Schistosoma mansoni: detection of circulating antigens in murine schistosomiasis by antigen-capture sandwich ELISA using a monoclonal antibody

A monoclonal antibody (MAb) 5H11/B1 that reacts with a repeating epitope on an excretory-secretory (E + S) antigen of adult worms of Schistosoma mansoni was used in the detection of circulating antigen (CA) in sera from S. mansoni-infected mice using an antigen-capture sandwich ELISA. Trichloroacetic acid (TCA) pretreatment of sera from mice infected for 8 or 16 weeks precipitated immune complexes and/or dissociated CA and allowed its detection. Sera obtained 8 weeks after infection contained high levels of CA. Upon treatment with praziquantel (100 mg/kg body wt), this level was significantly less within 1 week. A strong correlation was found between the worm count determined by perfusion and the level of antigenemia detected by the 5H11/B1 assay in light and heavy infection (r = 0.80). Based on the results of both TCA pretreatment and sodium periodate treatment, the 5H11/B1 sandwich ELISA assay detects a repeating carbohydrate epitope on an E + S antigen. This system appears to be a sensitive assay for the detection of schistosomal antigenemia in murine schistosomiasis. Studies on the detection of antigenemia in human schistosomiasis using this assay are in progress.