| Abstract: | Three subtypes—H1N1, H1N2 and H3N2—of influenza A viruses of swine (IAV s‐S) are currently endemic in swine worldwide, but there is considerable genotypic diversity among each subtype and limited geographical distribution. Through IAV s‐S monitoring in Vietnam, two H1N2 influenza A viruses were isolated from healthy pigs in Ba Ria‐Vung Tau Province, Southern Vietnam, on 2 December 2016. BLAST and phylogenetic analyses revealed that their HA and NA genes were derived from those of European avian‐like H1N2 IAV s‐S that contained avian‐origin H1 and human‐like N2 genes, and were particularly closely related to those of IAV s‐S circulating in the Netherlands, Germany or Denmark. In addition, the internal genes of these Vietnamese isolates were derived from human A(H1N1)pdm09 viruses, suggesting that the Vietnamese H1N2 IAV s‐S are reassortants between European H1N2 IAV s‐S and human A(H1N1)pdm09v. The appearance of European avian‐like H1N2 IAV s‐S in Vietnam marks their first transmission outside Europe. Our results and statistical analyses of the number of live pigs imported into Vietnam suggest that the European avian‐like H1N2 IAV s‐S may have been introduced into Vietnam with their hosts through international trade. These findings highlight the importance of quarantining imported pigs to impede the introduction of new IAV s‐S. |
