广西梧州地区近十年传染性法氏囊病病毒vVP2变化特征分析

为了解近10年来广西梧州地区鸡传染性法氏囊病病毒(IBDV)分子进化情况,对2013年—2014年间来自该地区传染性法氏囊病(Infectious bursal disease,IBD)的法氏囊样品进行IBDV的分离鉴定,并对分离株以及课题组2006年—2013年间分离的毒株,共24株的VP2高变区(vVP2)进行序列分析和遗传进化分析。结果表明,QX0601等23个分离株在关键氨基酸位点上具有256I、284A、294I等超强毒株(vvIBDV)的分子特征,遗传进化分析表明,这23株分离株与UK661、HK46等超强毒参考株同处一个分支中,亲缘关系较近;QX110603在关键性氨基酸位点上则具有256V、284T、294L等弱毒株的特征,遗传进化分析显示,其与BJ836等致弱株处于同一分支,亲缘关系较近。对所有分离株进行氨基酸位点分析发现,该地区IBDV进化出现了新的特点,212D-212N符合国内近年来的分离株的变化趋势,209T-209A、338R-338H、359T-359R则表现出地域特点,未曾见过相似报道。研究结果表明,具有vvIBDV分子特征的分离株是该地区近10年来主要流行毒株,该地区IBDV毒株在vVP2序列上仍处于不断进化中,且带有地域特点。

Molecular Characteristics Analysis of vVP2 Gene of IBDV in Guangxi Wuzhou during Past Ten Years

In order to study genetic variations of infectious bursal disease viruses (IBDV) in Wuzhou,Guangxi province during the past ten years,the sequence analysis and phylogenetic analysis based on VP2 hypervariable region (vVP2) of the field IBDV isolates (totally 24),which were isolated from IBD susceptible bursa between 2006-2014 in this region (the 11 isoaltes named as QX14-were newly isolated in this study) were performed.The sequence analysis indicated that the 23 isolates were characterized as very virulent IBDV (vvIBDV) according to critical amino acid sites which showed 256I,284A,294I.Phylogenetic analysis showed that these isolates were grouped with vvIBDV reference strains.Isolate QX110603 had typical amino acid sites as attenuated strains with 256V,284T, 294L.In the phylogenetic analysis,QX110603 was grouped with attenuated reference strains.Most of these isolates showed unique amino acid mutation in D212N, which was a common mutation trend in recent years.In addition,there were also some other amino acid sites such as T209A, R338H,T359R, which showed regional characteristics.The study suggests that IBDV with very virulent characters is the main strain prevalent in Wuzhou,Guangxi province,the genome of the isolates is still constantly evolved and showed specific regional characters.