Latency in Neuronal Tissues of Herpes Simplex and Varicella Zoster Virus

Abstract

Latent Herpes simplex virus in sensory ganglia of animals has now been repeatedly demonstrated after peripheral inoculation, and with a lesser frequency after intravenous injection. Persistence of virus in the central nervous system can also be demonstrated after peripheral inoculation. HSV type 1 has been recovered from trigeminal, superior cervical and vagus ganglia of humans and HSV type 2 has been recovered from human sacral ganglia. It is probable that these ganglionic sites serve as reservoirs for the recurrent oral or genital eruptions commonly encountered in clinical practice. Despite efforts by a number of investigators to determine how HSV persists in ganglia, this question has not been answered with certainty. Whether the common persistence of HSV 1 in trigeminal ganglia is related to HSV 1 encephalitis is also uncertain. Numerous attempts to recover latent HSV from olfactory bulbs at routine autopsy have been unrewarding, suggesting that the virus may not reside there in latent fashion. Restriction enzyme analysis of HSV 1 strains isolated from trigeminal ganglia and the brain of a patient with encephalitis revealed virtually identical patterns. However, virus was grown from the trigeminal ganglia 5 days after explantation, suggesting an acute infection at that site. Thus, the role of latent virus in the trigeminal or other sites in humans in the production of the encephalitic illness remains obscure.