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Musto C, Tamba M, Calzolari M, Rossi A, Grisendi A, Marzani K, Bonilauri P, Delogu M. Detection of West Nile and Usutu Virus RNA in Autumn Season in Wild Avian Hosts in Northern Italy. Viruses 2023; 15:1771. [PMID: 37632113 PMCID: PMC10458002 DOI: 10.3390/v15081771] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 08/17/2023] [Accepted: 08/18/2023] [Indexed: 08/27/2023] Open
Abstract
West Nile (WNV) and Usutu (USUV) viruses are two mosquito-borne viruses belonging to the family Flaviviridae and genus Flavivirus. The natural transmission cycle of WNV and USUV involves mosquitoes and birds, while mammals are thought to be accidental hosts. The goal of this study was to report-in the context of "off-season monitoring" and passive surveillance-the detection of WNV and USUV RNA in wild birds. To this end, we analyzed biological samples of wild birds in Northern Italy, from October to May, hence outside of the regional monitoring period (June-September). The virological investigations for the detection of USUV and WNV RNA were performed using real-time PCR on frozen samples of the brain, myocardium, kidney, and spleen. In a total sample of 164 wild birds belonging to 27 different species, sequences of both viruses were detected: four birds (2.44%) were positive for WNV and five (3.05%) for USUV. Off-season infections of WNV and especially USUV are still widely discussed and only a few studies have been published to date. To the best of our knowledge, this study is the first report on the detection of USUV RNA until December 22nd. Although further studies are required, our results confirm the viral circulation out-of-season of Flavivirus in wild birds, suggesting reconsidering the epidemiological monitoring period based on each individual climate zone and taking into consideration global warming which will play an important role in the epidemiology of vector-borne diseases.
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Affiliation(s)
- Carmela Musto
- Department of Veterinary Medical Sciences, University of Bologna, 40064 Bologna, Italy;
| | - Marco Tamba
- Istituto Zooprofilattico Sperimentale della Lombardia e dell’Emilia-Romagna, 25124 Brescia, Italy; (M.T.); (M.C.); (A.R.); (A.G.); (K.M.); (P.B.)
| | - Mattia Calzolari
- Istituto Zooprofilattico Sperimentale della Lombardia e dell’Emilia-Romagna, 25124 Brescia, Italy; (M.T.); (M.C.); (A.R.); (A.G.); (K.M.); (P.B.)
| | - Arianna Rossi
- Istituto Zooprofilattico Sperimentale della Lombardia e dell’Emilia-Romagna, 25124 Brescia, Italy; (M.T.); (M.C.); (A.R.); (A.G.); (K.M.); (P.B.)
| | - Annalisa Grisendi
- Istituto Zooprofilattico Sperimentale della Lombardia e dell’Emilia-Romagna, 25124 Brescia, Italy; (M.T.); (M.C.); (A.R.); (A.G.); (K.M.); (P.B.)
| | - Katia Marzani
- Istituto Zooprofilattico Sperimentale della Lombardia e dell’Emilia-Romagna, 25124 Brescia, Italy; (M.T.); (M.C.); (A.R.); (A.G.); (K.M.); (P.B.)
| | - Paolo Bonilauri
- Istituto Zooprofilattico Sperimentale della Lombardia e dell’Emilia-Romagna, 25124 Brescia, Italy; (M.T.); (M.C.); (A.R.); (A.G.); (K.M.); (P.B.)
| | - Mauro Delogu
- Department of Veterinary Medical Sciences, University of Bologna, 40064 Bologna, Italy;
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Foss L, Feiszli T, Kramer VL, Reisen WK, Padgett K. Epidemic versus endemic West Nile virus dead bird surveillance in California: Changes in sensitivity and focus. PLoS One 2023; 18:e0284039. [PMID: 37023091 PMCID: PMC10079120 DOI: 10.1371/journal.pone.0284039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Accepted: 03/21/2023] [Indexed: 04/07/2023] Open
Abstract
Since 2003, the California West Nile virus (WNV) dead bird surveillance program (DBSP) has monitored publicly reported dead birds for WNV surveillance and response. In the current paper, we compared DBSP data from early epidemic years (2004-2006) with recent endemic years (2018-2020), with a focus on specimen collection criteria, county report incidence, bird species selection, WNV prevalence in dead birds, and utility of the DBSP as an early environmental indicator of WNV. Although fewer agencies collected dead birds in recent years, most vector control agencies with consistent WNV activity continued to use dead birds as a surveillance tool, with streamlined operations enhancing efficiency. The number of dead bird reports was approximately ten times greater during 2004-2006 compared to 2018-2020, with reports from the Central Valley and portions of Southern California decreasing substantially in recent years; reports from the San Francisco Bay Area decreased less dramatically. Seven of ten counties with high numbers of dead bird reports were also high human WNV case burden areas. Dead corvid, sparrow, and quail reports decreased the most compared to other bird species reports. West Nile virus positive dead birds were the most frequent first indicators of WNV activity by county in 2004-2006, followed by positive mosquitoes; in contrast, during 2018-2020 mosquitoes were the most frequent first indicators followed by dead birds, and initial environmental WNV detections occurred later in the season during 2018-2020. Evidence for WNV impacts on avian populations and susceptibility are discussed. Although patterns of dead bird reports and WNV prevalence in tested dead birds have changed, dead birds have endured as a useful element within our multi-faceted WNV surveillance program.
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Affiliation(s)
- Leslie Foss
- Vector-Borne Disease Section, California Department of Public Health, Richmond, California, United States of America
| | - Tina Feiszli
- Vector-Borne Disease Section, California Department of Public Health, Richmond, California, United States of America
| | - Vicki L. Kramer
- Vector-Borne Disease Section, California Department of Public Health, Sacramento, California, United States of America
| | - William K. Reisen
- Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, CA, United States of America
| | - Kerry Padgett
- Vector-Borne Disease Section, California Department of Public Health, Richmond, California, United States of America
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Mencattelli G, Silverj A, Iapaolo F, Ippoliti C, Teodori L, Di Gennaro A, Curini V, Candeloro L, Conte A, Polci A, Morelli D, Perrotta MG, Marini G, Rosà R, Monaco F, Segata N, Rizzoli A, Rota-Stabelli O, Savini G. Epidemiological and Evolutionary Analysis of West Nile Virus Lineage 2 in Italy. Viruses 2022; 15:35. [PMID: 36680076 PMCID: PMC9866873 DOI: 10.3390/v15010035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 12/15/2022] [Accepted: 12/19/2022] [Indexed: 12/24/2022] Open
Abstract
West Nile virus (WNV) is a mosquito-borne virus potentially causing serious illness in humans and other animals. Since 2004, several studies have highlighted the progressive spread of WNV Lineage 2 (L2) in Europe, with Italy being one of the countries with the highest number of cases of West Nile disease reported. In this paper, we give an overview of the epidemiological and genetic features characterising the spread and evolution of WNV L2 in Italy, leveraging data obtained from national surveillance activities between 2011 and 2021, including 46 newly assembled genomes that were analysed under both phylogeographic and phylodynamic frameworks. In addition, to better understand the seasonal patterns of the virus, we used a machine learning model predicting areas at high-risk of WNV spread. Our results show a progressive increase in WNV L2 in Italy, clarifying the dynamics of interregional circulation, with no significant introductions from other countries in recent years. Moreover, the predicting model identified the presence of suitable conditions for the 2022 earlier and wider spread of WNV in Italy, underlining the importance of using quantitative models for early warning detection of WNV outbreaks. Taken together, these findings can be used as a reference to develop new strategies to mitigate the impact of the pathogen on human and other animal health in endemic areas and new regions.
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Affiliation(s)
- Giulia Mencattelli
- Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise, 64100 Teramo, Italy
- Centre Agriculture Food Environment, University of Trento, 38010 San Michele all’Adige, Italy
- Research and Innovation Centre, Fondazione Edmund Mach, 38010 San Michele all’Adige, Italy
| | - Andrea Silverj
- Centre Agriculture Food Environment, University of Trento, 38010 San Michele all’Adige, Italy
- Research and Innovation Centre, Fondazione Edmund Mach, 38010 San Michele all’Adige, Italy
- Department CIBIO, University of Trento, 38123 Trento, Italy
| | - Federica Iapaolo
- Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise, 64100 Teramo, Italy
| | - Carla Ippoliti
- Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise, 64100 Teramo, Italy
| | - Liana Teodori
- Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise, 64100 Teramo, Italy
| | - Annapia Di Gennaro
- Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise, 64100 Teramo, Italy
| | - Valentina Curini
- Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise, 64100 Teramo, Italy
| | - Luca Candeloro
- Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise, 64100 Teramo, Italy
| | - Annamaria Conte
- Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise, 64100 Teramo, Italy
| | - Andrea Polci
- Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise, 64100 Teramo, Italy
| | - Daniela Morelli
- Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise, 64100 Teramo, Italy
| | | | - Giovanni Marini
- Research and Innovation Centre, Fondazione Edmund Mach, 38010 San Michele all’Adige, Italy
| | - Roberto Rosà
- Centre Agriculture Food Environment, University of Trento, 38010 San Michele all’Adige, Italy
- Research and Innovation Centre, Fondazione Edmund Mach, 38010 San Michele all’Adige, Italy
| | - Federica Monaco
- Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise, 64100 Teramo, Italy
| | - Nicola Segata
- Department CIBIO, University of Trento, 38123 Trento, Italy
| | - Annapaola Rizzoli
- Research and Innovation Centre, Fondazione Edmund Mach, 38010 San Michele all’Adige, Italy
| | - Omar Rota-Stabelli
- Centre Agriculture Food Environment, University of Trento, 38010 San Michele all’Adige, Italy
- Research and Innovation Centre, Fondazione Edmund Mach, 38010 San Michele all’Adige, Italy
| | - Giovanni Savini
- Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise, 64100 Teramo, Italy
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Giglia G, Mencattelli G, Lepri E, Agliani G, Gobbi M, Gröne A, van den Brand JMA, Savini G, Mandara MT. West Nile Virus and Usutu Virus: A Post-Mortem Monitoring Study in Wild Birds from Rescue Centers, Central Italy. Viruses 2022; 14:v14091994. [PMID: 36146800 PMCID: PMC9503110 DOI: 10.3390/v14091994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 08/29/2022] [Accepted: 09/07/2022] [Indexed: 11/16/2022] Open
Abstract
West Nile virus (WNV) and Usutu virus (USUV) are mosquito-borne flaviviruses that have been associated with neurological diseases in humans and wild birds. Wild bird rescue centers are potential significant hot spots for avian infection surveillance, as recognized in the Italian Integrate National Surveillance Plan for Arboviruses. Here we report the results of a post-mortem active monitoring study conducted from November 2017 to October 2020 on animals hosted in five wild bird rescue centers of Central Italy. Five hundred seventy-six (n = 576) wild birds were tested by real-time polymerase chain reaction (RT-PCR) for the presence of WNV or USUV RNA fragments. No birds tested positive for USUV RNA (n = 0; 0.00%). Evidence of WNV RNA (Ct value = 34.36) was found in one bird (n = 1; 0.17%), an adult little grebe (Tachybaptus ruficollis subsp. ruficollis), that tested WNV positive in December 2019. This study highlights the strategic role of wildlife rescue centers in monitoring both the introduction and circulation of avian emerging zoonotic diseases. In addition, the presence of WNV during the cold season evidences the possible role of birds in overwintering mechanisms in the Italian territory and requires further investigations.
