Molecular characterization of protein p50 of Dendrolimus punctatus cytoplasmic polyhedrosis virus

Genome segment 7 of the 10-segmented RNA genomes of Dendrolimus punctatus cytoplasmic polyhedrosis virus (DpCPV) comprises 1502 nucleotides with one ORF of 1347 bp. This ORF was predicted to encode a protein of 448 amino acids with a molecular mass of 49,756 Da (p50). Antisera against both p50 and an antigen domain (AD) near the N-terminus of p50 specifically bound to a viral structural protein of ca. 33 kDa (V5), indicating that V5 was an N-terminal product of p50. Immunoblotting analysis with anti-p50 antibodies detected p50 and V5 molecules in the host midguts three days and five days post infection, respectively. The intracellular localization of p50 protein was examined by expressing truncations of p50 fused with GFP in recombinant baculovirus-infected Sf9 cells. The p50 protein was present in the cytoplasm of the cells, and the N-terminal portion (67-135 aa) of the protein played a key role in this localization.