Construction of polyhedrin-positive recombinant viruswith expression of truncated δ-endotoxin fromBacillus thuringiensis in insect cell

Baculoviruses have been widely used as biological agents because of their specificpathogenicity for target insect and harmlessness to mammals, birds and plants as well asadvantages with persistence and epidemics as pestcides. A major drawback for morewide-spread use of these viruses is their low virulenee and slow speed of action, which re-stricted their use. No enhancement in pathogenicity of recombinant viruses was observedwith insertion of the Bacillus thuringiensis full-length endotoxin cryIA(c) and cryIA(b) geneinto the AcNOV (Autographa californica nuclear polyhedrosis virus) genome under the con-trol of polyhedrin gene promoter. The reason may be that protoxin, full-length genesproduct of recombinant virus in infected insect cells, which was short of insect gut alkalienvironment, cannot be degraded into active toxic polypeptide. Expression level of 3’