Identification and nucleotide sequence of an ecdysteroid UDP-glucosyltransferase gene of Spodoptera littoralis multicapsid nuclear polyhedrosis virus.

The Spodoptera littoralis multicapsid nuclear polyhedrosis virus (SlMNPV) is a member of the Baculoviridae that shows a distant genetic relationship to the prototype Autographa californica MNPV (AcMNPV). Using an AcMNPV gene-specific probe, we identified and mapped an ecdysteroid UDP-glucosyltransferase (egt) gene in the genome of SlMNPV. Sequence determination of a part from the hybridizing DNA fragment revealed an open reading frame of 1548 nucleotides that exhibits 38% and 44% identity to the egt amino acid sequences of AcMNPV and Lymantria dispar MNPV (LdMNPV), respectively. Sequences flanking the SlMNPV egt gene, including the promoter region, were found to be unique to the virus. The presence of this nonstructural gene in SlMNPV and several other baculoviruses points to the importance of egt for the viral infection process.