Leishmaniasis is one of the world's most neglected diseases, largely affecting the poorest of the poor, mainly in developing countries. Over 350 million people are considered at risk of contracting leishmaniasis, and approximately 2 million new cases occur yearly(1). Leishmania donovani is the causative agent for visceral leishmaniasis (VL), the most fatal form of the disease. The choice of dru...

Phosphoinositide phospholipase C (PI-PLC) plays an essential role in cell signaling. A unique Trypanosoma cruzi PI-PLC (TcPI-PLC) is lipid modified in its N terminus and localizes to the outer surface of the plasma membrane of amastigotes. We show here that TcPI-PLC is developmentally regulated in amastigotes and shows two peaks of surface expression during the developmental cycle of T. cruzi, ...

BACKGROUND/OBJECTIVES The inoculation of a low number (10(4)) of L. amazonensis metacyclic promastigotes into the dermis of C57BL/6 and DBA/2 mouse ear pinna results in distinct outcome as assessed by the parasite load values and ear pinna macroscopic features monitored from days 4 to 22-phase 1 and from days 22 to 80/100-phase 2. While in C57BL/6 mice, the amastigote population size was increa...

BACKGROUND After loading with live Leishmania (L) amazonensis amastigotes, mouse myeloid dendritic leucocytes/DLs are known to undergo reprogramming of their immune functions. In the study reported here, we investigated whether the presence of live L. amazonensis amastigotes in mouse bone marrow-derived DLs is able to trigger re-programming of DL lipid, and particularly neutral lipid metabolism...

Signaling through exposed phosphatidylserine (PS) is fundamental for the TGFbeta1-dependent, noninflammatory phagocytosis of apoptotic cells. This same mechanism operates in the internalization of amastigotes of Leishmania (L) amazonensis (L(L)a) in a process quoted as apoptotic mimicry. Now we show that the host modulates PS exposure by the amastigotes and, as a consequence, BALB/c mice-derive...

The role of glycosphingolipids (GSLs) present in amastigote forms of Leishmania (Leishmania) amazonensis during infection of macrophages was analyzed, with particular emphasis on GSLs presenting the terminal Galpss1-3Galpa disaccharide. Macrophage invasion by L. (L.) amazonensis amastigotes was reduced by 37% when the disaccharide Galpss1-3Galp (1 mM) was added to the culture medium. The putati...

BACKGROUND T. cruzi strains have been divided into six discrete typing units (DTUs) according to their genetic background. These groups are designated T. cruzi I to VI. In this context, amastigotes from G strain (T. cruzi I) are highly infective in vitro and show no parasitemia in vivo. Here we aimed to understand why amastigotes from G strain are highly infective in vitro and do not contribute...

Leishmania donovani is the etiologic agent of fatal visceral leishmaniasis in man. During their life cycle, Leishmania exist as flagellated promastigotes within the sandfly vector and as nonflagellated amastigotes in the macrophage phagolysosomal compartment of the mammalian host. The transformation from promastigotes to amastigotes is a critical step for the establishment of infection, and the...

An in vitro system was developed for studying host-parasite cellular interactions in visceral leishmaniasis with amastigotes isolated from infected spleens of hamsters and their peritoneal macrophages maintained by an improved method. The culture system supports the growth of Leishmania donovani amastigotes with different parasite/macrophage ratios for up to 2 wk, yielding results more consiste...

We have raised monoclonal antibodies (mAbs) directed towards amastigote forms of Trypanosoma cruzi, and shown that mAbs ID9 and 4B9 are carbohydrate while mAb 4B5 activity is resistant to periodate oxidation of the antigen. Here we used an ELISA to quantitate and compare the expression of surface epitopes on fixed parasites among different parasite isolates. The expression of markers varied amo...