38th Annual Meeting of the Society for Invertebrate Pathology

Neodiprion sertifer nucleopolyhedrovirus (NeseNPV) and Neodiprion lecontei NPV (NeleNPV) are the first reported baculoviruses with trypsin-like serine proteases in their genomes. Both viral proteins contained 6 conserved cysteines as well as the trypsin catalytic triad of histidine, aspartic acid and serine conserved in trypsin-like proteins from other organisms including insects and vertebrates. NeseNPV ORF 7 (nese7) and NeleNPV ORF 6 (nele6) shared top blastp matches with similar proteins from insects including Hymenoptera, Diptera, Lepidoptera, Coleoptera and Siphonaptera. Trypsin serine proteases identified in hymenopterans include those from the European hornet (Vespa crabro) and the honeybee (Apis mellifera). These hymenopteran trypsins shared higher amino acid identities with nese7 and nele6 than many of the hymenopteran baculovirus ORFs to lepidopteran baculovirus homologues. To determine if a horizontal transfer from the host insects to the hymenopteran baculoviruses might have occurred, trypsin genes from Neodiprion sertifer and N. lecontei were amplified by PCR, cloned, sequenced and compared to the viral genes. The nucleotide and amino acid identities of nele6/nese7 to their host’s proteins corroborated our initial hypothesis of a possible horizontal transfer from insects to the viruses. The data were further confirmed by phylogenetic analysis of viral trypsins with trypsins from other species.