Identification of the apoptosis inhibitor gene p49 of Spodoptera litura multicapsid nucleopolyhedrovirus

Baculoviruses possess two types of genes that suppressed apoptosis, p35 and inhibitor of apoptosis (iap). Computer-assisted analysis indicated that Spodoptera litura multicapsid nucleopolyhedrovirus (SpltMNPV) ORF55 (designated as the p49 gene) display 79 and 31% amino acid identity with Spodoptera littoralis (Spli)MNPV P49 and Autographa californica (Ac)MNPV P35, respectively, Splt MNPV putative P49 contains a peptide cleavage site TVTDG recognized by death caspases. In marker rescue assay, Splt-p49 was able to suppress apoptosis induced by infection of a mutant AcMNPV deficient in p35 and rescue the mutant virus replication from apoptosis in Sf-9 cells.