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

Abstract

The experimental infection of two goats with Trypanosoma vivax trypanosomes provided samples for analysis using parasitology techniques and antigen-detection enzyme-linked immunosorbent assays (ELISAs) for T. vivax, T. congolense and T. brucei. Clinical, parasitological and serological findings were monitored during the course of infection to identify problems in the application of these ELISAs. The data clearly showed that the ELISAs examined were entirely unsuitable for the reliable detection of trypanosomal antigen. Consequently, research strategies pertinent to the development of a new generation of both antigen and antibody ELISAs are outlined considering the problems 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 compartmentalisation of trypanosomes between plasma, serum and red blood cells; (4) possible interference with the ELISA through immune complexing; and (5) the biology of the host/trypanosome relationship to gain an understanding of fluctuations in trypanosomes in the systemic circulation.

An Anti-proteome Nanobody Library Approach Yields a Specific Immunoassay for Trypanosoma congolense Diagnosis Targeting Glycosomal Aldolase

“…While both issues are obviously avoided using an antigen detection format, the development of the latter faces its own hurdles. First, the antigen should be present in detectable quantities during an active infection [ 14 ] and should not cross-react with diagnostic tests used for the detection of other endemic parasites. Second, the capture and detection antibodies of the ELISA should be able to out-compete the host anti-pathogen antibodies which usually form immune complexes with the circulating antigen [ 15 ].…”

Trypanosoma vivax GM6 Antigen: A Candidate Antigen for Diagnosis of African Animal Trypanosomosis in Cattle

“…On the other hand, antigen detection ELISAs developed for AAT suffer from low sensitivity and low species-specificity as confirmed with experimental infections [13,14]. …”

Isolation of two antigens from Trypanosoma evansi that are partially responsible for its cross-reactivity with Trypanosoma vivax

“…In particular PCR, which is a very sensitive technique for detecting trypanosomes (Moser et al, 1989;Masiga et al, 1992;Majiwa et al, 1994;Solano and Amsler-Delafosse, 1995;Reifenberg et al, 1997;Lefrançois et al, 1998), has limited use in routine diagnosis due to the need of specific laboratory facilities, common DNA cross-contamination, and high costs. While detection of trypanosome antigens lacks sensitivity and specificity (Desquesnes, 1996;Eisler et al, 1998;Rebeski et al, 1999), assays for detection of anti-trypanosome circulating antibodies have high measures of validity and are economical and applicable at a large scale (Reyna-Bello et al, 1998;Rebeski et al, 2000;Lejon et al, 2003).…”