An Ovarian Protein Involved in Passive Avoidance of an Endoparasitoid To Evade Its Host Immune Response

Through a combination
of transcriptomic and proteomic analyses,
we identified 817 secreted ovarian proteins from an endoparasitoid
wasp, Cotesia chilonis, of which five proteins are
probably involved in passive evasion. The results of an encapsulation
assay revealed that one of these passive evasion-associated proteins
(Crp32B), a homologue of a 32-kDa protein (Crp32) from C. rubecula, could protect resin beads from being encapsulated by host hemocytes
in a dose-dependent manner. Crp32B is transcribed in ovarian cells,
nurse cells, follicular cells, and oocytes, and the protein is located
throughout the ovary and on the egg surface. Moreover, Crp32B has
antigenic similarity to several host components. These results indicate
that C. chilonis may use molecular mimicry as
a mechanism to avoid host cellular immune response.