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Affiliation(s)
- Giuseppe Giglia
- Division of Pathology, Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, 3584 CL Utrecht, The Netherlands
- Department of Veterinary Medicine, University of Perugia, 06126 Perugia, Italy
- Correspondence:
| | - Giulia Mencattelli
- OIE National Reference Center for West Nile Disease, Istituto Zooprofilattico Sperimentale, dell’Abruzzo e Molise “G. Caporale”, 64100 Teramo, Italy
- Center Agriculture Food Environment, University of Trento, 38098 San Michele all’Adige, Italy
- Research and Innovation Centre, Fondazione Edmund Mach, 38098 San Michele all’Adige, Italy
| | - Elvio Lepri
- Department of Veterinary Medicine, University of Perugia, 06126 Perugia, Italy
| | - Gianfilippo Agliani
- Division of Pathology, Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, 3584 CL Utrecht, The Netherlands
| | - Marco Gobbi
- Department of Veterinary Medicine, University of Perugia, 06126 Perugia, Italy
- Istituto Zooprofilattico Sperimentale dell’Umbria e delle Marche “T. Rosati”, 06126 Perugia, Italy
| | - Andrea Gröne
- Division of Pathology, Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, 3584 CL Utrecht, The Netherlands
- Dutch Wildlife Health Centre, Utrecht University, 3584 CL Utrecht, The Netherlands
| | - Judith M. A. van den Brand
- Division of Pathology, Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, 3584 CL Utrecht, The Netherlands
- Dutch Wildlife Health Centre, Utrecht University, 3584 CL Utrecht, The Netherlands
| | - Giovanni Savini
- OIE National Reference Center for West Nile Disease, Istituto Zooprofilattico Sperimentale, dell’Abruzzo e Molise “G. Caporale”, 64100 Teramo, Italy
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Mencattelli G, Iapaolo F, Polci A, Marcacci M, Di Gennaro A, Teodori L, Curini V, Di Lollo V, Secondini B, Scialabba S, Gobbi M, Manuali E, Cammà C, Rosà R, Rizzoli A, Monaco F, Savini G. West Nile Virus Lineage 2 Overwintering in Italy. Trop Med Infect Dis 2022; 7:tropicalmed7080160. [PMID: 36006252 PMCID: PMC9414329 DOI: 10.3390/tropicalmed7080160] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 07/27/2022] [Accepted: 07/29/2022] [Indexed: 12/24/2022] Open
Abstract
In January 2022, West Nile virus (WNV) lineage 2 (L2) was detected in an adult female goshawk rescued near Perugia in the region of Umbria (Italy). The animal showed neurological symptoms and died 15 days after its recovery in a wildlife rescue center. This was the second case of WNV infection recorded in birds in the Umbria region during the cold season, when mosquitoes, the main WNV vectors, are usually not active. According to the National Surveillance Plan, the Umbria region is included amongst the WNV low-risk areas. The necropsy evidenced generalized pallor of the mucous membranes, mild splenomegaly, and cerebral edema. WNV L2 was detected in the brain, heart, kidney, and spleen homogenate using specific RT-PCR. Subsequently, the extracted viral RNA was sequenced. A Bayesian phylogenetic analysis performed through a maximum-likelihood tree showed that the genome sequence clustered with the Italian strains within the European WNV strains among the central-southern European WNV L2 clade. These results, on the one hand, confirmed that the WNV L2 strains circulating in Italy are genetically stable and, on the other hand, evidenced a continuous WNV circulation in Italy throughout the year. In this report case, a bird-to-bird WNV transmission was suggested to support the virus overwintering. The potential transmission through the oral route in a predatory bird may explain the relatively rapid spread of WNV, as well as other flaviviruses characterized by similar transmission patterns. However, rodent-to-bird transmission or mosquito-to-bird transmission cannot be excluded, and further research is needed to better understand WNV transmission routes during the winter season in Italy.
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Affiliation(s)
- Giulia Mencattelli
- Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise, 64100 Teramo, Italy; (F.I.); (A.P.); (M.M.); (A.D.G.); (L.T.); (V.C.); (V.D.L.); (B.S.); (S.S.); (C.C.); (F.M.); (G.S.)
- Center Agriculture Food Environment, University of Trento, 38098 Trento, Italy;
- Fondazione Edmund Mach, Research and Innovation Centre, San Michele all’Adige, 38098 Trento, Italy;
- Correspondence:
| | - Federica Iapaolo
- Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise, 64100 Teramo, Italy; (F.I.); (A.P.); (M.M.); (A.D.G.); (L.T.); (V.C.); (V.D.L.); (B.S.); (S.S.); (C.C.); (F.M.); (G.S.)
| | - Andrea Polci
- Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise, 64100 Teramo, Italy; (F.I.); (A.P.); (M.M.); (A.D.G.); (L.T.); (V.C.); (V.D.L.); (B.S.); (S.S.); (C.C.); (F.M.); (G.S.)
| | - Maurilia Marcacci
- Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise, 64100 Teramo, Italy; (F.I.); (A.P.); (M.M.); (A.D.G.); (L.T.); (V.C.); (V.D.L.); (B.S.); (S.S.); (C.C.); (F.M.); (G.S.)
| | - Annapia Di Gennaro
- Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise, 64100 Teramo, Italy; (F.I.); (A.P.); (M.M.); (A.D.G.); (L.T.); (V.C.); (V.D.L.); (B.S.); (S.S.); (C.C.); (F.M.); (G.S.)
| | - Liana Teodori
- Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise, 64100 Teramo, Italy; (F.I.); (A.P.); (M.M.); (A.D.G.); (L.T.); (V.C.); (V.D.L.); (B.S.); (S.S.); (C.C.); (F.M.); (G.S.)
| | - Valentina Curini
- Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise, 64100 Teramo, Italy; (F.I.); (A.P.); (M.M.); (A.D.G.); (L.T.); (V.C.); (V.D.L.); (B.S.); (S.S.); (C.C.); (F.M.); (G.S.)
| | - Valeria Di Lollo
- Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise, 64100 Teramo, Italy; (F.I.); (A.P.); (M.M.); (A.D.G.); (L.T.); (V.C.); (V.D.L.); (B.S.); (S.S.); (C.C.); (F.M.); (G.S.)
| | - Barbara Secondini
- Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise, 64100 Teramo, Italy; (F.I.); (A.P.); (M.M.); (A.D.G.); (L.T.); (V.C.); (V.D.L.); (B.S.); (S.S.); (C.C.); (F.M.); (G.S.)
| | - Silvia Scialabba
- Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise, 64100 Teramo, Italy; (F.I.); (A.P.); (M.M.); (A.D.G.); (L.T.); (V.C.); (V.D.L.); (B.S.); (S.S.); (C.C.); (F.M.); (G.S.)
| | - Marco Gobbi
- Istituto Zooprofilattico Sperimentale dell’Umbria e delle Marche “Togo Rosati”, 06126 Perugia, Italy; (M.G.); (E.M.)
| | - Elisabetta Manuali
- Istituto Zooprofilattico Sperimentale dell’Umbria e delle Marche “Togo Rosati”, 06126 Perugia, Italy; (M.G.); (E.M.)
| | - Cesare Cammà
- Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise, 64100 Teramo, Italy; (F.I.); (A.P.); (M.M.); (A.D.G.); (L.T.); (V.C.); (V.D.L.); (B.S.); (S.S.); (C.C.); (F.M.); (G.S.)
| | - Roberto Rosà
- Center Agriculture Food Environment, University of Trento, 38098 Trento, Italy;
| | - Annapaola Rizzoli
- Fondazione Edmund Mach, Research and Innovation Centre, San Michele all’Adige, 38098 Trento, Italy;
| | - Federica Monaco
- Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise, 64100 Teramo, Italy; (F.I.); (A.P.); (M.M.); (A.D.G.); (L.T.); (V.C.); (V.D.L.); (B.S.); (S.S.); (C.C.); (F.M.); (G.S.)
| | - Giovanni Savini
- Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise, 64100 Teramo, Italy; (F.I.); (A.P.); (M.M.); (A.D.G.); (L.T.); (V.C.); (V.D.L.); (B.S.); (S.S.); (C.C.); (F.M.); (G.S.)
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Reemtsma H, Holicki CM, Fast C, Bergmann F, Eiden M, Groschup MH, Ziegler U. Pathogenesis of West Nile Virus Lineage 2 in Domestic Geese after Experimental Infection. Viruses 2022; 14:v14061319. [PMID: 35746790 PMCID: PMC9230372 DOI: 10.3390/v14061319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Revised: 06/03/2022] [Accepted: 06/14/2022] [Indexed: 11/18/2022] Open
Abstract
West Nile virus (WNV) is an emerging infectious pathogen circulating between mosquitoes and birds but also infecting mammals. WNV has become autochthonous in Germany, causing striking mortality rates in avifauna and occasional diseases in humans and horses. We therefore wanted to assess the possible role of free-ranging poultry in the WNV transmission cycle and infected 15 goslings with WNV lineage 2 (German isolate). The geese were monitored daily and sampled regularly to determine viremia, viral shedding, and antibody development by molecular and serological methods. Geese were euthanized at various time points post-infection (pi). All infected geese developed variable degrees of viremia from day 1 to day 10 (maximum) and actively shed virus from days 2 to 7 post-infection. Depending on the time of death, the WN viral genome was detected in all examined tissue samples in at least one individual by RT-qPCR and viable virus was even re-isolated, except for in the liver. Pathomorphological lesions as well as immunohistochemically detectable viral antigens were found mainly in the brain. Furthermore, all of the geese seroconverted 6 days pi at the latest. In conclusion, geese are presumably not functioning as important amplifying hosts but are suitable sentinel animals for WNV surveillance.
