Immunochemical characteristics of an Iraqi Leishmania donovani

Abstract

The soluble cytoplasmic antigens of an Iraqi L. donovani stock, characterized by the possession of a unique glucose phosphate isomerase, revealed the presence of over 30 precipitation arcs when diffused against homologus antisera following electrophoresis. Using thin-layer Sephadex immunochromatography, the molecular weights of 18 cytoplasmic immunogens were determined and found to range from 16 460 to 291 230. Analytical isoelectric focusing resolved the constituent proteins into at least 30 bands, most with isoelectric points in the pH range 3·5–6·1. The most anodic band was found to be a glycoprotein. The soluble antigens were resolved, by DEAE-Sephacel chromatography, into nine fractions with variable antigenic activity. Fraction 1 contained nearly all of the antigenic activity that could be detected by the double antibody sandwich method; fraction 2 contained most of the immunogens which stimulate precipitin antibodies.