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研究一株神经毒力很强的乙型脑炎病毒株SA4株的生物学特性并进行基因组全序列分析,并找到其毒力强的分子基础。将SA4脑内接种昆明小鼠后每日观察发病和死亡鼠数并每日收取鼠脑,用空斑法检测接种后不同时间点的脑内病毒增殖滴度,同时以另一株乙脑病毒SA14按照相同方法进行平行实验作为对照。SA4株的全基因组测序序列结果与乙脑SA14株及世界各地共21株乙脑病毒的全基因组序列进行比较。结果显示,脑内接种SA4株的小鼠发病和死亡时间均比SA14株早1d,在相同时间点上SA4株的病毒滴度高0.5～1.0lgPFU/mL。SA4株与世界各地毒株基因同源性比对,核苷酸同源性为84.6%～99.0%,氨基酸同源性为95.2%～99.7%。与SA14相比,氨基酸序列存在17个位点的差异,分布于不同的区段,其中E区最多,为5个。证明SA4是一株在脑内具有较快繁殖力的神经毒力很强的毒株,其序列上17个氨基酸位点的替换很可能是其强神经毒力的分子基础。
To study the biological characteristics of a highly virulent Japanese encephalitis virus SA4 strain and to perform genome-wide sequence analysis and to find its molecular basis of virulence. The SA4 brain was inoculated Kunming mice daily observation of the incidence and death of mice and mice were harvested daily, using the plaque assay at different time points after inoculation virus proliferation titers, while another strain of JE virus SA14 parallel experiments were performed as controls. The whole genome sequence of SA4 strain was compared with that of JE SA14 and 21 JE viruses worldwide. The results showed that the SA4-inoculated mice inoculated with SA4 had a higher incidence and death time than the SA14 strain by 1 day. The virus titer of SA4 strain was 0.5-1.0 lgPFU / mL at the same time point. The homology of SA4 strains with those of other strains in the world was 84.6% -99.0%, and the amino acid homology was 95.2% -99.7%. Compared with SA14, the amino acid sequence has 17 differences in loci, which are distributed in different segments, of which E is the most, which is 5. SA4 proved to be a highly virulent strain with faster fertility in the brain. The substitution of 17 amino acid residues in its sequence is likely to be the molecular basis of its strong neurovirulence.