Vaccination of mice with DNA vaccine induces the immune response and partial protection against T. spiralis infection

Trichinellosis is a serious parasitic zoonosis which is widely distributed in the world. Pork still is the predominant source of outbreaks of human trichinellosis in many countries. Vaccines are urgently needed to prevent swine from Trichinella infection. The gene (TspE1) encoding a 31 kDa antigen of T. spiralis was cloned to a eukaryotic expression plasmid pcDNA3 as DNA vaccine. The ability of the DNA vaccine to express antigen in mammalian CHO cells was previously confirmed by indirect fluorescencent antibody test (IFAT) and Western blotting. To evaluate its immunogenicity and its host protective potential, BALB/c mice were immunized with the DNA vaccine by intramuscular injection and gene-gun delivery. The serum antibody response was assayed by IFAT, enzyme linked immunosorbant assay (ELISA) and Western blotting. The cellular immune response was investigated by splenocyte proliferation assay. Vaccine administration by either route induced both humoral and cellular immune response against TspE1, which provided the partial protection against challenge infection with T. spiralis, as shown by significant reduction of larval burden in muscles. Thus, DNA immunization may offer an attractive alternative strategy against swine trichinellosis.