A Polydnavirus Protein Tyrosine Phosphatase Negatively Regulates the Host Phenoloxidase Pathway.

Polydnavirus (PDV) is a parasitic factor of endoparasitic wasps and contributes greatly to overcoming the immune response of parasitized hosts. Protein tyrosine phosphatases (PTPs) regulate a wide variety of biological processes at the post-transcriptional level in mammals, but knowledge of PDV PTP action during a parasitoid-host interaction is limited. In this study, we characterized a PTP gene, , derived from bracovirus (CvBV), and explored its possible regulatory role in the immune response of the host . Our results from qPCR show that was highly expressed in hemocytes at an early stage of parasitization. To explore function, we specifically expressed in hemocytes. The results show that Hml-Gal4 > suppressed the phenoloxidase activity of hemolymph in , but exerted no effect on the total count or the viability of the hemocytes. In addition, the Hml-Gal4 > flies exhibited decreased antibacterial abilities against Similarly, we found that significantly suppressed the melanization of the host 24 h post parasitization and reduced the viability, but not the number, of hemocytes. In conclusion, negatively regulated both cellular and humoral immunity in , and the related molecular mechanism may be universal to insects.