Leveraging cross-reactivity for dual serological detection of closely related Schistosoma species

Abstract Schistosomiasis is a disease of poverty that is highly prevalent in Sub-Saharan African countries. Cross-reacting proteins in Schistosoma mansoni (Sm) and S. haematobium (Sh) have been reported to pose diagnostic challenges. Proteins from these two parasites may help overcome diagnostic limitations caused by cross-reactivity and poor species discrimination in serological assays. The study aims to identify cross-reacting protein markers from S. mansoni and S. haematobium for possible concurrent diagnosis of the two parasites. High-quality protein extracts were prepared from the eggs (soluble egg antigen, SEA) and adult worms ( Schistosoma worm antigens preparation, SWAP) of S. haematobium and S. mansoni . The diagnostic performance of the proteins was evaluated using a quantitative ELISA method with sera obtained from S. mansoni -infected mice. The immunoreactive proteins in the helminths were identified by conventional Western blot analyses and the specific protein markers for concurrent diagnosis of the two parasites were confirmed by double-binding Western blot analyses. SmSEA gave the best diagnostic performance (Sensitivity (SS) = 1.00, Specificity (SP) = 0.96, AUC = 0.96). ShSEA performed slightly better in diagnosing S. mansoni infection (SS = 0.96, SP = 0.87, AUC = 0.95) compared to SmSWAP (SS = 0.91, SP = 0.95, AUC = 0.93). Diagnostic protein markers of size 100 kDa in ShSWAP, > 250 kDa (ShSEA), and 25–37 kDa (SmSWAP) were specific for the two parasites. Shared antigenic markers support potential dual-species diagnosis, but validation using sera from S. haematobium -infected hosts is still required.