Application of the Leishmania infantum 21 kDa recombinant protein for the development of an immunochromatographic test.

BACKGROUND Visceral leishmaniasis (VL), caused by Leishmania infantum is a systemic parasitic disease and presents a global health problem which can be fatal if not diagnosed and treated. Dogs are the main hosts and provide reservoirs for the transmission of the disease to humans. METHODS In this study, the gene encoding a 21 kDa protein was cloned and expressed as a fusion protein in Escherichia coli strain BL21 (DE3) for developing a rapid immunochromatographic test (ICT) to identify infected dogs. The expression of the recombinant 21 kDa protein (r21) was investigated using SDS-PAGE and western blot methods. The purified r21 kDa protein was spotted onto ICT strips and tested by sera from experimentally infected, naturally infected, and uninfected dogs. RESULTS The SDS-PAGE and western blot methods showed the successful expression of r21 kDa protein. The ICT strip test revealed that the r21 kDa protein was detected by the sera of experimentally and naturally infected dogs. The specificity tests also confirmed no cross-reactivity with animals infected with Trypanosoma cruzi, Toxoplasma gondii, and Ehrlichia canis. CONCLUSIONS Based on these findings the new r21 kDa protein may be a suitable target for developing a new simple, specific and rapid serological method to detect VL in infected dogs.