犬冠状病毒纤突蛋白基因的序列测定与比较分析

Sequence Comparison and Analysis of Spike Protein Gene of Canine Coronavirus

将两株犬冠状病毒国内分离毒CCVYS1、CCVCI1接种于CCV中和抗体效价低于 1∶4的 2月龄幼犬 ,观察接种犬临床表现、体温和剖检变化。结果表明 ,CCVYS1株毒力较强 ,CCVCI1株毒力较弱。采用RT_PCR方法扩增出两株病毒部分S基因序列 ,克隆于pUC1 9SmaI位点或pGEM_T载体中 ,以双脱氧末端终止法测定插入质粒的cDNA核苷酸序列。用PROSIS计算机软件推导氨基酸序列 ,并与从Genbank上查到的CCV、TGEV和FIPV相应氨基酸序列进行多重比较。分别推测 ,CCVS蛋白上Ac抗原位点的氨基酸残基可能是影响病毒毒力的因素之一。

CRFK cell line cultures of CCV YS1 and CCV CI1 strains isolated from dogs in China were inoculated to dogs which CCV SN titers were lower than 1∶4 at the age of 2 months.Clinical symptoms,body temperature and pathogenic changes were observed.Results shows that the virulence of CCV YS1 strain is stronger than that of CCV CI1.S gene of 2 strains were amplified by RT-PCR,cloned into Sma I point of pUC19 or pGEM-T vector and sequenced with the method of the Sanger's.Amino acid sequences were deduced and compared with that of CCV,FIPV,TGEV.According to the results of the comparison,amino acid of antigenic sites were analyzed and suggested that the amino acid of Ac antigenic site in the S protein may play an important role on the virulence of CCV.