中国猪流行性腹泻病毒分子流行病学研究进展

Advances in Study of Molecular Epidemiology of Porcine Epidemic Diarrhea Virus in China

2010—2011年中国境内的猪流行性腹泻(PED)大流行给养猪业造成重大经济损失。因疫苗免疫无法控制疫病流行,因此学者普遍认为猪流行性腹泻病毒(PEDV)出现了新的变种。论文综合分析了这个时期国内学者PEDV分子流行病学的研究结果,又对国内新近分离的PEDV的11个毒株的全基因序列进行遗传进化分析,进一步确定了国内暴发流行的PEDV毒株已远离中国86年分离的毒株和欧洲毒株CV777,成为了一个新的基因型。毒株基因变异应该是造成免疫失败和仔猪死亡率高的主要原因。进一步分析发现分离毒株的全长基因序列和棘突蛋白(S)基因序列长度有差异,其他基因长度保守性强。S基因的变异率高于其他基因,特别是短期内基因突变主要发生于S基因。综合分析认为国内变异毒株虽与韩国毒株遗传关系较近,但从境内毒株衍生和进化而来的可能性更大。因2006年已经观察到PEDV的免疫失效和PED流行,2010—2011年PED集中暴发可能是病原长期突变和适应性积累的结果,提示今后应充分发挥全国动物疫病预警网络的作用,加强毒株进化检测和疫病预警,优化疫病的防控手段,降低疫病发生频次和规模,减小疫病发生损失。

Porcine epidemic diarrhea （PED） caused heavy economic losses to Chinese pig industry in 2010 and 2011. It was postulated that new variants of porcine epidemic diarrhea virus （PEDV） had played a major role because the vaccine made from previous strains failed to provide efficient protection for infected piglets. This review summarized the investigations on molecular epidemics of PEDV in this period of time in China and made a phylogenetic analysis with published complete genomic sequences. The analysis provided fiarther evidence for the existence a novel genotype PEDV, which was not clustered with Chinese 1986 strains and European CV777 strain. The growing genetic difference between prevailing and vaccine strains should be the cause of vaccination failure as well as high death rate of piglets. Complete genomic sequence analysis showed the length difference of their polymerase （lab） as well as their spike （S） genes. S gene had the highest mutation rate among the subgenomes, especially within a relatively short period of time. The analysis also implied that the new strains could evolve from domestic strains. Severe PED problem was reported early in 2006, therefore the 2010 to 2012 outbreak of PED could be the result of accumulation of pathogen mutations and adaotation, which also suggested, the imoortance of evolution surveillance of oatho^ens by national network.