Cross-reactions between Leishmania braziliensis and Trypanosoma cruzi caused by common antigenic determinants hinder the specific diagnosis of cutaneous and mucocutaneous leishmaniasis (CL and MCL). Therefore, the usefulness of the 70-kDa heat shock protein (Hsp70) from L. braziliensis for differential serodiagnosis was investigated. The single-copy gene encoding Hsp70, consisting of 663 amino acids, was isolated from a genomic DNA library. The antigenicity data show that Hsp70 is an immunodominant antigen highly recognized (84%) by sera of patients with CL and MCL and to a lesser extent by chagasic patients (18.75%). Antigenic mapping of the 5 overlapping fragments into which the protein was split showed that the main antigenic determinants are located in the carboxy-terminal end. The linear antigenic determinants that show cross-reactions with chagasic sera are located in the fragment rLb70(352-518). The carboxy-terminal fragment rLb70(513-663) presents 70% sensitivity and 100% specificity, so it could be a potential candidate for specific serodiagnosis of CL and MCL caused by L. braziliensis.

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Summary :Sera from individuals suffering from leishmaniasis have been shown to strongly react against conserved proteins from the parasite, such as ribosomal, histones and heat-shock proteins. Some of these proteins have also been described as immunogenic in several auto-immune syndromes, and the detection of antibodies against them is considered to be indicative of disorder of the immune system. In this paper, we investigate whether there is any relationship between the recognition of some conserved proteins from Leishmania braziliensis by individuals suffering from cutaneous (CL) and mucocutaneous (MCL) leishmaniasis, and the recognition of the human homologues of these antigens found in sufferers from autoimmune diseases. Our findings reveal that the immune response generated during CL and MCL is elicited specifically by the parasitic histone H1 and Hsp70, since the CL and MCL sera do not react against their human counterparts. In addition, evidence is presented showing the specific recognition of human proteins by the autoimmune sera, showing only a weak crossreaction with the most divergent regions of the parasitic proteins. Résumé : LES SÉRUMS DE PERSONNES SOUFFRANT DE LEISHMANIOSE CUTANÉE PRÉSENTENT UNE FORTE RÉACTION CONTRE LES PROTÉINES CONSERVÉES DES PARASITES, MAIS NE RÉAGISSENT PAS CONTRE LEURS HOMOLOGUES HUMAINS Les sérums de personnes souffrant de leishmaniose présentent une forte réaction contre les protéines conservées des parasites, comme par exemple les protéines ribosomales, les histones et les protéines de choc thermique (Hsp

In this paper, we report a method for isolation of high molecular weight DNA from Leishmania promastigotes. This technique is especially indicated for small-scale purification of DNA suitable for the construction of highly representative genomic libraries. In our protocol, lysis buffer is compatible with RNase treatment, avoiding an additional precipitation step and consequent shearing of DNA. In order to prove the quality of the DNA isolated by this method, a Leishmania braziliensis genomic library was constructed, and an L. braziliensis KMP-11 gene was cloned after screening the library with a heterologous probe.

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