Brief report: molecular characterization of a novel reassorted pandemic H1N1 2009 in Thai pigs Pravina Kitikoon • Donruethai Sreta • Suparlark Nuntawan Na Ayudhya • Manoosak Wongphatcharachai • Jiradej Lapkuntod • Duangduean Prakairungnamthip • Napawan Bunpapong • Sanipa Suradhat • Roongroje Thanawongnuwech • Alongkorn Amonsin Received: 11 January 2011 / Accepted: 7 March 2011 / Published online: 26 March 2011 Ó Springer Science+Business Media, LLC 2011 Abstract For the past 10 years, endemic swine influenza H1 viruses in Thailand have been characterized as reas- sortants 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 respi- ratory 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. Keywords Influenza Á Pandemic H1N1 2009 Á Swine Á Reassort Á Thailand In early 2009, a swine-origin H1N1 virus known as the pandemic H1N1 (pH1N1) 2009 virus emerged and spread rapidly among the human population [1]. Genetic analyses indicated that pH1N1 was derived from well established lineages of H1 swine influenza viruses (SIV) that have previously circulated among pig populations in North America and Europe. The H1 hemagglutinin (HA) genes of those circulating viruses were, respectively known as ‘‘classical swine’’ and ‘‘Eurasian swine’’ lineages [2]. The pH1N1 consists of classical-Eurasian swine lineage of the viral surface HA and neuraminidase (NA) genes with Electronic supplementary material The online version of this article (doi:10.1007/s11262-011-0597-5) contains supplementary material, which is available to authorized users. P. Kitikoon Á J. Lapkuntod Á D. Prakairungnamthip Á N. Bunpapong Á S. Suradhat Á R. Thanawongnuwech (&) Á A. Amonsin (&) Emerging and Re-emerging Infectious Diseases in Animals, Research Unit, Faculty of Veterinary Science, Chulalongkorn University, Henri Dunant Rd., Bangkok 10330, Thailand e-mail: Roongroje.T@chula.ac.th A. Amonsin e-mail: Alongkorn.A@chula.ac.th P. Kitikoon e-mail: kaewtoon@gmail.com N. Bunpapong e-mail: napawan.nb@gmail.com S. Suradhat e-mail: sanipa.s@chula.ac.th P. Kitikoon Á D. Sreta Á S. Nuntawan Na Ayudhya Á D. Prakairungnamthip Á R. Thanawongnuwech Department of Pathology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand D. Sreta e-mail: chopdon@hotmail.com S. Nuntawan Na Ayudhya e-mail: suparlark@yahoo.com M. Wongphatcharachai Á J. Lapkuntod Á A. Amonsin Department of Veterinary Public Health, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand S. Suradhat Department of Microbiology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand 123 Virus Genes (2011) 43:1–5 DOI 10.1007/s11262-011-0597-5