Oral Immunization of Mice with a Nonantibiotic Recombinant Lactobacillus plantarum Coexpressing Trichinella spiralis TsNd and gp43 Protein Vaccine Combined with a Murine Interleukin-33 Adjuvant

Trichinellosis, a zoonotic disease transmitted through food and caused by Trichinella spiralis, is a significant health concern worldwide. Therefore, developing a safe and effective vaccine to combat T. spiralis infection is essential. In this study, a nonantibiotic Lactobacillus plantarum strain lacking the alr gene served as a live bacterial vector to deliver antigens to the host, creating a novel oral vaccine. A nonantibiotic vaccine was constructed to coexpress T. spiralis Nudix hydrolase (TsNd protein) and the gp43 protein alongside a food-grade murine IL-33 adjuvant. The objective of this study was to evaluate the efficacy of this novel strategy in preventing trichinellosis and mitigating intestinal damage. The integrated vaccination strategy was found to increase specific serum immunoglobulin G and mucosal secretory IgA (sIgA) concentration in BALB/c mice. Additionally, this approach significantly increased the release of cytokines such as interleukin-4 (IL-4) from lymphocytes, along with increased CD4⁺ expression on lymph cells from both splenic and mesenteric sources. Post-larval exposure, significant reductions in the populations of adult worms by 59.80% at 7 d postinfection (dpi) and in the larval load by 51.29% at 28 dpi were documented. Furthermore, oral vaccination reduced the number of encysted larvae present in the tongue and masseter muscles after challenge with T. spiralis. Overall, the results demonstrated that combined vaccination with the IL-33 adjuvant effectively prevented trichinellosis and reduced intestinal damage, highlighting the potential of food-grade Lactobacillus vaccines in preventing intestinal parasitic infections, with IL-33 serving as an effective adjuvant.