Identification of apoptosis-inhibiting gene in Leucania separata nuclear polyhedrosis virus

A novel gene lsp40 from leucania separata nuclear polyhedrosis virus (LsNPV) which was homologous to the p35 gene from Autographa californica Nuclear Polyhedrosis Virus (AcNPV) was localized in the EcoRV-5.5 kb fragment of LsNPV genome DNA and was sequenced. The open reading frame (ORF) of lsp40 was 906 bp long and encoded an approximately 40 kDa peptide consisting of 302 amino acid residues. The Isp40 shares 80.4% and 70.4% identity of nucleotide and amino acid sequence, respectively, to the AcNPV-p35 gene. The identity in promoters of both genes was as high as 100%. It was found that there were two TATA and GC boxes, three ACGT motifs for initiation of early gene transcription and one typical TTAAG core sequence for initiation of late gene transcription at both gene's 5' end, and two AATAAA tail signals at 3' end. The Isp40 started to express 2 hours after being transfected into the Ls cells to produce an approximately 40 kDa protein. The expression of the lsp40 gene might also inhibit the apoptosis of the Ls cells induced by removing serum. The expression of lsp40 in Vero cells delayed the apoptosis of the Vero cells induced by poliovirus infection. The lsp40 gene rescued vAcAnh (a kind of AcNPV p35-deletion mutant) in the Sf9 cells resulting in inhibition of the apoptosis and production of polyhedra. All these data suggested that the lsp40 gene was a homologous and functional gene similar to AcNPV p35 gene.