A dysflagellar mutant of Leishmania (Viannia) braziliensis isolated from a cutaneous leishmaniasis patient

Abstract

BackgroundParasites of the Leishmania genus alternate between the flagellated extracellular promastigote stage and intracellular amastigotes. Here we report the characterization of a Leishmania isolate, obtained from a cutaneous leishmaniasis patient, which presents peculiar morphological features.MethodsThe parasite was cultured in vitro and characterized morphologically using optical and electron microscopy. Identification was performed based on monoclonal antibodies and internal ribosomal spacer typing. In vitro macrophage cultures, murine experimental models and sand fly infections were used to evaluate infectivity in vitro and in vivo.ResultsThe isolate was identified as Leishmania (Viannia) braziliensis. In the atypical promastigotes grown in culture, a short flagellum surrounded or interrupted by a protuberance of disorganized material was observed. A normal axoneme was present close to the basal body but without elongation much further outside the flagellar pocket. A disorganized swelling at the precocious end of the axoneme coincided with the lack of a paraflagellar rod structure. The isolate was able to infect macrophages in vitro, induce lesions in BALB/c mice and infect Lutzomyia longipalpis.ConclusionsNotwithstanding the lack of an extracellular flagellum, this isolate infects macrophages in vitro and produces lesions when inoculated into mice. Moreover, it is able to colonize phlebotomine sand flies. Considering the importance attributed to the flagellum in the successful infection and survival of Leishmania in the insect midgut and in the invasion of macrophages, these findings may bring new light into the infectious mechanisms of L. (V.) braziliensis.

Amastin Knockdown in Leishmania braziliensis Affects Parasite-Macrophage Interaction and Results in Impaired Viability of Intracellular Amastigotes

“…The close interaction between the L . braziliensis membrane and the PV membrane, also observed in macrophages from infected mouse ear tissues described by Zauli and colleagues [ 29 ] suggests a role of amastins in mediating this interaction. Images of macrophages infected with parasites with reduced δ-amastin expression showed not only that this interaction was drastically affected, but also that the structure of PV membrane bilayer became disorganized in the regions where there is no contact with the parasite membrane.…”

“…As shown by Zauli et al . [ 29 ], TEM of macrophages infected with L . braziliensis allowed the identification of amastigotes exhibiting their characteristic subpellicular microtubules, kDNA structure and a short flagellum inside tight parasitophorous vacuoles (PV) ( Fig 9A ).…”

Shape, form, function andLeishmaniapathogenicity: from textbook descriptions to biological understanding

“…Moreover, the length of the flagellum may also be playing a role: a shorter flagellum will be less effective at intercalating between the microvilli in the midgut, giving a smaller surface area with which to interact, reducing the strength of binding and increasing the likelihood of expulsion during defecation. However, recently, a L. braziliensis mutant was isolated from a patient lesion, which was unable to assemble a full-length flagellum when grown under promastigote culture conditions in vitro [ 85 ]. The flagellum in the mutant cells only just emerged from the flagellar pocket, and surprisingly these mutants successfully infected sand flies, though the infections were analysed only up to 4 days after feeding, so the ability of this mutant to maintain an infection over the longer term is unknown.…”

The Flagellar Protein FLAG1/SMP1 is a Candidate forLeishmania–Sand Fly Interaction

“…These assumptions were reinforced when Cuvillier et al (2003) demonstrated that L. amazonensis overexpressing the ADP-ribosylation factor-like protein 3A (LdARL-3A) lacked a flagellum and was incapable of developing in L. longipalpis. In contrast, more recent work indicated that a flagellum-less L. braziliensis isolated from a patient was capable of infecting this same vector (Zauli et al 2012). These apparently contradicting results suggest a possibly complex interplay of different components during the Leishmania-sand fly interaction and need to be investigated further.…”