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Blahove MR, Carter JR. Flavivirus Persistence in Wildlife Populations. Viruses 2021; 13:v13102099. [PMID: 34696529 PMCID: PMC8541186 DOI: 10.3390/v13102099] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 10/01/2021] [Accepted: 10/08/2021] [Indexed: 12/14/2022] Open
Abstract
A substantial number of humans are at risk for infection by vector-borne flaviviruses, resulting in considerable morbidity and mortality worldwide. These viruses also infect wildlife at a considerable rate, persistently cycling between ticks/mosquitoes and small mammals and reptiles and non-human primates and humans. Substantially increasing evidence of viral persistence in wildlife continues to be reported. In addition to in humans, viral persistence has been shown to establish in mammalian, reptile, arachnid, and mosquito systems, as well as insect cell lines. Although a considerable amount of research has centered on the potential roles of defective virus particles, autophagy and/or apoptosis-induced evasion of the immune response, and the precise mechanism of these features in flavivirus persistence have yet to be elucidated. In this review, we present findings that aid in understanding how vector-borne flavivirus persistence is established in wildlife. Research studies to be discussed include determining the critical roles universal flavivirus non-structural proteins played in flaviviral persistence, the advancement of animal models of viral persistence, and studying host factors that allow vector-borne flavivirus replication without destructive effects on infected cells. These findings underscore the viral–host relationships in wildlife animals and could be used to elucidate the underlying mechanisms responsible for the establishment of viral persistence in these animals.
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Pathogenesis of Two Western Mediterranean West Nile Virus Lineage 1 Isolates in Experimentally Infected Red-Legged Partridges ( Alectoris rufa). Pathogens 2021; 10:pathogens10060748. [PMID: 34199167 PMCID: PMC8231501 DOI: 10.3390/pathogens10060748] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2021] [Revised: 06/06/2021] [Accepted: 06/10/2021] [Indexed: 11/17/2022] Open
Abstract
West Nile virus (WNV) is the most widespread flavivirus in the world with a wide vertebrate host range. Its geographic expansion and activity continue to increase with important human and equine outbreaks and local bird mortality. In a previous experiment, we demonstrated the susceptibility of 7-week-old red-legged partridges (Alectoris rufa) to Mediterranean WNV isolates Morocco/2003 and Spain/2007, which varied in virulence for this gallinaceous species. Here we study the pathogenesis of the infection with these two strains to explain the different course of infection and mortality. Day six post-inoculation was critical in the course of infection, with the highest viral load in tissues, the most widespread virus antigen, and more severe lesions. The most affected organs were the heart, liver, and spleen. Comparing infections with Morocco/2003 and Spain/2007, differences were observed in the viral load, virus antigen distribution, and lesion nature and severity. A more acute and marked inflammatory reaction (characterized by participation of microglia and CD3+ T cells) as well as neuronal necrosis in the brain were observed in partridges infected with Morocco/2003 as compared to those infected with Spain/2007. This suggests a higher neurovirulence of Morocco/2003, probably related to one or more specific molecular determinants of virulence different from Spain/2007.
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Saiz JC, Martín-Acebes MA, Blázquez AB, Escribano-Romero E, Poderoso T, Jiménez de Oya N. Pathogenicity and virulence of West Nile virus revisited eight decades after its first isolation. Virulence 2021; 12:1145-1173. [PMID: 33843445 PMCID: PMC8043182 DOI: 10.1080/21505594.2021.1908740] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
West Nile virus (WNV) is a flavivirus which transmission cycle is maintained between mosquitoes and birds, although it occasionally causes sporadic outbreaks in horses and humans that can result in serious diseases and even death. Since its first isolation in Africa in 1937, WNV had been considered a neglected pathogen until its recent spread throughout Europe and the colonization of America, regions where it continues to cause outbreaks with severe neurological consequences in humans and horses. Although our knowledge about the characteristics and consequences of the virus has increased enormously lately, many questions remain to be resolved. Here, we thoroughly update our knowledge of different aspects of the WNV life cycle: virology and molecular classification, host cell interactions, transmission dynamics, host range, epidemiology and surveillance, immune response, clinical presentations, pathogenesis, diagnosis, prophylaxis (antivirals and vaccines), and prevention, and we highlight those aspects that are still unknown and that undoubtedly require further investigation.
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Affiliation(s)
- Juan-Carlos Saiz
- Department of Biotechnology, National Institute for Agricultural and Food Research and Technology (INIA), Madrid, Spain
| | - Miguel A Martín-Acebes
- Department of Biotechnology, National Institute for Agricultural and Food Research and Technology (INIA), Madrid, Spain
| | - Ana B Blázquez
- Department of Biotechnology, National Institute for Agricultural and Food Research and Technology (INIA), Madrid, Spain
| | - Estela Escribano-Romero
- Department of Biotechnology, National Institute for Agricultural and Food Research and Technology (INIA), Madrid, Spain
| | - Teresa Poderoso
- Molecular Virology Group, Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona, Spain
| | - Nereida Jiménez de Oya
- Department of Biotechnology, National Institute for Agricultural and Food Research and Technology (INIA), Madrid, Spain
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10
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Pathogenicity of West Nile Virus Lineage 1 to German Poultry. Vaccines (Basel) 2020; 8:vaccines8030507. [PMID: 32899581 PMCID: PMC7563189 DOI: 10.3390/vaccines8030507] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 08/27/2020] [Accepted: 09/02/2020] [Indexed: 12/17/2022] Open
Abstract
West Nile virus (WNV) is a mosquito-borne virus that originates from Africa and at present causes neurological disease in birds, horses, and humans all around the globe. As West Nile fever is an important zoonosis, the role of free-ranging domestic poultry as a source of infection for humans should be evaluated. This study examined the pathogenicity of an Italian WNV lineage 1 strain for domestic poultry (chickens, ducks, and geese) held in Germany. All three species were subcutaneously injected with WNV, and the most susceptible species was also inoculated via mosquito bite. All species developed various degrees of viremia, viral shedding (oropharyngeal and cloacal), virus accumulation, and pathomorphological lesions. Geese were most susceptible, displaying the highest viremia levels. The tested waterfowl, geese, and especially ducks proved to be ideal sentinel species for WNV due to their high antibody levels and relatively low blood viral loads. None of the three poultry species can function as a reservoir/amplifying host for WNV, as their viremia levels most likely do not suffice to infect feeding mosquitoes. Due to the recent appearance of WNV in Germany, future pathogenicity studies should also include local virus strains.
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11
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West Nile Virus: An Update on Pathobiology, Epidemiology, Diagnostics, Control and "One Health" Implications. Pathogens 2020; 9:pathogens9070589. [PMID: 32707644 PMCID: PMC7400489 DOI: 10.3390/pathogens9070589] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2020] [Revised: 07/16/2020] [Accepted: 07/16/2020] [Indexed: 02/06/2023] Open
Abstract
West Nile virus (WNV) is an important zoonotic flavivirus responsible for mild fever to severe, lethal neuroinvasive disease in humans, horses, birds, and other wildlife species. Since its discovery, WNV has caused multiple human and animal disease outbreaks in all continents, except Antarctica. Infections are associated with economic losses, mainly due to the cost of treatment of infected patients, control programmes, and loss of animals and animal products. The pathogenesis of WNV has been extensively investigated in natural hosts as well as in several animal models, including rodents, lagomorphs, birds, and reptiles. However, most of the proposed pathogenesis hypotheses remain contentious, and much remains to be elucidated. At the same time, the unavailability of specific antiviral treatment or effective and safe vaccines contribute to the perpetuation of the disease and regular occurrence of outbreaks in both endemic and non-endemic areas. Moreover, globalisation and climate change are also important drivers of the emergence and re-emergence of the virus and disease. Here, we give an update of the pathobiology, epidemiology, diagnostics, control, and “One Health” implications of WNV infection and disease.
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12
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Duggal NK, Langwig KE, Ebel GD, Brault AC. On the Fly: Interactions Between Birds, Mosquitoes, and Environment That Have Molded West Nile Virus Genomic Structure Over Two Decades. JOURNAL OF MEDICAL ENTOMOLOGY 2019; 56:1467-1474. [PMID: 31549720 PMCID: PMC7182917 DOI: 10.1093/jme/tjz112] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Indexed: 05/15/2023]
Abstract
West Nile virus (WNV) was first identified in North America almost 20 yr ago. In that time, WNV has crossed the continent and established enzootic transmission cycles, resulting in intermittent outbreaks of human disease that have largely been linked with climatic variables and waning avian seroprevalence. During the transcontinental dissemination of WNV, the original genotype has been displaced by two principal extant genotypes which contain an envelope mutation that has been associated with enhanced vector competence by Culex pipiens L. (Diptera: Culicidae) and Culex tarsalis Coquillett vectors. Analyses of retrospective avian host competence data generated using the founding NY99 genotype strain have demonstrated a steady reduction in viremias of house sparrows over time. Reciprocally, the current genotype strains WN02 and SW03 have demonstrated an inverse correlation between house sparrow viremia magnitude and the time since isolation. These data collectively indicate that WNV has evolved for increased avian viremia while house sparrows have evolved resistance to the virus such that the relative host competence has remained constant. Intrahost analyses of WNV evolution demonstrate that selection pressures are avian species-specific and purifying selection is greater in individual birds compared with individual mosquitoes, suggesting that the avian adaptive and/or innate immune response may impose a selection pressure on WNV. Phylogenomic, experimental evolutionary systems, and models that link viral evolution with climate, host, and vector competence studies will be needed to identify the relative effect of different selective and stochastic mechanisms on viral phenotypes and the capacity of newly evolved WNV genotypes for transmission in continuously changing landscapes.
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Affiliation(s)
- Nisha K Duggal
- Department of Biomedical Sciences and Pathobiology, Virginia Polytechnic Institute and State University, Blacksburg, VA
| | - Kate E Langwig
- Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA
| | - Gregory D Ebel
- Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO
| | - Aaron C Brault
- Division of Vector-borne Diseases, Centers for Disease Control and Prevention, Fort Collins, CO
- Corresponding author, e-mail:
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13
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Reisen WK, Wheeler SS. Overwintering of West Nile Virus in the United States. JOURNAL OF MEDICAL ENTOMOLOGY 2019; 56:1498-1507. [PMID: 31549726 DOI: 10.1093/jme/tjz070] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Indexed: 06/10/2023]
Abstract
The establishment of a tropical virus such as West Nile (WNV; Flaviviridae: Flavivirus) within the temperate latitudes of the continental United States was unexpected and perhaps contingent, in part, upon the ability of this invasive virus to persist during winter when temperatures become too cold for replication and vector mosquito gonotrophic activity. Our Forum article reviews research examining possible overwintering mechanisms that include consistent reintroduction and local persistence in vector mosquitoes and avian hosts, mostly using examples from research conducted in California. We conclude that the transmission of WNV involves so many vectors and hosts within different landscapes that multiple overwintering pathways are possible and collectively may be necessary to allow this virus to overwinter consistently within the United States.
