Pandemic (H1N1) 2009 virus in 3 wildlife species, San Diego, California, USA

Striking lineage diversity of severe acute respiratory syndrome coronavirus 2 from non-human sources

Due to the necessity to control human-to-human spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the overwhelming majority of the generated data on this virus was solely related to the genomic characteristics of strains infecting humans; conversely, this work aimed to recover and analyze the diversity of viral genomes from non-human sources. From a set of 3595 publicly available SARS-CoV-2 genome sequences, 128 lineages were identified in non-human hosts, the majority represented by the variants of concern Delta (n = 1105, 30.7%) and Alpha (n = 466, 12.9%), followed by B.1.1.298 lineage (n = 458, 12.7%). Environment, Neovison vison, Odocoileus virginianus and Felis catus were the non-human sources with the highest number of lineages (14, 12 and 10, respectively). Phylogenomic analyses showed viral clusters from environmental sources, N. vison, O. virginianus, Panthera tigris, and Panthera leo. These clusters were collectively related to human viruses as well as all other non-human sources that were heterogeneously distributed in the phylogenetic tree. Further, the genetic details of viral genomes from bats and pangolins were independently investigated owing to their high divergence, revealing five distinct clusters. Cluster 4 exclusively included bat-sourced genomes and the SARS-CoV-2 reference strain Wuhan-01. In summary, this study identified new genetic landmarks of SARS-CoV-2 evolution. We propose potential interspecies transmission routes of SARS-CoV-2 between animals and humans, which should be considered in order to establish better pathogen surveillance and containment strategies.

Serologic evidence of pandemic (H1N1) 2009 virus infection in camel and Eld's deer, Thailand

Background and Aim

The pandemic (H1N1) 2009 influenza (H1N1pdm09) virus has affected both human and animal populations worldwide. The transmission of the H1N1pdm09 virus from humans to animals is increasingly more evident. Captive animals, particularly zoo animals, are at risk of H1N1pdm09 virus infection through close contact with humans. Evidence of exposure to the H1N1pdm09 virus has been reported in several species of animals in captivity. However, there is limited information on the H1N1pdm09 virus infection and circulation in captive animals. To extend the body of knowledge on exposure to the H1N1pdm09 virus among captive animals in Thailand, our study investigated the presence of antibodies against the H1N1pdm09 virus in two captive animals: Camelids and Eld's deer.

Materials and Methods

We investigated H1N1pdm09 virus infection among four domestic camelid species and wild Eld's deer that were kept in different zoos in Thailand. In total, 72 archival serum samples from camelid species and Eld's deer collected between 2013 and 2014 in seven provinces in Thailand were analyzed for influenza antibodies using hemagglutination inhibition (HI), microneutralization, and western blotting (WB) assays.

Results

The presence of antibodies against the H1N1pdm09 virus was detected in 2.4% (1/42) of dromedary camel serum samples and 15.4% (2/13) of Eld's deer serum samples. No antibodies were detected in the rest of the serum samples derived from other investigated camelids, including Bactrian camels (0/3), alpacas (0/5), and llamas (0/9). The three positive serum samples showed HI antibody titers of 80, whereas the neutralization titers were in the range of 320-640. Antibodies specific to HA and NP proteins in the H1N1pdm09 virus were detected in positive camel serum samples using WB. Conversely, the presence of the specific antibodies in the positive Eld's deer serum samples could not be determined using WB due to the lack of commercially labeled secondary antibodies.

Conclusion

The present study provided evidence of H1N1pdm09 virus infection in the captive dromedary camel and Eld's deer in Thailand. Our findings highlight the need for continuous surveillance for influenza A virus in the population of dromedary camels and Eld's deer. The susceptible animal populations in close contact with humans should be closely monitored. Further study is warranted to determine whether Eld's deer are indeed a competent reservoir for human influenza virus.

