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SUMMARY Leishmania infantum causes visceral leishmaniasis (VL) in the New World. The diagnosis of VL is confirmed by parasitological and serological tests, which are not always sensitive or specific. Our aim was to design new primers to perform a Polymerase Chain Reaction (PCR) for detecting L. infantum. Sequences of the minicircle kinetoplast DNA (kDNA) were obtained from GenBank, and the FLC2/RLC2 primers were designed. Samples of DNA from L. infantum, Leishmania amazonensis,Leishmania braziliensis, Leishmania guyanensis, Leishmania naiffi, Leishmania lainsoni, Leishmania panamensis,Leishmania major and Trypanosoma cruzi were used to standardize the PCR. PCR with FLC2/RLC2 primers amplified a fragment of 230 bp and the detection limit was 0.2 fg of L. infantum DNA. Of the parasite species assayed, only L. infantum DNA was amplified. After sequencing, the fragment was aligned to GenBank sequences, and showed (99%) homology with L. infantum. In the analysis of blood samples and lesion biopsy from a dog clinically suspected to have VL, the PCR detected DNA from L. infantum. In biopsy lesions from humans and dogs with cutaneous leishmaniasis, the PCR was negative. The PCR with FLC2/RLC2 primers showed high sensitivity and specificity, and constitutes a promising technique for the diagnosis of VL.

Leishmaniases are infectious diseases with different clinical forms and prognoses, making accurate species identification particularly important. We evaluated the performance of LBF1/LBR1 L. (V.) braziliensis specific primers by PCR and compared the results with Leishmania spp. identified by monoclonal antibodies (mAbs). Of 29 L. (V.) braziliensis identified by mAbs, 16 (53.3%) were detected; and 7 (63.6%) of 11 unidentified Leishmania spp. showed the 536 bp band. 87.7% of serodeme III Leishmania isolates were identified by these primers. These results indicate a poor correlation between the two identification methods used, and also suggest the existence of genetic variability among L. (V.) braziliensis isolates from the northwest region of Paraná state.

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