Vaccination of mice against intestinal Trichinella spiralis infections by oral administration of antigens microencapsulated in methacrilic acid copolymers

BALB/c and NIH mice have been successfully vaccinated against the intestinal nematode Trichinella spiralis by oral administration of crude larval extracts (CLE) and excretory–secretory (ES) products derived from first stage T. spiralis larvae (L1) encapsulated in microcapsules made of copolymers of the metacrylic acid (Eudragit L100). Oral vaccination stimulated the secretion of IFN-γ and inhibited the secretion of IL-4 in spleen and mesenteric lymph nodes (MLN) of BALB/c mice. In vaccinated mice the proportion of CD4+ cells increased (p < 0.05) in Peyer's patches (PP) and decreased (p < 0.05) in spleen whereas the proportion of CD19+ cells decreased (p < 0.05) in both PP and spleen, with regard to unvaccinated controls. No variation was evident for the proportion of CD8+ cells. Oral vaccination elevated the antigen-specific serum IgG1 and IgA (p < 0.05) as well as the antigen-specific IgA response in MLN (p < 0.05). It is concluded that this way of vaccination induced a concurrent Th1/ Th2 local and systemic responses that are protective and at the same time they may help balancing the strong Th2 response triggered by helminth infections.