A novel antigenic cathepsin B protease induces protective immunity in Trichinella-infected mice

Trichinellosis is a foodborne disease that remains a public health hazard and an economic problem in food safety. Vaccines against the parasite can be an effective way to control this disease; however, commercial vaccines against Trichinella infection are not yet available. Trichinella cathepsin B proteins appear to be promising targets for vaccine development. Here, we reported for the first time the characterization of a novel cDNA that encodes Trichinella spiralis (T. spiralis) cathepsin B-like protease 2 gene (TsCPB2). The recombinant mature TsCPB2 protein was successfully expressed in E. coli system and purified with Ni-affinity chromatography. TsCPB2 expression was detected at all the developmental stages of T. spiralis and it was expressed as an excretory-secretory protein of T. spiralis muscle larvae. Immunization with TsCPB2 antigen induced a combination of humoral and cellular immune responses, which manifested as a mixed Th1/Th2 response, as well as remarkably elevated IgE level. Moreover, vaccination of mice with TsCPB2 that were subsequently challenged with T. spiralis larvae resulted in a 52.3% (P < .001) reduction in worm burden and a 51.2% (P < .001) reduction in muscle larval burden. Our results suggest that TsCPB2 induces protective immunity in Trichinella-infected mice and might be a novel vaccine candidate against trichinellosis.