The 3A1-La monoclonal antibody reveals key features of Leishmania (L) amazonensis metacyclic promastigotes and inhibits procyclics attachment to the sand fly midgut

Pinto-da-Silva, Lúcia Helena; Fampa, Patrı́cia; Soares, Deivid Costa; Oliveira, Sandra Maria de; Souto-Padrón, Thaïs; Saraiva, Elvira M.

doi:10.1016/j.ijpara.2005.03.004

Cited by 25 publications

(28 citation statements)

References 39 publications

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“…Finally, parasites from CGS-treated cultures present higher expression of the META-1 protein (Figure 2F), characteristic of metacyclic promastigotes [13]. Altogether, these results indicate that the morphological changes observed in CGS-treated cultures (Figure 1) are consistent with the development of a higher proportion of promastigotes with the same characteristics of those described as metacyclic promastigotes in the studies that initially identified this developmental stage of the parasite and others that further characterized this population [1], [18], [21], [31]. The different levels of metacyclogenesis indicated by the several assays presented here may be related to the fact that each protocol analyses a different aspect of the phenomenon that may not occur concomitantly during parasite development.…”

Section: Resultssupporting

confidence: 64%

Leishmania Metacyclogenesis Is Promoted in the Absence of Purines

et al. 2012

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Leishmania parasites, the causative agent of leishmaniasis, are transmitted through the bite of an infected sand fly. Leishmania parasites present two basic forms known as promastigote and amastigote which, respectively, parasitizes the vector and the mammalian hosts. Infection of the vertebrate host is dependent on the development, in the vector, of metacyclic promastigotes, however, little is known about the factors that trigger metacyclogenesis in Leishmania parasites. It has been generally stated that “stressful conditions” will lead to development of metacyclic forms, and with the exception of a few studies no detailed analysis of the molecular nature of the stress factor has been performed. Here we show that presence/absence of nucleosides, especially adenosine, controls metacyclogenesis both in vitro and in vivo. We found that addition of an adenosine-receptor antagonist to in vitro cultures of Leishmania amazonensis significantly increases metacyclogenesis, an effect that can be reversed by the presence of specific purine nucleosides or nucleobases. Furthermore, our results show that proliferation and metacyclogenesis are independently regulated and that addition of adenosine to culture medium is sufficient to recover proliferative characteristics for purified metacyclic promastigotes. More importantly, we show that metacyclogenesis was inhibited in sand flies infected with Leishmania infantum chagasi that were fed a mixture of sucrose and adenosine. Our results fill a gap in the life cycle of Leishmania parasites by demonstrating how metacyclogenesis, a key point in the propagation of the parasite to the mammalian host, can be controlled by the presence of specific purines.

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Section: Resultssupporting

confidence: 64%

Leishmania Metacyclogenesis Is Promoted in the Absence of Purines

et al. 2012

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“…To test whether partial deletion of LHR1 interferes with Leishmania differentiation into infective stages, we investigated the generation of metacyclic promastigotes by recovering metacyclic forms from stationary-phase cultures using the specific antibody m3A.1. This monoclonal antibody specifically agglutinates L. amazonensis promastigotes, yielding purified metacyclic forms in the supernatant (26). Wildtype, LHR1/⌬lhr1, and LHR1/⌬lhr1 plus LHR1 strains generated similar percentages of purified metacyclics after 6 days in culture (data not shown).…”

Section: Resultsmentioning

confidence: 89%

Heme Uptake Mediated by LHR1 Is Essential for Leishmania amazonensis Virulence

et al. 2013

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The protozoan parasite Leishmania amazonensis is a heme auxotroph and must acquire this essential factor from the environment. Previous studies showed that L. amazonensis incorporates heme through the transmembrane protein LHR1 (Leishmania Heme Response 1). LHR1-null promastigotes were not viable, suggesting that the transporter is essential for survival. Here, we compared the growth, differentiation, and infectivity for macrophages and mice of wild-type, LHR1-single-knockout (LHR1/ ⌬lhr1), and LHR1-complemented (LHR1/⌬lhr1 plus LHR1) L. amazonensis strains. LHR1/⌬lhr1 promastigotes replicated poorly in heme-deficient media and had lower intracellular heme content than wild-type parasites. LHR1/⌬lhr1 promastigotes were also less effective in reducing ferric iron to ferrous iron, a reaction mediated by the heme-containing parasite enzyme LFR1 (Leishmania Ferric Reductase 1). LHR1/⌬lhr1 parasites differentiated normally into aflagellated forms expressing amastigote-specific markers but were not able to replicate intracellularly after infecting macrophages. Importantly, the intracellular growth of LHR1/⌬lhr1 amastigotes was fully restored when macrophages were allowed to phagocytose red blood cells prior to infection. LHR1/⌬lhr1 parasites were also severely defective in the development of cutaneous lesions in mice. All phenotypes observed in LHR1/⌬lhr1 L. amazonensis were rescued by expression of episomal LHR1. Our results reveal the importance of efficient heme uptake for L. amazonensis replication and vertebrate host infectivity, reinforcing the potential usefulness of LHR1 as a target for new antileishmanial drugs.

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“…Metacyclic forms of L. amazonensis and L. major were purified by agglutination of stationary-phase promastigote cultures using the 3A.1 mAb (Pinto-da-Silva et al, 2005) and peanut agglutinin (Sigma) (Sacks and Melby, 2001), respectively. To generate L. amazonensis axenic amastigotes, cultures rich in metacyclic forms were incubated in M199 media supplemented with 0.25% glucose, 0.5% trypticase, 40 mM sodium succinate (pH 4.5), 20% FBS, 5% penicillin/ streptomycin at 2×10 6 /ml at 32°C for a minimum of 6 days, and then cultured axenically at 32°C.…”

Section: Methodsmentioning

confidence: 99%

Leishmania Promotes Its Own Virulence by Inducing Expression of the Host Immune Inhibitory Ligand CD200

Cortéz

Huynh

Fernandes

et al. 2011

Cell Host & Microbe

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Summary Leishmania parasites infect macrophages, cells normally involved in innate defense against pathogens. L. amazonensis and L. major cause severe or mild disease, respectively, consistent with each parasite’s ability to survive within activated macrophages. The mechanisms underlying increased virulence of L. amazonensis are mostly unknown. We show that L. amazonensis promotes its own survival by inducing expression of CD200, an immunoregulatory molecule that inhibits macrophage activation. L. amazonensis does not form typical non-healing lesions in CD200−/− mice and cannot replicate in CD200−/− macrophages, an effect reversed by exogenous administration of soluble CD200-Fc. The less virulent L. major does not induce CD200 expression and forms small, self-healing lesions in both wild type and CD200−/− mice. Notably, CD200-Fc injection transforms the course of L. major infection to one resembling L. amazonensis, with large, non-healing lesions. CD200-dependent iNOS inhibition allows parasite growth in macrophages, identifying a mechanism for the increased virulence of L. amazonensis.

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The 3A1-La monoclonal antibody reveals key features of Leishmania (L) amazonensis metacyclic promastigotes and inhibits procyclics attachment to the sand fly midgut

Cited by 25 publications

References 39 publications

Leishmania Metacyclogenesis Is Promoted in the Absence of Purines

Leishmania Metacyclogenesis Is Promoted in the Absence of Purines

Heme Uptake Mediated by LHR1 Is Essential for Leishmania amazonensis Virulence

Leishmania Promotes Its Own Virulence by Inducing Expression of the Host Immune Inhibitory Ligand CD200

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