Partially Protective Immunity Induced by a 20 kDa Protein Secreted by Trichinella spiralis Stichocytes.

Trichinella spiralis infection induces protective immunity against re-infection in animal models. Identification of the antigens eliciting acquired immunity during infection is important for vaccine development against Trichinella infection and immunodiagnosis.The T. spiralis adult cDNA library was immunoscreened with sera from pigs experimentally infected with 20,000 infective T. spiralis larvae. Total 43 positive clones encoding for 28 proteins were identified; one of the immunodominant proteins was 20 kDa Ts-ES-1 secreted by Trichinella stichocytes and existing in the excretory/secretory (ES) products of T. spiralis adult and muscle larval worms. Ts-ES-1 contains 172 amino acids with a typical signal peptide in the first 20 amino acids. The expression of Ts-ES-1 was detected in both the adult and muscle larval stages at the mRNA and protein expression levels. Mice immunized with recombinant Ts-ES-1 (rTs-ES-1) formulated with ISA50v2 adjuvant exhibited a significant worm reduction in both the adult worm (27%) and muscle larvae burden (42.1%) after a challenge with T. spiralis compared to the adjuvant control group (p