Newly recognized herpesvirus causing malignant catarrhal fever in white-tailed deer (Odocoileus virginianus)

Malignant catarrhal fever (MCF) was diagnosed by clinical signs and lesions in five out of six white-tailed deer (Odocoileus virginianus) in a North A merican zoo, The clinical signs and histopathological lesions in these deer were typical of MCF. Antibody to an epitope conserved among the MCF viruse s was detected in the sera collected from the deer. PCR failed to amplify v iral sequences from DNA extracted from peripheral blood leukocytes (PBL) an d/or spleens of the deer with primers specific for ovine herpesvirus 2 (OHV -2) or specific for alcelaphine herpesvirus 1 (AHV-1), By using degenerate primers targeting a conserved region of a herpesviral DNA polymerase gene, a DNA fragment was amplified from the PBL or spleens of all six deer and se quenced. Alignment of the sequences demonstrated that the virus in the deer belongs to the Gammaherpesvirinae subfamily, exhibiting 82% identity to OH V-2, 71% to AHV-1, and 60% to a newly identified bovine lymphotropic herpes virus, This virus, which causes classical MCF in white-tailed deer, is a ne wly recognized agent belonging to the MCF group of gammaherpesviruses, It i s the third reported pathogenic MCF virus, genetically distinct but closely related to OHV-2 and AHV-1. The reservoir for the virus has not been ident ified.