Phlebotomus perfiliewi transcaucasicus is circulating both Leishmania donovani and L. infantum in northwest Iran.

Leishmania infantum is the causative agent of infantile visceral leishmaniasis (IVL) in the Mediterranean Basin and, based on isoenzyme typing of the parasite isolated from dogs; this parasite was considered to predominate in the all foci of IVL in Iran. However, based on PCR detection and sequencing of parasite Cysteine Protease B (CPB), only one out of seven sandfly infections in Phlebotomus perfiliewi transcaucasicus was found to be L. infantum in the current investigation. The six other infections were haplotypes of Leishmania donovani, the causative agent of anthroponotic visceral leishmaniasis (AVL) in West Africa and India. The deduced amino acid of the L. donovani haplotype was found to be novel and the shortest CPB protein reported within the Leishmania spp. Circulation of both L. donovani and L. infantum by P. perfiliewi transcaucasicus, in addition to previous data indicating its ability to circulate L. tropica, suggests that this species, like other vectors of VL, is a permissive vector. Finding L. donovani infecting P. perfiliewi transcaucasicus in the area demands extensive and intensive typing of natural Leishmania infections in epidemiological investigations in Iran and the Mediterranean Basin in general.

Development of species-specific PCR and PCR-restriction fragment length polymorphism assays for L.infantum/L.donovani discrimination.

Discrimination of Leishmania infantum and L. donovani, the members of the L. (L.) donovani complex, is important for diagnosis and epidemiological studies of visceral leishmaniasis (VL). We have developed two molecular tools including a restriction fragment length polymorphisms of amplified DNA (PCR-RFLP) and a PCR that are capable to discriminate L. donovani from L. infantum. Typing of the complex was performed by a simple PCR of cysteine protease B (cpb) gene followed by digestion with DraIII. The enzyme cuts the 741-bp amplicon of L. donovani into 400 and 341 bp fragments whereas the 702 bp of L. infantum remains intact. The designed PCR species-specific primer pair is specific for L. donovani and is capable of amplifying a 317 bp of 3' end of cpb gene of L. donovani whereas it does not generate an amplicon for L. infantum. The species-specific primers and the restriction enzyme were designed based on a 39 bp insertion/deletion (indel) in the middle of the cpb gene. Both assays could differentiate correctly the two species and are reliable and high-throughput alternatives for molecular diagnosis and epidemiological studies of VL in various foci.

Identification of Old World Leishmania spp. by specific polymerase chain reaction amplification of cysteine proteinase B genes and rapid dipstick detection.

We used the cysteine proteinase B (cpb) gene family of the trypanosomatid genus Leishmania as a target to develop rapid, specific, and easy-to-use polymerase chain reaction (PCR) tests to discriminate Leishmania infantum, Leishmania donovani, Leishmania tropica, Leishmania aethiopica, and Leishmania major. Identification of all 5 Old World species and validation of intraspecies variability are features lacking in other species-specific PCRs. Amplicon analysis was done on agarose gels and was further simplified by using an oligochromatography dipstick to detect L. infantum and L. donovani products. Because the analytical sensitivity is lower than that of certain other species- and genus-specific PCRs, our assays are especially valuable for use on cultured isolates or directly on cryostabilates. As such, they can be implemented by research and health centers having access to culturing, DNA isolation, and PCR.

Species-specific PCR assay for L. infantum/L. donovani discrimination.

Leishmania infantum and Leishmania donovani both pertain to the L. (L.) donovani complex. The status of certain strains is questioned in the literature and there are no reliable discriminative markers to identify them. Molecular tools are needed to (i) identify diagnostic markers and (ii) to allow a better understanding of phylogenetic relationships. We have developed a PCR based on cysteine protease B (cpb). This PCR discriminates between L. infantum and L. donovani with 50-100pg of DNA. These two species are differentiated by their fragment length. Indeed, L. donovani strains were characterized by a 741-bp product and L. infantum strains by a 702-bp product, except for one strain, which revealed a heterozygous profile with the two products. This PCR does not generate amplification for other Leishmania or kinetoplastids and could contribute to clarify the phylogenetic status of several taxa that are also being debated, such as L. archibaldi.

Fluorogenic assay for molecular typing of the Leishmania donovani complex: taxonomic and clinical applications.

We describe a new fluorogenic assay for the identification of species and intraspecies groups within the Leishmania donovani complex. The assay combined (1) 2 polymerase chain reactions targeting the 2 cysteine proteinase b isogenes and (2) a fluorescence-resonance energy transfer/melting curve analysis of the polymorphisms within a 31-nt region. All strains within the L. donovani complex were distinguished from L. tropica, L. major, and L. aethiopica, and 5 distinct groups were identified within the L. donovani complex. Discrepancies were observed with the present taxonomy on the basis of isoenzyme analysis and concerned East African strains, which suggests the need for a systematic reevaluation of the taxonomy. The capacity to type parasites directly from clinical samples was demonstrated with blood and bone marrow samples. This rapid and high-throughput alternative for molecular diagnosis and epidemiological studies of visceral leishmaniasis could be adapted for use with other Leishmania species.