Genetic Polymorphism and Molecular Epidemiology ofLeishmania(Viannia)braziliensisfrom Different Hosts and Geographic Areas in Brazil

Abstract

Numerical zymotaxonomy and variability of the internal transcribed spacers (ITS) between the small and large subunits of the rRNA genes were used to examine strain variation and relationships in natural populations of Leishmania (Viannia) braziliensis. A total of 101 strains from distinct hosts and Brazilian geographic regions were assigned to 15 zymodemes clustered in two major genetic groups. The great number of isolates (48.5%) placed in zymodeme IOC/Z-27 were collected on the Atlantic coast. The high molecular diversity found in populations in the Amazon Basin was related to the great number of sandfly vector(s) in that region. The results of the restriction fragment length polymorphism analysis of the ITS depicted considerable intraspecific variation. Genotypic groups A, B, and C contained 39, 40, and 22 isolates, which were divided into 16, 10, and 15 genotypes, respectively. The genetic polymorphism observed demonstrates the degree of diversity of L. Infections with the parasitic protozoan Leishmania (Viannia) braziliensis Vianna 1911 (Kinetoplastida: Trypanosomatidae) or strain variants are recognized as causing human illness in many areas of (sub)tropical America (at least 15 countries), where it constitutes a significant public health problem. Many of these parasites seem to have a unique life cycle, with different phlebotomine sandfly (Diptera: Psychodidae) vectors and/or animal reservoirs and a different geographic distribution (13). This pathogen is capable of producing a variety of clinical manifestations, such as (i) cutaneous leishmaniasis (CL), which may heal spontaneously; (ii) mucosal leishmaniasis (ML), a hyperergic invasive ulcerative form that progresses in the absence of any apparent cellular defect (15); and (iii) disseminated CL (4).Most of the environmental factors affecting the epidemiology of the various leishmaniases are still poorly understood. Wild mammals serve as reservoirs for most of the New World Leishmania spp. (21), but there is increasing evidence that some of the human pathogenic Leishmania strains can be maintained in both sylvan and urban cycles. In the case of L. (V.) braziliensis, the principal vertebrate hosts in the sylvan cycle have not been identified, but there is evidence that dogs, horses, and donkeys may serve as reservoir hosts of this parasite (15). The existence of an urban cycle involving peridomestic sandfly species for L. (V.) braziliensis reflects the ability of these parasites and their vectors to adapt to changes in their original forested habitats with important public health implications. Studies using molecular techniques to characterize L. (V.) braziliensis populations from different regions have shown a relationship between level of similarity among the parasite populations (12, 24) and their geographic range, but recent data have also indicated that the considerable variability detected among these parasites is more probably related to the sandfly vector(s) and/or animal reservoir(s) involved in the transmission cycles (18).Pathogens that produce...

Ecology of the Leishmania Species in the Guianan Ecoregion Complex

“…However, isolates from different polymorphic species show plesiomorphic similarities in their enzymatic or genetic profiles, suggesting that they may have originated from one primary sylvatic enzootic form. 80,81 Globally, although L. (V.) braziliensis [82][83][84][85][86][87][88][89][90] and in a lesser extent L. (V.) amazonensis 85,91 were shown to be highly polymorphic, L. (V.) naiffi, 45,82,83 L. (V.) guyanensis, 46,83,88 and L. (L.) deanei 92 were shown to have less diversity. Leishmania (V.) lainsoni was shown to be more invariant.…”

“…The association of L. (V.) braziliensis genotypes with specific transmission cycles probably reflects an adaptation of different clones to some particular vector species. 86 The distribution of this parasite seems to be related to the origin of the gene pool, as well as to vector and reservoir movements. 85 Leishmania (V.) guyanensis.…”

Epidemiological and clinical features of Leishmania (Viannia) braziliensis American cutaneous and mucocutaneous leishmaniasis in the State of Espírito Santo, Brazil

“…Samples were tested for the activity of the following enzymes: aconitate hydratase (ACON, E.C.4.2.1.3), glucose-6-phosphate dehydrogenase (G6PDH, E.C.1.1.1.49), glucose phosphate isomerase (GPI, E.C.5.3.1.9), isocitrate dehydrogenase NAD and NADP (IDHNAD & IDHNADP, E.C.1.1.1.42), malate dehydrogenase (MDH, E.C.1.1.1.37), malic enzyme (ME, E.C.1.1.1.40), manose phosphate isomerase (MPI, E.C.5.3.1.8), nucleosidase (NH1 & NH2, E.C.3.2.2.1), 6-phospho-gluconate dehydrogenase (6PGDH, E.C.1.1.1.43), phospho-glucomutase (PGM, E.C.1.4.1.9), leu-pro dipeptidase (PEPD, 3.4.13.9), and leu-gly dipeptidase (PEP2, E.C.3.4.11.1). Leishmanial isolates with the same electromorphs were classified into the same zymodeme (Cupolillo et al 2003). Experiments using genomic restriction fragment length polymorphism (RFLP) analysis of the internal transcribed spacer (ITS) between the small (SSU) and large (LSU) subunits of the rDNA locus (PCR-RFLP ITSrDNA) of selected parasite strains were done to examine genetic polymorphism in this group.…”

“…High resolution electrophoresis using the Genephor® apparatus was carried out in 12% polyacrylamide gels following the manufacturer's instructions (Amersham Pharmacia Biotech). The restriction enzymes used were those found to produce clear distinct banding patterns useful for grouping the isolates in genotypes (each genotype grouped isolates with the same banding pattern for all the restriction enzyme used) and were subjected to numerical analysis, as described elsewhere (Cupolillo et al 1995(Cupolillo et al , 2003.…”

“…In many endemic regions in the Americas, two or more parasite species are often sympatric (Grimaldi et al 1989). Studies have also revealed genetic polymorphism in natural populations of different Leishmania species , Mauricio et al 2001, Ishikawa et al 2002, which could explain the plasticity of these parasites and of their ability to adapt to changing ecological conditions (Cupolillo et al 2003). Likewise, the intra-species variability could have a relationship with clinical pleomorphism of the disease (Guerbouj et al 2001).…”