Nucleotide sequence, insertional mutagenesis, and transcriptional mapping of a conserved region of the baculovirus Autographa californica nuclear polyhedrosis virus (map unit 64.8-66.9).

The nucleotide sequence of a 2773-bp region of the Autographa californica nuclear polyhedrosis virus HR3 variant (AcMNPV) (map unit 64.4-68.2) has been determined. This region lies between the previously analyzed p6.9 and p80 genes. Three open reading frames were contained within this region, potentially coding for proteins of 45, 40, and 12 kDa. The 5' ends of transcripts capable of coding for the 45- and 12-kDa proteins map to consensus baculovirus late transcription start sites (ATAAG), while the major 5' end of the transcript coding for the 40-kDa protein maps 16 nucleotides downstream from another late transcription start site sequence, GTAAG. Attempts to prepare recombinant viruses containing insertions within these three genes were negative, suggesting that they are all essential for virus replication in cell culture. The size and organization of transcripts expressed from this region of AcMNPV were very similar to those of the previously described homologous region of Orgyia pseudotsugata nuclear polyhedrosis virus (OpMNPV). The three AcMNPV protein sequences (p45, p40, and p12) showed amino acid sequence homology with the proteins p48, p45, and p12 of OpMNPV, suggesting this region is highly conserved in baculoviruses.