我国狂犬病流行毒株JX08-45适应细胞培养后的生物学特性

目的鉴定我国狂犬病流行毒株JX08-45适应细胞培养后(命名为JX08-45CC株)的生物学特性。方法通过全基因组序列分析比对、小鼠脑内和外周攻毒试验和免疫原性试验,分别对JX08-45CC株的基因组特点、毒力和免疫原性进行鉴定。结果 JX08-45CC株的基因组序列与JX08-45株比对,共出现16个核苷酸突变点和7个氨基酸突变点,其中6个氨基酸变异发生在G蛋白(333位精氨酸未改变)编码区,L蛋白仅有1个氨基酸突变;在G蛋白氨基酸变异中,4个突变序列在其他细胞适应毒株CVS-11、CTN-1、Nishigahara、SAG2、Flury-LEP和SRV9中也普遍存在。JX08-45CC株培养滴度≥107TCID50/ml时,脑内接种小鼠的致死率为100%,滴度为102～106TCID50/ml时,脑内接种小鼠的致死率为20%～80%;滴度为105～108TCID50/ml时,外周肌肉接种小鼠,致死率为10%～70%;脑内和外周攻毒小鼠的潜伏期均为7～9 d,并于发病后24～48 h死亡。JX08-45CC株与狂犬病病毒CVS-11、ERA、SRV9和Flury-LEP株的中和抗体滴度差异均无统计学意义(P>0.05)。结论已对JX08-45CC株的基因组序列、毒力和免疫原性等生物学特性进行了鉴定,为开发具有我国自主知识产权的兽用狂犬病灭活疫苗候选株奠定了基础。

Biological characteristics of cell culture-adapted rabies virus isolate JX08-45

Objective To determine the biological characteristics of cell culture-adapted JX08-45 epidemic in China,renamed as JX08-45CC.Methods The genetic characteristics,virulence and immunogenicity of strain JX08-45CC were analyzed by whole genome sequencing,intracerebral and peripheral challenge tests in mice as well as immunogenicity test.Results As compared with that of strain JX08-45,a total of 16 nucleotide mutation sites and 7 amino acid mutation sites were observed in the genome sequence of strain JX08-45CC,of which 6 amino acid mutations appeared in G protein(the arginine at site 333 showed no change) while one in L protein.Four of the 6 amino acid mutations in the encoding region of G protein were also popular in other cell-adapted strains such as CVS-11,CTN-1,Nishigahara,SAG2,Flury-LEP and SRV9.The death rate of mice challenged i.c.with strain JX08-45CC at a titer of not less than 107 TCID50 / ml were 100%,while that at a titer of 102 ~ 106 TCID50 / ml was 20% ~ 80%.However,the death of mice challenged i.m.with the strain at a titer of 105 ~ 108 TCID50 / ml was 10% ~ 70%.Both the incubation periods of the strain in mice challenged by intracerebral and peripheral routes were 7 ~ 9 d,and the mice died 24 ~ 48 h after onset.The neutralizing antibody titer induced by strain JX08-45CC showed no significant difference with those by strains CVS-11,ERA and SRV9(P > 0.05).Only one mutation of amino acid was distributed in region L protein.Conclusion The biological characteristics including genome sequence,virulence and immunogenicity of rabies virus strain JX08-45CC were identified,which laid a foundation of development of candidate strains for rabies vaccine for animal use with independent intellectual property rights in China.