States of America
| | - Andres Perez
- Veterinary Population Medicine Department, University of Minnesota, St. Paul, MN, United States of America
| | - Matthew Allerson
- Health and Research Division, Holden Farms Inc., Northfield, MN, United States of America
| | - Montserrat Torremorell
- Veterinary Population Medicine Department, University of Minnesota, St. Paul, MN, United States of America
- * E-mail:
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8
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Divergent Human-Origin Influenza Viruses Detected in Australian Swine Populations. J Virol 2018; 92:JVI.00316-18. [PMID: 29875251 DOI: 10.1128/jvi.00316-18] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2018] [Accepted: 05/28/2018] [Indexed: 11/20/2022] Open
Abstract
Global swine populations infected with influenza A viruses pose a persistent pandemic risk. With the exception of a few countries, our understanding of the genetic diversity of swine influenza viruses is limited, hampering control measures and pandemic risk assessment. Here we report the genomic characteristics and evolutionary history of influenza A viruses isolated in Australia from 2012 to 2016 from two geographically isolated swine populations in the states of Queensland and Western Australia. Phylogenetic analysis with an expansive human and swine influenza virus data set comprising >40,000 sequences sampled globally revealed evidence of the pervasive introduction and long-term establishment of gene segments derived from several human influenza viruses of past seasons, including the H1N1/1977, H1N1/1995, H3N2/1968, and H3N2/2003, and the H1N1 2009 pandemic (H1N1pdm09) influenza A viruses, and a genotype that contained gene segments derived from the past three pandemics (1968, reemerged 1977, and 2009). Of the six human-derived gene lineages, only one, comprising two viruses isolated in Queensland during 2012, was closely related to swine viruses detected from other regions, indicating a previously undetected circulation of Australian swine lineages for approximately 3 to 44 years. Although the date of introduction of these lineages into Australian swine populations could not be accurately ascertained, we found evidence of sustained transmission of two lineages in swine from 2012 to 2016. The continued detection of human-origin influenza virus lineages in swine over several decades with little or unpredictable antigenic drift indicates that isolated swine populations can act as antigenic archives of human influenza viruses, raising the risk of reemergence in humans when sufficient susceptible populations arise.IMPORTANCE We describe the evolutionary origins and antigenic properties of influenza A viruses isolated from two separate Australian swine populations from 2012 to 2016, showing that these viruses are distinct from each other and from those isolated from swine globally. Whole-genome sequencing of virus isolates revealed a high genotypic diversity that had been generated exclusively through the introduction and establishment of human influenza viruses that circulated in past seasons. We detected six reassortants with gene segments derived from human H1N1/H1N1pdm09 and various human H3N2 viruses that circulated during various periods since 1968. We also found that these swine viruses were not related to swine viruses collected elsewhere, indicating independent circulation. The detection of unique lineages and genotypes in Australia suggests that isolated swine populations that are sufficiently large can sustain influenza virus for extensive periods; we show direct evidence of a sustained transmission for at least 4 years between 2012 and 2016.
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9
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Takemae N, Tsunekuni R, Uchida Y, Ito T, Saito T. Experimental infection of pigs with H1 and H3 influenza A viruses of swine by using intranasal nebulization. BMC Vet Res 2018; 14:115. [PMID: 29587842 PMCID: PMC5870511 DOI: 10.1186/s12917-018-1434-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Accepted: 03/16/2018] [Indexed: 02/19/2023] Open
Abstract
BACKGROUND Experimental infection of pigs via direct intranasal or intratracheal inoculation has been mainly used to study the infectious process of influenza A viruses of swine (IAVs-S). Nebulization is known to be an alternative method for inoculating pigs with IAVs-S, because larger quantities of virus potentially can be delivered throughout the respiratory tract. However, there is very little data on the experimental infection of pigs by inhalation using nebulizer. In the current study, we used intranasal nebulization to inoculate pigs with 9 different IAVs-S-3 H1N1, 2 H1N2, and 4 H3N2 strains. We then assessed the process of infection by evaluating the clinical signs, nasal and oral viral shedding, and seroconversion rates of the pigs inoculated. RESULTS Lethargy and sneezing were the predominant clinical signs among pigs inoculated with 7 of the 9 strains evaluated; the remaining 2 strains (1 H1N1 and 1 H1N2 isolate) failed to induce any clinical signs throughout the experiments. Significantly increased rectal temperatures were observed with an H1N1 or H3N2 strains between 1 and 3 days post-inoculation (dpi). In addition, patterns of nasal viral shedding differed among the strains: nasal viral shedding began on 1 dpi for 6 strains, with all 9 viruses being shed from 2 to 5 dpi. The detection of viral shedding was less sensitive from oral samples than nasal secretions. Viral shedding was not detected in either nasal or oral swabs after 10 dpi. According to hemagglutination-inhibition assays, all inoculated pigs had seroconverted to the inoculating virus by 14 dpi, with titers ranging from 10 to 320. CONCLUSIONS Our current findings show that intranasal nebulization successfully established IAV-S infections in pigs and demonstrate that clinical signs, viral shedding, and host immune responses varied among the strains inoculated.
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Affiliation(s)
- Nobuhiro Takemae
- Division of Transboundary Animal Disease, National Institute of Animal Health, NARO, 3-1-5 Kannondai, Tsukuba, Ibaraki, 305-0856, Japan.,Thailand-Japan Zoonotic Diseases Collaboration Center, Kasetklang, Chatuchak, Bangkok, 10900, Thailand
| | - Ryota Tsunekuni
- Division of Transboundary Animal Disease, National Institute of Animal Health, NARO, 3-1-5 Kannondai, Tsukuba, Ibaraki, 305-0856, Japan.,Thailand-Japan Zoonotic Diseases Collaboration Center, Kasetklang, Chatuchak, Bangkok, 10900, Thailand
| | - Yuko Uchida
- Division of Transboundary Animal Disease, National Institute of Animal Health, NARO, 3-1-5 Kannondai, Tsukuba, Ibaraki, 305-0856, Japan.,Thailand-Japan Zoonotic Diseases Collaboration Center, Kasetklang, Chatuchak, Bangkok, 10900, Thailand
| | - Toshihiro Ito
- The Avian Zoonosis Research Center, Faculty of Agriculture, Tottori University, 4-101 Koyama-cho Minami, Tottori, Tottori, 680-8550, Japan
| | - Takehiko Saito
- Division of Transboundary Animal Disease, National Institute of Animal Health, NARO, 3-1-5 Kannondai, Tsukuba, Ibaraki, 305-0856, Japan. .,Thailand-Japan Zoonotic Diseases Collaboration Center, Kasetklang, Chatuchak, Bangkok, 10900, Thailand. .,United Graduate School of Veterinary Sciences, Gifu University, 1-1, Yanagito, Gifu, Gifu, 501-1112, Japan.
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10
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Longitudinal study of influenza A virus circulation in a nursery swine barn. Vet Res 2017; 48:63. [PMID: 29017603 PMCID: PMC5634873 DOI: 10.1186/s13567-017-0466-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 09/07/2017] [Indexed: 11/10/2022] Open
Abstract
Commercial production of swine often involves raising animals in large groups through the use of multi-stage production systems. In such systems, pigs can experience different degrees of contact with animals of the same or different ages. Population size and degree of contact can greatly influence transmission of endemic pathogens, including influenza A virus (IAV). IAV can display high genetic variability, which can further complicate population-level patterns. Yet, the IAV transmission in large multi-site swine production systems has not been well studied. The objectives of this study were to describe the IAV circulation in a multi-source nursery facility and identify factors associated with infection in nursery pigs. Pigs from five sow herds were mixed in one all-in/all-out nursery barn, with 81 and 75 pigs included in two longitudinal studies. Virus isolation was performed in Madin-Darby canine kidney cells and serology was performed using hemagglutination inhibition assays. Risk factor analysis for virological positivity was conducted using logistic regression and stratified Cox’s regression for recurrent events. In Study 1, at ≈30 days post-weaning, 100% of pigs were positive, with 43.2% of pigs being positive recurrently over the entire study period. In study 2, 48% of pigs were positive at the peak of the outbreak, and 10.7% were positive recurrently over the entire study period. The results suggest that IAV can circulate during the nursery phase in an endemic pattern and that the likelihood of recurrent infections was associated in a non-linear way with the level of heterologous (within-subtype) maternal immunity (p < 0.05). High within-pen intracluster correlation coefficients (> 0.75) were also observed for the majority of sampling times suggesting that pen-level factors played a role in infection dynamics in this study.
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11
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Cador C, Andraud M, Willem L, Rose N. Control of endemic swine flu persistence in farrow-to-finish pig farms: a stochastic metapopulation modeling assessment. Vet Res 2017; 48:58. [PMID: 28974251 PMCID: PMC5627436 DOI: 10.1186/s13567-017-0462-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Accepted: 09/12/2017] [Indexed: 12/26/2022] Open
Abstract
Swine influenza viruses (swIAVs) are known to persist endemically in farrow-to-finish pig farms, leading to repeated swine flu outbreaks in successive batches of pigs at a similar age (mostly around 8 weeks of age). This persistence in European swine herds involves swIAVs from European lineages including H1avN1, H1huN2, H3N2, the 2009 H1N1 pandemic virus and their reassortants. The specific population dynamics of farrow-to-finish pig farms, the immune status of the animals at infection-time, the co-circulation of distinct subtypes leading to consecutive or concomitant infections have been evidenced as factors favouring swIAV persistence within herds. We developed a stochastic metapopulation model representing the co-circulation of two distinct swIAVs within a typical farrow-to-finish pig herd to evaluate the risk of reassortant viruses generation due to co-infection events. Control strategies related to herd management and/or vaccination schemes (batch-to-batch or mass vaccination of the sow herd and vaccination of growing pigs) were implemented to assess their relative efficacy regarding viral persistence. The overall probability of a co-infection event for France, possibly leading to reassortment, was evaluated to 16.8%. The export of consecutive piglets batches was identified as the most efficient measure facilitating swIAV infection fade-out. Although some vaccination schemes (batch-to-batch vaccination) had a beneficial effect in breeding sows by reducing the persistence of swIAVs within this subpopulation, none of vaccination strategies achieved swIAVs fade-out within the entire farrow-to-finish pig herd.
