Brief report: molecular characterization of a novel reassorted pandemic H1N1 2009 in Thai pigs

Abstract

For the past 10 years, endemic swine influenza H1 viruses in Thailand have been characterized as reassortants of swine virus genes from swine influenza viruses (SIV) in US and European pigs. Here the authors report the emergence of a novel reassorted H1N1 (rH1N1) virus consisted of human, avian, and swine virus genes from the pandemic H1N1 2009 (pH1N1) virus with a neuraminidase (NA) gene from a Thai swine H1N1 (ThH1N1) isolate. The rH1N1 virus was detected in nursery pigs during a respiratory disease outbreak in central Thailand in early 2010. The rH1N1 virus was repeatedly isolated from infected pigs, suggesting that it can transmit efficiently among the pig population. The appearance of rH1N1 virus in the field occurred within months of the introduction of pH1N1 virus into the Thai swine population in late 2009. The finding highlights the role of pig in generating newly reassorted influenza A viruses and also the significance of continuing disease surveillance and genetic characterization of SIV in pigs.

Pathogenicity and Transmission in Pigs of the Novel A(H3N2)v Influenza Virus Isolated from Humans and Characterization of Swine H3N2 Viruses Isolated in 2010-2011

“…The pH1N1 virus had five gene segments (PB2, PB1, PA, NP, and NS) genetically related to the TRIG cassette, as well as an HA genetically related to the ␥-H1 cluster found in the North American swine lineage viruses, while the M and NA genes were from Eurasian lineage (avian-like) swine influenza viruses (10). Reports of pH1N1 reassortment with endemic H1 SIV resulting in different SIV genotypes detected in swine have been documented around the world (9,13,18,22,29). In contrast to the increasing genetic diversity and evolution detected in the H1 subtype in recent years, swine H3N2 viruses have not evolved further into additional distinct genotypes beyond the HA cluster IV.…”

2009 Pandemic H1N1 Influenza Virus Causes Disease and Upregulation of Genes Related to Inflammatory and Immune Responses, Cell Death, and Lipid Metabolism in Pigs

“…pH1N1 viruses have been isolated from swine herds worldwide, indicating that they are cocirculating in the pig population with currently circulating SIVs. Furthermore, reassortment between pH1N1 and circulating SIVs has been reported (22,54). Importantly, it is possible to generate via reassortment in the pig a more virulent virus that may infect humans.…”

Comparative study of pandemic (H1N1) 2009, swine H1N1, and avian H3N2 influenza viral infections in quails

“…This virus continued to spread among human populations and was transmitted to other animal species such as domestic pigs [18,25], turkeys [12], and cats [1]. Recent evidence has shown that novel pH1N1 viruses were generated by reassortment events between pH1N1 and endemic swine H1N1 (swH1N1) viruses in pigs in many countries, including Thailand [9]. It is known that influenza A virus (IAV) transmission between humans, pigs, and avian species is common [29].…”