IDENTIFICATION AND CHARACTERIZATION OF AN EARLY GENE IN THE LYMANTRIA-DISPAR MULTINUCLEOCAPSID NUCLEAR POLYHEDROSIS-VIRUS

The Lymantria dispar multinucleocapsid nuclear polyhedrosis virus (LdM NPV) gene encoding G22 was cloned and sequenced. The G22 gene codes fo r a 191 amino acid protein with a predicted M(r) of 22000. Expression of G22 in a rabbit reticulocyte system generated a protein with an M(r ) of 24000, in close agreement with the molecular mass predicted from the nucleotide sequence. G22 is not significantly homologous to any kn own protein, nor is a G22 homologue present in the Autographa californ ica MNPV (AcMNPV). Temporal expression studies indicated that the G22 gene was transcribed at readily detectable levels in the presence of c ycloheximide. Transcripts were detected immediately after the virus ad sorption period and throughout the infection cycle. The early transcri ptional start sites of G22 map to a sequence that resembles a subset o f RNA polymerase II promoters/start sites that are found upstream of D rosophila melanogaster developmental and retrotransposon genes which l ack TATA box motifs. Several consensus late baculovirus promoter/mRNA start site sequences (ATAAG) were identified upstream of the G22 gene start codon.