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Affiliation(s)
- Charlie Cador
- Swine Epidemiology and Welfare Research Unit, French Agency for Food, Environmental and Occupational Health & Safety (ANSES), BP 53, 22440, Ploufragan, France. .,Université Bretagne Loire, Rennes, France.
| | - Mathieu Andraud
- Swine Epidemiology and Welfare Research Unit, French Agency for Food, Environmental and Occupational Health & Safety (ANSES), BP 53, 22440, Ploufragan, France.,Université Bretagne Loire, Rennes, France
| | - Lander Willem
- Centre for Health Economics & Modeling Infectious Diseases, Vaccine and Infectious Disease Institute, University of Antwerp Research, Antwerp, Belgium
| | - Nicolas Rose
- Swine Epidemiology and Welfare Research Unit, French Agency for Food, Environmental and Occupational Health & Safety (ANSES), BP 53, 22440, Ploufragan, France.,Université Bretagne Loire, Rennes, France
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12
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Arunorat J, Charoenvisal N, Woonwong Y, Kedkovid R, Jittimanee S, Sitthicharoenchai P, Kesdangsakonwut S, Poolperm P, Thanawongnuwech R. Protection of human influenza vaccines against a reassortant swine influenza virus of pandemic H1N1 origin using a pig model. Res Vet Sci 2017; 114:6-11. [PMID: 28267619 DOI: 10.1016/j.rvsc.2017.02.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Revised: 01/27/2017] [Accepted: 02/23/2017] [Indexed: 01/03/2023]
Abstract
Since the pandemic H1N1 emergence in 2009 (pdmH1N1), many reassortant pdmH1N1 viruses emerged and found circulating in the pig population worldwide. Currently, commercial human subunit vaccines are used commonly to prevent the influenza symptom based on the WHO recommendation. In case of current reassortant swine influenza viruses transmitting from pigs to humans, the efficacy of current human influenza vaccines is of interest. In this study, influenza A negative pigs were vaccinated with selected commercial human subunit vaccines and challenged with rH3N2. All sera were tested with both HI and SN assays using four representative viruses from the surveillance data in 2012 (enH1N1, pdmH1N1, rH1N2 and rH3N2). The results showed no significant differences in clinical signs and macroscopic and microscopic findings among groups. However, all pig sera from vaccinated groups had protective HI titers to the enH1N1, pdmH1N1 and rH1N2 at 21DPV onward and had protective SN titers only to pdmH1N1and rH1N2 at 21DPV onward. SN test results appeared more specific than those of HI tests. All tested sera had no cross-reactivity against the rH3N2. Both studied human subunit vaccines failed to protect and to stop viral shedding with no evidence of serological reaction against rH3N2. SIV surveillance is essential for monitoring a novel SIV emergence potentially for zoonosis.
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Affiliation(s)
- Jirapat Arunorat
- Department of Pathology, Faculty of Veterinary Science, Chulalongkorn University, Henri-Dunant Rd, Bangkok 10330, Thailand
| | - Nataya Charoenvisal
- Department of Medicine, Faculty of Veterinary Science, Chulalongkorn University, Henri-Dunant Rd, Bangkok 10330, Thailand
| | - Yonlayong Woonwong
- Department of Pathology, Faculty of Veterinary Science, Chulalongkorn University, Henri-Dunant Rd, Bangkok 10330, Thailand
| | - Roongtham Kedkovid
- Department of Pathology, Faculty of Veterinary Science, Chulalongkorn University, Henri-Dunant Rd, Bangkok 10330, Thailand
| | - Supattra Jittimanee
- Department of Pathobiology, Faculty of Veterinary Medicine, Khonkhaen University, Bangkok 40002, Thailand
| | - Panchan Sitthicharoenchai
- Department of Pathology, Faculty of Veterinary Science, Chulalongkorn University, Henri-Dunant Rd, Bangkok 10330, Thailand
| | - Sawang Kesdangsakonwut
- Department of Pathology, Faculty of Veterinary Science, Chulalongkorn University, Henri-Dunant Rd, Bangkok 10330, Thailand
| | - Pariwat Poolperm
- Department of Farm Resources and Production Medicine, Faculty of Veterinary Medicine, Kasetsart University, KamphaengSaen Campus, Nakhon Pathom 73140, Thailand
| | - Roongroje Thanawongnuwech
- Department of Pathology, Faculty of Veterinary Science, Chulalongkorn University, Henri-Dunant Rd, Bangkok 10330, Thailand; Center of Excellence in Emerging Infectious Diseases in Animals, Chulalongkorn University (CU-EIDAs), Faculty of Veterinary Science, Chulalongkorn University, Pathumwan, Bangkok 10330, Thailand.
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13
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Rajão DS, Walia RR, Campbell B, Gauger PC, Janas-Martindale A, Killian ML, Vincent AL. Reassortment between Swine H3N2 and 2009 Pandemic H1N1 in the United States Resulted in Influenza A Viruses with Diverse Genetic Constellations with Variable Virulence in Pigs. J Virol 2017; 91:e01763-16. [PMID: 27928015 PMCID: PMC5286888 DOI: 10.1128/jvi.01763-16] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Accepted: 12/01/2016] [Indexed: 11/20/2022] Open
Abstract
Repeated spillovers of the H1N1 pandemic virus (H1N1pdm09) from humans to pigs resulted in substantial evolution of influenza A viruses infecting swine, contributing to the genetic and antigenic diversity of influenza A viruses (IAV) currently circulating in swine. The reassortment with endemic swine viruses and maintenance of some of the H1N1pdm09 internal genes resulted in the circulation of different genomic constellations in pigs. Here, we performed a whole-genome phylogenetic analysis of 368 IAV circulating in swine from 2009 to 2016 in the United States. We identified 44 different genotypes, with the most common genotype (32.33%) containing a clade IV-A HA gene, a 2002-lineage NA gene, an M-pdm09 gene, and remaining gene segments of triple reassortant internal gene (TRIG) origin. To understand how different genetic constellations may relate to viral fitness, we compared the pathogenesis and transmission in pigs of six representative genotypes. Although all six genotypes efficiently infected pigs, they resulted in different degrees of pathology and viral shedding. These results highlight the vast H3N2 genetic diversity circulating in U.S. swine after 2009. This diversity has important implications in the control of this disease by the swine industry, as well as a potential risk for public health if swine-adapted viruses with H1N1pdm09 genes have an increased risk to humans, as occurred in the 2011-2012 and 2016 human variant H3N2v cases associated with exhibition swine. IMPORTANCE People continue to spread the 2009 H1N1 pandemic (H1N1pdm09) IAV to pigs, allowing H1N1pdm09 to reassort with endemic swine IAV. In this study, we determined the 8 gene combinations of swine H3N2 IAV detected from 2009 to 2016. We identified 44 different genotypes of H3N2, the majority of which contained at least one H1N1pdm09 gene segment. We compared six representative genotypes of H3N2 in pigs. All six genotypes efficiently infected pigs, but they resulted in different degrees of lung damage and viral shedding. These results highlight the vast genetic diversity of H3N2 circulating in U.S. swine after 2009, with important implications for the control of IAV for the swine industry. Because H1N1pdm09 is also highly adapted to humans, these swine viruses pose a potential risk to public health if swine-adapted viruses with H1N1pdm09 genes also have an increased risk for human infection.
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Affiliation(s)
- Daniela S Rajão
- Virus and Prion Diseases Research Unit, National Animal Disease Center, Agricultural Research Service, United States Department of Agriculture, Ames, Iowa, USA
| | - Rasna R Walia
- Virus and Prion Diseases Research Unit, National Animal Disease Center, Agricultural Research Service, United States Department of Agriculture, Ames, Iowa, USA
| | - Brian Campbell
- Virus and Prion Diseases Research Unit, National Animal Disease Center, Agricultural Research Service, United States Department of Agriculture, Ames, Iowa, USA
| | - Phillip C Gauger
- Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, Iowa, USA
| | - Alicia Janas-Martindale
- Diagnostic Virology Laboratory, National Veterinary Services Laboratories, Science, Technology and Analysis Services, Veterinary Services, Animal and Plant Health Inspection Service, United States Department of Agriculture, Ames, Iowa, USA
| | - Mary Lea Killian
- Diagnostic Virology Laboratory, National Veterinary Services Laboratories, Science, Technology and Analysis Services, Veterinary Services, Animal and Plant Health Inspection Service, United States Department of Agriculture, Ames, Iowa, USA
| | - Amy L Vincent
- Virus and Prion Diseases Research Unit, National Animal Disease Center, Agricultural Research Service, United States Department of Agriculture, Ames, Iowa, USA
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14
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Sánchez-Betancourt JI, Cervantes-Torres JB, Saavedra-Montañez M, Segura-Velázquez RA. Complete genome sequence of a novel influenza A H1N2 virus circulating in swine from Central Bajio region, Mexico. Transbound Emerg Dis 2017; 64:2083-2092. [PMID: 28181421 DOI: 10.1111/tbed.12620] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Indexed: 11/29/2022]
Abstract
The aim of this study was to perform the complete genome sequence of a swine influenza A H1N2 virus strain isolated from a pig in Guanajuato, México (A/swine/Mexico/GtoDMZC01/2014) and to report its seroprevalence in 86 counties at the Central Bajio zone. To understand the evolutionary dynamics of the isolate, we undertook a phylogenetic analysis of the eight gene segments. These data revealed that the isolated virus is a reassortant H1N2 subtype, as its genes are derived from human (HA, NP, PA) and swine (M, NA, PB1, PB2 and NS) influenza viruses. Pig serum samples were analysed by the hemagglutination inhibition test, using wild H1N2 and H3N2 strains (A/swine/México/Mex51/2010 [H3N2]) as antigen sources. Positive samples to the H1N2 subtype were processed using the field-isolated H1N1 subtype (A/swine/México/Ver37/2010 [H1N1]). Seroprevalence to the H1N2 subtype was 26.74% in the sampled counties, being Jalisco the state with highest seroprevalence to this subtype (35.30%). The results herein reported demonstrate that this new, previously unregistered influenza virus subtype in México that shows internal genes from other swine viral subtypes isolated in the past 5 years, along with human virus-originated genes, is widely distributed in this area of the country.
