Genetic Evolution of Neuraminidase Gene of Influenza A/H1N1 Virus

【Objective】 This study was designed to investigate the genetic evolution of the neuraminidase (NA) gene of seasonal A/H1N1 and 2009 novel A/H1N1 influenza virus, and discuss the genetic variation of influenza A virus. 【Methods】 The virus strains were separately isolated from the clinical samples collected in 2006 and 2009, and then identified as seasonal A / H1N1 and novel A/H1N1. The full length of the NA gene of these strains was amplified by RT-PCR. Then the genetic evolution and mutations of important functional sites were analyzed. 【Results】 The homology of NA gene between the 2009 novel A/H1N1 isolates and 2006 seasonal A/H1N1 isolates was low (77.9% ～ 78.8%), so was the homology of NA gene between the 2009 novel A / H1N1 isolates and representative strains of different periods and 1979-2001 WHO recommended vaccine strains (78.1% ～ 79.3%). But compared with the WHO recommended vaccine strains of 2009 novel A/H1N1, the homology reached more than 99%. The genetic evolution analysis revealed that NA gene of 2009 novel A/H1N1 had the closest genetic relationship with the swine influenza A virus (A/swine/Belgium/1/1983) from Eurasian lineage, and some of the antigenic sites and neuraminidase active sites of NA gene of seasonal A/H1N1 were mutated after 2005. 【Conclusion】 The NA gene of 2009 novel A/H1N1 may originate from Eurasian lineage of swine influenza virus. The variation of NA gene of seasonal A/H1N1 has occurred in a certain degree. Hence, it is very necessary to continuously monitor the variant of influenza A virus.