猫杯状病毒分离株VP1基因序列与致病性分析

旨在了解上海地区猫杯状病毒（feline calicivirus，FCV）VP1基因与致病性，采用常规方法分离鉴定出13株FCV，经RT-PCR和测序获得分离株VP1的基因序列，与参考株VP1基因进行同源性和遗传演化分析，对2株分离株进行动物致病性试验。结果显示，13株上海地区分离株VP1基因核苷酸序列相互间相似性为74.3%~99.8%，与参考株核苷酸序列和氨基酸序列相似性也较低，符合FCV易突变的特征；进化树分析表明，上海地区FCV流行株主要来自国内北方地区，少数毒株来自国外地区；通过对宿主临床症状、VP1进化树和VS-FCV特征性氨基酸位点进行分析，筛选出7株FCV强毒株；动物致病性试结果验表明，FCV-SH202101株和FCV-SH202113株可导致感染猫发病和死亡，潜伏期为1~2 d，接种后第3天即可检测到排毒，不同年龄段猫的病程不一致，可导致幼猫5 d后死亡，成年猫病程可持续11~18 d，2株分离株在致病性方面均符合VS-FCV特征。本研究丰富了中国FCV的分子流行病学资料，为VS-FCV毒株的筛选提供了有力的证据，也为FCV疫苗的研究提供了技术支持。

VP1 Sequence and Pathogenicity Analysis of Feline Calicivirus Isolates

In order to understand VP1 genes and pathogenicity of feline calicivirus (FCV), 13 FCV strains were obtained after isolation and identification. The VP1 genes of these FCV strains were obtained by RT-PCR and sequencing. Then, phylogenetic analyses based on the VP1 sequences were performed with reference strains. Cat pathogenicity experiments were carried out with 2 FCV strains. The results showed that the nucleotide sequence similarity among these 13 FCV VP1 genes was 74.3%-99.8%, and the homology of the nucleotide and amino acid was low with reference strains. The characteristics of variation were consistent with FCV. The analysis of phylogenetic tree showed that the major strains in Shanghai were from northern China, and other strains were from foreign countries. Seven VS-FCV strains were obtained by clinical symptoms, phylogenetic tree of VP1 and VS-FCV characteristic amino acid sites analysis. Cat pathogenicity experiments showed that the strains of FCV-SH202101 and FCV-SH202113 could cause the disease and death of cats, and the incubation period was about 1 to 2 days. The FCV strains would be detected on the 3rd day after inoculation. The durations of FCV in different age groups were different, kittens would be 5 days, and adult cats would be 11 to 18 days. So the FCV-SH202101 strain and FCV-SH202113 strain had the same characteristics with VS-FCV strains in pathogenicity. This study enriched the molecular epidemiological data of FCV in China, provided strong evidence for the screening of VS-FCV strains, and also provided technical support for the research of FCV vaccine.