Immunoblot analysis as a diagnostic tool for detection of visceral leishmaniasis in Bangladesh

Abstract

Objective: Develop a specific diagnostic test for visceral leishmaniasis in Bangladesh. Methodology: Sera of 32 confirmed visceral leishmaniasis (VL) patients, obtained from different hospitals in Bangladesh during November 1996-April 1997, were studied by the immunoblot technique with antigen prepared from Leishmania donovani. Controls included sera of 34 healthy individuals from both endemic and non-endemic regions, 25 patients with non-lcishmanial infections, and one individual treated for visceral leishmaniasis. Direct agglutination test (DAT) was performed on all sera. Results: Sera of the VL patients showed heterogeneity of polypeptide recognition and identified many polypeptides with relative molecular mass ranging from 16 to > 106 kD. The 56-64-kD band was recognized by all sera, while the 106, 78, 76 and 66-kD polypeptide bands were identified by 91%, 91%, 97%, and 97% of the sera from the VL patients respectively. Three of these polypeptides and the 56-64 kD polypeptide were recognized by 97% of the sera from the VL patients. The 76-kD polypeptide band was not recognized by sera of only two patients, of whom one had been treated for VL. The recognition of the 56-64-kD band had a sensitivity and specificity of 100% and 90% respectively and that of the 76-kD band has a sensitivity and specificity of 97% and 98%. For both VL patients * and the treated individual, DAT was positive at high litre (1:102400). The sera of patients with non-leishmanial infection identified one or two of the five specific polypeptides, but in no case more than two. Conclusion: Immunoblot analysis can be a valuable tool in specific diagnosis of active visceral leishmaniasis in ^ ^ Bangladesh. The recognition of the 56-64-kD band, in addition to any three bands, may be considered diagnostic of - * VL. Additionally, further studies can confirm if this technique can differentiate active infection from treated infections unlike DAT, which is currently used in Bangladesh.