Herpes simplex virus thymidine kinase expression in infection of the trigeminal ganglion

Infection of the trigeminal ganglion was investigated using standard thymidine kinase-positive (TK⁺) herpes simplex virus (HSV) and two TK^- mutants. After corneal inoculation of mice with TK^- HSV, the incidence of acute and latent trigeminal ganglion infection was markedly decreased compared to TK⁺ virus. When cell-free virus was titered from mice 1 hr to 5 days post-corneal inoculation, ocular replication of TK^- HSV was found to be similar to TK⁺ HSV, but whereas TK⁺ HSV replicated well and was found in substantial amounts in trigeminal ganglia (2 × 10³ PFU/mg ganglion tissue), TK^- HSV did not replicate in the ganglia. Mean TK^- trigeminal ganglion virus titers were 10,000-fold less than TK⁺ titers. When a TK⁺ revertant of TK^- mutant virus was tested, however, trigeminal ganglion virus replication was similar to that with the parental TK⁺ virus. The results obtained were interpreted as being consistent with impaired axonal transport of TK^- HSV from cornea to trigeminal ganglion neurons or more likely, with impaired replication of TK^- HSV in ganglionic neurons.