Biologically active lipids generated by autolysis of T. congolense

Meeting: Conference on Recent Advances in the Knowledge of Pathogenicity of Trypanosomes, 20-23 Nov. 1978, Nairobi, KEIn IDL-329

Detection and differentiation between trypanosome species in experimentally infected tsetse flies (Glossina spp.) using dot-ELISA

A modified NC membrane-based dot-ELISA was used to detect and differentiate between Trypanosoma brucei, T. congolense and T. simiae procyclics in the midguts of experimentally infected tsetse flies. The modification of the assay consisted of (a) the lysis of T. congolense or T. simiae in NC membrane applied sample dots using Triton X-114, and (b) treatment of sample applied NC membrane strips with hydrogen peroxide to remove non-specific stains. Also, T. brucei was detected in the salivary glands, and T. congolense and T. vivax were detected in the mouthparts, however, in dot-ELISA without modification. In all the assays, T. brucei and T. congolense parasites were detected directly using MoAbs specific to each of them, whereas T. simiae parasites were detected by exclusion using a T. congolense specific and Nannomonas subgenus-specific MoAbs. The sensitivity of the assay for detecting midgut infections was 90.5 percent, 84.6 percent and 94.4 percent in detecting T. brucei, T. congolense and T. simiae, respectively. Sample dots stored at room temperature under desiccated conditions did not show any loss in activity in 90 days. However, after 7 days of storage, a ring-pattern reaction appeared on some sample dots that were tested with T. brucei specific MoAb, irrespective of whether T. brucei antigens were present or not. These ring reactions, however, did not interfere with correct interpretation of the assay results. The specificity of the assay for detection of T. brucei in the salivary glands was 100 percent and the sensitivity was 90 percent. Also, T. vivax and T. congolense organisms were each detected in the mouthparts of infected tsetse flies, with 100 percent specificity. The sensitivity was, however, lower, 43.8 percent for T. vivax and 55.6 percent for T. congolense

Field evaluation of a dot-ELISA for the detection and differentiation of trypanosome species in infected tsetse flies (Glossina spp.)

A rapid, visually read, dot-ELISA developed for the detection and differentiation of trypanosome species in tsetse flies (Glossina spp.), was field tested alongside the standard fly dissection method on a ranch in south eastern Kenya. Of 104 G. pallidipes dissected, 2 were found to be infected with trypanosomes in their midguts. By the dissection method the infecting trypanosome species could not be identified, as both flies had no salivary gland infections. However, using the dot-ELISA, the 2 flies were shown to be infected with Trypanosoma congolense in their midguts. The midguts of an additional 6 (5.8 percent) of the 104j G. pallidipes tested positive for T. congolense in the dot-ELISA, even though no trypanosomes were seen on dissection. The infection rate for this fly species as determined using the dot-ELISA, therefore was 7.7 percent for T. congolense in midgut infections compared to 1.9 percent identified by fly dissection. The salivary glands and mouthparts of the 6 additional tsetse flies identified by dot-ELISA were all negative as determined by the 2 techniques. None of 390 G. longipennis flies dissected and examined for trypanosomes in the midgut, salivary glands and mouthparts was shown by this method, to be infected. Using the dot-ELISA, however, 17 (4.4 percent) of the flies tested positive for T. congolense in the midgut, whilst the salivary glands and mouthparts of the same flies were negative. Thus, the dot-ELISA appears to be more sensitive than the fly dissection method under field conditions. Moreover, the dot-ELISA can be performed in the field without electricity. It is simple to perform, and was not affected by high ambient temperatures (22-32 degree centigrade) or by contamination of reactants with dust