Vaccination with DNA encoding ES 43-kDa /45-kDa antigens significantly reduces Trichinella spiralis infection in mice.

Trichinella spiralis is an intestinal nematode parasite that can cause trichinellosis in humans and animals worldwide. The most important known hosts of T. spiralis are pigs, horses, dogs and cats. Pork and its products are the main sources of infection in human trichinellosis. Vaccines against these infections are urgently needed. In this study, the genes encoding the 43-kDa or 45-kDa glycoprotein present in the excretory-secretory (ES) products from T. spiralis muscle larvae (ML) were cloned into the eukaryotic expression vector pVAX1, resulting plasmids pVAX1-Ts43 and pVAX1-Ts45, respectively. Then BALB/c mice were intramuscularly immunized with the DNA vaccine pVAX1-Ts43, pVAX1-Ts45, or both to evaluate their immunogenicity and host protective potential. After the third immunization, mice of each group were challenged with 300 T. spiralis ML. The results showed that the mice immunized with the DNA vaccine pVAX1-Ts43 or pVAX1-Ts45 developed significant numbers of FAS+ PNA+ B220+ B cells indicating the formation of the germinal centers (GCs), IFN-γ-secreting (mesenteric lymph nodes, MLN) cells, and IL-4-, and IL-10-secreting splenocytes. Mice immunized with the pVAX1-Ts43 or pVAX1-Ts45 vaccine elicited partial protective immunity against challenge infections with T. spiralis as shown by significant reduction in ML. Most notably, the combined immunity of pVAX1-Ts43 and pVAX1-Ts45 induced better immune responses than either of the DNA vaccines given alone and provided as high as 75.9% reductions in muscle larval burden. These results suggest that the plasmid DNA encoding the 43-kDa or 45-kDa glycoprotein could be considered as a potential vaccine candidate against T. Spiraling infection.