The immune protection induced by a serine protease from the Trichinella spiralis adult against Trichinella spiralis infection in pigs

Abstract

Trichinellosis is a major foodborne parasitosis caused by Trichinella spiralis. In the present study, a serine protease gene from an adult T. spiralis (Ts-Adsp) cDNA library was cloned, expressed in Escherichia coli and purified by Ni-affinity chromatography. Previous studies of our laboratory have found that mice vaccinated with recombinant Ts-Adsp protein (rTs-Adsp) exhibited partial protection against T. spiralis infection. In this study, the protective effect of rTs-Adsp against T. spiralis infection in pigs was further explored. The cell-mediated and humoral immune responses induced by rTs-Adsp were measured, including the dynamic trends of specific antibody levels (IgG, IgG1, IgG2a and IgM), as well as the levels of cytokines (IFN-γ, IL-2, IL-4, and IL-10) in the serum. Moreover, the changes in T lymphocytes, B lymphocytes, and neutrophils were measured to evaluate cellular immune responses in pigs vaccinated with rTs-Adsp. The results indicated that a Th1-Th2 mixed immune response with Th1 predominant was induced by rTs-Adsp after vaccination. Flow cytometric analysis showed that the proportions of CD4+ T cells, B cells, and neutrophils in the immunized groups were significantly increased. Furthermore, pigs vaccinated with rTs-Adsp exhibited a 50.9% reduction in the muscle larvae burden, compare with pigs from the PBS group five weeks after challenged. Our results suggested that rTs-Adsp elicited partial protection and it could be a potential target molecule for preventing and controlling Trichinella transmission from pigs to human.

Extracellular vesicles from Trichinella spiralis: Proteomic analysis and protective immunity

“…SP from T. spiralis showed the immune protective effects on sodium dextran sulfate (DSS) induced colitis in C57BL/6 mice by reducing the severity of intestinal inflammation and disease index [24]. And SP induced the mix immune response of Th1/Th2 in pig and mice, exhibited partial protective effect on T. spiralis infection [25]. Moreover, Cystatin-like protein (CLP) and DNase II identified in Ts-ML-EVs could also induce protective immunity against T. spiralis in mice and pig respectively [26,27].…”

Vaccines as a Strategy to Control Trichinellosis

“…However, the effectiveness of vaccines may vary depending on animal species. Previous studies of our laboratory have found that immune response induced by the same antigen is different between pigs and mice ( Feng et al, 2013 ; Xu et al, 2021 ). Therefore, high levels of protection induced by candidate antigens in murine models should be further verified in swine models.…”

“…A previous study in our laboratory has found that mice vaccinated with recombinant T. spiralis serine protease (rTs-Adsp) exhibited a 46.5% reduction in muscle larvae ( Feng et al, 2013 ). Further research showed a 50.9% reduced worm burden of ML in pigs immunized with rTs-Adsp ( Xu et al, 2021 ). Furthermore, cysteine proteases of parasites are also a focus of attention for parasite vaccines.…”

“…In a pig model, Marti et al (1987) reported that pigs were challenged 2000 T. spiralis ML to evaluate the protective effect of antigen. However, Xu et al (2020b , 2021) reported that pigs were inoculated with 5000 T. spiralis ML by oral administration to evaluate the effectiveness of vaccines. The effectiveness of the same candidate antigen may be influenced by infective dose in animal models.…”

“…Most studies of T. spiralis vaccines have been performed in murine models, whereas few studies have been conducted in swine models. Nevertheless, pigs are the natural host of T. spiralis , and studies have found that the immune responses induced by the same antigen are likely to differ between pigs and mice ( Feng et al, 2013 ; Habiela et al, 2014 ; Xu et al, 2021 ). Feng et al reported that mice vaccinated with a T. spiralis serine protease (rTs-Adsp) induced Th1-Th2 mixed immune response with Th2 predominant.…”