Heterologous prime-boost immunization based on a human adenovirus 5 vectored containing Trichinella spiralis Cystatin-like protein elicits protective mucosal immunity in mice.

Abstract

Trichinellosis is a globally distributed zoonotic parasitic disease. The Trichinella infective larvae migrate through the intestine after ingestion and settle in muscles, thus intestinal mucosal immunity plays a vital role against early infection with Trichinella. In this study, a recombinant adenovirus vector expressing the cysteine protease inhibitor of Trichinella spiralis (rAd5TsCLP) was constructed and combined with the recombinant protein rTsCLP in a heterologous prime-boost regimen. The regimen elicits strong, specific, and neutralizing antibodies in BALB/c mice, significantly enhancing cellular immunity through Th1 (IFN-γ, TNF-α) and Th2 (IL-13, IL-4) cytokine production in the peripheral blood, spleen, and cervical lymph nodes, driven by the activation of CD4+ and CD8+ T-cells. Notably, immunization with rAd5TsCLP:rTsCLP elevated mucosal secretory IgA (sIgA) levels, boosted histamine concentrations, and increased goblet cell numbers in the intestinal epithelium. Vaccinated mice showed a significant 61.17% reduction in adult worms and a 58.22% reduction in muscle larvae after the T. spiralis challenge. The adenovirus vector-delivered TsCLP amplifies local mucosal immunity, eliciting a Th1/Th2 mixed immune response that facilitates the expulsion of T. spiralis. Our study provides a feasible and promising approach for Trichinella vaccines, further highlighting the potential of an adenovirus vector for anti-helminth vaccine development.