Immunoadjuvant effect of diethylcarbamazine in experimental filariasis

Lymphatic filariasis caused by tissue dwelling nematodes is endemic in 73 countries and drugs have been administered to control or stop the infection. Resurgence of the infection after mass drug administration necessitates the study of several parasite antigens or adjuvants for vaccine developments. In this study, diethylcarbamazine (DEC) was evaluated for its efficacy as adjuvant against the filarial parasite; Brugia malayi microfilariae (mf) by combining with the Escherichia coli expressed recombinant BmShp-1 protein. Shp-1 is one of the sheath proteins expressed by adult female and microfilarial stage of the filarial parasite. Hence, immunoprophylactic efficacy of Shp-1 using DEC and alum adjuvants was compared in BALB/c mice model by an in situ micropore chamber method. Shp-1 antibody titre was high when the mice were immunized with Shp-1 along with DEC and they exhibited balanced Th1/Th2 profile. DEC also induced significantly high T-cell proliferation (P<0.001) when stimulated with Shp-1 compared to alum. Significantly high percentage protection against B. malayi microfilariae was observed in Shp-1+DEC immunized mice groups (P<0.05) and hence it is concluded that the need of repeated drug administration can be controlled when there is a possibility of developing protective immunity in the host against mf by vaccination.