Abstract

Ovine herpesvirus 2 (OvHV-2) is endemic in sheep populations worldwide and causes malignant
catarrhal fever (MCF), a lymphoproliferative disease, in cattle, bison and deer. OvHV-2 has been
placed in the gammaherpesvirus subfamily and is related closely to Alcelaphine herpesvirus 1
(AlHV-1). Here, the cloning, sequencing and analysis of the complete OvHV-2 genome derived
from a lymphoblastoid cell line from an affected cow (BJ1035) are reported. The unique portion of
the genome consists of 130 930 bp, with a mean G+C content of 52 mol%. The unique DNA is
flanked by multiple copies of terminal repeat elements 4205 bp in length, with a mean G+C content of 72 mol%. Analysis revealed 73 open reading frames (ORFs), the majority (62) of which showed homology to other gammaherpesvirus genes. A further subset of nine ORFs is shared with only the related AlHV-1. Three ORFs are entirely unique to OvHV-2, including a spliced homologue of cellular interleukin-10 that retains the exon structure of the cellular gene. The sequence of
OvHV-2 is a critical first step in the study of the pathogenesis and treatment of MCF.