Vaccines as a Strategy to Control Trichinellosis

Abstract

Trichinellosis caused by Trichinella spiralis is a worldwide food-borne parasitic zoonosis. Several approaches have been performed to control T. spiralis infection, including veterinary vaccines, which contribute to improving animal health and increasing public health by preventing the transmission of trichinellosis from animals to humans. In the past several decades, many vaccine studies have been performed in effort to control T. spiralis infection by reducing the muscle larvae and adult worms burden. Various candidate antigens, selected from excretory-secretory (ES) products and different functional proteins involved in the process of establishing infection have been investigated in rodent or swine models to explore their protective effect against T. spiralis infection. Moreover, different types of vaccines have been developed to improve the protective effect against T. spiralis infection in rodent or swine models, such as live attenuated vaccines, natural antigen vaccines, recombinant protein vaccines, DNA vaccines, and synthesized epitope vaccines. However, few studies of T. spiralis vaccines have been performed in pigs, and future research should focus on exploring the protective effect of different types of vaccines in swine models. Here, we present an overview of the strategies for the development of effective T. spiralis vaccines and summarize the factors of influencing the effectiveness of vaccines. We also discuss several propositions in improving the effectiveness of vaccines and may provide a route map for future T. spiralis vaccines development.

Keywords: Trichinella spiralis; antigens; effectiveness; trichinellosis; vaccines.

FIGURE 1

Discovery and identification vaccine candidates through different strategies in animal models. (A) Traditional Trichinella spiralis vaccines are derived from live attenuated vaccines, crude extracts of whole worms, excretory-secretory (ES) products. (B) Vaccine candidates can be screened through different strategies, including genome, transcriptome, proteome, immunoproteome. (C) Candidate antigens are selected for T. spiralis vaccines through bioinformatics analysis. (D) Analyzing structure of antigens contributes to designing effective vaccines in the future. (E) Immunogenicity and immune protection of vaccine candidates are identified through vitro and animal experiments. (F) High effective vaccines translate to meet people need and are applied in humans.

FIGURE 2

Factors influencing the effectiveness of Trichinella spiralis vaccines in animal models. (A) Various candidate antigens show different protective effects. (B) Several vaccine delivery routes have been used to improve the effectiveness of T. spiralis vaccines. (C) Suitable adjuvants play a very important role in vaccines effectiveness. (D) Infective doses of T. spiralis may determine the effectiveness of T. spiralis vaccines in animal models. (E) The efficiency of immunization also depends on inoculation doses of vaccines. (F) There is a lack of a standardized vaccination protocol in animal models. (G) Coinfection change the host’s immune response to affect the effectiveness of T. spiralis vaccines. (H) The same antigen may exhibit different protective effects in different animal models.