Javier R T, Thompson R L, Stevens J G
J Virol. 1987 Jun;61(6):1978-84. doi: 10.1128/JVI.61.6.1978-1984.1987.
RS6 is a herpes simplex virus intertypic recombinant derived from type 1 strain 17 syn+ and type 2 strain HG52. With a 50% lethal dose of about 10(5) PFU after intracerebral inoculation of mice, RS6 was approximately 100,000 times less neurovirulent than either of its wild-type parental viruses were. When compared with strains 17 syn+ and HG52, RS6 replicated intermediately in primary mouse embryo fibroblasts in vitro at 38.5 degrees C (mouse temperature) and to wild-type peak titers in mouse feet in vivo. In contrast, following intracranial inoculation of mice, RS6 replicated significantly less well than did either of its parental viruses in brains. The genetic defect(s) responsible for the reduced neurovirulence of RS6 was stable after in vitro and in vivo serial passage, was not manifested as temperature-sensitive plaquing in vitro, and did not affect thymidine kinase expression. These data indicate that RS6 has a genetic defect(s) specifically affecting its ability to replicate in the mouse brain. Using marker rescue technologies, we increased the neurovirulence of RS6 and localized one genetic determinant(s) involved with the reduced neurovirulence of this agent to 0.72 to 0.87 map units (and, tentatively, to 0.79 to 0.83 map units) of the herpes simplex virus genome. When coupled with the work suggesting that thymidine kinase expression is essential for efficient replication in nerve tissues and earlier reports from this laboratory and others, the results presented in this study indicate that more than one herpes simplex virus gene is involved with neurovirulence.
RS6是一种单纯疱疹病毒种间重组体，源自1型毒株17 syn+和2型毒株HG52。经脑内接种小鼠后，其半数致死剂量约为10(5) 个噬斑形成单位（PFU），RS6的神经毒力比其任一野生型亲本病毒低约100,000倍。与毒株17 syn+和HG52相比，RS6在38.5℃（小鼠体温）下于原代小鼠胚胎成纤维细胞中体外复制处于中等水平，在小鼠足部体内可达到野生型峰值滴度。相反，经小鼠颅内接种后，RS6在脑中的复制明显不如其任一亲本病毒。导致RS6神经毒力降低的遗传缺陷在体外和体内连续传代后稳定，在体外不表现为温度敏感噬斑形成，且不影响胸苷激酶表达。这些数据表明，RS6存在特异性影响其在小鼠脑中复制能力的遗传缺陷。利用标记拯救技术，我们提高了RS6的神经毒力，并将与该毒株神经毒力降低相关的一个遗传决定因素定位在单纯疱疹病毒基因组的0.72至0.87图谱单位（初步定位为0.79至0.83图谱单位）。结合提示胸苷激酶表达对于在神经组织中高效复制至关重要的研究工作以及本实验室和其他实验室的早期报告，本研究结果表明，不止一个单纯疱疹病毒基因与神经毒力有关。
