This study was undertaken to develop an immunodiagnostic test of active human
schistosomiasis mansoni using a
monoclonal antibody which targets urinary schistosomal
antigen. Polyclonal
antisera raised in rabbits against the processed urine of Schistosoma mansoni-infected patients showed very high and significant reactivity with ES product of ova compared with other different S. mansoni
antigens. The
monoclonal antibody (4.23) was reactive with repetitive
epitopes of S. mansoni soluble egg
antigen and ES product of ova with molecular mass range of 65-23 kDa and 80-23 kDa, respectively. It recognised different stages of the parasite life-cycle, with no cross reaction with Fasciola or hydatid
antigen. MAbs were characterised by isotyping, immunoelectrophoresis, SDS-PAGE and the
enzyme-linked immunoelectrotransfer blot technique, ELISA, and their recognition of
carbohydrate or
protein antigenic
epitopes by
periodate oxidation and
trichloroacetic acid treatment of the
antigen. It was used for detection of circulating schistosomal
antigen in an
antigen capture antibody sandwich ELISA on sera and urines of 58 S. mansoni-infected patients, 17 S. haematobium-infected patients, 15 parasite-free negative healthy controls and sera from 13
schistosomiasis-free patients harbouring Fasciola or hydatid
infections. The percentage sensitivity of the assay in the serum of S. mansoni-infected patients was 98.4% and in urine 94.8%. A positive correlation was found between the number of faecal S. mansoni eggs and the circulating
antigen, both in serum and in urine.
Antigen circulating in urine correlated with that in the sera of S. mansoni patients. These data provide a sensitive and non-invasive method almost comparable with the use of sera for immunodiagnosis of
schistosomiasis and an indirect way to reflect the intensity of
infection.