Virions of Heliothis armigera Entomopoxvirus contain a Homologue of the Vaccinia VP8 Major Core Protein

Abstract

An antigenic 30 K virion protein of Heliothis armigera entomopoxvirus (HaEPV) has been identified as a homologue of the chordopoxvirus (ChPV) VP8 major virion core protein. Like its homologue in vaccinia virus, the mature HaEPV 30 K protein is derived by post-translational cleavage of a precursor at a conserved AGA motif. The HaEPV 30 K protein is the first EPV structural virion protein to be described, and elucidation of its characteristics provides evidence for the assumption that morphological similarities observed between virions of the sub-families Entomopoxvirinae and Chordopoxvirinae by microscopy reflect corresponding similarities at a molecular level. Sequencing of the HaEPV genome adjacent to the 30 K locus identified an ORF encoding a homologue of the regulatory sub-unit of the ChPV poly(A) polymerase enzyme; the conceptual product of this ORF showed 25–31% aa sequence identity to those of various ChPVs. The presence of this gene in the HaEPV genome supports the hypothesis that there is a substantial correspondence in basic metabolic processes of members of the two poxvirus sub-families, despite their utilization of divergent host groups. In contrast, the relative positions of the 30 K and poly(A) polymerase loci in the HaEPV genome provide further evidence of substantial genomic re-arrangement subsequent to divergence of these viral taxa.