Detection of Trypanosoma congolense antibodies with indirect ELISAs using antigen-precoated microtitre plates.
The study reports the performance of four indirect enzyme-linked immunosorbent assays (ELISAs) for antibody (AB) detection using microtitre plates which were precoated with native or heat/detergent denatured antigens (AGs) from Trypanosoma congolense (T.c.) and T. vivax (T.v.), and stored for between 1 to 206 days at +37 degrees C. Bovine serum samples were obtained by sequential bleeding of 3-months old T.c.-infected bulls and their uninfected cohorts, as well as by a single bleeding of uninfected adult cattle. The first day of AB detection, and observations on samples after this (defined as estimated ELISA sensitivity), depended on the cut-off value in the specific ELISAs. Cut-off values from pre- and early post-infection samples of individual animals demonstrated a seroconversion in all ELISAs on average after 10-15 days post-infection (dpi). The AB detection was delayed in the T.c. native and denatured AG-based ELISAs using cut-off points from uninfected cohort cattle (16.5 dpi, 19.3 dpi) and the adult cattle population (22.1 dpi, 25.0 dpi). The T.v. AG-based ELISAs however lacked crossreactiviy to T.c. ABs. The estimated sensitivity of each T.c. AG-based ELISA was above 96% throughout, but significantly lower for the T.c. native AG-based ELISA (91.1%) when the adult cattle derived cut-off point was used (p<0.01). The sensitivity of the phase contrast buffy coat technique was similar to the T.c. AG-based ELISAs, but significantly lower when the T.c. denatured AG-based ELISA was used at the adult cattle derived cut-off point (p<0.05). The implications of the results and future research aspects on ELISAs to detect trypanosomal ABs and AGs are discussed.
Rebeski
D E
DE
Animal Production Unit, Food and Agriculture Organisation/International Atomic Energy Agency Agriculture and Biotechnology Laboratory, International Atomic Energy Agency, P.O. Box 100, A-1400, Vienna, Austria. d.rebeski@iaea.org
Winger
E M
EM
Okoro
H
H
Kowalik
S
S
Bürger
H J
HJ
Walters
D E
DE
Robinson
M M
MM
Dwinger
R H
RH
Crowther
J R
JR
D000818:Animals; D000913:Antibodies, Protozoan / Q000032:analysis*; D000953:Antigens, Protozoan / Q000276:immunology; D002417:Cattle; D002418:Cattle Diseases / Q000175:diagnosis / Q000469:parasitology*; D003429:Cross Reactions; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary*; D014348:Trypanosoma congolense / Q000276:immunology*; D014353:Trypanosomiasis, African / Q000175:diagnosis / Q000662:veterinary*
D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan