38th Annual Meeting of the Society for Invertebrate Pathology

Choristoneura fumiferana multiple nucleopolyhedrovirus (CfMNPV) productively infects the the C. fumiferana cell-line Cf-203 whereas infection by the type baculovirus Autographa californica MNPV induces apoptosis within the first 24 hours. In order to investigate what controls this block in host range, the CfMNPV inhibitor of apoptosis genes (iaps) were studied. CfMNPV encodes three genes from the iap class of proteins: iap-1, iap-2 and iap-3. All three putative IAP genes have conserved baculovirus early promoters in their upstream region and all putative gene products contain a C-terminal ring finger, while IAP-1 and IAP-3 have one and two copies of baculovirus iap repeats respectively. Phylogenetic analysis revealed the CfMNPV IAPs were most closely related to those from Orgyia pseudotsugata MNPV, Epihyas postvittana NPV andHymantria cunea NPV. Additionally, CfIAP-3 clustered within a group which included lepidopteran iaps from Trichoplusia ni, Spodoptera frugiperda and Bombyx mori, suggesting that CfIAP-3 may have been acquired from a lepidopteran host. Interestingly, AcMNPV does not encode an IAP-3 homologue. To determine which of the CfMNPV IAPs is a functional inhibitor of apoptosis, we created a polyclonal cell lines constitutively expressing either IAP-1, -2, or -3. These cell lines were tested for resistance to Actinomycin D and AcMNPV induced apoptosis.