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

Abstract

Malignant catarrhal fever (MCF) was diagnosed by clinical signs and lesions in five out of six white-tailed deer (Odocoileus virginianus) in a North American zoo. The clinical signs and histopathological lesions in these deer were typical of MCF. Antibody to an epitope conserved among the MCF viruses was detected in the sera collected from the deer. PCR failed to amplify viral sequences from DNA extracted from peripheral blood leukocytes (PBL) and/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 sequenced. Alignment of the sequences demonstrated that the virus in the deer belongs to the Gammaherpesvirinae subfamily, exhibiting 82% identity to OHV-2, 71% to AHV-1, and 60% to a newly identified bovine lymphotropic herpesvirus. This virus, which causes classical MCF in white-tailed deer, is a newly recognized agent belonging to the MCF group of gammaherpesviruses. It is 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 identified.

FIG. 1

(A) Hypothalamus from deer 1 (hemotoxylin and eosin). Note the marked lymphocytic vasculitis and perivasculitis (bar, 20 μm). (B) Heart and muscular artery from deer 3 (hematoxylin and eosin). Note the marked lymphocytic perivasculitis, vasculitis, and fibrinoid necrosis (bar, 20 μm).

FIG. 2

Agarose gel electrophoresis of ethidium bromide-stained PCR products amplified from different DNA samples with primers specific for OHV-2 (A) and AHV-1 (B) and consensus primers for the herpesviral DNA polymerase gene (C). Lane 1, 100-bp DNA ladder; lanes 2 to 5, DNA extracted from PBL of white-tailed deer 1, 2, 5, and 6; lane 6, DNA extracted from an axis deer with clinical OHV-2 MCF; lane 7, DNA from AHV-1 (Minnesota isolate); lane 8, no-DNA control.

FIG. 3

(A) Comparison of the nucleotide sequences of a region of the herpesviral DNA polymerase gene derived from white-tailed deer 1 from a North American zoo with the same region of OHV-2 from an axis deer with clinical SA-MCF, AHV-1, and BLHV. The black boxes represent nucleotides that vary from the sequence of OHV-2. (B) Comparison of the translated amino acid sequences of the same gene region as that shown in panel A. The white, light, white-framed, and black boxes represent identical residues, conservative substitutions, somewhat-similar residues, and dissimilar residues, respectively. The OHV-2, AHV-1, and BLHV DNA polymerase sequences used here were obtained from GenBank, the National Center for Biotechnology Information database. The accession numbers are as follows: OHV-2, AF031812; AHV-1, AF031809; and BLHV, AF031808.