Characterization of the chitinase from South American endemic Leishmania species: use in diagnosis in humans, dogs and sandflies.

Abstract

Leishmaniasis is a neglected infectious disease expanding in South America, including Brazil, caused by Leishmania parasites, from Kinetoplastida class and family Trypanosomatidae. There are more than 30 species of Leishmania and from these, 20 cause disease in humans worldwide. The transmission of the parasite occurs in dysphasic cycles by insect vectors of Psycodidae Family (sandflies), genera Phlebotomus (Old World) and Lutzomyia (New World - the Americas), to humans, domestic dogs and wild animals. The clinical presentation of this disease depend on the parasite species and host immune response being variable, with a spectrum ranging from asymptomatic individuals and animals; tegument lesions (TL), which may be cutaneous and mucocutaneous with disfiguring and disabling consequences; and the visceral form (VL) which is the most severe since if it is not treated properly, can lead to death. In South America, VL is caused by L. infantum chagasi, whereas TL is mainly caused by the species L. braziliensis, L. amazonensis, L. guyanensis, L. naiffi, L. shawi, and L. lainsoni. Each Leishmania species are transmitted by specific insect vectors. The ineffectiveness of current leishmaniasis control methods and treatment of is related to the difficulty in diagnosing and identifying circulating species of Leishmania. Correct Leishmania sp identification is essential for the correct treatment and also management of animal reservoirs, especially in endemic areas for several species of the parasite, as well as other trypanosomes, which leads to cross-reactions in diagnostic tests. A previous study conducted by our research group demonstrated that the gene encoding the L. i. chagasi chitinase showed high sensitivity and specificity in the diagnosis of this Leishmania specie in human samples. The nucleotide and aminoacid chitinase sequences are specific for each Leishmania specie; the expression of the protein takes place in vertebrate and invertebrate parasite development stages; and the protein is exported to the extracellular environment. All these characteristics support the hypothesis that the Leishmania chitinase correspond to an excellent tool for molecular diagnostics and for detection of specific antibodies produced against each parasite species. Thus, the objective of this project is to use the chitinase encoding gene as target for molecular diagnosis of South American endemic Leishmania species in humans, dogs and sandflies. Recombinant forms of the protein will be used in serological tests for different Leishmania species in humans and dogs (AU)