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Affiliation(s)
- J I Sánchez-Betancourt
- Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México (UNAM), Ciudad de México, CP, 04510, México
| | - J B Cervantes-Torres
- Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México (UNAM), Ciudad de México, CP, 04510, México
| | - M Saavedra-Montañez
- Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México (UNAM), Ciudad de México, CP, 04510, México
| | - R A Segura-Velázquez
- Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México (UNAM), Ciudad de México, CP, 04510, México
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15
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Amino Acids in Hemagglutinin Antigenic Site B Determine Antigenic and Receptor Binding Differences between A(H3N2)v and Ancestral Seasonal H3N2 Influenza Viruses. J Virol 2017; 91:JVI.01512-16. [PMID: 27807224 DOI: 10.1128/jvi.01512-16] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 10/15/2016] [Indexed: 01/03/2023] Open
Abstract
Influenza A H3N2 variant [A(H3N2)v] viruses, which have caused human infections in the United States in recent years, originated from human seasonal H3N2 viruses that were introduced into North American swine in the mid-1990s, but they are antigenically distinct from both the ancestral and current circulating H3N2 strains. A reference A(H3N2)v virus, A/Minnesota/11/2010 (MN/10), and a seasonal H3N2 strain, A/Beijing/32/1992 (BJ/92), were chosen to determine the molecular basis for the antigenic difference between A(H3N2)v and the ancestral viruses. Viruses containing wild-type and mutant MN/10 or BJ/92 hemagglutinins (HAs) were constructed and probed for reactivity with ferret antisera against MN/10 and BJ/92 in hemagglutination inhibition assays. Among the amino acids that differ between the MN/10 and BJ/92 HAs, those in antigenic site A had little impact on the antigenic phenotype. Within antigenic site B, mutations at residues 156, 158, 189, and 193 of MN/10 HA to those in BJ/92 switched the MN/10 antigenic phenotype to that of BJ/92. Mutations at residues 156, 157, 158, 189, and 193 of BJ/92 HA to amino acids present in MN/10 were necessary for BJ/92 to become antigenically similar to MN/10. The HA amino acid substitutions responsible for switching the antigenic phenotype also impacted HA binding to sialyl receptors that are usually present in the human respiratory tract. Our study demonstrates that antigenic site B residues play a critical role in determining both the unique antigenic phenotype and receptor specificity of A(H3N2)v viruses, a finding that may facilitate future surveillance and risk assessment of novel influenza viruses. IMPORTANCE Influenza A H3N2 variant [A(H3N2)v] viruses have caused hundreds of human infections in multiple states in the United States since 2009. Most cases have been children who had contact with swine in agricultural fairs. These viruses originated from human seasonal H3N2 viruses that were introduced into the U.S. swine population in the mid-1990s, but they are different from both these ancestral viruses and current circulating human seasonal H3N2 strains in terms of their antigenic characteristics as measured by hemagglutination inhibition (HI) assay. In this study, we identified amino acids in antigenic site B of the surface glycoprotein hemagglutinin (HA) that explain the antigenic difference between A(H3N2)v and the ancestral H3N2 strains. These amino acid mutations also alter binding to minor human-type glycans, suggesting that host adaptation may contribute to the selection of antigenically distinct H3N2 variants which pose a threat to public health.
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16
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17
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Cador C, Rose N, Willem L, Andraud M. Maternally Derived Immunity Extends Swine Influenza A Virus Persistence within Farrow-to-Finish Pig Farms: Insights from a Stochastic Event-Driven Metapopulation Model. PLoS One 2016; 11:e0163672. [PMID: 27662592 PMCID: PMC5035019 DOI: 10.1371/journal.pone.0163672] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Accepted: 09/12/2016] [Indexed: 12/28/2022] Open
Abstract
Swine Influenza A Viruses (swIAVs) have been shown to persist in farrow-to-finish pig herds with repeated outbreaks in successive batches, increasing the risk for respiratory disorders in affected animals and being a threat for public health. Although the general routes of swIAV transmission (i.e. direct contact and exposure to aerosols) were clearly identified, the transmission process between batches is still not fully understood. Maternally derived antibodies (MDAs) were stressed as a possible factor favoring within-herd swIAV persistence. However, the relationship between MDAs and the global spread among the different subpopulations in the herds is still lacking. The aim of this study was therefore to understand the mechanisms induced by MDAs in relation with swIAV spread and persistence in farrow-to-finish pig herds. A metapopulation model has been developed representing the population dynamics considering two subpopulations—breeding sows and growing pigs—managed according to batch-rearing system. This model was coupled with a swIAV-specific epidemiological model, accounting for partial passive immunity protection in neonatal piglets and an immunity boost in re-infected animals. Airborne transmission was included by a between-room transmission rate related to the current prevalence of shedding pigs. Maternally derived partial immunity in piglets was found to extend the duration of the epidemics within their batch, allowing for efficient between-batch transmission and resulting in longer swIAV persistence at the herd level. These results should be taken into account in the design of control programmes for the spread and persistence of swIAV in swine herds.
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Affiliation(s)
- Charlie Cador
- Swine epidemiology and welfare research unit, French Agency for Food, Environmental and Occupational Health & Safety (ANSES), Ploufragan, France
- Université Bretagne Loire, Rennes, France
- * E-mail:
| | - Nicolas Rose
- Swine epidemiology and welfare research unit, French Agency for Food, Environmental and Occupational Health & Safety (ANSES), Ploufragan, France
- Université Bretagne Loire, Rennes, France
| | - Lander Willem
- Centre for Health Economics Research & Modeling of Infectious Diseases, Vaccine and Infectious Disease Institute, University of Antwerp, Wilrijk, Belgium
| | - Mathieu Andraud
- Swine epidemiology and welfare research unit, French Agency for Food, Environmental and Occupational Health & Safety (ANSES), Ploufragan, France
- Université Bretagne Loire, Rennes, France
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18
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Beato MS, Tassoni L, Milani A, Salviato A, Di Martino G, Mion M, Bonfanti L, Monne I, Watson SJ, Fusaro A. Circulation of multiple genotypes of H1N2 viruses in a swine farm in Italy over a two-month period. Vet Microbiol 2016; 195:25-29. [PMID: 27771067 DOI: 10.1016/j.vetmic.2016.08.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Revised: 08/12/2016] [Accepted: 08/16/2016] [Indexed: 12/09/2022]
Abstract
In August 2012 repeated respiratory outbreaks caused by swine influenza A virus (swIAV) were registered for a whole year in a breeding farm in northeast Italy that supplied piglets for fattening. The virus, initially characterized in the farm, was a reassortant Eurasian avian-like H1N1 (H1avN1) genotype, containing a haemagglutinin segment derived from the pandemic H1N1 (A(H1N1)pdm09) lineage. To control infection, a vaccination program using vaccines against the A(H1N1)pdm09, human-like H1N2 (H1huN2), human-like H3N2 (H3N2), and H1avN1 viruses was implemented in sows in November 2013. Vaccine efficacy was assessed by sampling nasal swabs for two months in 35-75 day-old piglets born from vaccinated sows. Complete genome sequencing of eight swIAV-positive nasal swabs collected longitudinally from piglets after the implementation of the vaccination program was conducted to investigate the virus characteristics. Over the two-month period, two different genotypes involving multiple reassortment events were detected. The unexpected circulation of multiple reassortant genotypes in such a short time highlights the complexity of the genetic diversity of swIAV and the need for a better surveillance plan, based on the combination of clinical signs, epidemiological data and whole genome characterization.
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Affiliation(s)
- Maria Serena Beato
- Istituto Zooprofilattico Sperimentale delle Venezie, Legnaro, PD, Italy.
| | - Luca Tassoni
- Istituto Zooprofilattico Sperimentale delle Venezie, Legnaro, PD, Italy
| | - Adelaide Milani
- Istituto Zooprofilattico Sperimentale delle Venezie, Legnaro, PD, Italy
| | - Annalisa Salviato
- Istituto Zooprofilattico Sperimentale delle Venezie, Legnaro, PD, Italy
| | - Guido Di Martino
- Istituto Zooprofilattico Sperimentale delle Venezie, Legnaro, PD, Italy
| | - Monica Mion
- Istituto Zooprofilattico Sperimentale delle Venezie, Legnaro, PD, Italy
| | - Lebana Bonfanti
- Istituto Zooprofilattico Sperimentale delle Venezie, Legnaro, PD, Italy
| | - Isabella Monne
- Istituto Zooprofilattico Sperimentale delle Venezie, Legnaro, PD, Italy
| | | | - Alice Fusaro
- Istituto Zooprofilattico Sperimentale delle Venezie, Legnaro, PD, Italy
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19
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Arunorat J, Charoenvisal N, Woonwong Y, Kedkovid R, Thanawongnuwech R. Determination of current reference viruses for serological study of swine influenza viruses after the introduction of pandemic 2009 H1N1 (pdmH1N1) in Thailand. J Virol Methods 2016; 236:5-9. [PMID: 27355862 DOI: 10.1016/j.jviromet.2016.06.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Revised: 06/17/2016] [Accepted: 06/25/2016] [Indexed: 11/19/2022]
Abstract
Since the introduction of pandemic H1N1 2009 virus (pdmH1N1) in pigs, the status of Thai swine influenza virus (SIV) has changed. The pdmH1N1 and its reassortant viruses have become the predominant strain circulating in the Thai swine population based on the surveillance data from 2012 to 2014. For this reason, the reference viruses for serological assays using the hemagglutination inhibition (HI) test needed to be updated. Six anti-sera against reference viruses from 2006 to 2009 (enH1N1-06, enH1N1-09, enH1N2-09, pdmH1N1-09, enH3N2-07 and enH3N2-09) were used for the HI test with four contemporary viruses (enH1N1-10, pdmH1N1-10, rH1N2 and rH3N2) and the selected reference viruses were tested with sera collected from the field to determine the current SIV status. The results showed that anti-sera of swH1N1-06 had the highest titers against enH1N1-10. Anti-sera of pdmH1N1-09 had the highest titers against pdmH1N1-10 and rH1N2, whereas, anti-sera of enH3N2-09 had the highest titers against rH3N2. The results demonstrated that enH1N1-06, pdmH1N1-09 and enH3N2-09 should be selected as reference viruses for contemporary serological studies and HI tests. The seroprevalence results from 410 samples revealed enH1N1 (37.79%), pdmH1N1 (37.32%) and H3N2 (35.86%), respectively. The present study indicated that pdmH1N1 was widespread and commonly found in the Thai pig population increasing the risk of novel reassortant viruses and should be added as a reference virus for HI test. SIV surveillance program and serological studies should be conducted for the benefits of SIV control and prevention as well as monitoring for zoonotic potential.
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Affiliation(s)
- Jirapat Arunorat
- Department of Pathology, Faculty of Veterinary Science, Chulalongkorn University, Henri-Dunant Rd., Bangkok 10330, Thailand
| | - Nataya Charoenvisal
- Department of Pathology, Faculty of Veterinary Science, Chulalongkorn University, Henri-Dunant Rd., Bangkok 10330, Thailand
| | - Yonlayong Woonwong
- Department of Pathology, Faculty of Veterinary Science, Chulalongkorn University, Henri-Dunant Rd., Bangkok 10330, Thailand
| | - Roongtham Kedkovid
- Department of Pathology, Faculty of Veterinary Science, Chulalongkorn University, Henri-Dunant Rd., Bangkok 10330, Thailand
| | - Roongroje Thanawongnuwech
- Department of Pathology, Faculty of Veterinary Science, Chulalongkorn University, Henri-Dunant Rd., Bangkok 10330, Thailand; Center of Emerging and Re-emerging Infectious Diseases in Animals, Faculty of Veterinary Science, Chulalongkorn University, Henri-Dunant Rd., Bangkok 10330, Thailand.
