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Circulation of multiple genotypes of H1N2 viruses in a swine farm in Italy over a two-month period

Beato, Maria Serena, Tassoni, Luca, Milani, Adelaide, Salviato, Annalisa, Di Martino, Guido, Mion, Monica, Bonfanti, Lebana, Monne, Isabella, Watson, Simon James, Fusaro, Alice
Veterinary microbiology 2016 v.195 pp. 25-29
Influenza A virus, breeding, disease control, finishing, genetic variation, genome, genotype, hemagglutinins, livestock and meat industry, monitoring, nose, pandemic, piglets, sequence analysis, sows, vaccination, vaccines, viruses, Italy
In August 2012 repeated respiratory outbreaks caused by swine influenza A virus (swIAV) were registered for a whole year in a breeding farm in northeast Italy that supplied piglets for fattening. The virus, initially characterized in the farm, was a reassortant Eurasian avian-like H1N1 (H1avN1) genotype, containing a haemagglutinin segment derived from the pandemic H1N1 (A(H1N1)pdm09) lineage. To control infection, a vaccination program using vaccines against the A(H1N1)pdm09, human-like H1N2 (H1huN2), human-like H3N2 (H3N2), and H1avN1 viruses was implemented in sows in November 2013. Vaccine efficacy was assessed by sampling nasal swabs for two months in 35–75 day-old piglets born from vaccinated sows. Complete genome sequencing of eight swIAV-positive nasal swabs collected longitudinally from piglets after the implementation of the vaccination program was conducted to investigate the virus characteristics.Over the two-month period, two different genotypes involving multiple reassortment events were detected. The unexpected circulation of multiple reassortant genotypes in such a short time highlights the complexity of the genetic diversity of swIAV and the need for a better surveillance plan, based on the combination of clinical signs, epidemiological data and whole genome characterization.