Molecular Epidemiology Survey Of H9N2 AIV In Jiangxi And Zhejiang During 2011 To 2012

The H9N2 subtype avian influenza virus has been already isolated and confirmed in the avian circulate from worldwide.There is an available evidence suggests that H9N2 virus did not appear in China until 1994s.For the accumulation of antigenic drift and antigenic shift,the barrier between avian and human is weakened or disappeared.There is a huge risk for the human public health security.It is necessary to forecast the nest human flu pandemic virus and develop an effective or relative vaccine,within the constantly knowledge of the genetic variations and antigenic shift of AIVs.In order to acquire and monitor the molecular evolution of the H9N2 subtype avian influenza virus,14th virus isolated from 2011 to 2012 were chose to sequence their whole genomes and established the phylogenetic analysis by MEGA 5.0.Thus,it can reveal the epidemic regularity of the H9N2 AIVs.The results show that,14th virus separated from Jiangsu and Zhejiang provinces had the typical character of low pathogenic avian influenza.HA gene originated from Y280-like virus.The 234th site of most viruses are L,having the preference to binding the SA a-2,6-Gal moieties in human cell.It shows that in recent years the H9N2 AIV has the pathogenic ability to infect mammalian.NA gene originated from Y280-like,all have a deletion in the neck.PA,PB1,NP all originated from SH/F/98-like,but many amino acid sites have mutations compared with the classical strains.M gene originated from G1-like,all had no molecular characterization of amantadine resistance.Most virus bear the SH/F/98-like NS genes,only one belongs to the Y439-like.Two breed had obvious differences in amino acid sites,but all had the typical character of evaded from IFN and TNF-a.PB2 gene had formed a new branch.The site amino acid of 14 H9N2 strains'internal genes are consistent with of H7N9 strains'.There is a significant change in antigenicity within the monitoring of H9N2 AIVs in recent years.Vaccination is the most universal and useful method used in China to prevent and control the disease.Even though the side effect was that the mutation and recombination of AIVs appeared more frequently,leading to an immune failure phenomena.From the result of antigenicity,we knew the 14th H9N2 AIVs had a similar antigenicity,the average titer of HI was 81og2 and the difference was no more 31og2.Antigen related value was from 0.8 to 1.From the result of immunogenicity analysis,we knew the control group's detoxification ratio was 5/5,5/5,4/5,4/5,but the immunity group was all negative.The representative viruses had a good immunogenicity and could provide immune protection between each other.