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The C-polyhedrin genes of two different geographic isolates of a type 5 cytoplasmic polyhedrosis virus (CPV) were cloned. A CPV infecting Orgyia pseudotsugata (OpCPV), isolated in the Pacific Northwest of the U.S.A., and a CPV infecting Heliothis armigera, isolated in South Africa, were studied. Both genes were found to be 883 nucleotides in length and encoded a predicted protein of 246 residues (M r of 28890). Comparison of the nucleotide sequences of these two viruses with another type 5 geographic isolate, infecting Euxoa seandens (EsCPV; isolated in Eastern Canada), showed that there were only 17 nucleotide differences among the three genes. The only nucleotide variation that had an effect on the encoded protein was a deletion of nucleotide 774 in the gene of EsCPV. The deletion introduces a frameshift mutation resulting in the alteration of the carboxyl-terminal amino acid sequence. Sequence alignment of the OpCPV C-polyhedrin showed little homology to a type 1 CPV (infecting Bombyx mori) or with analogous proteins (N-polyhedrins) from two baculoviruses infecting O. pseudotsugata. Interestingly, most of the conserved residues between the N-and C-polyhedrins were either basic or aromatic amino acids.

We have previously demonstrated that the temperature sensitivity of a human parainfluenza virus type 3 (HPIV-3) candidate vaccine strain (cp45), which is currently under evaluation in humans, is associated with poor transcriptional activity of the virus at the nonpermissive temperature (R.