Identification and molecular characterization of the Choristoneura fumiferana multicapsid nucleopolyhedrovirus genomic region encoding the regulatorygenes pkip, p47, lef-12, and gta

Choristoneura fumiferana multicapsid nucleopolyhedrovirus (CfMNPV) is a bac ulovirus pathogenic to spruce budworm, the most damaging insect pest in Can adian forestry. CfMNPV is less virulent to its host insect and its replicat ion cycle is slower than the baculovirus type species Autographa californic a multicapsid nucleopolyhedrovirus (AcMNPV) but the basis of these characte ristics is not known. We have now identified, localized, and determined the sequence of the region of CfMNPV carrying potentially important regulatory genes including p47 lef-12 gta, and pkip. DNA database searches revealed t hat this region of CfMNPV is most closely related to the homologous OpMNPV genes. Transcription analysis demonstrated that CfMNPV P47 is encoded by a 1.6-kb transcript, LEF-12 is encoded by a 2.6-kb transcript, and GTA is enc oded by a 2.1-kb transcript. Transcripts for these genes were detectable at 6 h postinfection but all of them showed a burst in expression levels betw een 12 and 24 h postinfection corresponding to the time of initiation of Cf MNPV DNA replication. A polyclonal antibody, raised against CfMNPV P47, det ected a nuclear 43-kDa polypeptide from 12 to 72 h postinfection, demonstra ting that the CfMNPV p47 gene product is first expressed at a time correspo nding to the burst of transcriptional activity between the early and the la te phases. Both AcMNPV and CfMNPV P47 translocate to the nucleus of infecte d cells. (C) 2000 Academic Press.