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20
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A North American H7N3 Influenza Virus Supports Reassortment with 2009 Pandemic H1N1 and Induces Disease in Mice without Prior Adaptation. J Virol 2016; 90:4796-4806. [PMID: 26937034 DOI: 10.1128/jvi.02761-15] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 02/22/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Reassortment between H5 or H9 subtype avian and mammalian influenza A viruses (IAV) can generate a novel virus that causes disease and transmits between mammals. Such information is currently not available for H7 subtype viruses. We evaluated the ability of a low-pathogenicity North American avian H7N3 virus (A/shorebird/Delaware/22/2006) to reassort with mammalian or avian viruses using a plasmid-based competition assay. In addition to genome segments derived from an avian H7N9 virus, the H7N3 virus reassorted efficiently with the PB2, NA, and M segments from the 2009 pandemic H1N1 (PH1N1) virus.In vitro and in vivo evaluation of the H7N3:PH1N1 (7 + 1) reassortant viruses revealed that the PB2, NA, or M segments from PH1N1 largely do not attenuate the H7N3 virus, whereas the PB1, PA, NP, or NS genome segments from PH1N1 do. Additionally, we assessed the functionality of the H7N3:PH1N1 7 + 1 reassortant viruses by measuring the inflammatory response in vivo We found that infection with wild-type H7N3 resulted in increased inflammatory cytokine production relative to that seen with the PH1N1 strain and that the increase was further exacerbated by substitution of PH1N1 PB2 but not NA or M. Finally, we assessed if any adaptations occurred in the individually substituted segments after in vivo inoculation and found no mutations, suggesting that PH1N1 PB2, NA, and M are genetically stable in the background of this H7N3 virus. Taking the data together, we demonstrate that a North American avian H7N3 IAV is genetically and functionally compatible with multiple gene segments from the 2009 pandemic influenza virus strain without prior adaptation. IMPORTANCE The 2009 pandemic H1N1 virus continues to circulate and reassort with other influenza viruses, creating novel viruses with increased replication and transmission potential in humans. Previous studies have found that this virus can also reassort with H5N1 and H9N2 avian influenza viruses. We now show that several genome segments of the 2009 H1N1 virus are also highly compatible with a low-pathogenicity avian H7N3 virus and that these reassortant viruses are stable and not attenuated in an animal model. These results highlight the potential for reassortment of H1N1 viruses with avian influenza virus and emphasize the need for continued surveillance of influenza viruses in areas of cocirculation between avian, human, and swine viruses.
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Poon LLM, Song T, Rosenfeld R, Lin X, Rogers MB, Zhou B, Sebra R, Halpin RA, Guan Y, Twaddle A, DePasse JV, Stockwell TB, Wentworth DE, Holmes EC, Greenbaum B, Peiris JSM, Cowling BJ, Ghedin E. Quantifying influenza virus diversity and transmission in humans. Nat Genet 2016; 48:195-200. [PMID: 26727660 PMCID: PMC4731279 DOI: 10.1038/ng.3479] [Citation(s) in RCA: 126] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Accepted: 12/07/2015] [Indexed: 01/26/2023]
Abstract
Influenza A virus is characterized by high genetic diversity. However, most of what is known about influenza evolution has come from consensus sequences sampled at the epidemiological scale that only represent the dominant virus lineage within each infected host. Less is known about the extent of within-host virus diversity and what proportion of this diversity is transmitted between individuals. To characterize virus variants that achieve sustainable transmission in new hosts, we examined within-host virus genetic diversity in household donor-recipient pairs from the first wave of the 2009 H1N1 pandemic when seasonal H3N2 was co-circulating. Although the same variants were found in multiple members of the community, the relative frequencies of variants fluctuated, with patterns of genetic variation more similar within than between households. We estimated the effective population size of influenza A virus across donor-recipient pairs to be approximately 100-200 contributing members, which enabled the transmission of multiple lineages, including antigenic variants.
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Affiliation(s)
- Leo L M Poon
- Public Health Laboratory Sciences, School of Public Health, The University of Hong Kong, Hong Kong, China
| | - Timothy Song
- Department of Computational and Systems Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.,Center for Genomics and Systems Biology, Department of Biology, New York University, New York, New York, USA
| | - Roni Rosenfeld
- School of Computer Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA
| | - Xudong Lin
- J. Craig Venter Institute, Rockville, Maryland, USA
| | - Matthew B Rogers
- Department of Computational and Systems Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Bin Zhou
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, New York, USA
| | - Robert Sebra
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | | | - Yi Guan
- Public Health Laboratory Sciences, School of Public Health, The University of Hong Kong, Hong Kong, China
| | - Alan Twaddle
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, New York, USA
| | - Jay V DePasse
- Pittsburgh Supercomputer Center, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA
| | | | | | - Edward C Holmes
- Marie Bashir Institute for Infectious Diseases and Biosecurity, Charles Perkins Centre, School of Biological Sciences, The University of Sydney, Sydney, New South Wales, Australia.,Sydney Medical School, The University of Sydney, Sydney, New South Wales, Australia
| | - Benjamin Greenbaum
- Tisch Cancer Institute, Departments of Medicine, Hematology and Medical Oncology, and Pathology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Joseph S M Peiris
- Public Health Laboratory Sciences, School of Public Health, The University of Hong Kong, Hong Kong, China
| | - Benjamin J Cowling
- Epidemiology and Biostatistics, School of Public Health, The University of Hong Kong, Hong Kong, China
| | - Elodie Ghedin
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, New York, USA.,College of Global Public Health, New York University, New York, New York, USA
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22
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Zhao J, Ragupathy V, Liu J, Wang X, Vemula SV, El Mubarak HS, Ye Z, Landry ML, Hewlett I. Nanomicroarray and multiplex next-generation sequencing for simultaneous identification and characterization of influenza viruses. Emerg Infect Dis 2015; 21:400-8. [PMID: 25694248 PMCID: PMC4344273 DOI: 10.3201/eid2103.141169] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Conventional methods for detection and discrimination of influenza viruses are time consuming and labor intensive. We developed a diagnostic platform for simultaneous identification and characterization of influenza viruses that uses a combination of nanomicroarray for screening and multiplex next-generation sequencing (NGS) assays for laboratory confirmation. The nanomicroarray was developed to target hemagglutinin, neuraminidase, and matrix genes to identify influenza A and B viruses. PCR amplicons synthesized by using an adapted universal primer for all 8 gene segments of 9 influenza A subtypes were detected in the nanomicroarray and confirmed by the NGS assays. This platform can simultaneously detect and differentiate multiple influenza A subtypes in a single sample. Use of these methods as part of a new diagnostic algorithm for detection and confirmation of influenza infections may provide ongoing public health benefits by assisting with future epidemiologic studies and improving preparedness for potential influenza pandemics.
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23
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Decorte I, Steensels M, Lambrecht B, Cay AB, De Regge N. Detection and Isolation of Swine Influenza A Virus in Spiked Oral Fluid and Samples from Individually Housed, Experimentally Infected Pigs: Potential Role of Porcine Oral Fluid in Active Influenza A Virus Surveillance in Swine. PLoS One 2015; 10:e0139586. [PMID: 26431039 PMCID: PMC4592207 DOI: 10.1371/journal.pone.0139586] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Accepted: 09/15/2015] [Indexed: 12/31/2022] Open
Abstract
Background The lack of seasonality of swine influenza A virus (swIAV) in combination with the capacity of swine to harbor a large number of co-circulating IAV lineages, resulting in the risk for the emergence of influenza viruses with pandemic potential, stress the importance of swIAV surveillance. To date, active surveillance of swIAV worldwide is barely done because of the short detection period in nasal swab samples. Therefore, more sensitive diagnostic methods to monitor circulating virus strains are requisite. Methods qRT-PCR and virus isolations were performed on oral fluid and nasal swabs collected from individually housed pigs that were infected sequentially with H1N1 and H3N2 swIAV strains. The same methods were also applied to oral fluid samples spiked with H1N1 to study the influence of conservation time and temperature on swIAV infectivity and detectability in porcine oral fluid. Results All swIAV infected animals were found qRT-PCR positive in both nasal swabs and oral fluid. However, swIAV could be detected for a longer period in oral fluid than in nasal swabs. Despite the high detectability of swIAV in oral fluid, virus isolation from oral fluid collected from infected pigs was rare. These results are supported by laboratory studies showing that the PCR detectability of swIAV remains unaltered during a 24 h incubation period in oral fluid, while swIAV infectivity drops dramatically immediately upon contact with oral fluid (3 log titer reduction) and gets lost after 24 h conservation in oral fluid at ambient temperature. Conclusions Our data indicate that porcine oral fluid has the potential to replace nasal swabs for molecular diagnostic purposes. The difficulty to isolate swIAV from oral fluid could pose a drawback for its use in active surveillance programs.
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Affiliation(s)
- Inge Decorte
- Operational Direction Viral Diseases, Enzootic and (re)emerging diseases, CODA-CERVA, Ukkel, Belgium
| | - Mieke Steensels
- Operational Direction Viral Diseases, Avian virology and immunology, CODA-CERVA, Ukkel, Belgium
| | - Bénédicte Lambrecht
- Operational Direction Viral Diseases, Avian virology and immunology, CODA-CERVA, Ukkel, Belgium
| | - Ann Brigitte Cay
- Operational Direction Viral Diseases, Enzootic and (re)emerging diseases, CODA-CERVA, Ukkel, Belgium
| | - Nick De Regge
- Operational Direction Viral Diseases, Enzootic and (re)emerging diseases, CODA-CERVA, Ukkel, Belgium
- * E-mail:
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Novel reassortant influenza viruses between pandemic (H1N1) 2009 and other influenza viruses pose a risk to public health. Microb Pathog 2015; 89:62-72. [PMID: 26344393 DOI: 10.1016/j.micpath.2015.09.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Revised: 09/01/2015] [Accepted: 09/02/2015] [Indexed: 12/21/2022]
Abstract
Influenza A virus (IAV) is characterized by eight single-stranded, negative sense RNA segments, which allows for gene reassortment among different IAV subtypes when they co-infect a single host cell simultaneously. Genetic reassortment is an important way to favor the evolution of influenza virus. Novel reassortant virus may pose a pandemic among humans. In history, three human pandemic influenza viruses were caused by genetic reassortment between avian, human and swine influenza viruses. Since 2009, pandemic (H1N1) 2009 (pdm/09 H1N1) influenza virus composed of two swine influenza virus genes highlighted the genetic reassortment again. Due to wide host species and high transmission of the pdm/09 H1N1 influenza virus, many different avian, human or swine influenza virus subtypes may reassert with it to generate novel reassortant viruses, which may result in a next pandemic among humans. So, it is necessary to understand the potential threat of current reassortant viruses between the pdm/09 H1N1 and other influenza viruses to public health. This study summarized the status of the reassortant viruses between the pdm/09 H1N1 and other influenza viruses of different species origins in natural and experimental conditions. The aim of this summarization is to facilitate us to further understand the potential threats of novel reassortant influenza viruses to public health and to make effective prevention and control strategies for these pathogens.
