Lentinan improved the efficacy of vaccine against Trichinella spiralis in an NLRP3 dependent manner

There is an urgent need for the development of new, improved vaccine adjuvants against T. spiralis infection. Polysaccharides are effective, safe, and biodegradable as adjuvant. In our study, we first observed the protective efficacy of lentinan as adjuvant against helminth T. spiralis infection. Recombinant T. spiralis Serpin (rTs-Serpin) immunoscreened from a cDNA library of T. spiralis, as a vaccine, protect host against Trichinella infection. The reduction rate of helminth burden of rTs-Serpin+lentinan–immunized mice was significantly increased compared with rTs-Serpin+FCA -immunized mice. rTs-Serpin+lentinan induced IgG1-dominant immune response and higher levels of IFN-γ and IL-4. rTs-Serpin+lentinan displayed a lower reduction rate of parasite burden in NLRP3(-/-) mice than that in WT mice and lower level of IgG1 than that in WT mice. The level of IL-4, but not IFN-γ, from NLRP3(-/-) mice immunized by rTs-Serpin+lentinan was significantly lower than that from WT mice, suggesting that NLRP3 is associated with rTs-Serpin+lentinan -triggering Th2 protective immunity against T. spiralis infection. In summary, we revealed that lentinan was a novel adjuvant against T. spiralis infection via NLRP3. NLRP3 therefore represents an important target for adjuvant discovery and the control of T. spiralis infection.