Diagnostic mimotopes for antibody detection in visceral leishmaniasis

Background: The currently available rk39 dipstick test for antibody detection in visceral leishmaniasis (VL) patients has high diagnostic accuracy in the Indian subcontinent but not in East Africa. Therefore in East Africa, the direct agglutination test (DAT) is still the method of choice for serodiagnosis of VL. However, DAT cannot be applied in field conditions and takes several hours. These two limitations of the DAT hinder accurate diagnosis and control of VL in East Africa.
Methodology: Using biopanning of phage-displayed random peptide libraries we will identify peptides that mimic the immunodominant DAT antigens. The selected peptides will be characterised and optimised, and their diagnostic potential will be measured by ELISA in a phase I evaluation study with sera from the ITM biobank. Peptides showing the highest diagnostic potential will be used to build an immunochromatography-based rapid diagnostic test (RDT). The sensitivity and specificity of the RDT will be evaluated in a phase II study in Ethiopia on 100 VL cases and 100 endemic controls. A similar strategy has been successfully applied for screening of mimotopes for serodiagnosis of human African trypanosomiasis. Feasibility of the use of peptides in an immunochromatographic test has already been shown at Coris BioConcept (CORIS). The phase II study will be conducted in collaboration with the University of Gondar (UoG), Ethiopia.