MAPPING AND POLYHEDRIN GENE ANALYSIS OF THE EPIPHYAS-POSTVITTANA NUCLEOPOLYHEDROVIRUS GENOME

The light brown apple moth, Epiphyas postvittana, is a major insect pe st of a variety of fruit crops grown in New Zealand and we are studyin g a nucleopolyhedrovirus, EppoNPV, isolated from this insect. Restrict ion endonuclease analysis of EppoNPV DNA shows that this is a single s train of virus with a genome size of approximately 119kbp and a comple te library of the EppoNPV genome has been cloned. A strategy of single -stranded sequencing of the termini of REN fragment clones was employe d to map the virus genome. Sequence homologies to NPV gene sequences p resent in the GenBank database allowed a nearly complete restriction m ap of the EppoNPV genome to be constructed, The mapping was completed with Southern blotting and restriction analysis. Fifty-five open readi ng frames (ORFs) with similarity to genes from other NPVs have been id entified and placement of these on the restriction map shows that Eppo NPV has a nearly identical genome organization to Orgyia pseudotsugata (Op)MNPV, The polyhedrin gene of EppoNPV has been fully sequenced and an ORF of 738 bp encodes a predicted protein of 28.8 kDa. The conserv ed 12 bp consensus sequence typical of very late baculovirus gene prom oters, AATAAGTAATTT, has been located upstream of the ATG initiation c odon, An ORF located downstream of the polyhedrin gene shows homology to the 1629-capsid protein from OpMNPV, Phylogenetic comparison to pol yhedrin gene sequences from 23 other NPVs shows EppoNPV to be a group I NPV closely related to OpMNPV.