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Novel Reassortant Human-Like H3N2 and H3N1 Influenza A Viruses Detected in Pigs Are Virulent and Antigenically Distinct from Swine Viruses Endemic to the United States. J Virol 2015; 89:11213-22. [PMID: 26311895 DOI: 10.1128/jvi.01675-15] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 08/19/2015] [Indexed: 12/19/2022] Open
Abstract
UNLABELLED Human-like swine H3 influenza A viruses (IAV) were detected by the USDA surveillance system. We characterized two novel swine human-like H3N2 and H3N1 viruses with hemagglutinin (HA) genes similar to those in human seasonal H3 strains and internal genes closely related to those of 2009 H1N1 pandemic viruses. The H3N2 neuraminidase (NA) was of the contemporary human N2 lineage, while the H3N1 NA was of the classical swine N1 lineage. Both viruses were antigenically distant from swine H3 viruses that circulate in the United States and from swine vaccine strains and also showed antigenic drift from human seasonal H3N2 viruses. Their pathogenicity and transmission in pigs were compared to those of a human H3N2 virus with a common HA ancestry. Both swine human-like H3 viruses efficiently infected pigs and were transmitted to indirect contacts, whereas the human H3N2 virus did so much less efficiently. To evaluate the role of genes from the swine isolates in their pathogenesis, reverse genetics-generated reassortants between the swine human-like H3N1 virus and the seasonal human H3N2 virus were tested in pigs. The contribution of the gene segments to virulence was complex, with the swine HA and internal genes showing effects in vivo. The experimental infections indicate that these novel H3 viruses are virulent and can sustain onward transmission in pigs, and the naturally occurring mutations in the HA were associated with antigenic divergence from H3 IAV from humans and swine. Consequently, these viruses could have a significant impact on the swine industry if they were to cause more widespread outbreaks, and the potential risk of these emerging swine IAV to humans should be considered. IMPORTANCE Pigs are important hosts in the evolution of influenza A viruses (IAV). Human-to-swine transmissions of IAV have resulted in the circulation of reassortant viruses containing human-origin genes in pigs, greatly contributing to the diversity of IAV in swine worldwide. New human-like H3N2 and H3N1 viruses that contain a mix of human and swine gene segments were recently detected by the USDA surveillance system. The human-like viruses efficiently infected pigs and resulted in onward airborne transmission, likely due to the multiple changes identified between human and swine H3 viruses. The human-like swine viruses are distinct from contemporary U.S. H3 swine viruses and from the strains used in swine vaccines, which could have a significant impact on the swine industry due to a lack of population immunity. Additionally, public health experts should consider an appropriate assessment of the risk of these emerging swine H3 viruses for the human population.
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Rajao DS, Vincent AL. Swine as a Model for Influenza A Virus Infection and Immunity. ILAR J 2015; 56:44-52. [DOI: 10.1093/ilar/ilv002] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
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Neumann G, Kawaoka Y. Transmission of influenza A viruses. Virology 2015; 479-480:234-46. [PMID: 25812763 PMCID: PMC4424116 DOI: 10.1016/j.virol.2015.03.009] [Citation(s) in RCA: 116] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2015] [Revised: 02/10/2015] [Accepted: 03/02/2015] [Indexed: 12/25/2022]
Abstract
Influenza A viruses cause respiratory infections that range from asymptomatic to deadly in humans. Widespread outbreaks (pandemics) are attributable to 'novel' viruses that possess a viral hemagglutinin (HA) gene to which humans lack immunity. After a pandemic, these novel viruses form stable virus lineages in humans and circulate until they are replaced by other novel viruses. The factors and mechanisms that facilitate virus transmission among hosts and the establishment of novel lineages are not completely understood, but the HA and basic polymerase 2 (PB2) proteins are thought to play essential roles in these processes by enabling avian influenza viruses to infect mammals and replicate efficiently in their new host. Here, we summarize our current knowledge of the contributions of HA, PB2, and other viral components to virus transmission and the formation of new virus lineages.
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Affiliation(s)
- Gabriele Neumann
- Influenza Research Institute, Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, 575 Science Drive, Madison, WI 53711, USA
| | - Yoshihiro Kawaoka
- Influenza Research Institute, Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, 575 Science Drive, Madison, WI 53711, USA; Division of Virology, Department of Microbiology and Immunology and International Research Center for Infectious Diseases, Institute of Medical Science, University of Tokyo, Tokyo 108-8639, Japan.
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Analysis of Coinfections with A/H1N1 Strain Variants among Pigs in Poland by Multitemperature Single-Strand Conformational Polymorphism. BIOMED RESEARCH INTERNATIONAL 2015; 2015:535908. [PMID: 25961024 PMCID: PMC4413886 DOI: 10.1155/2015/535908] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 03/25/2015] [Accepted: 03/26/2015] [Indexed: 12/28/2022]
Abstract
Monitoring and control of infections are key parts of surveillance systems and epidemiological risk prevention. In the case of influenza A viruses (IAVs), which show high variability, a wide range of hosts, and a potential of reassortment between different strains, it is essential to study not only people, but also animals living in the immediate surroundings. If understated, the animals might become a source of newly formed infectious strains with a pandemic potential.
Special attention should be focused on pigs, because of the receptors specific for virus strains originating from different species, localized in their respiratory tract. Pigs are prone to mixed infections and may constitute a reservoir of potentially dangerous IAV strains resulting from genetic reassortment. It has been reported that a quadruple reassortant, A(H1N1)pdm09, can be easily transmitted from humans to pigs and serve as a donor of genetic segments for new strains capable of infecting humans. Therefore, it is highly desirable to develop a simple, cost-effective, and rapid method for evaluation of IAV genetic variability. We describe a method based on multitemperature single-strand conformational polymorphism (MSSCP), using a fragment of the hemagglutinin (HA) gene, for detection of coinfections and differentiation of genetic variants of the virus, difficult to identify by conventional diagnostic.
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Pathogenicity and transmissibility of novel reassortant H3N2 influenza viruses with 2009 pandemic H1N1 genes in pigs. J Virol 2014; 89:2831-41. [PMID: 25540372 DOI: 10.1128/jvi.03355-14] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED At least 10 different genotypes of novel reassortant H3N2 influenza viruses with 2009 pandemic H1N1 [A(H1N1)pdm09] gene(s) have been identified in U.S. pigs, including the H3N2 variant with a single A(H1N1)pdm09 M gene, which has infected more than 300 people. To date, only three genotypes of these viruses have been evaluated in animal models, and the pathogenicity and transmissibility of the other seven genotype viruses remain unknown. Here, we show that three H3N2 reassortant viruses that contain 3 (NP, M, and NS) or 5 (PA, PB2, NP, M, and NS) genes from A(H1N1)pdm09 were pathogenic in pigs, similar to the endemic H3N2 swine virus. However, the reassortant H3N2 virus with 3 A(H1N1)pdm09 genes and a recent human influenza virus N2 gene was transmitted most efficiently among pigs, whereas the reassortant H3N2 virus with 5 A(H1N1)pdm09 genes was transmitted less efficiently than the endemic H3N2 virus. Interestingly, the polymerase complex of reassortant H3N2 virus with 5 A(H1N1)pdm09 genes showed significantly higher polymerase activity than those of endemic and reassortant H3N2 viruses with 3 A(H1N1)pdm09 genes. Further studies showed that an avian-like glycine at position 228 at the hemagglutinin (HA) receptor binding site is responsible for inefficient transmission of the reassortant H3N2 virus with 5 A(H1N1)pdm09 genes. Taken together, our results provide insights into the pathogenicity and transmissibility of novel reassortant H3N2 viruses in pigs and suggest that a mammalian-like serine at position 228 in the HA is critical for the transmissibility of these reassortant H3N2 viruses. IMPORTANCE Swine influenza is a highly contagious zoonotic disease that threatens animal and public health. Introduction of 2009 pandemic H1N1 virus [A(H1N1)pdm09] into swine herds has resulted in novel reassortant influenza viruses in swine, including H3N2 and H1N2 variants that have caused human infections in the United States. We showed that reassortant H3N2 influenza viruses with 3 or 5 genes from A(H1N1)pdm09 isolated from diseased pigs are pathogenic and transmissible in pigs, but the reassortant H3N2 virus with 5 A(H1N1)pdm09 genes displayed less efficient transmissibility than the endemic and reassortant H3N2 viruses with 3 A(H1N1)pdm09 genes. Further studies revealed that an avian-like glycine at the HA 228 receptor binding site of the reassortant H3N2 virus with 5 A(H1N1)pdm09 genes is responsible for less efficient transmissibility in pigs. Our results provide insights into viral pathogenesis and the transmission of novel reassortant H3N2 viruses that are circulating in U.S. swine herds and warrant future surveillance.
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Powell JD, Dlugolenski D, Nagy T, Gabbard J, Lee C, Tompkins SM, Tripp RA. Polymerase discordance in novel swine influenza H3N2v constellations is tolerated in swine but not human respiratory epithelial cells. PLoS One 2014; 9:e110264. [PMID: 25330303 PMCID: PMC4199677 DOI: 10.1371/journal.pone.0110264] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Accepted: 09/04/2014] [Indexed: 12/03/2022] Open
Abstract
Swine-origin H3N2v, a variant of H3N2 influenza virus, is a concern for novel reassortment with circulating pandemic H1N1 influenza virus (H1N1pdm09) in swine because this can lead to the emergence of a novel pandemic virus. In this study, the reassortment prevalence of H3N2v with H1N1pdm09 was determined in swine cells. Reassortants evaluated showed that the H1N1pdm09 polymerase (PA) segment occurred within swine H3N2 with ∼80% frequency. The swine H3N2-human H1N1pdm09 PA reassortant (swH3N2-huPA) showed enhanced replication in swine cells, and was the dominant gene constellation. Ferrets infected with swH3N2-huPA had increased lung pathogenicity compared to parent viruses; however, swH3N2-huPA replication in normal human bronchoepithelial cells was attenuated - a feature linked to expression of IFN-β and IFN-λ genes in human but not swine cells. These findings indicate that emergence of novel H3N2v influenza constellations require more than changes in the viral polymerase complex to overcome barriers to cross-species transmission. Additionally, these findings reveal that while the ferret model is highly informative for influenza studies, slight differences in pathogenicity may not necessarily be indicative of human outcomes after infection.