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Affiliation(s)
- William K Reisen
- Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, CA
| | - Sarah S Wheeler
- Sacramento-Yolo Mosquito and Vector Control District, Elk Grove, CA
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14
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Jiménez de Oya N, Escribano-Romero E, Blázquez AB, Martín-Acebes MA, Saiz JC. Current Progress of Avian Vaccines Against West Nile Virus. Vaccines (Basel) 2019; 7:vaccines7040126. [PMID: 31547632 PMCID: PMC6963603 DOI: 10.3390/vaccines7040126] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 09/19/2019] [Accepted: 09/19/2019] [Indexed: 01/15/2023] Open
Abstract
Birds are the main natural host of West Nile virus (WNV), the worldwide most distributed mosquito-borne flavivirus, but humans and equids can also be sporadic hosts. Many avian species have been reported as susceptible to WNV, particularly corvids. In the case that clinical disease develops in birds, this is due to virus invasion of different organs: liver, spleen, kidney, heart, and mainly the central nervous system, which can lead to death 24–48 h later. Nowadays, vaccines have only been licensed for use in equids; thus, the availability of avian vaccines would benefit bird populations, both domestic and wild ones. Such vaccines could be used in endangered species housed in rehabilitation and wildlife reserves, and in animals located at zoos and other recreational installations, but also in farm birds, and in those that are grown for hunting and restocking activities. Even more, controlling WNV infection in birds can also be useful to prevent its spread and limit outbreaks. So far, different commercial and experimental vaccines (inactivated, attenuated, and recombinant viruses, and subunits and DNA-based candidates) have been evaluated, with various regimens, both in domestic and wild avian species. However, there are still disadvantages that must be overcome before avian vaccination can be implemented, such as its cost-effectiveness for domestic birds since in many species the pathogenicity is low or zero, or the viability of being able to achieve collective immunity in wild birds in freedom. Here, a comprehensive review of what has been done until now in the field of avian vaccines against WNV is presented and discussed.
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Affiliation(s)
- Nereida Jiménez de Oya
- Department of Biotechnology, National Agricultural and Food Research and Technology Institute (INIA), 28040 Madrid, Spain.
| | - Estela Escribano-Romero
- Department of Biotechnology, National Agricultural and Food Research and Technology Institute (INIA), 28040 Madrid, Spain.
| | - Ana-Belén Blázquez
- Department of Biotechnology, National Agricultural and Food Research and Technology Institute (INIA), 28040 Madrid, Spain.
| | - Miguel A Martín-Acebes
- Department of Biotechnology, National Agricultural and Food Research and Technology Institute (INIA), 28040 Madrid, Spain.
| | - Juan-Carlos Saiz
- Department of Biotechnology, National Agricultural and Food Research and Technology Institute (INIA), 28040 Madrid, Spain.
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15
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Michel F, Sieg M, Fischer D, Keller M, Eiden M, Reuschel M, Schmidt V, Schwehn R, Rinder M, Urbaniak S, Müller K, Schmoock M, Lühken R, Wysocki P, Fast C, Lierz M, Korbel R, Vahlenkamp TW, Groschup MH, Ziegler U. Evidence for West Nile Virus and Usutu Virus Infections in Wild and Resident Birds in Germany, 2017 and 2018. Viruses 2019; 11:v11070674. [PMID: 31340516 PMCID: PMC6669720 DOI: 10.3390/v11070674] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 07/18/2019] [Accepted: 07/18/2019] [Indexed: 11/26/2022] Open
Abstract
Wild birds play an important role as reservoir hosts and vectors for zoonotic arboviruses and foster their spread. Usutu virus (USUV) has been circulating endemically in Germany since 2011, while West Nile virus (WNV) was first diagnosed in several bird species and horses in 2018. In 2017 and 2018, we screened 1709 live wild and zoo birds with real-time polymerase chain reaction and serological assays. Moreover, organ samples from bird carcasses submitted in 2017 were investigated. Overall, 57 blood samples of the live birds (2017 and 2018), and 100 organ samples of dead birds (2017) were positive for USUV-RNA, while no WNV-RNA-positive sample was found. Phylogenetic analysis revealed the first detection of USUV lineage Europe 2 in Germany and the spread of USUV lineages Europe 3 and Africa 3 towards Northern Germany. USUV antibody prevalence rates were high in Eastern Germany in both years. On the contrary, in Northern Germany, high seroprevalence rates were first detected in 2018, with the first emergence of USUV in this region. Interestingly, high WNV-specific neutralizing antibody titers were observed in resident and short-distance migratory birds in Eastern Germany in 2018, indicating the first signs of a local WNV circulation.
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Affiliation(s)
- Friederike Michel
- Friedrich-Loeffler Insitut (FLI), Federal Research Institute for Animal Health, Institute of Novel and Emerging Infectious Diseases, Südufer 10, D-17493 Greifswald-Insel Riems, Germany
- German Centre for Infection Research (DZIF), Partner Site Hamburg-Luebeck-Borstel, 17493 Greifswald-Insel Riems, Germany
| | - Michael Sieg
- Institute of Virology (Faculty of veterinary medicine), Leipzig University, An den Tierkliniken 29, D-04103 Leipzig, Germany
| | - Dominik Fischer
- Clinic for Birds, Reptiles, Amphibians and Fish, Justus Liebig University Giessen, Frankfurter Straße 91, D-35392 Giessen, Germany
| | - Markus Keller
- Friedrich-Loeffler Insitut (FLI), Federal Research Institute for Animal Health, Institute of Novel and Emerging Infectious Diseases, Südufer 10, D-17493 Greifswald-Insel Riems, Germany
| | - Martin Eiden
- Friedrich-Loeffler Insitut (FLI), Federal Research Institute for Animal Health, Institute of Novel and Emerging Infectious Diseases, Südufer 10, D-17493 Greifswald-Insel Riems, Germany
| | - Maximilian Reuschel
- Clinic for Small Mammals, Reptiles and Birds, University of Veterinary Medicine Hannover, Foundation, Bünteweg 9, D-30559 Hannover, Germany
| | - Volker Schmidt
- Clinic for Birds and Reptiles (Faculty of veterinary medicine), Leipzig University, An den Tierkliniken 17, D-04103 Leipzig, Germany
| | - Rebekka Schwehn
- Clinic for Small Mammals, Reptiles and Birds, University of Veterinary Medicine Hannover, Foundation, Bünteweg 9, D-30559 Hannover, Germany
- Seehundstation Nationalpark-Haus Norden-Norddeich, Dörper Weg 24, D-26506 Norden, Germany
| | - Monika Rinder
- Clinic for Birds, Small Mammals, Reptiles and Ornamental Fish, Centre for Clinical Veterinary Medicine, Ludwig Maximilians University Munich, Sonnenstraße 18, D-85764 Oberschleißheim, Germany
| | - Sylvia Urbaniak
- Birds of Prey Rehab Center Rhineland (Greifvogelhilfe Rheinland)/Tierarztpraxis Sudhoff, Hehnerholt 105, D-41069 Mönchengladbach, Germany
| | - Kerstin Müller
- Department of Veterinary Medicine, Small Animal Clinic, Freie Universität Berlin, Oertzenweg 19 b, D-14163 Berlin, Germany
| | - Martina Schmoock
- Wildpark Schwarze Berge GmbH & Co. KG, Am Wildpark 1, D-21224 Rosengarten, Germany
- Tiermedizin am Rothenbaum, Rothenbaumchaussee 195, D-20149 Hamburg, Germany
| | - Renke Lühken
- Bernhard-Nocht-Institute for Tropical Medicine, WHO Collaborating Centre for Arbovirus and Hemorrhagic Fever Reference and Research, Bernhardt-Nocht Straße 74, D-20359 Hamburg, Germany
| | - Patrick Wysocki
- Friedrich-Loeffler-Institut (FLI), Federal Research Institute for Animal Health, Institute of Epidemiology, Südufer 10, D-17493 Greifswald-Insel Riems, Germany
| | - Christine Fast
- Friedrich-Loeffler Insitut (FLI), Federal Research Institute for Animal Health, Institute of Novel and Emerging Infectious Diseases, Südufer 10, D-17493 Greifswald-Insel Riems, Germany
| | - Michael Lierz
- Clinic for Birds, Reptiles, Amphibians and Fish, Justus Liebig University Giessen, Frankfurter Straße 91, D-35392 Giessen, Germany
| | - Rüdiger Korbel
- Clinic for Birds, Small Mammals, Reptiles and Ornamental Fish, Centre for Clinical Veterinary Medicine, Ludwig Maximilians University Munich, Sonnenstraße 18, D-85764 Oberschleißheim, Germany
| | - Thomas W Vahlenkamp
- Institute of Virology (Faculty of veterinary medicine), Leipzig University, An den Tierkliniken 29, D-04103 Leipzig, Germany
| | - Martin H Groschup
- Friedrich-Loeffler Insitut (FLI), Federal Research Institute for Animal Health, Institute of Novel and Emerging Infectious Diseases, Südufer 10, D-17493 Greifswald-Insel Riems, Germany
- German Centre for Infection Research (DZIF), Partner Site Hamburg-Luebeck-Borstel, 17493 Greifswald-Insel Riems, Germany
| | - Ute Ziegler
- Friedrich-Loeffler Insitut (FLI), Federal Research Institute for Animal Health, Institute of Novel and Emerging Infectious Diseases, Südufer 10, D-17493 Greifswald-Insel Riems, Germany.
- German Centre for Infection Research (DZIF), Partner Site Hamburg-Luebeck-Borstel, 17493 Greifswald-Insel Riems, Germany.
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16
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Swetnam D, Widen SG, Wood TG, Reyna M, Wilkerson L, Debboun M, Symonds DA, Mead DG, Beaty BJ, Guzman H, Tesh RB, Barrett ADT. Terrestrial Bird Migration and West Nile Virus Circulation, United States. Emerg Infect Dis 2019; 24:2184-2194. [PMID: 30457531 PMCID: PMC6256381 DOI: 10.3201/eid2412.180382] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Host migration and emerging pathogens are strongly associated, especially with regard to zoonotic diseases. West Nile virus (WNV), a mosquitoborne pathogen capable of causing severe, sometimes fatal, neuroinvasive disease in humans, is maintained in highly mobile avian hosts. Using phylogeographic approaches, we investigated the relationship between WNV circulation in the United States and the flight paths of terrestrial birds. We demonstrated southward migration of WNV in the eastern flyway and northward migration in the central flyway, which is consistent with the looped flight paths of many terrestrial birds. We also identified 3 optimal locations for targeted WNV surveillance campaigns in the United States—Illinois, New York, and Texas. These results illustrate the value of multidisciplinary approaches to surveillance of infectious diseases, especially zoonotic diseases.
