Nucleotide sequence of the polyhedrin gene region of Helicoverpa zea single nucleocapsid nuclear polyhedrosis virus: placement of the virus in lepidopteran nuclear polyhedrosis virus group II.

The polyhedrin gene (polh) of Helicoverpa zea single nucleocapsid nuclear polyhedrosis virus (HzSNPV) was identified and shown by sequence analysis of the EcoRI I genomic fragment to encode a 246 amino acid polypeptide that has greater than 80% sequence identity to known polyhedrins. It is preceded by an AT-rich region containing the conserved late promoter motif TAAG, which was identified as a transcription start point. Downstream of polh there were several similarities in genome arrangement to other nuclear polyhedrosis viruses (NPVs). These include open reading frame (ORF) 8, immediately downstream of polh, encoding a 412 amino acid protein with multiple tandem proline residues, which is homologous to ORF8 (ORF1629) of Autographa californica multiple nucleocapsid NPV. Phylogenetic analysis of the polh gene region shows that HzSNPV is a member of the previously described lepidopteran NPV group II and that it is most closely related to polh of the NPVs of Malacosoma nuestria, Spodoptera littoralis, Orgyia pseudotsugata (single nucleocapsid-type virus) and Buzura supressaria.