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Affiliation(s)
- Joshua D. Powell
- Department of Infectious Diseases, Animal Health Research Center, University of Georgia, Athens, Georgia, United States of America
| | - Daniel Dlugolenski
- Department of Infectious Diseases, Animal Health Research Center, University of Georgia, Athens, Georgia, United States of America
| | - Tamas Nagy
- Department of Pathology, College of Veterinary Medicine, University of Georgia, Athens, Georgia, United States of America
| | - Jon Gabbard
- Department of Infectious Diseases, Animal Health Research Center, University of Georgia, Athens, Georgia, United States of America
| | - Christopher Lee
- Department of Infectious Diseases, Animal Health Research Center, University of Georgia, Athens, Georgia, United States of America
| | - Stephen M. Tompkins
- Department of Infectious Diseases, Animal Health Research Center, University of Georgia, Athens, Georgia, United States of America
| | - Ralph A. Tripp
- Department of Infectious Diseases, Animal Health Research Center, University of Georgia, Athens, Georgia, United States of America
- * E-mail:
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Kitikoon P, Gauger PC, Anderson TK, Culhane MR, Swenson S, Loving CL, Perez DR, Vincent AL. Swine influenza virus vaccine serologic cross-reactivity to contemporary US swine H3N2 and efficacy in pigs infected with an H3N2 similar to 2011-2012 H3N2v. Influenza Other Respir Viruses 2014; 7 Suppl 4:32-41. [PMID: 24224818 DOI: 10.1111/irv.12189] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND Swine influenza A virus (IAV) reassortment with 2009 H1N1 pandemic (H1N1pdm09) virus has been documented, and new genotypes and subclusters of H3N2 have since expanded in the US swine population. An H3N2 variant (H3N2v) virus with the H1N1pdm09 matrix gene and the remaining genes of swine triple reassortant H3N2 caused outbreaks at agricultural fairs in 2011-2012. METHODS To assess commercial swine IAV vaccines' efficacy against H3N2 viruses, including those similar to H3N2v, antisera to three vaccines were tested by hemagglutinin inhibition (HI) assay against contemporary H3N2. Vaccine 1, with high HI cross-reactivity, was further investigated for efficacy against H3N2 virus infection in pigs with or without maternally derived antibodies (MDA). In addition, efficacy of a vaccine derived from whole inactivated virus (WIV) was compared with live attenuated influenza virus (LAIV) against H3N2. RESULTS Hemagglutinin inhibition cross-reactivity demonstrated that contemporary swine H3N2 viruses have drifted from viruses in current swine IAV vaccines. The vaccine with the highest level of HI cross-reactivity significantly protected pigs without MDA. However, the presence of MDA at vaccination blocked vaccine efficacy. The performance of WIV and LAIV was comparable in the absence of MDA. CONCLUSIONS Swine IAV in the United States is complex and dynamic. Vaccination to minimize virus shedding can help limit transmission of virus among pigs and people. However, vaccines must be updated. A critical review of the use of WIV in sows is required in the context of the current IAV ecology and vaccine application in pigs with MDA.
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Affiliation(s)
- Pravina Kitikoon
- Virus and Prion Research Unit, National Animal Disease Center, USDA-ARS, Ames, IA, USA
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Protective efficacy of intranasally administered bivalent live influenza vaccine and immunological mechanisms underlying the protection. Vaccine 2014; 32:3835-42. [DOI: 10.1016/j.vaccine.2014.04.065] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Revised: 03/04/2014] [Accepted: 04/21/2014] [Indexed: 02/03/2023]
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North American triple reassortant and Eurasian H1N1 swine influenza viruses do not readily reassort to generate a 2009 pandemic H1N1-like virus. mBio 2014; 5:e00919-13. [PMID: 24618255 PMCID: PMC3952159 DOI: 10.1128/mbio.00919-13] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The 2009 pandemic H1N1 virus (pH1N1) was derived through reassortment of North American triple reassortant and Eurasian avian-like swine influenza viruses (SIVs). To date, when, how and where the pH1N1 arose is not understood. To investigate viral reassortment, we coinfected cell cultures and a group of pigs with or without preexisting immunity with a Eurasian H1N1 virus, A/Swine/Spain/53207/2004 (SP04), and a North American triple reassortant H1N1 virus, A/Swine/Kansas/77778/2007 (KS07). The infected pigs were cohoused with one or two groups of contact animals to investigate viral transmission. In coinfected MDCK or PK15 continuous cell lines with KS07 and SP04 viruses, more than 20 different reassortant viruses were found. In pigs without or with preexisting immunity (immunized with commercial inactivated swine influenza vaccines) and coinfected with both viruses, six or seven reassortant viruses, as well as the parental viruses, were identified in bronchoalveolar lavage fluid samples from the lungs. Interestingly, only one or two viruses transmitted to and were detected in contact animals. No reassortant containing a gene constellation similar to that of pH1N1 virus was found in either coinfected cells or pigs, indicating that the reassortment event that resulted in the generation of this virus is a rare event that likely involved specific viral strains and/or a favorable, not-yet-understood environment. IMPORTANCE The 2009 pandemic-like H1N1 virus could not be reproduced either in cell cultures or in pigs coinfected with North American triple reassortant H1N1 and Eurasian H1N1 swine influenza viruses. This finding suggests that the generation of the 2009 pandemic H1N1 virus by reassortment was a rare event that likely involved specific viral strains and unknown factors. Different reassortant viruses were detected in coinfected pigs with and without preexisting immunity, indicating that host immunity plays a relevant role in driving viral reassortment of influenza A virus.
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Wang Z, Burwinkel M, Chai W, Lange E, Blohm U, Breithaupt A, Hoffmann B, Twardziok S, Rieger J, Janczyk P, Pieper R, Osterrieder N. Dietary Enterococcus faecium NCIMB 10415 and zinc oxide stimulate immune reactions to trivalent influenza vaccination in pigs but do not affect virological response upon challenge infection. PLoS One 2014; 9:e87007. [PMID: 24489827 PMCID: PMC3904981 DOI: 10.1371/journal.pone.0087007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Accepted: 12/16/2013] [Indexed: 11/18/2022] Open
Abstract
Swine influenza viruses (SIV) regularly cause significant disease in pigs worldwide. Since there is no causative treatment of SIV, we tested if probiotic Enterococcus (E.) faecium NCIMB 10415 or zinc (Zn) oxide as feed supplements provide beneficial effects upon SIV infection in piglets. Seventy-two weaned piglets were fed three different diets containing either E. faecium or different levels of Zn (2500 ppm, Znhigh; 50 ppm, Znlow). Half of the piglets were vaccinated intramuscularly (VAC) twice with an inactivated trivalent SIV vaccine, while all piglets were then infected intranasally with H3N2 SIV. Significantly higher weekly weight gains were observed in the E. faecium group before virus infection, and piglets in Znhigh and E. faecium groups gained weight after infection while those in the control group (Znlow) lost weight. Using ELISA, we found significantly higher H3N2-specific antibody levels in the E. faecium+VAC group 2 days before and at the day of challenge infection as well as at 4 and 6 days after challenge infection. Higher hemagglutination inhibition (HI) titers were also observed in the Znhigh+VAC and E. faecium+VAC groups at 0, 1 and 4 days after infection. However, there were no significant differences in virus shedding and lung lesions between the dietary groups. Using flow cytometry analysis significantly higher activated T helper cells and cytotoxic T lymphocyte percentages in the PBMCs were detected in the Znhigh and E. faecium groups at single time points after infection compared to the Znlow control group, but no prolonged effect was found. In the BAL cells no influence of dietary supplementation on immune cell percentages could be detected. Our results suggest that feeding high doses of zinc oxide and particularly E. faecium could beneficially influence humoral immune responses after vaccination and recovery from SIV infection, but not affect virus shedding and lung pathology.
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Affiliation(s)
- Zhenya Wang
- Institut für Virologie, Freie Universität Berlin, Berlin, Germany
| | - Michael Burwinkel
- Institut für Virologie, Freie Universität Berlin, Berlin, Germany
- * E-mail:
| | - Weidong Chai
- Institut für Virologie, Freie Universität Berlin, Berlin, Germany
| | - Elke Lange
- Abteilung für experimentelle Tierhaltung und Biosicherheit, Friedrich-Loeffler-Institut, Greifswald-Insel Riems, Germany
| | - Ulrike Blohm
- Institut für Immunologie, Friedrich-Loeffler-Institut, Greifswald-Insel Riems, Germany
| | - Angele Breithaupt
- Abteilung für experimentelle Tierhaltung und Biosicherheit, Friedrich-Loeffler-Institut, Greifswald-Insel Riems, Germany
- Institut für Veterinärpathologie, Freie Universität Berlin, Berlin, Germany
| | - Bernd Hoffmann
- Institut für Virusdiagnostik, Friedrich-Loeffler-Institut, Greifswald-Insel Riems, Germany
| | - Sven Twardziok
- Molekularbiologie und Bioinformatik, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Juliane Rieger
- Institut für Veterinäranatomie, Freie Universität Berlin, Berlin, Germany
| | - Pawel Janczyk
- Bundesinstitut für Risikobewertung, Abteilung für Biologische Sicherheit, Fachgruppe für Molekulare Diagnostik und Genetik, Berlin, Germany
| | - Robert Pieper
- Institut für Tierernährung, Freie Universität Berlin, Berlin, Germany
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Exploration of risk factors contributing to the presence of influenza A virus in swine at agricultural fairs. Emerg Microbes Infect 2014; 3:e5. [PMID: 26038494 PMCID: PMC3913824 DOI: 10.1038/emi.2014.5] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2013] [Revised: 12/03/2013] [Accepted: 12/05/2013] [Indexed: 11/10/2022]
Abstract
Influenza A virus infections occurring in exhibition swine populations at agricultural fairs during 2012 served as a source of H3N2 variant influenza A viruses transmitted to humans resulting in more than 300 documented cases. Prior to the outbreak, this investigation was initiated to identify fair-level risk factors contributing to influenza A virus infections in pigs at agricultural fairs. As part of an ongoing active surveillance program, nasal swabs and associated fair-level metadata were collected from pigs at 40 junior fair market swine shows held in Ohio during the 2012 fair season. Analyses of the data show that the adjusted odds of having influenza A virus-infected pigs at a fair were 1.27 (95% confidential interval (CI): 1.04–1.66) higher for every 20 pig increase in the size of the swine show. Additionally, four of the five fairs that hosted breeding swine shows in addition to their junior fair market swine shows had pigs test positive for influenza A virus. While the current study was limited to 40 fairs within one state, the findings provided insight for veterinary and public health officials developing mitigation strategies to decrease the intra- and inter-species transmission of influenza A virus at fairs.
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Li C, Chen H. Enhancement of influenza virus transmission by gene reassortment. Curr Top Microbiol Immunol 2014; 385:185-204. [PMID: 25048543 DOI: 10.1007/82_2014_389] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Influenza A virus is characterized by a genome composed of eight single-stranded, negative sense RNA segments, which allow for reassortment between different strains when they co-infect the same host cell. Reassortment is an important driving force for the evolution of influenza viruses. The ability of reassortment allows influenza virus to endlessly reinvent itself and pose a constant threat to the health of humans and other animals. Of the four human influenza pandemics since the beginning of the last century, three of them were caused by reassortant viruses bearing genes of avian, human or swine influenza virus origin. In the past decade, great efforts have been made to understand the transmissibility of influenza viruses. The use of reverse genetics technology has made it substantially easier to generate reassortant viruses and evaluate the contribution of individual virus gene on virus transmissibility in animal models such as ferrets and guinea pigs. H5, H7, and H9 avian influenza viruses represent the top three subtypes that are candidates to cause the next human influenza pandemic. Many studies have been conducted to determine whether the transmission of these avian influenza viruses could be enhanced by acquisition of gene segments from human influenza viruses. Moreover, the 2009 pdmH1N1 viruses and the triple reassortant swine influenza viruses were extensively studied to identify the gene segments that contribute to their transmissibility. These studies have greatly deepened our understanding of the transmissibility of reassortant influenza viruses, which, in turn, has improved our ability to be prepared for reassortant influenza virus with enhanced transmissibility and pandemic potential.
