Abstract:In order to explore the synergistic activity of baculovirus chitinase with the baculovirus in infecting its host insects, the coding region of the complete chitinase of Spodoptera exigua nucleopolyhedrovirus (SeNPVChiA) and the matured chitinase gene of Spodoptera litura nucleopolyhedrovirus (SpltNPVChiA/S-) were amplified by PCR from the genomic DNA, and then chitinase genes were separately cloned into the prokaryotic expression vector pET-28a for highly efficient expression in Escherichia coli BL21 (DE3). Molecular weight of SeNPVChiA and SpltNPVChiA/S- fusion proteins expressed in E.coli was 66kD and 62kD respectively. The total cellular proteins involving one of the chitinases expressed in E.coli were mixed with SpltNPV or SeNPV, and fed to the third instar larvae of S.litura or S.exigua. The results showed that the lethal time of the third S.litura or S.exigua are all significantly shorter than that of controls. LT50 of S.litura fed with SpltNPV and one of the expressed chitinases was shorter 0.90 and 0.89 days, LT90 was shorter 1.90 and 1.97 days than that of larvae fed with SpltNPV alone. LT50 of S.exigua larvae fed with SeNPV and one of the expressed chitinases was shorter 0.47 and 0.50 days, LT90 was shorter 0.57 and 0.59 days than that of larvae fed with SeNPV alone, too. pET-28a/BL21 had not any synergistic activity with the baculovirus. It’s revealed herein that the baculovirus chitinases expressed in E.coli showed an evident synergistic effect with the baculoviruses upon infecting the host insects, and the homologous synergism between the chitinases and the baculoviruses had not significantly different with heterologous synergism.