Molecular evidence for interspecies transmission of H3N2pM/H3N2v influenza A viruses at an Ohio agricultural fair, July 2012

Bowman, Andrew S.; Sreevatsan, Srinand; Killian, Mary Lea; Page, Shannon L.; Nelson, Sarah W.; Nolting, Jacqueline M.; Cardona, Carol J.; Slemons, Richard D.

doi:10.1038/emi.2012.33

Cited by 58 publications

(48 citation statements)

References 28 publications

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“…This strain (H3N2pM) was found to be identical to virus later isolated from the human cases (H3N2v). Additional swine and human sampling associated with a fair in Ohio documented similar findings (Bowman et al, 2012 (Myers et al, 2007). There are only five recent reports of human infection with swine-origin influenza A infections in Europe (ECDC, 2012c).…”

Section: Transmission From Pigs To Humanssupporting

confidence: 60%

“…These reports coincided with information from animal health officials that febrile illness had been identified among some pigs at one of the first implicated fair events. The preliminary results showed that samples collected from some of these ill animals were positive for H3N2pM (Bowman et al, 2012). This SIV was found to be similar to virus later isolated from the human cases.…”

Section: Infection With H3n2v In Humansmentioning

confidence: 79%

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Scientific opinion on the possible risks posed by the influenza A (H3N2v) virus for animal health and its potential spread and implications for animal and human health

Authié¹,

Berg²,

Bøtner³

et al. 2013

EFS2

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Swine are an important host in influenza virus ecology since they are susceptible to infections with both avian and human influenza A viruses. In 2011 and 2012, clusters of human infection with a swine‐origin influenza A(H3N2) variant virus (H3N2v) containing the matrix (M) gene from the 2009 H1N1 pandemic virus were reported in the United States (US). The likelihood of introduction of H3N2v virus into the EU, and subsequent exposure and infection of EU pig herds was assessed. The overall likelihood of a pig holding in the EU being infected by exposure to H3N2v virus through either imported infectious pigs or humans coming from the US was estimated to be low. Efficient separation of imported pigs for 30 days would reduce the likelihood of exposure to a negligible level. The likelihood that H3N2v would spread to other pig holdings was judged to be high, assuming frequent movements of pigs between holdings. Currently, applied real time RT‐PCRs can detect all swine influenza A viruses and, combined with gene sequencing, would identify the emergence of H3N2v virus. However, sequencing is not done on a routine basis in EU. Experimental studies in pigs show that the infection is purely of respiratory nature and follows a relatively mild course with fever, coughing and inappetence, similar to that of the endemic swine influenza viruses. Immunity resulting from vaccination with European vaccines may provide some cross‐protection against infection with H3N2v virus whereas vaccines based on US swine H3N2 strains would offer superior protection. It is not possible to predict which changes within H3N2v virus might enable it to develop pandemic properties. Hence, it is not possible at present to set up a specific system to monitor such a risk. Nevertheless, it is recommended to reinforce the monitoring of influenza strains circulating in pigs in EU.

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Section: Transmission From Pigs To Humanssupporting

confidence: 60%

Section: Infection With H3n2v In Humansmentioning

confidence: 79%

Scientific opinion on the possible risks posed by the influenza A (H3N2v) virus for animal health and its potential spread and implications for animal and human health

Authié¹,

Berg²,

Bøtner³

et al. 2013

EFS2

View full text Add to dashboard Cite

show abstract

“…Three genes (the HA, NA, and M genes) of the swine isolates were initially sequenced and submitted to GenBank by the submitting NAHLN veterinary diagnostic lab. Following the identification of the human-origin HA gene, 9 swine isolates were subjected to wholegenome next-generation sequencing using an Ion 316 (v2) chip and an Ion PGM 200 (v2) sequencing kit (Life Technologies, Carlsbad, CA) as previously described (16). The HA genes from viruses recovered from pigs directly challenged with virus (referred to throughout as primary pigs) and pigs with indirect contact with primary pigs (referred to throughout as indirect contact pigs) in the in vivo studies were sequenced directly from clinical material by conventional sequencing using a BigDye Terminator (v3.1) cycle sequencing kit (Applied Biosystems, Foster City, CA) per the manufacturer's instruction using previously described primers (17).…”

Section: Methodsmentioning

confidence: 99%

Novel Reassortant Human-Like H3N2 and H3N1 Influenza A Viruses Detected in Pigs Are Virulent and Antigenically Distinct from Swine Viruses Endemic to the United States

