Identification and characterization of a DNA photolyase-containing baculovirus from Chrysodeixis chalcites

A hitherto unknown single nucleocapsid nucleopolyhedrovirus (SNPV) with a unique property was isolated from larvae of the looper Chrysodeixis chalcites (Lepidoptera, Noctuidae, Plusiinae). Polyhedrin, lef-8, and pif-2 gene sequences were obtained by PCR with degenerate primers and used for phylogenetic analysis. ChchNPV belonged to class II NPVs and its polyhedrin sequence was most similar to that of class II NPVs of other members of the subfamily Plusiinae. Further genetic characterization involved the random cloning of HindIII fragments into a plasmid vector and analysis by end-in sequencing. A gene so far unique to baculoviruses was identified, which encodes a putative DNA repair enzyme: cyclobutane pyrimidine dimer (CPD) DNA photolyase (dpl). The transcriptional activity of this gene was demonstrated in both ChchNPV-infected C. chalcites larvae and infected Trichoplusia ni High Five cells by RT-PCR and 5' and 3' RACE analysis. The possible role of this gene in the biology of the virus is discussed.