Heterologous Prime-Boost Vaccination Enhances TsPmy's Protective Immunity against Trichinella spiralis Infection in a Murine Model

TsPmy is a paramyosin expressed by parasitic Trichinella spiralis and confers a protective immunity when its recombinant protein or DNA was used as an immunogen. To improve its immunogenicity and vaccine efficacy, we conducted a heterologous prime-boost strategy by orally delivering one dose of TsPmy DNA carried by attenuated Salmonella typhimurium (SL7207), followed by two doses of recombinant TsPmy intramuscularly. This strategy effectively induced intestinal mucosal sIgA response and an enhanced and balanced Th1/Th2 immune responses that improve protection against T. spiralis larval challenge, with 55.4% muscle larvae reduction and 41.8% adult worm reduction compared to PBS control. The muscle larvae reduction induced by heterologous primeboost regimen was significant higher than that induced by the homologous DNA or protein prime-boost regimens, which could act as a practical prophylactic approach to prevent T. spiralis infection.