Comparative Microsatellite Typing of New World Leishmania infantum Reveals Low Heterogeneity among Populations and Its Recent Old World Origin

Abstract

Leishmania infantum (syn. L. chagasi) is the causative agent of visceral leishmaniasis (VL) in the New World (NW) with endemic regions extending from southern USA to northern Argentina. The two hypotheses about the origin of VL in the NW suggest (1) recent importation of L. infantum from the Old World (OW), or (2) an indigenous origin and a distinct taxonomic rank for the NW parasite. Multilocus microsatellite typing was applied in a survey of 98 L. infantum isolates from different NW foci. The microsatellite profiles obtained were compared to those of 308 L. infantum and 20 L. donovani strains from OW countries previously assigned to well-defined populations. Two main populations were identified for both NW and OW L. infantum. Most of the NW strains belonged to population 1, which corresponded to the OW MON-1 population. However, the NW population was much more homogeneous. A second, more heterogeneous, population comprised most Caribbean strains and corresponded to the OW non-MON-1 population. All Brazilian L. infantum strains belonged to population 1, although they represented 61% of the sample and originated from 9 states. Population analysis including the OW L. infantum populations indicated that the NW strains were more similar to MON-1 and non-MON-1 sub-populations of L. infantum from southwest Europe, than to any other OW sub-population. Moreover, similarity between NW and Southwest European L. infantum was higher than between OW L. infantum from distinct parts of the Mediterranean region, Middle East and Central Asia. No correlation was found between NW L. infantum genotypes and clinical picture or host background. This study represents the first continent-wide analysis of NW L. infantum population structure. It confirmed that the agent of VL in the NW is L. infantum and that the parasite has been recently imported multiple times to the NW from southwest Europe.

Effects of soluble extracts from Leishmania infantum promastigotes, Toxoplasma gondii tachyzoites on TGF-β mediated pathways in activated CD4+ T lymphocytes

“…Our data show that either treatment with a cocktail containing inhibitors of cysteine and serine proteases and of cathepsin B and heat-treatment at 80 C completely inhibited latent TGF-b activation by L. infantum extracts suggesting the role of protein molecules with proteases activity. Our results are in agreement with those reported by Gantt et al showing the property to activate latent TGF-b of live L. chagasi promastigotes [14] likely because L. infantum and L. chagasi (the most prevalent species in South America) belong to the same species [36].…”

Studies on protozoa in ancient remains - A Review

“…An analogous situation was proposed for leishmaniasis in Egypt, where expeditions to Nubia (modern Sudan), currently a highly endemic country for VL (Zink et al 2006), would explain the high incidence of Leishmania DNA in the Middle Kingdom, as opposed to its absence in earlier or later periods. Leishmania infantum was recently identified in Eleanor of Toledo (1522-1562), a Spanish noble woman and wife of Cosimo I de'Medici and in mummies from the Brazilian Colonial Period, 1530-1815 (ongoing research), which is in accordance with studies confirming the recent importation of this parasite into the New World from southwest Europe (Kuhls et al 2011).…”

Molecular and serological detection of tick-borne pathogens in dogs from an area endemic for Leishmania infantumin Mato Grosso do Sul, Brazil

“…The latter is endemic in the New World in regions extending from the southern United States to northern Argentina, including Brazil (KUHLS et al, 2011). The diagnosis of VL has proved to be problematic, mainly because of the wide variety of non-specific clinical symptoms, including a broad spectrum of presentations (BLAVIER et al, 2001).…”