The development of a vaccine against this parasitic disease would contribute to a
long-lasting decrease in disease spectrum and transmission. Our group has chosen to target Schistosoma
mansoni Cathepsin B as a prospective vaccine candidate. The recombinant protein was tested in the
presence of synthetic oligodeoxynucleotides containing unmethylated CpG dinucleotides, which are Tolllike
receptor 9 agonists known to stimulate a Th1 response. This formulation conferred a 59% decrease
in worm burden as well as a reduction in egg burden. Hepatic egg burden and intestinal egg burden were
decreased by 56% and 54% respectively. Immunizations with the formulation elicited robust production of
Sm-Cathepsin B specific antibodies, both IgG1 and IgG2c but with the latter predominating. Furthermore,
splenocytes isolated from the immunized animals, compared to control animals, had increased secretion
levels of key Th1 cytokines, IFN- and TNF-, as well as the chemokine CCL5 when stimulated with
recombinant Sm-Cathepsin B. These results highlight the potential of Sm-Cathepsin B/CpG as a vaccine
candidate against schistosomiasis.