Identification of Reassortant Pandemic H1N1 Influenza Virus in Korean Pigs

Abstract

Since the 2009 pandemic human H1N1 influenza A virus emerged in April 2009, novel reassortant strains have been identified throughout the world. This paper describes the detection and isolation of reassortant strains associated with human pandemic influenza H1N1 and swine influenza H1N2 (SIV) viruses in swine populations in South Korea. Two influenza H1N2 reassortants were detected, and subtyped by PCR. The strains were isolated using Madin-Darby canine kidney (MDCK) cells, and genetically characterized by phylogenetic analysis for genetic diversity. They consisted of human, avian, and swine virus genes that were originated from the 2009 pandemic H1N1 virus and a neuraminidase (NA) gene from H1N2 SIV previously isolated in North America. This identification of reassortment events in swine farms raises concern that reassortant strains may continuously circulate within swine populations, calling for the further study and surveillance of pandemic H1N1 among swine.

Novel triple reassortant H1N2 influenza viruses bearing six internal genes of the pandemic 2009/H1N1 influenza virus were detected in pigs in China

“…The gene constellations of the two reassortants were distinct from the previously identified reassortant H1N2 viruses from pigs in other countries [35][36][37][38][39][40]. Although it was unclear as to whether these novel viruses were transient or they had acquired pathogenicity and transmissibility in pigs, the finding that new reassortants emerged in pigs further underscores the fact that influenza virus reassortment is an ongoing process.…”

“…The M gene of the 2009/H1N1 virus plays an important role in its transmissibility [29,30], and both the PA and NS genes of 2009/H1N1 virus can make an H5N1 influenza virus highly transmissible by respiratory droplet in guinea pigs [26]. H3N2, H1N1, and H1N2 influenza viruses bearing different genes from the 2009/H1N1 virus have been detected in pigs in many countries since 2009 [31][32][33][34][35][36][37][38][39][40], and it would be of value to fully evaluate the biologic properties of these viruses.…”

Continual Reintroduction of Human Pandemic H1N1 Influenza A Viruses into Swine in the United States, 2009 to 2014

“…Since 2009, pH1N1 viruses and pH1N1 reassortants (i.e., viruses with at least one segment of pH1N1 origin) have been identified in swine populations in the Americas (United States [20], Canada [21], Mexico [22], Argentina [6], Brazil [23], and Colombia [24]), Europe (United Kingdom [25], Germany [26], Norway [8], and Italy [27]), Asia (China [3], South Korea [28], Sri Lanka [10], Thailand [29], and Vietnam [7]), Africa (4), and Australia (5). We previously estimated that the pH1N1 virus was introduced at least 49 times from humans to swine on a global scale (9).…”

Emergence of H3N2pM‐like and novel reassortant H3N1 swine viruses possessing segments derived from the A (H1N1)pdm09 influenza virus, Korea

“…In this study, we show that A(H1N1)pdm 09‐like viruses remain in circulation among swine herds of Korea, providing opportunities to undergo reassortment with currently circulating animal influenza viruses. Indeed, A(H1N1)pdm09‐derived H1N2 reassortants were isolated in 2010 bearing N2 segments from pre‐existing Korean H1N2 swine strains . Meanwhile, H1N2 isolates in the present study appear to be intact Korean swine viruses without any indications of genetic reassortment.…”