A monoclonal antibody against Schistosoma haematobium soluble egg antigen: efficacy for diagnosis and monitoring of cure of S. haematobium infection

Abstract

A monoclonal antibody (mAb), 2F/11F, raised against Schistosoma haematobium soluble egg antigen (SEA) was found to be nonreactive with S. mansoni SEA or other parasite antigens (Fasciola hepatica, Echinococcus granulosus). This IgG1 mAb recognized a repetitive epitope on S. haematobium SEA in the molecular-weight regions of 70, 42, and 35 kDa. It was employed as both an antigen-capture and a biotinylated detection antibody in a sandwich enzyme-linked immunosorbent assay (ELISA) for the detection of circulating schistosome antigen (CSA) and had a detection limit of <1 ng S. haematobium SEA/ml. CSA levels were measured in serum and urine samples from 116 S. haematobium-infected rural students before therapy and at 4, 8, and 12 weeks after praziquantel treatment. Serum and urine samples from 50 S. mansoni -infected patients, 15 patients harboring other parasites, and 30 noninfected individuals were also assessed. CSA was detected in 90.5% of serum samples and 94% of urine samples from S. haematobium-infected patients. CSA was undetectable in serum from the 15 patients harboring other parasites and in 94% of serum samples and 84% of urine samples from S. mansoni-infected patients. In the S. haematobium-infected group a positive correlation was detected between CSA levels in serum and urine samples and the egg load per 10 ml urine. A significant reduction in CSA levels was detected in serum and urine samples after praziquantel therapy. CSA was undetectable in 87% of serum samples and 81.5% of urine samples from schistosomiasis haematobium patients at 12 weeks post-treatment. These data demonstrate that the use of mAb 2F/11F for detection of CSA provides a sensitive method for the immunodiagnosis and monitoring of cure of schistosomiasis haematobium.