Malignant Catarrhal Fever-Like Disease in Barbary Red Deer (Cervus elaphus barbarus) Naturally Infected with a Virus Resembling Alcelaphine Herpesvirus 2

Malignant catarrhal fever (MCF) is a systemic disease of ruminants caused by herpesvirus. Infection with an MCF herpesvirus is usually fatal, although some ruminants, such as wildebeest, hartebeest, and domestic sheep, are well adapted to particular strains of virus and function as clinically normal reservoirs (9, 13). MCF has been recognized in at least 13 species of deer, including mule deer (Odocoileus hemionus), Pere David's deer (Elaphurus davidianus), white-tailed deer (Odocoileus virginianus), and red deer (Cervus elaphus) (2, 18, 33, 36). Among these, molecular characterization of the causative virus has been done only for the white-tailed deer outbreaks from 1998 to 2001 (15, 18). In recent years the use of PCR primers for conserved regions of the herpesvirus DNA polymerase gene has facilitated identification of previously unknown viruses (46). Among ruminants, these include bovine lymphotropic herpesvirus (42), caprine herpesvirus 2 (CpHV-2) (4, 19), caprine lymphotropic herpesvirus (CpLHV) (19), and a herpesvirus of unknown origin in white-tailed deer (Odocoileus virginianus) (18). Two of these, CpHV-2 and the herpesvirus found in white-tailed deer, have been provisionally classified as members of the MCF group under Gammaherpesvirinae on the basis of a common antigenic epitope and DNA sequence similarity within the DNA polymerase gene (18, 19). CpHV-2 has been associated with chronic dermatitis and weight loss in sika deer (Cervus nippon) (19), while the virus found in white-tailed deer produced a disease with typical MCF clinical signs but had a prolonged course and chronic histologic lesions (18). These viruses are now included with alcelaphine herpesvirus 1 (AlHV-1) and ovine herpesvirus 2 (OvHV-2) as members of the MCF virus group with known pathogenic potential. AlHV-1, first described and linked to MCF in 1960 (31), can presently be detected by PCR (14, 17, 29) or by serologic methods (17, 20-22) in clinical MCF cases or herd screening. However, unambiguous identification of AlHV-1 may require sequencing of PCR-amplified DNA. OvHV-2 is similarly identifiable by a virus-specific PCR assay (1, 5, 23, 48) and by the same competitive-inhibition enzyme-linked immunosorbent assay (CI-ELISA) that detects antibodies to AlHV-1 (7, 20, 22). In contrast, two members of the MCF group have not been associated with disease: hippotragine herpesvirus 1 (HiHV-1) (34) and alcelaphine herpesvirus 2 (AlHV-2) (9, 13). The latter has been isolated several times from clinically normal topi or Cape hartebeest, members of the bovid subfamily Alcelaphinae (30, 38, 44, 45), but experimental infections of cattle produce no discernible effects; moreover, inoculation of cattle with AlHV-2 does not elicit antibodies protective against subsequent AlHV-1 challenge (30). AlHV-2 can be detected by AlHV-2-specific PCR as well as by a PCR that will amplify both AlHV-1 and AlHV-2 (14, 17, 29) and by CI-ELISA (19). We now report evidence that a virus closely related to AlHV-2 caused disease resembling MCF in eight Barbary red deer (Cervus elaphus barbarus) and that the virus may have derived from cohoused, clinically normal Jackson's hartebeest (Alcelaphus buselaphus jacksoni).