Eurasian Avian-like M1 Plays More Important Role than M2 in Pathogenicity of 2009 Pandemic H1N1 Influenza Virus in Mice

Reassortant variant viruses generated between 2009 H1N1 pandemic influenza virus [A(H1N1)pdm09] and endemic swine influenza viruses posed a potential risk to humans. Surprisingly, genetic analysis showed that almost all of these variant viruses contained the M segment from A(H1N1)pdm09, which originated from Eurasian avian-like swine influenza viruses. Studies have shown that the A(H1N1)pdm09 M gene is critical for the transmissibility and pathogenicity of the variant viruses. However, the M gene encodes two proteins, M1 and M2, and which of those plays a more important role in virus pathogenicity remains unknown. In this study, the M1 and M2 genes of A(H1N1)pdm09 were replaced with those of endemic H3N2 swine influenza virus, respectively. The chimeric viruses were rescued and evaluated in vitro and in mice. Both M1 and M2 of H3N2 affected the virus replication in vitro. In mice, the introduction of H3N2 M1 attenuated the chimeric virus, where all the mice survived from the infection, compared with the wild type virus that caused 100 % mortality. However, the chimeric virus containing H3N2 M2 was still virulent to mice, and caused 16.6% mortality, as well as similar body weight loss to the wild type virus infected group. Compared with the wild type virus, the chimeric virus containing H3N2 M1 induced lower levels of inflammatory cytokines and higher levels of anti-inflammatory cytokines, whereas the chimeric virus containing H3N2 M2 induced substantial pro-inflammatory responses, but higher levels of anti-inflammatory cytokines. The study demonstrated that Eurasian avian-like M1 played a more important role than M2 in the pathogenicity of A(H1N1)pdm09 in mice.

Reverse Zoonosis of COVID-19: Lessons From the 2009 Influenza Pandemic

Over the past decade, pandemics caused by pandemic H1N1 (pH1N1) influenza virus in 2009 and severe acute respiratory syndrome virus type 2 (SARS-CoV-2) in 2019 have emerged. Both are high-impact respiratory pathogens originating from animals. Their wide distribution in the human population subsequently results in an increased risk of human-to-animal transmission: reverse zoonosis. Although there have only been rare reports of reverse zoonosis events associated with the ongoing coronavirus disease 2019 (COVID-19) pandemic from SARS-CoV-2 so far, comparison with the pH1N1 influenza pandemic can provide a better understanding of the possible consequences of such events for public and animal health. The results of our review suggest that similar factors contribute to successful crossing of the host species barriers in both pandemics. Specific risk factors include sufficient interaction between infected humans and recipient animals, suitability of the animal host factors for productive virus infection, and suitability of the animal host population for viral persistence. Of particular concern is virus spread to susceptible animal species, in which group housing and contact network structure could potentially result in an alternative virus reservoir, from which reintroduction into humans can take place. Virus exposure in high-density populations could allow sustained transmission in susceptible animal species. Identification of the risk factors and serological surveillance in SARS-CoV-2-susceptible animal species that are group-housed should help reduce the threat from reverse zoonosis of COVID-19.

Possibility for reverse zoonotic transmission of SARS-CoV-2 to free-ranging wildlife: A case study of bats

The COVID-19 pandemic highlights the substantial public health, economic, and societal consequences of virus spillover from a wildlife reservoir. Widespread human transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) also presents a new set of challenges when considering viral spillover from people to naïve wildlife and other animal populations. The establishment of new wildlife reservoirs for SARS-CoV-2 would further complicate public health control measures and could lead to wildlife health and conservation impacts. Given the likely bat origin of SARS-CoV-2 and related beta-coronaviruses (β-CoVs), free-ranging bats are a key group of concern for spillover from humans back to wildlife. Here, we review the diversity and natural host range of β-CoVs in bats and examine the risk of humans inadvertently infecting free-ranging bats with SARS-CoV-2. Our review of the global distribution and host range of β-CoV evolutionary lineages suggests that 40+ species of temperate-zone North American bats could be immunologically naïve and susceptible to infection by SARS-CoV-2. We highlight an urgent need to proactively connect the wellbeing of human and wildlife health during the current pandemic and to implement new tools to continue wildlife research while avoiding potentially severe health and conservation impacts of SARS-CoV-2 "spilling back" into free-ranging bat populations.

Serological evidence of influenza virus infection in captive wild felids, Thailand

Influenza virus is known to affect wild felids. To explore the prevalence of influenza viruses in these animal species, 196 archival sera from 5 felid species including Panthera tigris (N=147), Prionailurus viverrinus (N=35), Panthera leo (N=5), Pardofelis temminckii (N=8) and Neofelis nebulosa (N=1) collected between 2011 and 2015 in 10 provinces of Thailand were determined for the presence of antibody to avian and human influenza viruses. Blocking enzyme-linked immunosorbent (ELISA) assay and hemagglutination inhibition (HI) assay were employed as the screening tests, which the serum samples with HI antibody titers ≥20 were further confirmed by cytopathic effect/hemagglutination based-microneutralization (CPE/HA-based microNT) test. Based on HI and microNT assays, the seropositive rates of low pathogenic avian influenza (LPAI) H5 virus, highly pathogenic avian influenza (HPAI) H5 virus and human H1 virus were 1.53% (3/196), 2.04% (4/196) and 6.63% (13/196), respectively. In addition, we also found antibody against both LPAI H5 virus and HPAI H5 virus in 2 out of 196 tested sera (1.02%). Evidences of influenza virus infection were found in captive P. tigris in Kanchanaburi, Nakhon Sawan and Ratchaburi provinces of Thailand. The findings of our study highlights the need of a continuous active surveillance program of influenza viruses in wild felid species.

