A single amino acid change in nsP1 attenuates neurovirulence of the Sindbis-group alphavirus SAAR86
A single amino acid change in nsP1 attenuates neurovirulence of the Sindbis-group alphavirus SAAR86
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DOI：
10.1128/jvi.74.9.4207-4213.2000
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发表时间：
2000-05-01
影响因子：
5.4
通讯作者：
Johnston, RE
中科院分区：
文献类型：
--
作者：
Heise, MT;Simpson, DA;Johnston, RE
S.A.AR86是Sindbis类甲病毒的一员，对成年小鼠具有神经毒性，在nsP1的538位有一个独特的苏氨酸；这组甲病毒的非神经毒性成员编码异亮氨酸，异亮氨酸在野生型s.a.a ar86感染克隆ps55的538位被引入，从该突变克隆ps51衍生的病毒与ps55衍生的病毒相比，其神经毒性显著减弱，颅内（i.c） s55感染导致严重疾病，包括89%的动物后肢麻痹、结膜炎、体重减轻和死亡。相比之下，s51引起的临床症状更少，没有死亡。然而，将突变体（ps51）和野生型（ps55） S.A.AR86分子克隆衍生的病毒进行比较，结果表明，s51在组织培养中的生长能力与野生型s55病毒一样好，甚至更好，并且在感染s51后，大脑中的病毒滴度与野生型s55病毒的滴度相当。通过原位杂交分析病毒在大脑内的复制，发现两种病毒在感染后早期（12至72小时）在大脑的相似区域建立了感染。然而，在感染后的后期，野生型s55病毒已经扩散到大脑的大片区域，而s51突变体表现出有限的复制模式。这表明s51在感染后的后期在整个大脑中传播有缺陷，或者比s55更快被清除。在Sindbis病毒株TR339的nsP1位点538中引入苏氨酸残基的实验进一步证明了nsP1 Thr 538对S.A.AR86神经毒性的贡献，该病毒在断奶小鼠中无神经毒性，由此产生的病毒39ns1显示出显著增加的神经毒性和发病率。包括体重减轻和后肢麻痹。这些结果证明了甲病毒非结构蛋白基因在成年小鼠神经毒力中的作用。
S.A.AR86, a member of the Sindbis group of alphaviruses, is neurovirulent in adult mice and has a unique threonine at position 538 of nsP1; nonneurovirulent members of this group of alphaviruses encode isoleucine, Isoleucine was introduced at position 538 in the wild-type S.A.AR86 infectious clone, ps55, and virus derived from this mutant clone, ps51, was significantly attenuated for neurovirulence compared to that derived from ps55, Intracranial (i.c.) s55 infection resulted in severe disease, including hind limb paresis, conjunctivitis, weight loss, and death in 89% of animals. In contrast, s51 caused fewer clinical signs and no mortality. Nevertheless, comparison of the virus derived from the mutant (ps51) and wild-type (ps55) S.A.AR86 molecular clones demonstrated that s51 grew as well as or better than the wild-type s55 virus in tissue culture and that viral titers in the brain following i.c. infection with s51 were equivalent to those of wild-type s55 virus, Analysis of viral replication within the brain by in situ hybridization revealed that both viruses established infection in similar regions of the brain at early times postinfection (12 to 72 h). However, at late times postinfection, the wild-type s55 virus had spread throughout large areas of the brain, while the s51 mutant exhibited a restricted pattern of replication. This suggests that s51 is either defective in spreading throughout the brain at late times postinfection or is cleared more rapidly than s55, Further evidence for the contribution of nsP1 Thr 538 to S.A.AR86 neurovirulence was provided by experiments in which a threonine residue was introduced at nsP1 position 538 of Sindbis virus strain TR339, which is nonneurovirulent in weanling mice, The resulting virus, 39ns1, demonstrated significantly increased neurovirulence and morbidity, including weight loss and hind limb paresis. These results demonstrate a role for alphavirus nonstructural protein genes in adult mouse neurovirulence.