Complement plays a minimal role in Sm-p80-mediated protection against Schistosoma mansoni.

Sm-p80, the large subunit of Schistosoma masoni calpain, is a leading antigen candidate for a schistosome vaccine. Prophylactic and antifecundity efficacy of Sm-p80 has been tested using a variety of vaccine approaches. However, the mechanism of Sm-p80-mediated killing is still unknown. In this study, potential role of complement in Sm-p80-mediated protection was studied using both in vitro (cobra venom factor inhibition) and in vivo using mice deficient in C3 (C3 -/-; B6.129S4-C3tm1Crr/J). In the absence of C3, Sm-p80-based vaccine was able to provide significant reduction in adult worm burden following challenge with schistosome cercariae in mice suggesting the effector functions of complement may be limited in this vaccine-induced protection.