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Genotype patterns of contemporary reassorted H3N2 virus in U.S. swine
- Pravina Kitikoon, Martha I. Nelson, Mary Lea Killian, Tavis K. Anderson, Leo Koster, Marie R. Culhane, Amy L. Vincent
- Journal of general virology 2013 v.94 no.Pt 6 pp. 1236-1241
- Influenza A virus, antigenic variation, cross reaction, genotype, humans, mutation, phylogeny, swine, vertebrate viruses, United States
- To understand the evolution of swine-origin H3N2v influenza viruses that have infected 320 humans in the USA since August 2011, we performed a phylogenetic analysis at a whole genome scale of North American swine influenza viruses (n = 200). All viral isolates evolved from the prototypical North American H3 cluster 4 (c4), with evidence for further diversification into subclusters. At least ten distinct reassorted H3N2/pandemic H1N1 (rH3N2p) genotypes were identified in swine. Genotype 1 (G1) was most frequently detected in swine and all human H3N2v viruses clustered within a single G1 clade. These data suggest that the genetic requirements for transmission to humans may be restricted to a specific subset of swine viruses. Mutations at putative antigenic sites as well as reduced serological cross-reactivity among the H3 subclusters suggest antigenic drift of these contemporary viruses.