Beta-mercaptoethanol-modified ELISA for diagnosis of visceral leishmaniasis.
Following antigen preparation procedures similar to those of the direct agglutination test (DAT), an IgG ELISA employing intact beta-mercaptoethanol (beta-ME)-treated Leishmania donovani promastigotes was developed. The performance of the beta-ME ELISA thus developed was assessed in patients with confirmed visceral leishmaniasis (VL), revealing slightly lower sensitivity (39/40=97.5%) than that of the DAT (40/40=100%). When challenged with sera of individuals with non-VL conditions, including leukaemia and African trypanosomiasis, the specificity of the beta-ME ELISA was 100% (158/158), compared to 98.8% (156/158) for DAT. In an endemic population (n=145) manifesting a clinical suspicion of VL, results obtained with the beta-ME ELISA were highly concordant with those of DAT, both in the seropositive (65/68=95.6%) and seronegative (77/80=96.3%) groups. Furthermore, the incorporated intact antigen demonstrated higher sensitivity in ELISA (16/18=88.9%) than the water-soluble equivalent (13/18=72.2%). The stability of the formaldehyde-fixed antigen (2 months at 4 degrees C) in beta-ME ELISA, as well as the option for direct testing of whole-blood samples and visual reading of results (within 2 h, compared to 18 h for DAT), advocate the simultaneous application of the technique with DAT for confirmation of VL in laboratories with limited facilities.
Abass
Elfadil M
EM
Ahfad University for Women, PO Box 167, Omdurman, Sudan.
Mansour
Durria
D
Ahfad University for Women, PO Box 167, Omdurman, Sudan.
El Mutasim
Mohamed
M
Ahfad University for Women, PO Box 167, Omdurman, Sudan.
Hussein
Muna
M
Omdurman Hospital for Tropical Diseases, Omdurman, Sudan.
El Harith
Abdallah
A
Dutch Ministry of Foreign Affairs/Mission to Ahfad University for Women, Omdurman, Sudan.
D000372:Agglutination Tests; D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood; D000953:Antigens, Protozoan / Q000737:chemistry / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D007893:Leishmania donovani / Q000276:immunology*; D007898:Leishmaniasis, Visceral / Q000175:diagnosis*; D008623:Mercaptoethanol / Q000494:pharmacology*; D019163:Reducing Agents / Q000494:pharmacology*; D012680:Sensitivity and Specificity; D013223:Statistics as Topic
D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D007074:Immunoglobulin G; D019163:Reducing Agents; D008623:Mercaptoethanol