Interspecies Transmission and Serological Study of Current Reassortant Swine Influenza Viruses After the Introduction of Pandemic H1n1 2009 in Thailand

Abstract

Interspecies transmission is one of the most interesting aspects for influenza A virus (IAV) research since the virus is able to infect multi-host species, especially, for three main important hosts including human, avian and swine. In 2009, pandemic H1N1 (H1N1pdm09) emerged and caused infection in both humans and pigs worldwide. The virus origin came from the reassortant between two swine influenza viruses (SIVs) and later, found circulated in pig population since 2010 in many parts of the world. In this study, the pathogenesis of H1N1pdm09 and its reassortant viruses using domestic ducks and the use of human influenza vaccines against H1N1pdm09 and its reassortant viruses of swine origin were investigated. The results demonstrated that H1N1pdm09 and its reassortant viruses could infect experimental ducks showing asymptomatic to mild clinical signs with small amount of virus shedding. This suggested that ducks could be one of the H1N1pdm09 reservoirs. Surveillance program of IAV in ducks is of importance. Additionally, current human influenza vaccines could protect only H1N1pdm09 and H1pdm reassortant viruses. The studied vaccines, however, did not completely protect all SIVs and reassortants of H1N1pdm09 origin. The finding data benefited human vaccine development and future plan. Moreover, the SIV surveillance data during 2012-2014 showed that SIV status in Thailand had changed after the H1N1pdm09 introduction. SIV serological assay especially for HI test was also investigated. The data showed that H1N1dpm09 has become endemic in the Thai pig population and should be added into the routine reference viruses for serological study. In conclusion, after the emergence of H1N1pdm09 in Thailand, multi-species influenza active surveillance is necessary for getting up to date influenza status, vaccine strategy and prevention among interspecies transmission.