Route of infection, systemic host resistance, and integrity of ganglionic axons influence acute and latent herpes simplex virus infection of the superior cervical ganglion.

The character of acute and latent herpes simplex virus (HSV) infection of the superior cervical ganglion (SCG) in mice depended on the route by which the virus reached the ganglion, the level of systemic host resistance, and the integrity of postganglionic nerves. Prevention of ganglionic infection by postganglionic neurectomy carried out before intraocular (i.o.) virus challenge established the importance of the neural route in the development of SCG infection. However, hematogenous virus dissemination also led to SCG infection although with reduced frequency compared to that with i.o. inoculation. Enhanced host systemic antiviral resistance had two divergent effects on ganglionic infection depending on the dose and timing of virus inoculation. Thus, both acute and latent ganglionic infections were concomitantly reduced when resistant C57B1/6 mice were challenged with low doses of virus or when less resistant BALB/c mice were actively immunized 1 week before virus challenge. On the other hand, when resistant mice were challenged with high doses of virus or when either active or passive (antibody) immunization was delayed long enough to assure viral access to the ganglion, intraganglionic viral replication during the acute phase of infection was reduced, but the prevalence of subsequent latent infection was either unaffected or actually enhanced. Postganglionic neurectomy, performed after virus had reached the ganglion, altered the course of SCG infection in a direction opposite that of immunization, augmenting the acute phase of viral replication while reducing latency. In athymic nude mice and mice immunosuppressed with cyclophosphamide, intraganglionic viral replication was prolonged. These results emphasize that host factors both extrinsic and intrinsic to the SCG modify the course of ganglionic infection.