The sequence of the Helicoverpa armigera single nucleocapsid nucleopolyhedrovirus genome

The nucleotide sequence of the Helicoverpa armigera single-nucleocapsid nuc leopolyhedrovirus (HaSNPV) DNA genome was determined and analysed. The circ ular genome encompasses 131 403 bp, has a G+C content of 39.1 mol% and cont ains five homologous regions with a unique pattern of repeats. Computer-ass isted analysis revealed 135 putative ORFs of 150 nt or larger; 100 ORFs hav e homologues in Autographa californica multicapsid NPV (AcMNPV) and a furth er 15 ORFs have homologues in other baculoviruses such as Lymantria dispar MNPV (LdMNPV), Spodoptera exigua MNPV (SeMNPV) and Xestia c-nigrum granulov irus (XcGV). Twenty ORFs are unique to HaSNPV without homologues in GenBank . Among the six previously sequenced baculoviruses, AcMNPV, Bombyx mori NPV (BmNPV), Orgyia pseudotsugata MNPV (OpMNPV), SeMNPV, LdMNPV and XcGV, 65 O RFs are conserved and hence are considered as core baculovirus genes. The m ean overall amino acid identity of HaSNPV ORFs was the highest with SeMNPV and LdMNPV homologues. Other than three 'baculovirus repeat ORFs' (bro) and two 'inhibitor of apoptosis' (iap) genes, no duplicated ORFs were found. A putative ORF showing similarity to poly(ADP-ribose) glycohydrolases (parg) was newly identified. The HaSNPV genome lacks a homologue of the major bud ded virus (BV) glycoprotein gene, gp64, of AcMNPV, BmNPV and OpMNPV. Instea d, a homologue of SeMNPV ORF8, encoding the major BV envelope protein, has been identified. GeneParityPlot analysis suggests that HaSNPV, SeMNPV and L dMNPV (group II) have structural genomic features in common and are distinc t from the group I NPVs and from the granuloviruses. Cluster alignment betw een group I and group II baculoviruses suggests that they have a common anc estor.