CHARACTERIZATION, SEQUENCING AND PHYLOGENY OF THE ECDYSTEROID UDP-GLUCOSYLTRANSFERASE GENE FROM 2 DISTINCT NUCLEAR POLYHEDROSIS VIRUSES ISOLATED FROM CHORISTONEURA-FUMFERANA

The ecdysteroid UDP-glucosyitransferase (egt) gene isolated from a pla que-purified isolate of Choristoneura a fumiferana multinucleocapsid n uclear polyhedrosis virus (CfMNPV) was compared to its homologue from a defective MNPV virus (CfDEF) present in wild-type virus populations infecting the eastern spruce budworm, C. fumiferana. The egt genes wer e located in the same relative position within the virus genomes and t heir genomic location and arrangement were similar to that found in Au tographa californica MNPV (AcMNPV) and Orgyia pseudotsugata MNPV (OpMN PV). The genes encoded 491 and 494 amino acid open reading frames resp ectively, and were 67% identical at the amino acid level and 74% ident ical at the nucleotide level. Transcripts of the egt of CfMNPV peaked around 12 h postinfection (p.i.) and disappeared after 36 h p.i. Trans cripts of the egt of CfDEF peaked between 6 and 9 h p.i. and were not detected 24 h p.i. The egt from CfMNPV was more similar to the partial ly sequenced egt identified from OpMNPV, at the nucleotide and amino a cid levels, than it was to the egt from the CfDEF, AcMNPV, Bombyx mori NPV, Lymantria dispar MNPV or Spodoptera exigua MNPV. Phylogenetic an alysis of egt supported the baculovirus evolution scheme suggested by polyhedrin sequence analysis.