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17
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Benzarti E, Linden A, Desmecht D, Garigliany M. Mosquito-borne epornitic flaviviruses: an update and review. J Gen Virol 2019; 100:119-132. [PMID: 30628886 DOI: 10.1099/jgv.0.001203] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
West Nile Virus, Usutu virus, Bagaza virus, Israel turkey encephalitis virus and Tembusu virus currently constitute the five flaviviruses transmitted by mosquito bites with a marked pathogenicity for birds. They have been identified as the causative agents of severe neurological symptoms, drop in egg production and/or mortalities among avian hosts. They have also recently shown an expansion of their geographic distribution and/or a rise in cases of human infection. This paper is the first up-to-date review of the pathology of these flaviviruses in birds, with a special emphasis on the difference in susceptibility among avian species, in order to understand the specificity of the host spectrum of each of these viruses. Furthermore, given the lack of a clear prophylactic approach against these viruses in birds, a meta-analysis of vaccination trials conducted to date on these animals is given to constitute a solid platform from which designing future studies.
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Affiliation(s)
- Emna Benzarti
- 1FARAH Research Center, Department of Pathology, Faculty of Veterinary Medicine, University of Liège, Sart Tilman B43, B-4000 Liège, Belgium
| | - Annick Linden
- 2FARAH Research Center, Surveillance Network for Wildlife Diseases, Faculty of Veterinary Medicine, University of Liège, Sart Tilman B43, B-4000 Liège, Belgium
| | - Daniel Desmecht
- 1FARAH Research Center, Department of Pathology, Faculty of Veterinary Medicine, University of Liège, Sart Tilman B43, B-4000 Liège, Belgium
| | - Mutien Garigliany
- 1FARAH Research Center, Department of Pathology, Faculty of Veterinary Medicine, University of Liège, Sart Tilman B43, B-4000 Liège, Belgium
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18
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Townsend AK, Taff CC, Wheeler SS, Weis AM, Hinton MG, Jones ML, Logsdon RM, Reisen WK, Freund D, Sehgal RNM, Saberi M, Suh YH, Hurd J, Boyce WM. Low heterozygosity is associated with vector‐borne disease in crows. Ecosphere 2018. [DOI: 10.1002/ecs2.2407] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Affiliation(s)
| | - Conor C. Taff
- Cornell University Laboratory of Ornithology Ithaca New York 14850 USA
| | - Sarah S. Wheeler
- Sacramento‐Yolo Mosquito and Vector Control District Elk Grove California 95624 USA
| | - Allison M. Weis
- Department of Population Health and Reproduction School of Veterinary Medicine 100K Pathogen Genome Project University of California Davis California 95616 USA
| | - Mitch G. Hinton
- Animal Behavior Graduate Group University of California Davis California 95616 USA
| | - Melissa L. Jones
- Avian Sciences Graduate Group University of California Davis California 95616 USA
| | - Ryane M. Logsdon
- Animal Behavior Graduate Group University of California Davis California 95616 USA
| | - William K. Reisen
- Department of Pathology, Microbiology, and Immunology School of Veterinary Medicine University of California Davis California 95616 USA
| | - David Freund
- Department of Biology San Francisco State University San Francisco California 94132 USA
| | - Ravinder N. M. Sehgal
- Department of Biology San Francisco State University San Francisco California 94132 USA
| | - Mojan Saberi
- Department of Wildlife, Fish, and Conservation Biology University of California Davis California 95616 USA
| | - Young Ha Suh
- Department of Ecology and Evolutionary Biology Cornell University Ithaca New York 14853 USA
| | - Jacqueline Hurd
- Department of Wildlife, Fish, and Conservation Biology University of California Davis California 95616 USA
| | - Walter M. Boyce
- Department of Pathology, Microbiology, and Immunology School of Veterinary Medicine University of California Davis California 95616 USA
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19
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Overwintering of West Nile virus in a bird community with a communal crow roost. Sci Rep 2018; 8:6088. [PMID: 29666401 PMCID: PMC5904116 DOI: 10.1038/s41598-018-24133-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 03/22/2018] [Indexed: 02/04/2023] Open
Abstract
In temperate climates, transmission of West Nile virus (WNV) is detectable rarely during the coldest months (late fall through early spring), yet the virus has reappeared consistently during the next warm season. Several mechanisms may contribute to WNV persistence through winter, including bird-to-bird transmission among highly viremic species. Here we consider whether, under realistic scenarios supported by field and laboratory evidence, a winter bird community could sustain WNV through the winter in the absence of mosquitoes. With this purpose we constructed a deterministic model for a community of susceptible birds consisting of communally roosting crows, raptors and other birds. We simulated WNV introduction and subsequent transmission dynamics during the winter under realistic initial conditions and model parameterizations, including plausible contact rates for roosting crows. Model results were used to determine whether the bird community could yield realistic outbreaks that would result in WNV infectious individuals at the end of the winter, which would set up the potential for onward horizontal transmission into summer. Our findings strongly suggest that winter crow roosts could allow for WNV persistence through the winter, and our model results provide synthesis to explain inconclusive results from field studies on WNV overwintering in crow roosts.
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20
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Tamba M, Caminiti A, Prosperi A, Desprès P, Lelli D, Galletti G, Moreno A, Paternoster G, Santi A, Licata E, Lecollinet S, Gelmini L, Rugna G, Procopio A, Lavazza A. Accuracy estimation of an indirect ELISA for the detection of West Nile Virus antibodies in wild birds using a latent class model. J Virol Methods 2017; 248:202-206. [PMID: 28756236 DOI: 10.1016/j.jviromet.2017.07.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Revised: 06/16/2017] [Accepted: 07/19/2017] [Indexed: 11/30/2022]
Abstract
West Nile virus (WNV) and Usutu virus (USUV), genus Flavivirus, are members of the Japanese encephalitis virus antigenic complex, and are maintained primarily in an enzootic cycle between mosquitoes and birds. WNV is zoonotic, and poses a threat to public health, especially in relation to blood transfusion. Serosurveillance of wild birds is suitable for early detection of WNV circulation, although concerns remain to be addressed as regards i) the type of test used, whether ELISA, virus neutralization test (VNT), plaque reduction neutralization test (PRNT), ii) the reagents (antigens, revealing antibodies), iii) the different bird species involved, and iv) potential cross-reactions with other Flaviviruses, such as USUV. The authors developed an indirect IgG ELISA with pan-avian specificity using EDIII protein as antigen and a monoclonal antibody (mAb 1A3) with broad reactivity for avian IgG. A total of 140 serum samples were collected from juvenile European magpies (Pica pica) in areas where both WNV and USUV were co-circulating. The samples were then tested using this in-house ELISA and VNT in parallel. Estimation of test accuracy was performed using different Bayesian two latent class models. At a cut-off set at an optical density percentage (OD%) of 15, the ELISA showed a posterior median of diagnostic sensitivity (DSe) of 88% (95%PCI: 73-99%) and a diagnostic specificity (DSp) of 86% (95%PCI: 68-99%). At this cut-off, ELISA and VNT (cut-off 1/10) performances were comparable: DSe=91% (95%PCI: 79-99%), and DSp=77% (95%PCI: 59-98%). With the cut-off increased to 30 OD%, the ELISA DSe dropped to 78% (95%PCI: 52-99%), and the DSp rose to 94% (95%PCI: 83-100%). In field conditions, the cut-off that yields the best accuracy for the ELISA appears to correspond to 15 OD%. In areas where other Flaviviruses are circulating, however, it might be appropriate to raise the cut-off to 30 OD% in order to achieve higher specificity and reduce the detection of seropositive birds infected by other Flaviviruses, such as USUV.
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Affiliation(s)
- Marco Tamba
- Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna. Via Antonio Bianchi, 7. 25126 Brescia, Italy.
| | - Antonino Caminiti
- Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna. Via Antonio Bianchi, 7. 25126 Brescia, Italy
| | - Alice Prosperi
- Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna. Via Antonio Bianchi, 7. 25126 Brescia, Italy
| | - Philippe Desprès
- La Reunion island University and UM 134 PIMIT, Technology platform CYROI, 97491, Sainte-Clotilde, France
| | - Davide Lelli
- Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna. Via Antonio Bianchi, 7. 25126 Brescia, Italy
| | - Giorgio Galletti
- Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna. Via Antonio Bianchi, 7. 25126 Brescia, Italy
| | - Ana Moreno
- Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna. Via Antonio Bianchi, 7. 25126 Brescia, Italy
| | - Giulia Paternoster
- Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna. Via Antonio Bianchi, 7. 25126 Brescia, Italy
| | - Annalisa Santi
- Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna. Via Antonio Bianchi, 7. 25126 Brescia, Italy
| | - Elio Licata
- Local Health Unit of Modena, Public Health Department. Strada Martiniana, 21.41126, Baggiovara, Modena, Italy
| | - Sylvie Lecollinet
- UMR Virologie, ANSES, INRA, ENVA, Université Paris-Est, 14, rue Pierre et Marie Curie, 94700 Maisons-Alfort, France
| | - Luca Gelmini
- Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna. Via Antonio Bianchi, 7. 25126 Brescia, Italy
| | - Gianluca Rugna
- Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna. Via Antonio Bianchi, 7. 25126 Brescia, Italy
| | - Anna Procopio
- Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna. Via Antonio Bianchi, 7. 25126 Brescia, Italy
| | - Antonio Lavazza
- Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna. Via Antonio Bianchi, 7. 25126 Brescia, Italy
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Kuno G, Mackenzie JS, Junglen S, Hubálek Z, Plyusnin A, Gubler DJ. Vertebrate Reservoirs of Arboviruses: Myth, Synonym of Amplifier, or Reality? Viruses 2017; 9:E185. [PMID: 28703771 PMCID: PMC5537677 DOI: 10.3390/v9070185] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 07/10/2017] [Accepted: 07/10/2017] [Indexed: 02/07/2023] Open
Abstract
The rapid succession of the pandemic of arbovirus diseases, such as dengue, West Nile fever, chikungunya, and Zika fever, has intensified research on these and other arbovirus diseases worldwide. Investigating the unique mode of vector-borne transmission requires a clear understanding of the roles of vertebrates. One major obstacle to this understanding is the ambiguity of the arbovirus definition originally established by the World Health Organization. The paucity of pertinent information on arbovirus transmission at the time contributed to the notion that vertebrates played the role of reservoir in the arbovirus transmission cycle. Because this notion is a salient feature of the arbovirus definition, it is important to reexamine its validity. This review addresses controversial issues concerning vertebrate reservoirs and their role in arbovirus persistence in nature, examines the genesis of the problem from a historical perspective, discusses various unresolved issues from multiple points of view, assesses the present status of the notion in light of current knowledge, and provides options for a solution to resolve the issue.
