Role of the Subtilisin-like Serine Protease CJPRB from Cordyceps javanica in Eliciting an Immune Response in Hyphantria cunea

Hyphantria cunea is a globally distributed quarantine plant pest. In a previous study, the Cordyceps javanica strain BE01 with a strong pathogenic effect on H. cunea was identified, and overexpression of the subtilisin-like serine protease CJPRB of this strain was found to accelerate the death of H. cunea (previous research results). In this study, the active recombinant CJPRB protein was obtained through the Pichia pastoris expression system. It was found that CJPRB protein administration to H. cunea via infectation, feeding and injection was able to induce changes in protective enzymes, including superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and polyphenol oxidase (PPO), and the expression of immune defense-related genes in H. cunea. In particular, CJPRB protein injection induced a more rapid, widespread and intense immune response in H. cunea compared to the other two treatment methods. The results suggest that the CJPRB protein may play a role in eliciting a host immune response during infectation by C. javanica.