Cloning and Expression of SpltMNPV Sl136 Gene and Functions of the Expressed Product.

By computer-assisted analysis, it was revealed that ORF136 gene product in SpltMNPV genome had the basic properties of membrane protein. A putative signal peptide was present at the N-terminal and a transmembrane region near the C-terminal of SL136 protein. In the N-terminal half region, there was a coiled-coil domain, which is a typical feature of a number of viral fusion proteins. After PCR amplification, a recombinant plasmid pBVSl136 and a recombinant AcMNPV containing Sl 136 were constructed, in order to express Sl136 gene in E.coli and insect Hi5 cells, respectively. The SDS-PAGE results showed that both expression levels were high. Cell membrane fusion was induced in the Sl-zsu-1 cells, which had been transfected with Sl136 gene alone, by lowering pH of the medium. These results suggested that SL136 protein may be an envelope fusion protein.