Antigenic variation of caprine arthritis-encephalitis virus during persistent infection of goats

Six caprine arthritis-encephalitis virus (CAEV)-free goats kept in strict isolation were inoculated intravenously with a cloned CAEV isolate (virus 020). At 78 weeks post-infection a virus (virus 095) isolated from one of the goats was shown to have the characteristics of CAEV, but was antigenically distinct from virus 020 and two other CAEV isolates by serum neutralization tests. Serum from the goat that had the variant virus neutralized the inoculum virus and the variant virus but serum from other inoculated goats neutralized only the inoculum virus. The variant virus and the inoculum virus were shown to co-exist in the infected goat, but the presence of the antigenic variant did not appear to be associated with an increase in severity of lesions compared with other inoculated goats.