Whereas infections of macrophages by promastigote forms of Leishmania mexicana pifanoi induce the production of superoxide, infections by amastigotes barely induce superoxide production. Several approaches were employed to gain insight into the mechanism by which amastigotes avoid eliciting superoxide production. First, in experiments with nitroblue tetrazolium, we found that 25% of parasitopho...

Amastigotes arc main pathogenic stage of I.eishmania parasite in mammalian host. During the course of leishmania infection the amastigotc surface would be covered by host proteins like immunoglobulins and complement components. These proteins produce false positive reaction and low signal/noise ratio in evaluation of antibody raising against lesion-dcrived amastigotc by indirect ELISA. 1'0 over...

In their amastigote stage, Leishmania live in mammalian macrophages within parasitophorous vacuoles (PV), organelles of phagolysosomal origin that, in macrophages activated with IFN-gamma, contain major histocompatibility complex (MHC) class II molecules apparently devoid of invariant chains. We have now studied the fate of PV-associated class II molecules in mouse bone marrow-derived macrophag...

Infection with lesion-derived Leishmania mexicana amastigotes inhibited LPS-induced IL-12 production by mouse bone marrow-derived macrophages. This effect was associated with expression of cysteine peptidase B (CPB) because amastigotes of CPB deletion mutants had limited ability to inhibit IL-12 production, whereas preincubation of cells with a CPB inhibitor, cathepsin inhibitor IV, was able to...

Amastigotes of the protozoan parasite Leishmania proliferate in phagolysosomes of mammalian macrophages. Propagation of the infection is considered to occur by host-cell rupture and uptake of released parasites by uninfected macrophages. In this study, the kinetics of binding of L mexicana mexicana amastigotes to COS cells and to COS cells transfected with three different macrophage receptors (...

The leishmaniases are severe parasitic diseases that occur worldwide, caused by protozoa of the genus Leishmania. Studies with medicinal plants can lead to a range of possibilities for treating and improving the patients’ quality of life. Research on Azadirachta indica fractions and extracts has shown that they have excellent anti-leishmanial activity based on bioactivity-guided fractionation o...

We studied the effect of complement on two life cycle stages of the protozoan parasite Trypanosoma cruzi: epimastigotes, found in the insect vector, and amastigotes, found in the mammalian host. We found that while both stages activate vigorously the alternative pathway, only epimastigotes are destroyed. The amounts of C3 and C5b-7 deposited on the amastigotes were similar to those bound to the...

In order to invade mammalian cells, Trypanosoma cruzi infective forms cause distinct rearrangements of membrane and host cell cytoskeletal components. Rho GTPases have been shown to regulate three separate signal transduction pathways, linking plasma membrane receptors to the assembly of distinct actin filament structures. Here, we examined the role of Rho GTPases on the interaction between dif...

ABSTRACT        Background and Objective: Leishmania major is a flagellate protozoan parasite causing cutaneous leishmaniasis. Although pentavalent antimony compounds are the first-line drugs for leishmaniasis, their application is often accompanied by numerous limitations and side effects. Therefore, it is necessary to seek drugs of herbal origin that have fa...