Analysis of transcription initiation in the Panolis flammea nuclear polyhedrosis virus polyhedrin gene

The nucleotide sequence of the polyhedrin gene of Panolis flammea multiple nucleocapsid polyhedrosis virus (PfMNPV) has been determined. The coding sequences of this gene shared 82% similarity at the DNA level and 88% similarity at the protein level with the polyhedrin gene from Autographa californica (Ac) MNPV. A single nucleotide deviation from the consensus transcription initiation sequence for baculovirus very late genes was identified in the PfMNPV polyhedrin gene. RNA was prepared from Mamestra brassicae larvae infected with PfMNPV and compared with RNA harvested at 24 h post-infection from AcMNPV-infected Spodoptera frugiperda cells using Northern blotting with an AcMNPV polyhedrin gene-specific probe. The PfMNPV mRNA was estimated to be 1.0 kb compared with a larger size of 1.15 kb for the AcMNPV polyhedrin mRNA. A cDNA copy of the 5' end of the PfMNPV polyhedrin mRNA was made using the technique of primer extension and sequenced to demonstrate that the point of transcription initiation was similar to that of AcMNPV polyhedrin mRNA.