Protective immune response induced by co-immunization with the Trichinella spiralis recombinant Ts87 protein and a Ts87 DNA vaccine

Ts87 is an immunodominant antigen that induces protective immunity against Trichinella spiralis larval challenge in mice. To determine if a combination of recombinant Ts87 protein and its coding DNA induces a stronger immune response in female C57BL/6 mice were immunized with 100 μg of recombinant Ts87 protein plus its coding DNA cloned in vector pVAX1, or the same amount of recombinant protein or DNA only. Mouse subclass IgG responses showed that both co-immunized and single-immunized mice produced a balanced IgG2a/IgG1 (Th1/Th2) response. T-cell proliferation in co-immunized animals was significantly higher than in single-immunized mice. Cytokine profiling in the co-immunization group showed a significant increase in the levels of IL-2, IL-4, IL-6 and IFN-γ in the splenocytes of mice upon stimulation with the recombinant Ts87 protein; however, the expression of IL-17 was down-regulated. Challenge results showed that mice immunized with the recombinant Ts87 protein and its coding DNA produced reduced the muscle larval burden to a greater extent (43.8%) than the groups immunized with only the protein (39.7%) or the DNA (9.7%). A better Th1/Th2 immune response and consequent protection induced by co-immunization with the recombinant Ts87 protein and its coding DNA may result from an adjuvant effect of DNA and a specific persistent expression of Ts87.