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Affiliation(s)
- Chengjun Li
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, 427 Maduan Street, Harbin, 150001, Nangang, China,
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Abstract
Influenza has been recognized as a respiratory disease in swine since its first appearance concurrent with the 1918 "Spanish flu" human pandemic. All influenza viruses of significance in swine are type A, subtype H1N1, H1N2, or H3N2 viruses. Influenza viruses infect epithelial cells lining the surface of the respiratory tract, inducing prominent necrotizing bronchitis and bronchiolitis and variable interstitial pneumonia. Cell death is due to direct virus infection and to insult directed by leukocytes and cytokines of the innate immune system. The most virulent viruses consistently express the following characteristics of infection: (1) higher or more prolonged virus replication, (2) excessive cytokine induction, and (3) replication in the lower respiratory tract. Nearly all the viral proteins contribute to virulence. Pigs are susceptible to infection with both human and avian viruses, which often results in gene reassortment between these viruses and endemic swine viruses. The receptors on the epithelial cells lining the respiratory tract are major determinants of infection by influenza viruses from other hosts. The polymerases, especially PB2, also influence cross-species infection. Methods of diagnosis and characterization of influenza viruses that infect swine have improved over the years, driven both by the availability of new technologies and by the necessity of keeping up with changes in the virus. Testing of oral fluids from pigs for virus and antibody is a recent development that allows efficient sampling of large numbers of animals.
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Affiliation(s)
- B H Janke
- DVM, PhD, Veterinary Diagnostic Laboratory, Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA 50011, USA.
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38
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Schweiger B, Buda S. [Detection of local influenza outbreaks and role of virological diagnostics]. Bundesgesundheitsblatt Gesundheitsforschung Gesundheitsschutz 2013; 56:28-37. [PMID: 23275953 DOI: 10.1007/s00103-012-1580-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
For many years, the Working Group on Influenza (AGI) has been the most important influenza surveillance system in Germany. An average sample of the population is covered by both syndromic and virological surveillance, which provides timely data regarding the onset and course of the influenza wave as well as its burden of disease. However, smaller influenza outbreaks cannot be detected by the AGI sentinel system. This is achieved by the information reported by the mandatory notification system (Protection Against Infection Act, IfSG), which serves as the second pillar of the national influenza surveillance. Approaches to recognize such outbreaks are based either on reported influenza virus detection and subsequent investigations by local health authorities or by notification of an accumulation of respiratory diseases or nosocomial infections and subsequent laboratory investigations. In this context, virological diagnostics plays an essential role. This has been true particularly for the early phase of the 2009 pandemic, but generally timely diagnostics is essential for the identification of outbreaks. Regarding potential future outbreaks, it is also important to keep an eye on animal influenza viruses that have repeatedly infected humans. This mainly concerns avian influenza viruses of the subtypes H5, H7, and H9 as well as porcine influenza viruses for which a specific PCR has been established at the National Influenza Reference Centre. An increased incidence of respiratory infections, both during and outside the season, should always encourage virological laboratory diagnostics to be performed as a prerequisite of further extensive investigations and an optimal outbreak management.
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Affiliation(s)
- B Schweiger
- Fachgebiet Influenza und respiratorische Infektionen, Robert Koch-Institut, Nordufer 20, 13353, Berlin, Deutschland.
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Fuller TL, Gilbert M, Martin V, Cappelle J, Hosseini P, Njabo KY, Abdel Aziz S, Xiao X, Daszak P, Smith TB. Predicting hotspots for influenza virus reassortment. Emerg Infect Dis 2013; 19:581-8. [PMID: 23628436 PMCID: PMC3647410 DOI: 10.3201/eid1904.120903] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
TOC summary: Reassortment is most likely to occur in eastern China, central China, or the Nile Delta in Egypt. The 1957 and 1968 influenza pandemics, each of which killed ≈1 million persons, arose through reassortment events. Influenza virus in humans and domestic animals could reassort and cause another pandemic. To identify geographic areas where agricultural production systems are conducive to reassortment, we fitted multivariate regression models to surveillance data on influenza A virus subtype H5N1 among poultry in China and Egypt and subtype H3N2 among humans. We then applied the models across Asia and Egypt to predict where subtype H3N2 from humans and subtype H5N1 from birds overlap; this overlap serves as a proxy for co-infection and in vivo reassortment. For Asia, we refined the prioritization by identifying areas that also have high swine density. Potential geographic foci of reassortment include the northern plains of India, coastal and central provinces of China, the western Korean Peninsula and southwestern Japan in Asia, and the Nile Delta in Egypt.
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Affiliation(s)
- Trevon L Fuller
- Institute of the Environment and Sustainability, University of California, Los Angeles, California 90095-1496, USA.
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40
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Crisci E, Mussá T, Fraile L, Montoya M. Review: Influenza virus in pigs. Mol Immunol 2013; 55:200-11. [DOI: 10.1016/j.molimm.2013.02.008] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2012] [Revised: 02/23/2013] [Accepted: 02/25/2013] [Indexed: 12/19/2022]
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41
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Scientific opinion on the possible risks posed by the influenza A (H3N2v) virus for animal health and its potential spread and implications for animal and human health. EFSA J 2013. [DOI: 10.2903/j.efsa.2013.3383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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42
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Gauger PC, Loving CL, Lager KM, Janke BH, Kehrli ME, Roth JA, Vincent AL. Vaccine-Associated Enhanced Respiratory Disease Does Not Interfere with the Adaptive Immune Response Following Challenge with Pandemic A/H1N1 2009. Viral Immunol 2013; 26:314-21. [DOI: 10.1089/vim.2013.0018] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Affiliation(s)
- Phillip C. Gauger
- Virus and Prion Research Unit, National Animal Disease Center, USDA, Agricultural Research Service, Ames, Iowa
- Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, Iowa
| | - Crystal L. Loving
- Virus and Prion Research Unit, National Animal Disease Center, USDA, Agricultural Research Service, Ames, Iowa
| | - Kelly M. Lager
- Virus and Prion Research Unit, National Animal Disease Center, USDA, Agricultural Research Service, Ames, Iowa
| | - Bruce H. Janke
- Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, Iowa
| | - Marcus E. Kehrli
- Virus and Prion Research Unit, National Animal Disease Center, USDA, Agricultural Research Service, Ames, Iowa
| | - James A. Roth
- Department of Veterinary Microbiology and Preventive Medicine, College of Veterinary Medicine, Iowa State University, Ames, Iowa
| | - Amy L. Vincent
- Virus and Prion Research Unit, National Animal Disease Center, USDA, Agricultural Research Service, Ames, Iowa
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43
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Jhung MA, Epperson S, Biggerstaff M, Allen D, Balish A, Barnes N, Beaudoin A, Berman L, Bidol S, Blanton L, Blythe D, Brammer L, D'Mello T, Danila R, Davis W, de Fijter S, Diorio M, Durand LO, Emery S, Fowler B, Garten R, Grant Y, Greenbaum A, Gubareva L, Havers F, Haupt T, House J, Ibrahim S, Jiang V, Jain S, Jernigan D, Kazmierczak J, Klimov A, Lindstrom S, Longenberger A, Lucas P, Lynfield R, McMorrow M, Moll M, Morin C, Ostroff S, Page SL, Park SY, Peters S, Quinn C, Reed C, Richards S, Scheftel J, Simwale O, Shu B, Soyemi K, Stauffer J, Steffens C, Su S, Torso L, Uyeki TM, Vetter S, Villanueva J, Wong KK, Shaw M, Bresee JS, Cox N, Finelli L. Outbreak of variant influenza A(H3N2) virus in the United States. Clin Infect Dis 2013; 57:1703-12. [PMID: 24065322 PMCID: PMC5733625 DOI: 10.1093/cid/cit649] [Citation(s) in RCA: 128] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Background. Variant influenza virus infections are rare but may have pandemic potential if person-to-person transmission is efficient. We describe the epidemiology of a multistate outbreak of an influenza A(H3N2) variant virus (H3N2v) first identified in 2011. Methods. We identified laboratory-confirmed cases of H3N2v and used a standard case report form to characterize illness and exposures. We considered illness to result from person-to-person H3N2v transmission if swine contact was not identified within 4 days prior to illness onset. Results. From 9 July to 7 September 2012, we identified 306 cases of H3N2v in 10 states. The median age of all patients was 7 years. Commonly reported signs and symptoms included fever (98%), cough (85%), and fatigue (83%). Sixteen patients (5.2%) were hospitalized, and 1 fatal case was identified. The majority of those infected reported agricultural fair attendance (93%) and/or contact with swine (95%) prior to illness. We identified 15 cases of possible person-to-person transmission of H3N2v. Viruses recovered from patients were 93%–100% identical and similar to viruses recovered from previous cases of H3N2v. All H3N2v viruses examined were susceptible to oseltamivir and zanamivir and resistant to adamantane antiviral medications. Conclusions. In a large outbreak of variant influenza, the majority of infected persons reported exposures, suggesting that swine contact at an agricultural fair was a risk for H3N2v infection. We identified limited person-to-person H3N2v virus transmission, but found no evidence of efficient or sustained person-to-person transmission. Fair managers and attendees should be aware of the risk of swine-to-human transmission of influenza viruses in these settings.
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Affiliation(s)
- Michael A Jhung
- Influenza Division, National Center for Immunization and Respiratory Disease
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44
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Rose N, Hervé S, Eveno E, Barbier N, Eono F, Dorenlor V, Andraud M, Camsusou C, Madec F, Simon G. Dynamics of influenza A virus infections in permanently infected pig farms: evidence of recurrent infections, circulation of several swine influenza viruses and reassortment events. Vet Res 2013; 44:72. [PMID: 24007505 PMCID: PMC3846378 DOI: 10.1186/1297-9716-44-72] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Accepted: 08/27/2013] [Indexed: 11/29/2022] Open
Abstract
Concomitant infections by different influenza A virus subtypes within pig farms increase the risk of new reassortant virus emergence. The aims of this study were to characterize the epidemiology of recurrent swine influenza virus infections and identify their main determinants. A follow-up study was carried out in 3 selected farms known to be affected by repeated influenza infections. Three batches of pigs were followed within each farm from birth to slaughter through a representative sample of 40 piglets per batch. Piglets were monitored individually on a monthly basis for serology and clinical parameters. When a flu outbreak occurred, daily virological and clinical investigations were carried out for two weeks. Influenza outbreaks, confirmed by influenza A virus detection, were reported at least once in each batch. These outbreaks occurred at a constant age within farms and were correlated with an increased frequency of sneezing and coughing fits. H1N1 and H1N2 viruses from European enzootic subtypes and reassortants between viruses from these lineages were consecutively and sometimes simultaneously identified depending on the batch, suggesting virus co-circulations at the farm, batch and sometimes individual levels. The estimated reproduction ratio R of influenza outbreaks ranged between 2.5 [1.9-2.9] and 6.9 [4.1-10.5] according to the age at infection-time and serological status of infected piglets. Duration of shedding was influenced by the age at infection time, the serological status of the dam and mingling practices. An impaired humoral response was identified in piglets infected at a time when they still presented maternally-derived antibodies.
