广西猫杯状病毒全基因组序列测定及其遗传进化分析

Sequencing of the Whole Genome and ORF2 Phylogenetic Analysis of A Feline Calicivirus Isolate from Guangxi

为了掌握广西猫杯状病毒(FCV)的流行情况及其变异规律。本研究于2018年3月至2019年9月采集疑似FCV鼻拭子59份,其中阳性检出率49.2%(29/59)。将阳性病料接种CRFK细胞,成功分离获得一株FCV毒株,命名为NN01-19。为深入了解其遗传进化规律和分子特征,本研究通过RT-PCR方法扩增获得该毒株的全基因组序列,并对其ORF2基因进行了遗传进化和序列分析。结果表明,NN01-19毒株基因组全长7709 bp,其中ORF2基因全长2010 bp。遗传进化分析发现该毒株与广西早期分离株GX01-13同属基因I群,但核苷酸和氨基酸同源性仅为77.9%和86.5%。其中,超变区(E区)抗原线性表位新增T448A、T450G、G451Q和T454S四个突变位点。重要的是,该区域还发生了V430T的突变,符合VS-FCV致病性氨基酸突变特点。本研究为深入了解FCV的流行特点及其变异规律提供了参考依据,同时也为今后防控FCV提供了重要的理论基础。

In order to investigate the prevalence of feline calicivirus(FCV)and its variation in Guangxi,59 cat nose swabs were collected from March 2018 to September 2019 and 29 swabs were tested positive(49.2%).An FCV isolate NN01-19 was obtained by inoculating the positive samples into CRFK cells.In order to understand its genetic evolution and molecular characteristics,the whole genome sequence of the strain NN01-19 was amplified by RT-PCR and the phylogenetic analysis of its ORF2 gene were carried out for genetic evolution study.The results showed that the genome of the strain NN01-19 strain was 7709 bp,of which the full length of ORF2 gene was 2010 bp.The phylogenetic analysis revealed that the strain NN01-19 and an early isolate GX01-13 also from Guangxi belonged to the high-pathogenic group of the GI but their nucleotide and amino acid sequences shared only 77.9% and 86.5%homology.In addition,four mutation sites T448A,T450G,G451Q and T454S were added to the linear epitope of E region antigen.Importantly,this region also had a mutation in V430T,which was consistent with the characteristics of pathogenic amino acid mutations of VS-FCV.This study provided a reference for further understanding of the epidemic characteristics and variation of FCV and important theoretical foundation for the prevention and control in the future.