我国流行的4株狂犬病街毒株G基因序列及分子流行病学研究

目的探讨我国流行的狂犬病毒(RV)基因差异,评价现有疫苗的适用性。方法通过RT-PCR并对其产物测序后获得4株RV街毒株的G基因序列以及G与M和L基因的区间序列。利用计算机分析软件比较4株RV与已经发表的毒株的核苷酸和推导的氨基酸序列。结果糖蛋白(GP)完整的编码基因序列长度为1575 bp。GP氨基酸序列同源性明显高于相应的核苷酸序列(除Mokola外),4株街毒与CTN的同源性高于aG株。GP不同区段比较显示,膜外区同源性高于膜内区。G-M区间核苷酸序列长度为5 bp;除广西4外,其余毒株100％同源。GL区间核苷酸序列长度为2,4 bp,越1与肥东同源性为100％。结论4株RV均属于基因I型。广西的毒株之间存在不同的来源。街毒与疫苗株之间基因存在差异。4株RV与SAD-B19进化途径相近,与PV株相差较远。越1与肥东株亲缘关系极近,可能是由同一毒株演化而来。

G Gene Sequence and Molecular Epidemiology of 4 Street Virus Strains of Rabie Virus Isolated in China

Objective To explore the gene variation of rabies virus (RV) prevalent in China and evaluate the availability of the current vaccine. Methods Amplify the G gene as well as the gene between G-L and G-M intergenic regions of 4 street virus strains of RV by RT-PCR and identify the PCR products by direct sequencing. Compare the nucleotide and deduced amino acid sequences of the 4 strains with those of strains reported by computer software. Results The coding region of G gene consisted of 1 575 nucleotides. The homologies of the amino acid sequences of G proteins of the 4 strains to those of reported strains (except Mokola strain) were significantly higher than those of their corresponding nucleotide sequences. The homologies of 4 street virus strains to CTN were significantly higher than those to aG strain. Compared with the sequences at intracellular regions, the homologies of the sequences at extracellular regions of the 4 strains to those of reported strains were significantly high. The lengths of nucleotide sequences at G-M intergenic regions of the 4 strains were 5 bp. Except Guangxi 4 strain, the homology of the rest 3 strains was 100%. All the lengths of nucleotide sequences at G-L intergenic regions of the 4 strains were 24 bp, however, only the homology of Yue 1 and Feidong strains was 100% . Conclusion All the 4 strains prevalent in China were genotype I. The strains isolated in Guangxi Province might be derived from different origins. Gene variation was observed between the street virus strain and vaccine strain. The evolutionary modes of the 4 street virus strains were similar to that of SAD-B19 strains but significantly different from that of PV strain. Yue 1 and Feidong strains showed a significantly close consanguinity, so they might be evolved from the same strain.