Schistosoma mansoni Cathepsin B1 (SmCB1) (SmCB1)

Schistosoma mansoni Cathepsin B1 (SmCB1), also known as the Sm31 antigen, is a 31 kDa cysteine protease belonging to the papain-like (C1) family and is the most abundant peptidase in the gut of the adult Schistosoma mansoni parasite (Sajid et al., 2003; UniProt Q8MNY2). It plays a vital role in the parasite's survival by degrading host blood proteins, primarily hemoglobin, into absorbable peptides and amino acids to support growth, development, and egg production (Jilkova et al., 2014; Fajtova et al., 2015). SmCB1 is a validated therapeutic target for schistosomiasis, with small-molecule inhibitors like the vinyl sulfone K11777 demonstrating potent anti-parasitic activity by irreversibly blocking the enzyme's active site and causing parasite starvation (Sajid et al., 2011; Fajtova et al., 2015). Beyond its role as a drug target, SmCB1 is a major vaccine candidate; immunization with recombinant SmCB1 has been shown to reduce worm and egg burdens in animal models by eliciting protective humoral and cellular immune responses (Ricciardi et al., 2018; Ricciardi et al., 2021). The enzyme also serves as a serodiagnostic biomarker (Sm31) for detecting active schistosome infections in patients (Parasitol Int. 2016).

Other names

Sm31 antigenCathepsin B-like cysteine proteinaseSmCB1.1SmCB1.2Sm31cb1.1

Irreversible inhibition of the cysteine protease activity, which prevents the degradation of host hemoglobin and other serum proteins, leading to parasite starvation and death.