Serosurveillance for pandemic influenza A (H1N1) 2009 virus infection in domestic elephants, Thailand

The present study conducted serosurveillance for the presence of antibody to pandemic influenza A (H1N1) 2009 virus (H1N1pdm virus) in archival serum samples collected between 2009 and 2013 from 317 domestic elephants living in 19 provinces situated in various parts of Thailand.

To obtain the most accurate data, hemagglutination-inhibition (HI) assay was employed as the screening test; and sera with HI antibody titers ≥20 were further confirmed by other methods, including cytopathic effect/hemagglutination based-microneutralization (microNT) and Western blot (WB) assays using H1N1pdm matrix 1 (M1) or hemagglutinin (HA) recombinant protein as the test antigen. Conclusively, the appropriate assays using HI in conjunction with WB assays for HA antibody revealed an overall seropositive rate of 8.5% (27 of 317). The prevalence of antibody to H1N1pdm virus was 2% (4/172) in 2009, 32% (17/53) in 2010, 9% (2/22) in 2011, 12% (1/8) in 2012, and 5% (3/62) in 2013. Notably, these positive serum samples were collected from elephants living in 7 tourist provinces of Thailand. The highest seropositive rate was obtained from elephants in Phuket, a popular tourist beach city. Young elephants had higher seropositive rate than older elephants.

The source of H1N1pdm viral infection in these elephants was not explored, but most likely came from close contact with the infected mahouts or from the infected tourists who engaged in activities such as elephant riding and feeding. Nevertheless, it could not be excluded that elephant-to-elephant transmission did occur.

Pathogenicity and transmissibility of novel reassortant H3N2 influenza viruses with 2009 pandemic H1N1 genes in pigs

At least 10 different genotypes of novel reassortant H3N2 influenza viruses with 2009 pandemic H1N1 [A(H1N1)pdm09] gene(s) have been identified in U.S. pigs, including the H3N2 variant with a single A(H1N1)pdm09 M gene, which has infected more than 300 people. To date, only three genotypes of these viruses have been evaluated in animal models, and the pathogenicity and transmissibility of the other seven genotype viruses remain unknown. Here, we show that three H3N2 reassortant viruses that contain 3 (NP, M, and NS) or 5 (PA, PB2, NP, M, and NS) genes from A(H1N1)pdm09 were pathogenic in pigs, similar to the endemic H3N2 swine virus. However, the reassortant H3N2 virus with 3 A(H1N1)pdm09 genes and a recent human influenza virus N2 gene was transmitted most efficiently among pigs, whereas the reassortant H3N2 virus with 5 A(H1N1)pdm09 genes was transmitted less efficiently than the endemic H3N2 virus. Interestingly, the polymerase complex of reassortant H3N2 virus with 5 A(H1N1)pdm09 genes showed significantly higher polymerase activity than those of endemic and reassortant H3N2 viruses with 3 A(H1N1)pdm09 genes. Further studies showed that an avian-like glycine at position 228 at the hemagglutinin (HA) receptor binding site is responsible for inefficient transmission of the reassortant H3N2 virus with 5 A(H1N1)pdm09 genes. Taken together, our results provide insights into the pathogenicity and transmissibility of novel reassortant H3N2 viruses in pigs and suggest that a mammalian-like serine at position 228 in the HA is critical for the transmissibility of these reassortant H3N2 viruses.