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Affiliation(s)
- Goro Kuno
- Formerly at the Division of Vector-Borne Infectious Diseases, Centers for Control and Prevention, Fort Collins, CO, USA.
| | - John S Mackenzie
- Faculty of Medical Sciences, Curtin University, GPO Box U1987, Perth, WA 6845, Australia.
- Division of Microbiology & Infectious Diseases, PathWest, Nedlands, Western Australia 6009.
| | - Sandra Junglen
- Institute of Virology, Charité-Universitätsmedizin Berlin, Helmut-Ruska-Haus, Chariteplatz 1, 10117 Berlin, Germany.
| | - Zdeněk Hubálek
- Institute of Vertebrate Biology, Academy of Sciences of Czech Republic, 60365 Brno, Czech Republic.
| | - Alexander Plyusnin
- Department of Virology, University of Helsinki, Haartmaninkatu 3, University of Helsinki, 00014 Helsinki, Finland.
| | - Duane J Gubler
- Program in Emerging Infectious Diseases, Duke-NUS Medical School, 8 College Rd., Singapore 169857 Singapore.
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22
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Nyamwaya D, Wang'ondu V, Amimo J, Michuki G, Ogugo M, Ontiri E, Sang R, Lindahl J, Grace D, Bett B. Detection of West Nile virus in wild birds in Tana River and Garissa Counties, Kenya. BMC Infect Dis 2016; 16:696. [PMID: 27881079 PMCID: PMC5121970 DOI: 10.1186/s12879-016-2019-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 11/11/2016] [Indexed: 12/03/2022] Open
Abstract
Background West Nile fever virus is a zoonotic arboviral infection maintained in a sylvatic cycle involving mosquito vectors and birds. It is one the arboviruses whose geographical range is expanding because of climate and land use changes that enhance the densities of mosquitoes and promote mosquito-bird-human interactions. We carried out a survey to determine the reservoirs of WNV among wild birds in Tana River and Garissa counties, Kenya. Methods Blood samples were obtained from 361 randomly trapped wild birds. Using real-time polymerase chain reaction (PCR), all samples were screened for WNV using gene specific primer sets amplifying a portion of the E region of the genome encoding the envelope protein. Results Sixty five (65) out of 361 birds screened tested positive for WNV on real-time PCR assay. Sequencing of the selected positive samples reveals that the isolated WNV were most closely related to strains isolated from China (2011). A regression analysis indicated that sampling location influenced the occurrence of WNV while species, age, weight and sex of the birds did not have any effect. Conclusions This study provides baseline information on the existing circulation of WNV in this region among wild bird reservoirs that could spill over to the human population and points to the need for implementation of surveillance programs to map the distribution of the virus among reservoirs. Awareness creation about West Nile fever in this region is important to improve its detection and management. Electronic supplementary material The online version of this article (doi:10.1186/s12879-016-2019-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Doris Nyamwaya
- International Livestock Research Institute, P. O. Box 30709, 00100, Nairobi, Kenya. .,Department of Microbiology and Marine Botany, School of Biological Sciences, University of Nairobi, P. O. BOX 30197, 00100, Nairobi, Kenya.
| | - Virginia Wang'ondu
- Department of Microbiology and Marine Botany, School of Biological Sciences, University of Nairobi, P. O. BOX 30197, 00100, Nairobi, Kenya
| | - Joshua Amimo
- Faculty of Veterinary Medicine, University of Nairobi, P. O. Box 29053, 00625, Nairobi, Kenya
| | - George Michuki
- International Livestock Research Institute, P. O. Box 30709, 00100, Nairobi, Kenya
| | - Moses Ogugo
- International Livestock Research Institute, P. O. Box 30709, 00100, Nairobi, Kenya
| | - Enoch Ontiri
- International Livestock Research Institute, P. O. Box 30709, 00100, Nairobi, Kenya
| | - Rosemary Sang
- U.S. Army Medical Research Unit (USAMRD-K), P.O. Box 606, 00621, Nairobi, Kenya
| | - Johanna Lindahl
- International Livestock Research Institute, P. O. Box 30709, 00100, Nairobi, Kenya
| | - Delia Grace
- International Livestock Research Institute, P. O. Box 30709, 00100, Nairobi, Kenya
| | - Bernard Bett
- International Livestock Research Institute, P. O. Box 30709, 00100, Nairobi, Kenya.
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Bakonyi T, Gajdon GK, Schwing R, Vogl W, Häbich AC, Thaller D, Weissenböck H, Rudolf I, Hubálek Z, Nowotny N. Chronic West Nile virus infection in kea (Nestor notabilis). Vet Microbiol 2015; 183:135-9. [PMID: 26790946 DOI: 10.1016/j.vetmic.2015.12.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Revised: 12/21/2015] [Accepted: 12/23/2015] [Indexed: 10/22/2022]
Abstract
Six kea (Nestor notabilis) in human care, naturally infected with West Nile virus (WNV) lineage 2 in Vienna, Austria, in 2008, developed mild to fatal neurological signs. WNV RNA persisted and the virus evolved in the birds' brains, as demonstrated by (phylo)genetic analyses of the complete viral genomes detected in kea euthanized between 2009 and 2014. WNV antibodies persisted in the birds, too. Chronic WNV infection in the brain might contribute to the circulation of the virus through oral transmission to predatory birds.
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Affiliation(s)
- Tamás Bakonyi
- Institute of Virology, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210 Vienna, Austria; Department of Microbiology and Infectious Diseases, Faculty of Veterinary Science, Szent István University, Hungária krt. 23-25, 1143 Budapest, Hungary.
| | - Gyula K Gajdon
- Messerli Research Institute, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210 Vienna, Austria.
| | - Raoul Schwing
- Messerli Research Institute, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210 Vienna, Austria.
| | - Wolfgang Vogl
- Konrad Lorenz Institute of Ethology, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210 Vienna, Austria.
| | - Annett-Carolin Häbich
- Clinic for Avian, Reptile and Fish Medicine, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210 Vienna, Austria.
| | - Denise Thaller
- Institute of Pathology and Forensic Veterinary Medicine, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210 Vienna, Austria.
| | - Herbert Weissenböck
- Institute of Pathology and Forensic Veterinary Medicine, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210 Vienna, Austria.
| | - Ivo Rudolf
- Institute of Vertebrate Biology, Academy of Sciences, v.v.i., Kvetná 8, 60365 Brno, Czech Republic.
| | - Zdenek Hubálek
- Institute of Vertebrate Biology, Academy of Sciences, v.v.i., Kvetná 8, 60365 Brno, Czech Republic.
| | - Norbert Nowotny
- Institute of Virology, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210 Vienna, Austria; Department of Microbiology and Immunology, College of Medicine and Health Sciences, Sultan Qaboos University, P.O. Box 35, 123 Al-Khoudh, Oman.
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24
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Wong HV, Vythilingam I, Sulaiman WYW, Lulla A, Merits A, Chan YF, Sam IC. Detection of Persistent Chikungunya Virus RNA but not Infectious Virus in Experimental Vertical Transmission in Aedes aegypti from Malaysia. Am J Trop Med Hyg 2015; 94:182-6. [PMID: 26598564 DOI: 10.4269/ajtmh.15-0318] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 10/19/2015] [Indexed: 01/08/2023] Open
Abstract
Vertical transmission may contribute to the maintenance of arthropod-borne viruses, but its existence in chikungunya virus (CHIKV) is unclear. Experimental vertical transmission of infectious clones of CHIKV in Aedes aegypti mosquitoes from Malaysia was investigated. Eggs and adult progeny from the second gonotrophic cycles of infected parental mosquitoes were tested. Using polymerase chain reaction (PCR), 56.3% of pooled eggs and 10% of adult progeny had detectable CHIKV RNA, but no samples had detectable infectious virus by plaque assay. Transfected CHIKV RNA from PCR-positive eggs did not yield infectious virus in BHK-21 cells. Thus, vertical transmission of viable CHIKV was not demonstrated. Noninfectious CHIKV RNA persists in eggs and progeny of infected Ae. aegypti, but the mechanism and significance are unknown. There is insufficient evidence to conclude that vertical transmission exists in CHIKV, as positive results reported in previous studies were almost exclusively based only on viral RNA detection.
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Affiliation(s)
- Hui Vern Wong
- Department of Medical Microbiology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia; Department of Parasitology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia; Institute of Technology, University of Tartu, Nooruse 1, 50411, Tartu, Estonia
| | - Indra Vythilingam
- Department of Medical Microbiology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia; Department of Parasitology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia; Institute of Technology, University of Tartu, Nooruse 1, 50411, Tartu, Estonia
| | - Wan Yusof Wan Sulaiman
- Department of Medical Microbiology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia; Department of Parasitology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia; Institute of Technology, University of Tartu, Nooruse 1, 50411, Tartu, Estonia
| | - Aleksei Lulla
- Department of Medical Microbiology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia; Department of Parasitology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia; Institute of Technology, University of Tartu, Nooruse 1, 50411, Tartu, Estonia
| | - Andres Merits
- Department of Medical Microbiology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia; Department of Parasitology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia; Institute of Technology, University of Tartu, Nooruse 1, 50411, Tartu, Estonia
| | - Yoke Fun Chan
- Department of Medical Microbiology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia; Department of Parasitology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia; Institute of Technology, University of Tartu, Nooruse 1, 50411, Tartu, Estonia
| | - I-Ching Sam
- Department of Medical Microbiology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia; Department of Parasitology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia; Institute of Technology, University of Tartu, Nooruse 1, 50411, Tartu, Estonia
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Worwa G, Wheeler SS, Brault AC, Reisen WK. Comparing competitive fitness of West Nile virus strains in avian and mosquito hosts. PLoS One 2015; 10:e0125668. [PMID: 25965850 PMCID: PMC4428627 DOI: 10.1371/journal.pone.0125668] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Accepted: 03/23/2015] [Indexed: 11/21/2022] Open
Abstract
Enzootic transmission of West Nile virus (WNV; Flaviviridae, Flavivirus) involves various species of birds and ornithophilic mosquitoes. Single nucleotide substitutions in the WNV genome may impact viral fitness necessary for WNV adaptation and evolution as previously shown for the WN02 genotype. In an effort to study phenotypic change, we developed an in vivo fitness competition model in two biologically relevant hosts for WNV. The House Finch (HOFI; Haemorhous mexicanus) and Culex tarsalis mosquitoes represent moderately susceptible hosts for WNV, are highly abundant in Western North America and frequently are infected with WNV in nature. Herein, we inoculated HOFIs and Cx. tarsalis competitively (dually) and singly with infectious-clone derived viruses of the founding California isolate COAV997-2003 (COAV997-IC), the founding North American isolate NY99 (NY99-IC), and a 2004 field isolate from California (CA-04), and compared the replicative capacities (fitness) of these viruses to a genetically marked virus of COAV997 (COAV997-5nt) by measuring RNA copy numbers. COAV997 and COAV997-5nt exhibited neutral fitness in HOFIs and Cx. tarsalis, and the temperature-sensitive phenotype of COAV997 did not affect replication in HOFIs as none of the infected birds became febrile. The NY99 and CA-04 isolates demonstrated elevated fitness in HOFIs compared to COAV997-5nt, whereas all viruses replicated to similar titers and RNA copies in Cx. tarsalis, and the only fitness differences were related to infection rates. Our data demonstrated that competitive replication allows for the sensitive comparison of fitness differences among two genetically closely related viruses using relevant hosts of WNV while eliminating host-to-host differences. In conclusion, our approach may be helpful in understanding the extent of phenotypic change in fitness associated with genetic changes in WNV.
