Antigenic Characterization of H3N2 Influenza A Viruses from Ohio Agricultural Fairs

Feng, Zhixin; Gomez, Janet; Bowman, Andrew S.; Ye, Jianqiang; Li, Long; Nelson, Sarah W.; Yang, Jialiang; Martin, Brigitte E.; Jia, Kun; Nolting, Jacqueline M.; Cunningham, Fred L.; Cardona, Carol J.; Zhang, Jianqiang; Yoon, Karina J.; Slemons, Richard D.; Wan, Xiu Feng

doi:10.1128/jvi.00804-13

Cited by 35 publications

(46 citation statements)

References 52 publications

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“…In the antigenic maps, we saw a clustered antigenic evolution similar to that shown for the H1 viruses (␣, ␤, ␥, ␦-1, and ␦-2) (28), with marked antigenic distances within and between two antigenic clusters, demonstrating the substantial antigenic diversity in the milieu of genetically evolving H3N2 viruses circulating in U.S. pigs. Although a previous study utilizing different methodology with a ferret antiserum panel against 8 swine H3N2 viruses identified two antigenic clusters of swine H3N2 from 2006 to 2012, primarily from one U.S. state (20), our study with a serum panel of 18 swine H3N2 viruses covering 12 states and major hog-producing regions and generated in the natural host demonstrated greater overall antigenic diversity and a greater number of outliers. In addition, our study included representatives from each of the newly emerging phylogenetically defined clusters, contributing significantly to the amount of antigenic diversity we observed.…”

Section: Discussionmentioning

confidence: 99%

“…However, in the summers of 2011 to 2013 there were multiple infections with an H3N2 variant (H3N2v) in people attending agricultural fairs in a number of states in the United States (20,21), with nearly 350 cases of H3N2v infection now detected in humans (http://www.cdc.gov/flu/swineflu/variant-cases-us.htm). A factor in the increased frequency of H3N2v detections is the relative lack of human population immunity against variants of IAV that have continued to circulate independently in swine, with the ever present potential for these variants to evolve antigenically, perhaps away from their respective human seasonal precursor viruses and the strains used in contemporary human seasonal vaccines.…”

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confidence: 99%

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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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Section: Discussionmentioning

confidence: 99%

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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“…We also tested 81 nasal swab samples that had been collected from swine at the pig exhibits at agricultural fairs in Ohio during 2009 to 2013; 61 of the samples were positive for IAV using matrix gene-based quantitative RT-PCR (qRT-PCR) (11,30), and 20 of the samples were negative for IAV. A power analysis (OpenEpi, version 3) suggested that a sample size of 20 gave 95% probability to detect Ϯ10% with expected specificity (31).…”

Section: Methodsmentioning

confidence: 99%

“…Seven contemporary (2009 to 2011) swine H3N2 IAV isolates and their homologous ferret serum samples were chosen to represent the swine IAV antigenic groups H3␣ and H3ß (Table 1); antigenic characterization of these isolates is described elsewhere (11). The strain of A/California/04/2009(H1N1) (abbreviated as CA/04) [A(H1N1)pdm09] and homologous ferret serum were used as negative controls.…”

Section: Methodsmentioning

confidence: 99%

“…A recent study suggested the proportion for the number of swine subtype H3N2 IAVs over the total number of swine IAVs recovered from domestic swine has increased, and these viruses are widely spread across the United States (10). Molecular characterization suggested that the hemagglutinin (HA) genes of contemporary swine subtype H3 IAVs belong genetically to cluster IV, and these viruses can be antigenically separated into two groups, H3N2 swine IAV-␣ and H3N2 swine IAV-ß (abbreviated as H3␣ and H3ß) (11).…”

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confidence: 99%

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Detection of Antigenic Variants of Subtype H3 Swine Influenza A Viruses from Clinical Samples

Martin

Bowman

et al. 2017

J Clin Microbiol

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A large population of genetically and antigenically diverse influenza A viruses (IAVs) are circulating among the swine population, playing an important role in influenza ecology. Swine IAVs not only cause outbreaks among swine but also can be transmitted to humans, causing sporadic infections and even pandemic outbreaks. Antigenic characterizations of swine IAVs are key to understanding the natural history of these viruses in swine and to selecting strains for effective vaccines. However, influenza outbreaks generally spread rapidly among swine, and the conventional methods for antigenic characterization require virus propagation, a timeconsuming process that can significantly reduce the effectiveness of vaccination programs. We developed and validated a rapid, sensitive, and robust method, the polyclonal serum-based proximity ligation assay (polyPLA), to identify antigenic variants of subtype H3N2 swine IAVs. This method utilizes oligonucleotide-conjugated polyclonal antibodies and quantifies antibody-antigen binding affinities by quantitative reverse transcription-PCR (RT-PCR). Results showed the assay can rapidly detect H3N2 IAVs directly from nasal wash or nasal swab samples collected from laboratorychallenged animals or during influenza surveillance at county fairs. In addition, polyPLA can accurately separate the viruses at two contemporary swine IAV antigenic clusters (H3N2 swine IAV-␣ and H3N2 swine IAV-ß) with a sensitivity of 84.9% and a specificity of 100.0%. The polyPLA can be routinely used in surveillance programs to detect antigenic variants of influenza viruses and to select vaccine strains for use in controlling and preventing disease in swine.

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Global evolution of influenza A viruses in swine

2016

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Antigenic Characterization of H3N2 Influenza A Viruses from Ohio Agricultural Fairs

Cited by 35 publications

References 52 publications

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

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

Detection of Antigenic Variants of Subtype H3 Swine Influenza A Viruses from Clinical Samples

Global evolution of influenza A viruses in swine

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