Pathologic and Virologic Characterization of Neuroinvasion by HSV-2 in a Mouse Encephalitis Model

Herpes simplex virus type 2 (HSV-2), a ubiquitous human pathogen associated with genital infections, is neurotropic. It establishes latent infections in local dorsal root ganglia from which it reactivates causing recurrent lesions and frequent episodes of viral shedding. Herpes simplex virus type 2 can also be transmitted from mother to child during birth, causing major neonatal complications including encephalitis. Animal models of HSV-2 genital infection are well described and used for testing of therapies; little is known about animal models of HSV-2-induced encephalitis. We analyzed the pathologic and immunohistochemical features of the nasal rostrum and brain tissue and correlated them with viral distribution in a mouse model of HSV-2 encephalitis induced by intranasal infection and examined viral replication in the brain tissue using quantitative polymerase chain reaction and traditional plaque assay. Our results suggest that the primary route for HSV-2 neuroinvasion after intranasal infection is via the trigeminal pathway, ultimately leading to infection of the brainstem and meningoencephalitis.