The effects of Helicoverpa armigera single nucleopolyhedrovirus origin of chitinase and catepsin proteins on virulance of Chilo iridescent virus

Chilo iridescent virus (CIV) is of particular economic and ecological importance as it infects some pests in agriculture. However, it causes low virulence in CIV-infected hosts. Accordingly, it was determined that baculovirus chitinase and cathepsin proteins could be used to increase the virulence of CIV. Chitinase in baculoviruses is expressed together with cathepsin in the late phase of virus replication. It is known that cathepsin is effective on the insect by destroying the structure of the peritrophic membrane, and chitinase is effective on the insect by destroying the chitin layer. In the light of this information, in this study, it was aimed to increase the virulence of CIV by using chitinase and cathepsin proteins belonging to baculoviruses. Accordingly, it is primarily aimed to produce chitinase and cathepsin proteins in the bacterial expression system and to investigate the effects of the obtained proteins on CIV virulence after ingestion of the insect. Chitinase and cathepsin genes from the baculovirus genome were amplified by polymerase chain reaction (PCR) using appropriate primers. The amplified genes were cloned into the pJET1.2 vector. After the necessary validations were made, both genes were transferred separately into the pET28a+ expression vector to ensure their expression in Escherichia coli BL21(DE3) cell. After the chitinase (64 kDa) and cathepsin (43 kDa) proteins were determined by SDS-PAGE and western blot analysis methods, they were purified by nickel affinity chromatography. They were infected with CIV after feeding to Galleria mellonella larvae at concentration of 500 ng, 1000 ng, 1500 ng, 2000 ng, 2500 ng, 5000 ng from the obtained proteins. As a result of this study, it was determined that the chitinase and cathepsin proteins of baculovirus increased the virulence of CIV by 23%. Accordingly, it was determined that baculovirus chitinase and cathepsin proteins could be used to increase the virulence of CIV.