The Attachment and Entry of Leishmania (Leishmania) Major into Macrophages: Observation by Scanning Electron Microscope

Abstract

Leishmaniasis, a zoonotic protozoan disease, starts with the inoculation of the Leishmania promastigotes into the skin at the time of blood ingestion by a female sandfly. The infection of leishmaniasis is established when the Leishmania organisms start their own intracellular multiplication after having been phagocytized by the host's macrophages. In the earliest stage of the infection, therefore, the attachment of the promastigates to the macrophages is essential. We incubated a mixed culture of macrophages (JM774-1A) and Leishmania (Leishmania) major for 6 hours in vitro and observed the process of the attachment between the parasite and host cell by scanning electron microscope. We found for the first time that the attachment between the two occurred at the site of the parasite body, in addition to the previously reported sites of the flagellar tip, flagellar base, and aflagellar tip (posterior pole).

The Leishmania donovani chaperone cyclophilin 40 is essential for intracellular infection independent of its stage‐specific phosphorylation status

“…An important functional characteristic of stationary‐phase parasites is a significant increase in motility, which is of physiological relevance in the natural setting for migration of metacyclic parasites from sand fly midgut to larynx (Walters et al ., 1989; 1993), or the establishment of host cell infection (Uezato et al ., ; Forestier et al ., ). We quantified motility in at least 741 WT, cyp40−/− and add‐back promastigotes obtained from logarithmic and stationary‐phase cultures utilizing video microscopy and in silico tracking analysis.…”

Infection of retinal epithelial cells with L. amazonensis impacts in extracellular matrix proteins

“…The interactions between Leishmania and host macrophages are complex and involve several paradoxical functions that are important for host protection as well as to parasite survival (Dey et al 2007). The attachment of Leishmania promastigotes to the macrophages is essential in the earliest stage of infection (Uezato et al 2005), and its attachment can occur in different ways, depending on the Leishmania species (Aikawa et al 1982;Alexander 1975;Lewis 1974;Pearson et al 1983;Rahman and Sethi 1978).…”

Cell invasion by intracellular parasites – the many roads to infection

“…2D) appears to start only after two minutes of contact with parasites (Aikawa et al, 1982). It is remarkable that, during the first moments of contact, 90% of promastigotes are attached, with low affinity, to macrophages (Uezato et al, 2005) through their flagellar tip (Aikawa et al, 1982), suggesting a role for this structure in triggering phagocytosis. It is worth pointing out that promastigotes generally move in the direction of the flagellum, an anterior structure (Krüger and Engstler, 2015), that has been proposed to have a role in sensing the environment (Rotureau et al, 2009), probably as it is the first structure to encounter a host cell.…”

“…It is worth pointing out that promastigotes generally move in the direction of the flagellum, an anterior structure (Krüger and Engstler, 2015), that has been proposed to have a role in sensing the environment (Rotureau et al, 2009), probably as it is the first structure to encounter a host cell. After five minutes, however, parasites are tightly bound to macrophages and phagocytosed with no preferred orientation (Aikawa et al, 1982;Uezato et al, 2005). The vast majority of phagocytosed promastigotes clearly localize inside phagosomes (Courret et al, 2002), which promptly fuse with lysosomes (James et al, 2006;Courret et al, 2002); this creates an appropriate milieu for their fully differentiation into amastigotes (see Glossary), and subsequent replication (Alexander and Vickerman, 1975;Chang and Dwyer, 1976;Moradin and Descoteaux, 2012).…”