Gp63 gene polymorphism and population structure of Leishmania donovani complex: influence of the host selection pressure?

Abstract

The gp63 encoding genes were characterized by PCR-RFLP in 35 isolates representative of the Leishmania donovani complex (L. infantum, L. donovani, L. archibaldi and L. chagasi), with special attention to Mediterranean L. infantum from different geographical origins, and in separate groups from Old World Leishmania (L. major, L. tropica and L. aethiopica). The aim was to evaluate how the possible selective pressure by the host on these important surface proteins would influence structuring of our sample. Comparison was carried out with the structure obtained (i) from reported isoenzyme data, characters supposed to vary neutrally, and (ii) from PCR-RFLP analysis of gp63 inter-genic regions, containing nontranslated spacers and regulatory genes. Polymorphism within the gp63-encoding region, was much higher than in gp63 inter-genic regions. In the gp63 intra-genic dendrogram, the 4 species of L. donovani complex were discriminated and quite distinct from outgroups. Within L. infantum, geographical structuring was observed and did not overlap with the structure built-up from isoenzymes and inter-genic data. These results support the idea of a strong host-selection on gp63, at vector level but most of all at vertebrate (human or dog) immunological level. Furthermore, they illustrate how the nature of genetic characters may influence the perception of population structuring.

Genetic diversity of Leishmania infantum field populations from Brazil

“…In the Mediterranean region, the distribution of L. infantum strains from southern Spain, characterized by rAPD analysis, was also found to be related to their geographic origin (Toledo et al 2002). Similar results were observed by Guerbouj et al (2001) when strains from southern France were analysed on the basis of chromosomal size. On the other hand, many authors did not find an association between isolate variability and their geographic distribution , de Oliveira et al 2007, Seridi et al 2008).…”

DNA Polymorphism Assay Distinguishes Isolates ofLeishmania donovaniThat Cause Kala-Azar from Those That Cause Post-Kala-Azar Dermal Leishmaniasis in Humans

“…Molecular techniques such as PCR-restriction fragment length polymorphism, random amplified polymorphic DNA, and single-strand conformation polymorphism analyses have been used to demonstrate the genetic variability within and between different Leishmania species including L. donovani complex (4,8,15). Earlier studies to differentiate between VL and PKDL patient isolates in Sudan did not reveal any correlation between sequence polymorphisms and clinical manifestations of human disease (3,7).…”

Species Typing in Dermal Leishmaniasis

“…For the Old World, intra-and intergenic gp63 regions have been used primarily for looking at intraspecies variability (171)(172)(173)(174), even though all species could be distinguished (Table 1). Nevertheless, a proper validation with several strains of each species is lacking.…”