Immunoprophylaxis against filarial parasite, Brugia malayi: potential of excretory-secretory antigens in inducing immunity.

ABSTRACT

The role of excretory-secretory antigens in inducing immunity in the host against Brugia malayi microfilariae and infective larvae was studied by in vitro antibody dependent cell-mediated reaction as well as in vivo inoculation of filarial parasites within a microchamber in the host. The immune sera of jirds raised against Brugia malayi microfilarial and infective larval excretory-secretory antigens (Bm Mf ESA and Bm L3 ESA) promoted the adherence of peritoneal exudate cells to Brugia malayi microfilariae and infective larvae in vitro and induced cytotoxicity to the parasites within 48 h. The anti Bm Mf ESA serum was more effective than anti Bm L3 ESA serum in inducing cytotoxicity to microfilariae and both antisera had a similar cytotoxic effect on infective larvae. In the microchambers implanted in the immune jirds, host cells could migrate and adhere to the microfilariae and infective larvae and kill them within 48–72 h. Further, Mastomys natalensis immunized against Bm Mf ESA and L3 ESA generated a high degree of protective response against circulating microfilariae. These results suggest that excretorysecretory antigens are effective in inducing resistance against filarial parasites and thus have potential in immunoprophylaxis.