Detection of circulating schistosome antigens in serum and urine of schistosomiasis patients and assessment of cure by monoclonal antibody

ABSTRACT

From a panel of monoclonal antibodies [MAb], an IgM monoclonal antibody [7F1/6B] reactive with repetitive epitopes on S. Mansoni soluble egg antigen was selected. This MAb was employed both as antigen capture and detection antibody in a sandwich ELISA and had a detection limit <1 ng S. mansoni SEA/mi. Serum and urine samples were collected from rural students who had S. mansoni [169 subjects] or mixed S. mansoni and S. hematobium [64 subjects] infections. Samples were collected before and at 4, 8 and 12 weeks after praziquantel therapy. Circulating schistosome antigens [CSA] were demonstrated in 90% of sera and 97% of urine samples of S. mansoni group and in 91% of sera and 100% of urine samples of mixed infection group. All sera from 29 uninfected individuals, 30 patients with other parasites and 70% of 55 S. hematobium-infected subjects were negative in this assay. CSA level in serum and urine samples correlated positively with the number of S. mansoni eggs/g stool in both groups. A significant reduction in CSA level was observed in serum and urine samples after praziquantel therapy. By 12 weeks post-treatments, negativity was 98% in sera and 97% in urine of S. mansoni-infected group and 98% in sera and 91% in urine of mixed infection group. The data demonstrated that the use of MAb 7F1/6B for the detection of CSA provides a sensitive method of immunodiagnosis of schistosomiasis and monitoring of cure