Experimental infection of European wild boars and domestic pigs with pseudorabies viruses with differing virulence

Objective-To determine susceptibility of European wild boars (Sus scrofa) t o infection with pseudorabies virus (PrV) and to characterize the virulence of a wild-boar PrV isolate for wild and domestic pigs. Animals-18 wild boars and 16 domestic pigs. Procedure-Three groups of 4 wild boars were inoculated with PrV Bartha, Kap lan, and a wild-boar isolate (BFW1) and housed with uninfected pigs. Two gr oups of domestic pigs (4 and 8 pigs/group, respectively) were inoculated wi th various doses of BFW1. Animals were observed daily for clinical signs, a nd samples were tested for PrV excretion and homologous antibodies. After r eactivation of latent infection by induced immunosuppression, PrV was detec ted in tissues of necropsied animals, using cell culture and a polymerase c hain reaction (PCR). Results-Clinical signs depended on virulence of the PrV strain and dose of inoculum. Only infection with PrV Kaplan resulted in severe disease and dea th. Virus was isolated from nasal and genital swab specimens. Antibodies we re first detected on day 7 after inoculation; a specific humoral immune res ponse was delayed in BFW1-infected animals. Virus was isolated from various tissues of Kaplan-infected wild boars, whereas mainly viral DNA was detect ed in a few tissues of Bartha- and BFW1-infected animals, using PCR after i mmunosuppression. Conclusions and Clinical Relevance-European wild boars are susceptible to t ransmission of PrV infection from domestic pigs and vice-versa. The PrV iso late BFW1 is of low virulence and seems to be adapted to the wild boar popu lation from which it was isolated.