Virology and Pathology of Encephalitis in Alien Hosts by Neurotropic Equine Herpesvirus 9

Herpesviruses occasionally cause lethal infection in alien hosts by interspecies transmission such as B virus infection in humans from Macaques and pseudorabies virus infection in various animals from pigs. Most of the infection can be characterized as lethal encephalitis. One of typical examples is equine herpesvirus 9 (EHV-9), also called as gazelle herpesvirus 1 (GHV-1), which was isolated from enzootic encephalitis of Thomson’s gazelles (Gazella thomsoni) in 1993 (Fukushi et al., 1996, Yanai et al., 1998). EHV-9 infection has been reported in non-equid species such as Thomson’s gazelles, a reticulated giraffe (Giraffa camelopardalis reticulata) (Hoenerhoff et al., 2006), and a polar bear (Ursus maritimus) (Donovan et al., 2006). Experimental infections have also been investigated including domestic horses, pigs, cattle, and goats, companion animals including cats and dogs and common marmosets (Callithrix jacchus) (Section 3). These interspecies or cross-species infections can be characterized as viral lethal and inapparent encephalitis (Table 1).