猫传染性腹膜炎病毒的检测及ORF 7 ab、N和S基因遗传进化分析

Detection and Analysis of the Genetic Evolution of the ORF 7 ab,N and S Genes of Feline Infectious Peritonitis Virus

采用剖检、组织病理学和免疫组织化学的方法检测并确诊了2例猫传染性腹膜炎(FIP)病例,并通过RT-PCR扩增2例组织样品中猫传染性腹膜炎病毒(FIPV)的ORF 7 ab、N和S基因,测序后进行基因遗传进化分析,阐明病毒的遗传进化特征。结果显示,2个病例均表现典型的混合型FIP的大体病变,腹腔积满浆液纤维素性渗出物,在腹腔浆膜面散在或弥漫分布细小的灰白色结节。组织病理学显示腹膜表面上附着大小不等的炎性细胞浸润灶,以及坏死性肠炎、间质性胰腺炎和间质性肺炎。免疫组织化学染色结果显示,FPIV特异性的强阳性信号见于炎性细胞浸润灶、脾脏和胰腺内。基因同源性和遗传进化分析结果显示,2例基因均属于FCoVⅠ型。IMAU No.11685与浙江杭州ZJU1709毒株(MT239440)同源性最高,亲缘关系最近;IMAU No.11824与湖北武汉QS毒株(MW030108)同源性最高,亲缘关系最近。说明2例FIPV与国内流行毒株起源于共同祖先,其中ORF 7 ab、N基因相对保守,变异不明显,S基因发生一定的变异。研究结果可为我国FIP的分子流行病学研究和防控提供参考。

In this study,two cases of feline infectious peritonitis(FIP)were detected and diagnosed using autopsy,histopathology and immunohistochemistry(IHC),and the ORF 7 ab,N and S genes of feline infectious peritonitis virus(FIPV)were amplified by RT-PCR in two tissue samples.The genes were sequenced and subjected to genetic evolutionary analysis to elucidate the genetic evolutionary characteristics of the virus.The results showed that both cases presented with the typical gross lesions of mixed FIP,with an accumulation of plasma fibrinous exudate in the peritoneal cavity and scattered or diffuse distribution of small grey-white nodules on the peritoneal plasma surface.Histopathology showed the foci of inflammatory cell infiltration of variable size attached to the peritoneal surface,as well as necrotizing enterocolitis,interstitial pancreatitis and interstitial pneumonia.Strong positive signals specific for FPIV were seen in the foci of inflammatory cell infiltration,in the spleen and the pancreas.The genetic homology and genetic evolution analysis showed that the genes of the two cases belonged to FCoV typeⅠ.IMAU No.11685 had the highest homology with ZJU1709 strain(MT239440)from Hangzhou,Zhejiang province,and was the closest relative;IMAU No.11824 had the highest homology with QS strain(MW030108)from Wuhan,Hubei province,and was the closest relative.It indicateed that the two FIPV cases originated from a common ancestor with the domestic epidemic strain,in which the ORF 7ab and N genes are relatively conserved with insignificant variation,and some variation occurred in the S gene.It can provide data reference for the molecular epidemiological study and prevention and control of FIP in China.