Pitfalls in the application of enzyme-linked immunoassays for the detection of circulating trypanosomal antigens in serum samples

The experimental infection of two goats with Trypanosoma vivax trypanosomes provided samples for analysis using parasitology techniques-and antigen-de tection enzyme-linked immunosorbent assays (ELISAs) for T. vivax, T. congol ense and T. brucei. Clinical, parasitological and serological findings were monitored during the course of infection to identify problems in the appli cation of these ELISAs. The data clearly showed that the ELISAs examined we re entirely unsuitable for the reliable detection of trypanosomal antigen. Consequently, research strategies pertinent to the development of a new gen eration of both antigen and antibody ELISAs are outlined considering the pr oblems encountered. These were (1) the reactivity of the reagents; (2) the specificity of the reagents; (3) the nature of the test sample, e.g. the co mpartmentalisation of trypanosomes between plasma, serum and red blood cell s; (4) possible interference with the ELISA through immune complexing; and (5) the biology of the host/trypanosome relationship to gain an understandi ng of fluctuations in trypanosomes in the systemic circulation.