Coen D M, Kosz-Vnenchak M, Jacobson J G, Leib D A, Bogard C L, Schaffer P A, Tyler K L, Knipe D M
Department of Biological Chemistry and Molecular Pharmacology, Dana-Farber Cancer Institute, Boston, MA.
Proc Natl Acad Sci U S A. 1989 Jun;86(12):4736-40. doi: 10.1073/pnas.86.12.4736.
Herpes simplex virus infection of mammalian hosts involves lytic replication at a primary site, such as the cornea, translocation by axonal transport to sensory ganglia and replication, and latent infection at a secondary site, ganglionic neurons. The virus-encoded thymidine kinase, which is a target for antiviral drugs such as acyclovir, is not essential for lytic replication yet evidently is required at the secondary site for replication and some phase of latent infection. To determine the specific stage in viral pathogenesis at which this enzyme is required, we constructed virus deletion mutants that were acyclovir resistant and exhibited no detectable thymidine kinase activity. After corneal inoculation of mice, the mutants replicated to high titers in the eye but were severely impaired for acute replication in trigeminal ganglia and failed to reactivate from ganglia upon cocultivation with permissive cells. Nevertheless, latency-associated transcripts were expressed in neuronal nuclei of ganglia from mutant-infected mice and superinfection of the ganglia with a second virus rescued the latent mutant virus. Thus, contrary to a widely accepted hypothesis, the thymidine kinase-negative mutants established latent infections, implying that neither thymidine kinase activity nor ganglionic replication is necessary for establishment of latency. Rather, thymidine kinase appears to be necessary for reactivation from latency. These results suggest that acyclovir-resistant viruses could establish latent infections in clinical settings and have implications for the use of genetically engineered herpesviruses to deliver foreign genes to neurons.
单纯疱疹病毒感染哺乳动物宿主涉及在原发部位（如角膜）的裂解性复制、通过轴突运输转移至感觉神经节并进行复制，以及在继发部位（神经节神经元）的潜伏感染。病毒编码的胸苷激酶是阿昔洛韦等抗病毒药物的作用靶点，它对于裂解性复制并非必需，但显然在继发部位的复制及潜伏感染的某个阶段是必需的。为了确定该酶在病毒致病过程中发挥作用的具体阶段，我们构建了对阿昔洛韦耐药且无明显胸苷激酶活性的病毒缺失突变体。给小鼠角膜接种后，这些突变体在眼中能复制至高滴度，但在三叉神经节中的急性复制严重受损，与允许性细胞共培养时也无法从神经节中重新激活。然而，在突变体感染小鼠的神经节神经元核中表达了潜伏相关转录本，用第二种病毒对神经节进行超感染可拯救潜伏的突变病毒。因此，与一个广泛接受的假说相反，胸苷激酶阴性突变体能够建立潜伏感染，这意味着胸苷激酶活性和神经节复制对于潜伏感染的建立都不是必需的。相反，胸苷激酶似乎对于从潜伏状态重新激活是必需的。这些结果表明，阿昔洛韦耐药病毒可能在临床环境中建立潜伏感染，这对于利用基因工程改造的疱疹病毒向神经元递送外源基因具有启示意义。