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Affiliation(s)
- Gabriella Worwa
- Center for Vectorborne Diseases, Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, California, United States of America
| | - Sarah S. Wheeler
- Center for Vectorborne Diseases, Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, California, United States of America
| | - Aaron C. Brault
- Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, Colorado, United States of America
| | - William K. Reisen
- Center for Vectorborne Diseases, Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, California, United States of America
- * E-mail:
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26
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Abstract
Antibody duration, following a humoral immune response to West Nile virus (WNV) infection, is poorly understood in free-ranging avian hosts. Quantifying antibody decay rate is important for interpreting serologic results and for understanding the potential for birds to serorevert and become susceptible again. We sampled free-ranging birds in Chicago, Illinois, US, from 2005 to 2011 and Atlanta, Georgia, US, from 2010 to 2012 to examine the dynamics of antibody decay following natural WNV infection. Using serial dilutions in a blocking enzyme-linked immunosorbent assay, we quantified WNV antibody titer in repeated blood samples from individual birds over time. We quantified a rate of antibody decay for 23 Northern Cardinals (Cardinalis cardinalis) of 0.198 natural log units per month and 24 individuals of other bird species of 0.178 natural log units per month. Our results suggest that juveniles had a higher rate of antibody decay than adults, which is consistent with nonlinear antibody decay at different times postexposure. Overall, most birds had undetectable titers 2 yr postexposure. Nonuniform WNV antibody decay rates in free-ranging birds underscore the need for cautious interpretation of avian serology results in the context of arbovirus surveillance and epidemiology.
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27
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Barton AJ, Prow NA, Hall RA, Kidd L, Bielefeldt-Ohmann H. A case of Murray Valley encephalitis in a 2-year-old Australian Stock Horse in south-east Queensland. Aust Vet J 2015; 93:53-7. [DOI: 10.1111/avj.12294] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/20/2014] [Indexed: 10/23/2022]
Affiliation(s)
- AJ Barton
- School of Veterinary Science; The University of Queensland; Gatton Queensland 4343 Australia
| | - NA Prow
- Australian Infectious Diseases Research Centre; University of Queensland; St Lucia Queensland Australia
| | - RA Hall
- Australian Infectious Diseases Research Centre; University of Queensland; St Lucia Queensland Australia
| | - L Kidd
- School of Veterinary Science; The University of Queensland; Gatton Queensland 4343 Australia
| | - H Bielefeldt-Ohmann
- School of Veterinary Science; The University of Queensland; Gatton Queensland 4343 Australia
- Australian Infectious Diseases Research Centre; University of Queensland; St Lucia Queensland Australia
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28
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Barzon L, Pacenti M, Ulbert S, Palù G. Latest developments and challenges in the diagnosis of human West Nile virus infection. Expert Rev Anti Infect Ther 2015; 13:327-42. [PMID: 25641365 DOI: 10.1586/14787210.2015.1007044] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
West Nile virus (WNV) is a mosquito-borne flavivirus responsible for an increasing number of human outbreaks of neuroinvasive disease in Europe and in North America. Notwithstanding the improvements in the knowledge of virus epidemiology and clinical course of infection and the development of new laboratory tests, the diagnosis of WNV infection remains challenging and many cases still remain unrecognized. WNV genome diversity, transient viremia with low viral load and cross-reactivity with other flaviviruses of the antibodies induced by WNV infection are important hurdles that require the diagnosis to be performed by experienced laboratories. Herein, we present and discuss the novel findings on the molecular epidemiology and clinical features of WNV infection in humans with special focus on Europe, the performance of diagnostic tests and the novel methods that have been developed for the diagnosis of WNV infection. A view on how the field might evolve in the future is also presented.
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Affiliation(s)
- Luisa Barzon
- Department of Molecular Medicine, University of Padova, via A. Gabelli 63, 35121 Padova, Italy
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29
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Mlera L, Melik W, Bloom ME. The role of viral persistence in flavivirus biology. Pathog Dis 2014; 71:137-63. [PMID: 24737600 PMCID: PMC4154581 DOI: 10.1111/2049-632x.12178] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Revised: 04/08/2014] [Accepted: 04/09/2014] [Indexed: 12/30/2022] Open
Abstract
In nature, vector borne flaviviruses are persistently cycled between either the tick or mosquito vector and small mammals such as rodents, skunks, and swine. These viruses account for considerable human morbidity and mortality worldwide. Increasing and substantial evidence of viral persistence in humans, which includes the isolation of RNA by RT PCR and infectious virus by culture, continues to be reported. Viral persistence can also be established in vitro in various human, animal, arachnid, and insect cell lines in culture. Although some research has focused on the potential roles of defective virus particles, evasion of the immune response through the manipulation of autophagy and/or apoptosis, the precise mechanism of flavivirus persistence is still not well understood. We propose additional research for further understanding of how viral persistence is established in different systems. Avenues for additional studies include determining whether the multifunctional flavivirus protein NS5 has a role in viral persistence, the development of relevant animal models of viral persistence, and investigating the host responses that allow vector borne flavivirus replication without detrimental effects on infected cells. Such studies might shed more light on the viral–host relationships and could be used to unravel the mechanisms for establishment of persistence. Persistent infections by vector borne flaviviruses are an important, but inadequately studied topic.
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Affiliation(s)
- Luwanika Mlera
- Rocky Mountain Laboratories, Laboratory of Virology, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, USA
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30
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Experimental infections of wild birds with West Nile virus. Viruses 2014; 6:752-81. [PMID: 24531334 PMCID: PMC3939481 DOI: 10.3390/v6020752] [Citation(s) in RCA: 108] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Revised: 02/04/2014] [Accepted: 02/04/2014] [Indexed: 01/16/2023] Open
Abstract
Avian models of West Nile virus (WNV) disease have become pivotal in the study of infection pathogenesis and transmission, despite the intrinsic constraints that represents this type of experimental research that needs to be conducted in biosecurity level 3 (BSL3) facilities. This review summarizes the main achievements of WNV experimental research carried out in wild birds, highlighting advantages and limitations of this model. Viral and host factors that determine the infection outcome are analyzed in detail, as well as recent discoveries about avian immunity, viral transmission, and persistence achieved through experimental research. Studies of laboratory infections in the natural host will help to understand variations in susceptibility and reservoir competence among bird species, as well as in the epidemiological patterns found in different affected areas.
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31
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Abstract
West Nile virus (WNV), the causative agent of West Nile fever and West Nile neuroinvasive disease in humans, has become endemic in many countries in all continents. Concerns on long-term mobility from WNV have arisen from recent studies that reported chronic kidney disease in patients who recovered from WNV infection, supported by data from animal models that showed prolonged excretion of the virus with urine. The purpose of this review is to summarize and discuss the results of studies in the literature that investigated WNV infection of the kidney in humans and in animal models and WNV excretion with urine, the potential damage to the kidney caused by WNV infection, the risk of WNV disease in kidney transplant recipients, the significance of detecting WNV in urine and its use in the diagnosis of WNV infection, and kidney involvement by other mosquito-borne flaviviruses.
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Affiliation(s)
- Luisa Barzon
- Department of Molecular Medicine, University of Padova, Via A. Gabelli 63, 35121 Padova, Italy.
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32
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The complex epidemiological scenario of West Nile virus in Italy. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2013; 10:4669-89. [PMID: 24084676 PMCID: PMC3823324 DOI: 10.3390/ijerph10104669] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Revised: 09/17/2013] [Accepted: 09/22/2013] [Indexed: 12/16/2022]
Abstract
Entomological, veterinary, and human surveillance systems for West Nile virus (WNV) infection have been implemented in Italy since the first detection of the virus in 1998. These surveillance activities documented a progressive increase of WNV activity and spread in different regions and the emergence of new WNV lineages and strains. Italy is a paradigmatic example of the complex epidemiology of WNV in Europe, where sporadic cases of WNV infection, clusters, and small outbreaks have been reported in several regions. In addition, different strains of both WNV lineage 1 and lineage 2 have been identified, even co-circulating in the same area.
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33
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Abstract
The introduction, dispersal and establishment of West Nile virus in North America were reviewed, focusing on factors that may have enhanced receptivity and enabled the invasion process. The overwintering persistence of this tropical virus within temperate latitudes was unexpected, but was key in the transition from invasion to endemic establishment. The cascade of temporal events allowing sporadic amplification to outbreak levels was discussed within a future perspective.
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34
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Kilpatrick AM, Peters RJ, Dupuis AP, Jones MJ, Marra PP, Kramer LD. Predicted and observed mortality from vector-borne disease in small songbirds. BIOLOGICAL CONSERVATION 2013; 165:79-85. [PMID: 23956457 PMCID: PMC3743256 DOI: 10.1016/j.biocon.2013.05.015] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Numerous diseases of wildlife have recently emerged due to trade and travel. However, the impact of disease on wild animal populations has been notoriously difficult to detect and demonstrate, due to problems of attribution and the rapid disappearance of bodies after death. Determining the magnitude of avian mortality from West Nile virus (WNV) is emblematic of these challenges. Although correlational analyses may show population declines coincident with the arrival of the virus, strong inference of WNV as a cause of mortality or a population decline requires additional evidence. We show how integrating field data on mosquito feeding patterns, avian abundance, and seroprevalence can be used to predict relative mortality from vector-borne pathogens. We illustrate the method with a case study on WNV in three species of small songbirds, tufted titmouse (Baeolophus bicolor), Carolina wrens (Thryothorus ludovicianus), and northern cardinals (Cardinalis cardinalis). We then determined mortality, infectiousness, and behavioral response of wrens and titmouse following infection with WNV in laboratory experiments and compared them to a previous study on WNV mortality in cardinals. In agreement with predictions, we found titmouse had the highest mortality from WNV infection, with 100% of eleven birds perishing within seven days after infection. Mortality in wrens was significantly lower at 27% (3/11), but still substantial. Viremia profiles indicated that both species were highly infectious for WNV and could play roles in WNV amplification. These findings suggest that WNV may be killing many small-bodied birds, despite the absence of large numbers of dead birds testing positive for WNV. More broadly, they illustrate a framework for predicting relative mortality in hosts from vector-borne disease.
