Derivation of a DNA clone corresponding to the viral agent of sheep-associated malignant catarrhal fever.

Malignant catarrhal fever is a fatal lymphoproliferative and degenerative disease of ruminants. One causative agent is the gammaherpesvirus alcelaphine herpesvirus 1 (AHV-1), which produces no disease in its natural host, the wildebeest (Connochaetes species). Epidemiological evidence implicates sheep as the carrier of a similar virus. However, attempts to culture this virus from sheep or from animals affected with sheep-associated malignant catarrhal fever (SA-MCF) have failed. Lymphoblastoid cells have been propagated from cattle, deer and rabbits with SA-MCF. Although these cells show no evidence of viral particles or antigens, hybridisation experiments now show that they contain DNA sequences homologous to those of AHV-1. A genomic library was constructed from one of these lymphoblastoid cell lines and a clone identified which hybridised to cloned AHV-1 DNA. The authors believe that this clone contains part of the SA-MCF viral genome, and that the SA-MCF virus and AHV-1 are closely related gammaherpesviruses.