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

Abstract

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.