Rajão

Gauger

Anderson

et al. 2015

J Virol

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Human-like swine H3 influenza A viruses (IAV) were detected by the USDA surveillance system. We characterized two novel swine human-like H3N2 and H3N1 viruses with hemagglutinin (HA) genes similar to those in human seasonal H3 strains and internal genes closely related to those of 2009 H1N1 pandemic viruses. The H3N2 neuraminidase (NA) was of the contemporary human N2 lineage, while the H3N1 NA was of the classical swine N1 lineage. Both viruses were antigenically distant from swine H3 viruses that circulate in the United States and from swine vaccine strains and also showed antigenic drift from human seasonal H3N2 viruses. Their pathogenicity and transmission in pigs were compared to those of a human H3N2 virus with a common HA ancestry. Both swine human-like H3 viruses efficiently infected pigs and were transmitted to indirect contacts, whereas the human H3N2 virus did so much less efficiently. To evaluate the role of genes from the swine isolates in their pathogenesis, reverse genetics-generated reassortants between the swine human-like H3N1 virus and the seasonal human H3N2 virus were tested in pigs. The contribution of the gene segments to virulence was complex, with the swine HA and internal genes showing effects in vivo. The experimental infections indicate that these novel H3 viruses are virulent and can sustain onward transmission in pigs, and the naturally occurring mutations in the HA were associated with antigenic divergence from H3 IAV from humans and swine. Consequently, these viruses could have a significant impact on the swine industry if they were to cause more widespread outbreaks, and the potential risk of these emerging swine IAV to humans should be considered. IMPORTANCE Pigs are important hosts in the evolution of influenza A viruses (IAV). Human-to-swine transmissions of IAV have resulted in the circulation of reassortant viruses containing human-origin genes in pigs, greatly contributing to the diversity of IAV in swine worldwide. New human-like H3N2 and H3N1 viruses that contain a mix of human and swine gene segments were recently detected by the USDA surveillance system. The human-like viruses efficiently infected pigs and resulted in onward airborne transmission, likely due to the multiple changes identified between human and swine H3 viruses. The human-like swine viruses are distinct from contemporary U.S. H3 swine viruses and from the strains used in swine vaccines, which could have a significant impact on the swine industry due to a lack of population immunity. Additionally, public health experts should consider an appropriate assessment of the risk of these emerging swine H3 viruses for the human population.

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“…The current human seasonal vaccines containing H3N2 do not appear to protect against H3N2v (22,24). Since the vast majority of cases of H3N2v infection have been in children with close contact and long periods of exposure at agricultural fairs, all of these factors point to a unique set of circumstances that collectively increased the odds for H3N2v infection in these spillover events (25). The unique circumstances do not diminish the epidemic or pandemic risk of H3N2v to humans if these viruses gain the ability to be efficiently transmitted from human to human, allowing the virus further opportunity to mutate and adapt to the human host.…”

mentioning

confidence: 99%

Substitutions near the Hemagglutinin Receptor-Binding Site Determine the Antigenic Evolution of Influenza A H3N2 Viruses in U.S. Swine

Lewis

Anderson

Kitikoon

et al. 2014

J Virol

122

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Swine influenza A virus is an endemic and economically important pathogen in pigs, with the potential to infect other host species. The hemagglutinin (HA) protein is the primary target of protective immune responses and the major component in swine influenza A vaccines. However, as a result of antigenic drift, vaccine strains must be regularly updated to reflect currently circulating strains. Characterizing the cross-reactivity between strains in pigs and seasonal influenza virus strains in humans is also important in assessing the relative risk of interspecies transmission of viruses from one host population to the other. Hemagglutination inhibition (HI) assay data for swine and human H3N2 viruses were used with antigenic cartography to quantify the antigenic differences among H3N2 viruses isolated from pigs in the United States from 1998 to 2013 and the relative cross-reactivity between these viruses and current human seasonal influenza A virus strains. Two primary antigenic clusters were found circulating in the pig population, but with enough diversity within and between the clusters to suggest updates in vaccine strains are needed. We identified single amino acid substitutions that are likely responsible for antigenic differences between the two primary antigenic clusters and between each antigenic cluster and outliers. The antigenic distance between current seasonal influenza virus H3 strains in humans and those endemic in swine suggests that population immunity may not prevent the introduction of human viruses into pigs, and possibly vice versa, reinforcing the need to monitor and prepare for potential incursions. IMPORTANCEInfluenza A virus (IAV) is an important pathogen in pigs and humans. The hemagglutinin (HA) protein is the primary target of protective immune responses and the major target of vaccines. However, vaccine strains must be updated to reflect current strains. Characterizing the differences between seasonal IAV in humans and swine IAV is important in assessing the relative risk of interspecies transmission of viruses. We found two primary antigenic clusters of H3N2 in the U.S. pig population, with enough diversity to suggest updates in swine vaccine strains are needed. We identified changes in the HA protein that are likely responsible for these differences and that may be useful in predicting when vaccines need to be updated. The difference between human H3N2 viruses and those in swine is enough that population immunity is unlikely to prevent new introductions of human IAV into pigs or vice versa, reinforcing the need to monitor and prepare for potential introductions.

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Molecular evidence for interspecies transmission of H3N2pM/H3N2v influenza A viruses at an Ohio agricultural fair, July 2012

Cited by 58 publications

References 28 publications

Scientific opinion on the possible risks posed by the influenza A (H3N2v) virus for animal health and its potential spread and implications for animal and human health

Scientific opinion on the possible risks posed by the influenza A (H3N2v) virus for animal health and its potential spread and implications for animal and human health

Novel Reassortant Human-Like H3N2 and H3N1 Influenza A Viruses Detected in Pigs Are Virulent and Antigenically Distinct from Swine Viruses Endemic to the United States

Substitutions near the Hemagglutinin Receptor-Binding Site Determine the Antigenic Evolution of Influenza A H3N2 Viruses in U.S. Swine

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