长春地区犬细小病毒VP2基因的遗传进化及基因型分析

Evolutionary analysis of the VP2 gene of canine parvovirus and its genotypes in Changchun,China

目的了解吉林省长春地区犬细小病毒(Canineparvovirus,CPV)的流行及VP2基因的遗传进化特征。方法通过比对GenBank中已收录的不同地区、不同时间的CPV毒株基因序列,筛选保守区,设计特异性扩增完整VP2基因的通用型引物,采集疑似犬细小病毒病的犬粪便样品15份,提取DNA,PCR扩增获得完整的VP2基因并测序。将15份样品的测序结果与GenBank中已收录的22株CPV的VP2基因进行同源性比对并构建进化树,分析亚型以及遗传进化情况。结果PCR检测15份样品均为CPV阳性。样品株与参考株的核苷酸同源性为98.7%~99.9%,与4株商品化疫苗株的核苷酸同源性在98.1%~98.9%,遗传进化分析显示,15个分离株均为CPV-2c亚型,且所在分支十分接近,但未与所选CPV-2c亚型参考株在同一分支上。结论长春地区CPV流行亚型由CPV-2a、CPV-2b逐渐转变为CPV-2c,表明CPV-2c亚型的流行性越来普遍,CPV遗传变异趋势的监测和新型疫苗的研发应得到更多关注。

Objective To study the prevalence of canine parvovirus(CPV)and the evolutionary characteristics of the VP2 gene in Changchun area.Methods Conserved regions were screened for by comparing the gene sequences of CPV strains in different regions and at different times registered in GenBank,and a pair of universal primers was designed for specific amplification of the entire VP2 gene.DNA was extracted from 15 fecal samples from dogs suspected of having CPV disease,and the complete VP2 gene was obtained via amplification with PCR and sequenced.Sequencing indicated that 15 samples were similar to the VP2 gene of 22 CPV strains in GenBank.An evolutionary tree was constructed,and the subtypes and genetic evolution of CPV were analyzed.Results All 15 samples tested positive for CPV according to PCR.The nucleotide similarity between the sample strain and the reference strain was 98.7-99.9%,and the nucleotide similarity between the sample strain and 4 vaccine strains was 98.1-98.9%.Genetic evolutionary analysis indicated that all 15 isolates were of the CPV-2c subtype;their branches were very close but not in the same branch as the selected reference strains of the CPV-2c subtype.Conclusion The CPV subtype prevalent in dogs in Changchun has gradually changed from CPV-2a and CPV-2b to CPV-2c,and results indicated that the CPV-2c subtype has become increasingly prevalent.More attention should be paid to monitoring trends in CPV genetic variation and the development of new vaccines.