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Affiliation(s)
- Nicolas Rose
- Anses, Laboratoire de Ploufragan/Plouzané, Unité Epidémiologie et Bien-Être du Porc, BP 53, 22440 Ploufragan, France
- Université Européenne de Bretagne, Rennes, France
| | - Séverine Hervé
- Anses, Laboratoire de Ploufragan/Plouzané, Unité Virologie Immunologie Porcines, BP 53, 22440 Ploufragan, France
- Université Européenne de Bretagne, Rennes, France
| | - Eric Eveno
- Anses, Laboratoire de Ploufragan/Plouzané, Unité Epidémiologie et Bien-Être du Porc, BP 53, 22440 Ploufragan, France
- Université Européenne de Bretagne, Rennes, France
| | - Nicolas Barbier
- Anses, Laboratoire de Ploufragan/Plouzané, Unité Virologie Immunologie Porcines, BP 53, 22440 Ploufragan, France
- Université Européenne de Bretagne, Rennes, France
| | - Florent Eono
- Anses, Laboratoire de Ploufragan/Plouzané, Unité Epidémiologie et Bien-Être du Porc, BP 53, 22440 Ploufragan, France
- Université Européenne de Bretagne, Rennes, France
| | - Virginie Dorenlor
- Anses, Laboratoire de Ploufragan/Plouzané, Unité Epidémiologie et Bien-Être du Porc, BP 53, 22440 Ploufragan, France
- Université Européenne de Bretagne, Rennes, France
| | - Mathieu Andraud
- Anses, Laboratoire de Ploufragan/Plouzané, Unité Epidémiologie et Bien-Être du Porc, BP 53, 22440 Ploufragan, France
- Université Européenne de Bretagne, Rennes, France
| | - Claire Camsusou
- Anses, Laboratoire de Ploufragan/Plouzané, Unité Epidémiologie et Bien-Être du Porc, BP 53, 22440 Ploufragan, France
- Université Européenne de Bretagne, Rennes, France
| | - François Madec
- Anses, Laboratoire de Ploufragan/Plouzané, Unité Epidémiologie et Bien-Être du Porc, BP 53, 22440 Ploufragan, France
- Université Européenne de Bretagne, Rennes, France
| | - Gaëlle Simon
- Anses, Laboratoire de Ploufragan/Plouzané, Unité Virologie Immunologie Porcines, BP 53, 22440 Ploufragan, France
- Université Européenne de Bretagne, Rennes, France
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Nie K, Zhao X, Ding X, Li X, Zou S, Guo J, Wang D, Gao R, Li X, Huang W, Shu Y, Ma X. Visual detection of human infection with influenza A (H7N9) virus by subtype-specific reverse transcription loop-mediated isothermal amplification with hydroxynaphthol blue dye. Clin Microbiol Infect 2013; 19:E372-5. [DOI: 10.1111/1469-0691.12263] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Accepted: 05/03/2013] [Indexed: 11/28/2022]
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46
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Efficacy in pigs of inactivated and live attenuated influenza virus vaccines against infection and transmission of an emerging H3N2 similar to the 2011-2012 H3N2v. J Virol 2013; 87:9895-903. [PMID: 23824815 DOI: 10.1128/jvi.01038-13] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Vaccines provide a primary means to limit disease but may not be effective at blocking infection and pathogen transmission. The objective of the present study was to evaluate the efficacy of commercial inactivated swine influenza A virus (IAV) vaccines and experimental live attenuated influenza virus (LAIV) vaccines against infection with H3N2 virus and subsequent indirect transmission to naive pigs. The H3N2 virus evaluated was similar to the H3N2v detected in humans during 2011-2012, which was associated with swine contact at agricultural fairs. One commercial vaccine provided partial protection measured by reduced nasal shedding; however, indirect contacts became infected, indicating that the reduction in nasal shedding did not prevent aerosol transmission. One LAIV vaccine provided complete protection, and none of the indirect-contact pigs became infected. Clinical disease was not observed in any group, including nonvaccinated animals, a consistent observation in pigs infected with contemporary reassortant H3N2 swine viruses. Serum hemagglutination inhibition antibody titers against the challenge virus were not predictive of efficacy; titers following vaccination with a LAIV that provided sterilizing immunity were below the level considered protective, yet titers in a commercial vaccine group that was not protected were above that level. While vaccination with currently approved commercial inactivated products did not fully prevent transmission, certain vaccines may provide a benefit by limitating shedding, transmission, and zoonotic spillover of antigenically similar H3N2 viruses at agriculture fairs when administered appropriately and used in conjunction with additional control measures.
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47
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Isolation of influenza A(H3N2)v virus from pigs and characterization of its biological properties in pigs and mice. Arch Virol 2013; 158:2351-7. [PMID: 23674250 DOI: 10.1007/s00705-012-1571-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2012] [Accepted: 10/26/2012] [Indexed: 10/26/2022]
Abstract
Recently, a novel reassortant virus, influenza A(H3N2)v [A(H3N2)v], was identified as the causative pathogen in 307 human cases of influenza in the United States. A(H3N2)v contains the matrix gene from the 2009 pandemic H1N1 (pH1N1) virus, while its other genes originate from H3N2 viruses with triple-reassorted internal genes. In this study, we isolated three A(H3N2)v viruses from commercial pigs in Korea that showed similarities with published human A(H3N2)v viruses in eight segment sequence alignments. After genetic characterization, the pathogenicity of one of these viruses was assessed in pigs and mice. Infection of pigs with this novel virus resulted in mild interstitial pneumonia with marked oronasal shedding of viral RNA for about 14 days. In mice, the virus replicated efficiently in the lungs; viral RNA was detected up to 9 days post-inoculation. However, the virus did not cause severe disease or death in mice, despite the administration of a high infectious dose (10(5.2) TCID50). This study demonstrates that A(H3N2)v causes a high morbidity rate with low virulence; however, global monitoring of A(H3N2)v outbreaks in mammals will be needed to determine whether this novel subtype will shift to a highly pathogenic virus.
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48
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Wong KK, Greenbaum A, Moll ME, Lando J, Moore EL, Ganatra R, Biggerstaff M, Lam E, Smith EE, Storms AD, Miller JR, Dato V, Nalluswami K, Nambiar A, Silvestri SA, Lute JR, Ostroff S, Hancock K, Branch A, Trock SC, Klimov A, Shu B, Brammer L, Epperson S, Finelli L, Jhung MA. Outbreak of influenza A (H3N2) variant virus infection among attendees of an agricultural fair, Pennsylvania, USA, 2011. Emerg Infect Dis 2013; 18:1937-44. [PMID: 23171635 PMCID: PMC3557885 DOI: 10.3201/eid1812.121097] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Avoiding or limiting contact with swine at agricultural events may help prevent A(H3N2)v virus infections in such settings. During August 2011, influenza A (H3N2) variant [A(H3N2)v] virus infection developed in a child who attended an agricultural fair in Pennsylvania, USA; the virus resulted from reassortment of a swine influenza virus with influenza A(H1N1)pdm09. We interviewed fair attendees and conducted a retrospective cohort study among members of an agricultural club who attended the fair. Probable and confirmed cases of A(H3N2)v virus infection were defined by serology and genomic sequencing results, respectively. We identified 82 suspected, 4 probable, and 3 confirmed case-patients who attended the fair. Among 127 cohort study members, the risk for suspected case status increased as swine exposure increased from none (4%; referent) to visiting swine exhibits (8%; relative risk 2.1; 95% CI 0.2–53.4) to touching swine (16%; relative risk 4.4; 95% CI 0.8–116.3). Fairs may be venues for zoonotic transmission of viruses with epidemic potential; thus, health officials should investigate respiratory illness outbreaks associated with agricultural events.
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Affiliation(s)
- Karen K Wong
- Centers for Disease Control and Prevention, Atlanta, Georgia 30329, USA.
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Abstract
Influenza pandemics pose a continuous risk to human and animal health and may engender food security issues worldwide. As novel influenza A virus infections in humans are identified, pandemic preparedness strategies necessarily involve decisions regarding which viruses should be included for further studies and mitigation efforts. Resource and time limitations dictate that viruses determined to pose the greatest risk to public or animal health should be selected for further research to fill information gaps and, potentially, for development of vaccine candidates that could be put in libraries, manufactured and stockpiled, or even administered to protect susceptible populations of animals or people. A need exists to apply an objective, science-based risk assessment to the process of evaluating influenza viruses. During the past year, the Centers for Disease Control and Prevention began developing a tool to evaluate influenza A viruses that are not circulating in the human population but pose a pandemic risk. The objective is to offer a standardized set of considerations to be applied when evaluating prepandemic viruses. The tool under consideration is a simple, additive model, based on multiattribute decision analysis. The model includes elements that address the properties of the virus itself and population attributes, considers both veterinary and human findings, and integrates both laboratory and field observations. Additionally, each element is assigned a weight such that all elements are not considered of equal importance within the model.
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Affiliation(s)
- Susan C Trock
- Centers for Disease Control and Prevention, Influenza Division, 1600 Clifton Road, Atlanta, GA 30333, USA.
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50
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Abstract
Influenza virus infects a wide variety of species including humans, pigs, horses, sea mammals and birds. Weight loss caused by influenza infection and/or co-infection with other infectious agents results in significant financial loss in swine herds. The emergence of pandemic H1N1 (A/CA/04/2009/H1N1) and H3N2 variant (H3N2v) viruses, which cause disease in both humans and livestock constitutes a concerning public health threat. Influenza virus contains eight single-stranded, negative-sense RNA genome segments. This genetic structure allows the virus to evolve rapidly by antigenic drift and shift. Antigen-specific antibodies induced by current vaccines provide limited cross protection to heterologous challenge. In pigs, this presents a major obstacle for vaccine development. Different strategies are under development to produce vaccines that provide better cross-protection for swine. Moreover, overriding interfering maternal antibodies is another goal for influenza vaccines in order to permit effective immunization of piglets at an early age. Herein, we present a review of influenza virus infection in swine, including a discussion of current vaccine approaches and techniques used for novel vaccine development.
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