一株麻鸡传染性法氏囊病毒新型变异株的分离鉴定

Isolation and Identification of a Novel Mutated Strain of Infectious Bursal Disease Virus in Spotted Chicken

近几年,鸡传染性法氏囊病毒新型变异株在我国广泛流行,主要发生于肉鸡,其致病力弱、隐蔽性强但能造成法氏囊严重萎缩。本研究从山东济宁地区临床出现法氏囊萎缩的发病麻鸡中采集法氏囊病料,接种SPF鸡胚进行病毒分离,通过RT-PCR方法进行病毒鉴定,将分离毒株回归SPF鸡进行致病性试验,同时对其主要抗原基因VP2进行进化分析。结果发现,该毒株能致死鸡胚;对其VP2基因进行测序比对和进化树分析发现,其与近几年的新型变异株基因序列的进化关系较近,同源性为96.1%~99.2%;人工感染SPF鸡第7 d法氏囊即出现较为明显的萎缩,第14 d萎缩更为明显,囊体比显著小于对照组(P<0.01)。本研究分离到的麻鸡源传染性法氏囊病毒JN22株属于新型变异株,能导致SPF鸡法氏囊显著萎缩。

In recent years,a novel variant of chicken infectious bursal disease virus has been widely prevalent in China,mainly occurring in broiler chickens.It has the characteristics of weak pathogenicity and strong concealment,but it can cause severe atrophy of the bursa of Fabricius.This study collected the atrophic bursa of Fabricius from spotted chickens in Jining area,Shandong Province,to isolate the virus by SPF chicken embryos.The virus was identified through RT-PCR detection and injected to SPF chickens for pathogenicity testing,and then its main antigen gene VP2 was analyzed for evolution.It was found that the strain could kill chicken embryos.Sequencing comparison and evolutionary tree analysis of gene VP2 revealed a close evolutionary relationship with the gene sequences of recent novel variants,with homology ranging from 96.1%to 99.2%.On the 7th day of artifi cial infection in SPF chickens,there was a signifi cant atrophy of the bursa of Fabricius,and on the 14th day,the atrophy was more pronounced,with a signifi cantly smaller bursa to body ratio than the control group(P<0.01).The JN22 strain of infectious bursal disease virus isolated in this study belongs to a novel mutant strain,which can cause signifi cant atrophy of the bursal disease in SPF chickens.