Meningoencephalitis in Mice Infected with an Equine Herpesvirus 1 Strain KyA Recombinant Expressing Glycoprotein I and Glycoprotein E

One of the consequences of equine herpesvirus 1 (EHV1) infection in the natural host is a neurological disease that can lead to paralysis. The pathology associated with EHV-1-induced neurological disease includes vasculitis of the small blood vessels within the central nervous system and subsequent damage to the surrounding neural tissue. In a previous study, an EHV-1 recombinant KyA virus (KgI/gE/75) was generated in which the sequences encoding glycoprotein I (gI) and glycoprotein E (gE) were repaired [Frampton et al. 2002 (Virus Research 90: 287-301)] using genes of the pathogenic EHV-1 strain 89c25. In contrast to the parental KyA virus that lacks gI and gE, the recombinant KgI/gE/75 was able to spread to the brains of CBA mice after intranasal infection. Infection resulted in a meningoencephalitis characterized by lymphocytic cuffing of small blood vessels within the brain, consistent with that observed in EHV-1-infected horses exhibiting neurological signs. KgI/gE/75 was able to elicit cytopathology in the lung prior to spread to the brain. However, like the attenuated KyA strain, KgI/gE/75 did not persist in the lung and was completely cleared from lung tissue by day 5 postinfection. We propose that gI and gE are neurovirulence factors for EHV-1, and that the CBA mouse model can be extended to study neurologic sequelae resulting after EHV-1 infection.