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Affiliation(s)
- A. Marm Kilpatrick
- University of California, Ecology and Evolutionary Biology, Santa Cruz, CA, 95060, USA
- To whom correspondence should be addressed: A. Marm Kilpatrick Dept. Ecology and Evolutionary Biology University of California, Santa Cruz Santa Cruz, CA 95064 (831) 459-5070
| | - Ryan J. Peters
- Wadsworth Center, New York State Department of Health, Slingerlands, NY 12159, USA
| | - Alan P. Dupuis
- Wadsworth Center, New York State Department of Health, Slingerlands, NY 12159, USA
| | - Matthew J. Jones
- Wadsworth Center, New York State Department of Health, Slingerlands, NY 12159, USA
| | - Peter P. Marra
- Smithsonian Migratory Bird Center, National Zoological Park, Washington, DC 20008, USA
| | - Laura D. Kramer
- Wadsworth Center, New York State Department of Health, Slingerlands, NY 12159, USA
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35
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Lim SM, Koraka P, Osterhaus ADME, Martina BEE. Development of a strand-specific real-time qRT-PCR for the accurate detection and quantitation of West Nile virus RNA. J Virol Methods 2013; 194:146-53. [PMID: 23965252 DOI: 10.1016/j.jviromet.2013.07.050] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Revised: 07/17/2013] [Accepted: 07/22/2013] [Indexed: 01/12/2023]
Abstract
Studying the tropism and replication kinetics of West Nile virus (WNV) in different cell types in vitro and in tissues in animal models is important for understanding its pathogenesis. As detection of the negative strand viral RNA is a more reliable indicator of active replication for single-stranded positive-sense RNA viruses, the specificity of qRT-PCR assays currently used for the detection of WNV positive and negative strand RNA was reassessed. It was shown that self- and falsely-primed cDNA was generated during the reverse transcription step in an assay employing unmodified primers and several reverse transcriptases. As a result, a qRT-PCR assay using the thermostable rTth in combination with tagged primers was developed, which greatly improved strand specificity by circumventing the events of self- and false-priming. The reliability of the assay was then addressed in vitro using BV-2 microglia cells as well as in C57/BL6 mice. It was possible to follow the kinetics of positive and negative-strand RNA synthesis both in vitro and in vivo; however, the sensitivity of the assay will need to be optimized in order to detect and quantify negative-strand RNA synthesis in the very early stages of infection. Overall, the strand-specific qRT-PCR assay developed in this study is an effective tool to quantify WNV RNA, reassess viral replication, and study tropism of WNV in the context of WNV pathogenesis.
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Affiliation(s)
- Stephanie M Lim
- Department of Viroscience, Erasmus Medical Center, Rotterdam, The Netherlands
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VanDalen KK, Hall JS, Clark L, McLean RG, Smeraski C. West Nile virus infection in American Robins: new insights on dose response. PLoS One 2013; 8:e68537. [PMID: 23844218 PMCID: PMC3699668 DOI: 10.1371/journal.pone.0068537] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Accepted: 06/05/2013] [Indexed: 12/20/2022] Open
Abstract
West Nile virus (WNV) is a vector-borne pathogen that was first detected in the United States in 1999. The natural transmission cycle of WNV involves mosquito vectors and avian hosts, which vary in their competency to transmit the virus. American robins are an abundant backyard species in the United States and appear to have an important role in the amplification and dissemination of WNV. In this study we examine the response of American robins to infection with various WNV doses within the range of those administered by some natural mosquito vectors. Thirty American robins were assigned a WNV dosage treatment and needle inoculated with 10(0.95) PFU, 10(1.26) PFU, 10(2.15) PFU, or 10(3.15) PFU. Serum samples were tested for the presence of infectious WNV and/or antibodies, while oral swabs were tested for the presence of WNV RNA. Five of the 30 (17%) robins had neutralizing antibodies to WNV prior to the experiment and none developed viremia or shed WNV RNA. The proportion of WNV-seronegative birds that became viremic after WNV inoculation increased in a dose dependent manner. At the lowest dose, only 40% (2/5) of the inoculated birds developed productive infections while at the highest dose, 100% (7/7) of the birds became viremic. Oral shedding of WNV RNA followed a similar trend where robins inoculated with the lower two doses were less likely to shed viral RNA (25%) than robins inoculated with one of the higher doses (92%). Viremia titers and morbidity did not increase in a dose dependent manner; only two birds succumbed to infection and, interestingly, both were inoculated with the lowest dose of WNV. It is clear that the disease ecology of WNV is a complex interplay of hosts, vectors, and viral dose delivered.
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Affiliation(s)
- Kaci K VanDalen
- United States Department of Agriculture, Animal and Plant Health Inspection Service, Wildlife Services, National Wildlife Research Center, Fort Collins, Colorado, United States of America.
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Gamino V, Höfle U. Pathology and tissue tropism of natural West Nile virus infection in birds: a review. Vet Res 2013; 44:39. [PMID: 23731695 PMCID: PMC3686667 DOI: 10.1186/1297-9716-44-39] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2013] [Accepted: 04/24/2013] [Indexed: 01/26/2023] Open
Abstract
West Nile virus (WNV) is a globally distributed arthropod-borne flavivirus capable of infecting a wide variety of vertebrates, with birds as its natural reservoir. Although it had been considered a pathogen of little importance for birds, from the 1990's, and especially after its introduction in the North American continent in 1999, thousands of birds have succumbed to West Nile infection. This review summarizes the pathogenesis and pathology of WNV infection in birds highlighting differences in lesion and antigen distribution and severity among bird orders and families. Despite significant species differences in susceptibility to infection, WNV associated lesions and viral antigen are present in the majority of organs of infected birds. The non-progressive, acute or more prolonged course of the disease accounts for part of the differences in lesion and viral antigen distribution and lesion severity. Most likely a combination of host variables and environmental factors in addition to the intrinsic virulence and pathogenicity of the infecting WNV strain influence the pathogenesis of the infection.
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Affiliation(s)
- Virginia Gamino
- SaBio Instituto de Investigación en Recursos Cinegéticos IREC, (CSIC-UCLM-JCCM) Ronda de Toledo s/n, Ciudad Real 13005, Spain
| | - Ursula Höfle
- SaBio Instituto de Investigación en Recursos Cinegéticos IREC, (CSIC-UCLM-JCCM) Ronda de Toledo s/n, Ciudad Real 13005, Spain
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Reisen WK, Padgett K, Fang Y, Woods L, Foss L, Anderson J, Kramer V. Chronic infections of West Nile virus detected in California dead birds. Vector Borne Zoonotic Dis 2013; 13:401-5. [PMID: 23488452 DOI: 10.1089/vbz.2012.1097] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
During 2010 and 2011, 933 recently deceased birds, submitted as part of the dead bird surveillance program, tested positive for West Nile virus RNA at necropsy. The relative amount of RNA measured by qRT-PCR cycles ranged from 8.2 to 37.0 cycle threshold (Ct) and formed a bimodal frequency distribution, with maxima at 20 and 36 Ct and minima at 28-30 Ct. On the basis of frequency distributions among different avian species with different responses to infection following experimental inoculation, field serological data indicating survival of infection, and the discovery of persistent RNA in experimentally infected birds, dead birds collected in nature were scored as "recent" or "chronic" infections on the basis of Ct scores. The percentage of birds scored as having chronic infections was highest during late winter/spring, when all birds were after hatching year, and lowest during late summer, when enzootic transmission was typically highest as indicated by mosquito infections. Our data indicated that intervention efforts should not be based on dead birds with chronic infections unless supported by additional surveillance metrics.
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Affiliation(s)
- William K Reisen
- Center for Vectorborne Diseases, Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, California, USA.
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Wheeler SS, Vineyard MP, Woods LW, Reisen WK. Dynamics of West Nile virus persistence in House Sparrows (Passer domesticus). PLoS Negl Trop Dis 2012; 6:e1860. [PMID: 23056663 PMCID: PMC3464288 DOI: 10.1371/journal.pntd.0001860] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Accepted: 08/29/2012] [Indexed: 12/03/2022] Open
Abstract
West Nile Virus (WNV) is now endemic throughout North America, with annual recurrence dependent upon successful overwintering when cold temperatures drive mosquito vectors into inactivity and halt transmission. To investigate whether avian hosts may serve as an overwintering mechanism, groups of eight to ten House Sparrows were experimentally infected with a WN02 genotype of WNV and then held until necropsy at 3, 5, 7, 9, 12, 15, or 18 weeks post-infection (pi) when they were assessed for the presence of persistent infection. Blood was collected from all remaining birds every two weeks pi, and sera tested for WNV RNA and WNV neutralizing antibodies. West Nile virus RNA was present in the sera of some birds up to 7 weeks pi and all birds retained neutralizing antibodies throughout the experiment. The detection of persistently infected birds decreased with time, from 100% (n = 13) positive at 3 weeks post-infection (pi) to 12.5% (n = 8) at 18 weeks pi. Infectious virus was isolated from the spleens of birds necropsied at 3, 5, 7 and 12 weeks pi. The current study confirmed previous reports of infectious WNV persistence in avian hosts, and further characterized the temporal nature of these infections. Although these persistent infections supported the hypothesis that infected birds may serve as an overwintering mechanism, mosquito-infectious recrudescent viremias have yet to be demonstrated thereby providing proof of principle. House Sparrows experimentally infected with West Nile virus [WNV] were necropsied at multiple time points from 3 to 18 weeks post infection (pi). The percent of birds with tissues positive for WNV RNA decreased from 100% at 3 wks to 13% at 18 wks pi; infectious virus was recovered from some birds by tissue co-cultivation and Vero cell passage from 3 to 12 wks pi, even though positive birds retained neutralizing antibody. WNV RNA also was detected in sera at 2 to 7 wks pi. Collectively, these data indicated that House Sparrows frequently developed persistent infections and could serve as an overwintering mechanism for WNV. However, recrudescent viremias suitable to infect mosquitoes have yet to be demonstrated and would seem to require host Immunosuppression.
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Affiliation(s)
- Sarah S. Wheeler
- Center for Vectorborne Diseases, Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California Davis, Davis, California, United States of America
| | - Meighan P. Vineyard
- Center for Vectorborne Diseases, Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California Davis, Davis, California, United States of America
| | - Leslie W. Woods
- California Animal Health and Food Safety, Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California Davis, Davis, California, United States of America
| | - William K. Reisen
- Center for Vectorborne Diseases, Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California Davis, Davis, California, United States of America
- * E-mail:
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