IMPORTANCE

Swine influenza is a highly contagious zoonotic disease that threatens animal and public health. Introduction of 2009 pandemic H1N1 virus [A(H1N1)pdm09] into swine herds has resulted in novel reassortant influenza viruses in swine, including H3N2 and H1N2 variants that have caused human infections in the United States. We showed that reassortant H3N2 influenza viruses with 3 or 5 genes from A(H1N1)pdm09 isolated from diseased pigs are pathogenic and transmissible in pigs, but the reassortant H3N2 virus with 5 A(H1N1)pdm09 genes displayed less efficient transmissibility than the endemic and reassortant H3N2 viruses with 3 A(H1N1)pdm09 genes. Further studies revealed that an avian-like glycine at the HA 228 receptor binding site of the reassortant H3N2 virus with 5 A(H1N1)pdm09 genes is responsible for less efficient transmissibility in pigs. Our results provide insights into viral pathogenesis and the transmission of novel reassortant H3N2 viruses that are circulating in U.S. swine herds and warrant future surveillance.

Extended viral shedding of a low pathogenic avian influenza virus by striped skunks (Mephitis mephitis)

BACKGROUND

Striped skunks (Mephitis mephitis) are susceptible to infection with some influenza A viruses. However, the viral shedding capability of this peri-domestic mammal and its potential role in influenza A virus ecology are largely undetermined.

METHODOLOGY/PRINCIPAL FINDINGS

Striped skunks were experimentally infected with a low pathogenic (LP) H4N6 avian influenza virus (AIV) and monitored for 20 days post infection (DPI). All of the skunks exposed to H4N6 AIV shed large quantities of viral RNA, as detected by real-time RT-PCR and confirmed for live virus with virus isolation, from nasal washes and oral swabs (maximum ≤ 10(6.02) PCR EID50 equivalent/mL and ≤ 10(5.19) PCR EID50 equivalent/mL, respectively). Some evidence of potential fecal shedding was also noted. Following necropsy on 20 DPI, viral RNA was detected in the nasal turbinates of one individual. All treatment animals yielded evidence of a serological response by 20 DPI.

CONCLUSIONS/SIGNIFICANCE

These results indicate that striped skunks have the potential to shed large quantities of viral RNA through the oral and nasal routes following exposure to a LP AIV. Considering the peri-domestic nature of these animals, along with the duration of shedding observed in this species, their presence on poultry and waterfowl operations could influence influenza A virus epidemiology. For example, this species could introduce a virus to a naive poultry flock or act as a trafficking mechanism of AIV to and from an infected poultry flock to naive flocks or wild bird populations.

Selected emerging diseases in ferrets

Since their introduction as pets several decades ago, ferrets have become an increasingly popular household pet. Great strides have been made in improving their diet and understanding common diseases (eg, insulinoma, hyperadrenocorticism, lymphoma) that affect them. With the frequency with which these conditions are seen, it sometimes is easy to forget that ferrets can be affected by other diseases. Some of these diseases, such as cryptococcosis, are known, but may be increasing in incidence and range, whereas others, such as hypothyroidism and pure red cell aplasia, may be underrecognized or underreported. This review highlights new and emerging diseases not already well reviewed in the literature.

Pandemic (H1N1) 2009 in captive cheetah

We describe virus isolation, full genome sequence analysis, and clinical pathology in ferrets experimentally inoculated with pandemic (H1N1) 2009 virus recovered from a clinically ill captive cheetah that had minimal human contact. Evidence of reverse zoonotic transmission by fomites underscores the substantial animal and human health implications of this virus.

The neuraminidase and matrix genes of the 2009 pandemic influenza H1N1 virus cooperate functionally to facilitate efficient replication and transmissibility in pigs

The 2009 pandemic H1N1 virus (pH1N1) contains neuraminidase (NA) and matrix (M) genes from Eurasian avian-like swine influenza viruses (SIVs), with the remaining six genes from North American triple-reassortant SIVs. To characterize the role of the pH1N1 NA and M genes in pathogenesis and transmission, their impact was evaluated in the background of an H1N1 triple-reassortant (tr1930) SIV in which the HA (H3) and NA (N2) of influenza A/swine/Texas/4199-2/98 virus were replaced with those from the classical H1N1 A/swine/Iowa/15/30 (1930) virus. The laboratory-adapted 1930 virus did not shed nor transmit in pigs, but tr1930 was able to shed in infected pigs. The NA, M or both genes of the tr1930 virus were then substituted by those of pH1N1. The resulting virus with both NA and M from pH1N1 grew to significantly higher titre in cell cultures than the viruses with single NA or M from pH1N1. In a pig model, only the virus containing both NA and M from pH1N1 was transmitted to and infected sentinels, whereas the viruses with single NA or M from pH1N1 did not. These results demonstrate that the right combination of NA and M genes is critical for the replication and transmissibility of influenza viruses in pigs.