Authors

R M Ranatunga¹; G Getti¹;  ¹ University of Greenwich

Discussion

Leishmania parasites establish themselves inside mammalian host following a carrier sandfly bit. Once inside the macrophages parasites establish themselves within membrane bound organelle known as parasitophorous vacuoles. Established amastigotes replicate and spread to neighbouring cells causing a range of diseases that affect 20million people worldwide. Even though the mechanism of parasites bind and enter has been investigated, very little is known about Leishmania’s movement through the endocytic pathway and no data is available defining L.aethiopica trafficking. In this research, GFP expressing L.aethiopica were used to investigate parasite trafficking inside the host macrophages. Terminally differentiated THP-1 cells infected with metacyclic promastigotes, newly developed & validated axenic amastigotes and infected cells were analysed for early and late endosomal colocalization up to 72h from infection. Colocalization with EEA-1 was only detectable from 10min to 4h after infection with axenic amastigotes. Interestingly EEA-1 colocalization following promastigotes and cell-mediated amastigote infection was not detectable. When infected cells were used to start infection, parasites colocalized with LAMP-1 as early as 10min after co-culture. Axenic amastigotes colocalized with LAMP-1 at 1h after infection and promastigotes at 4h after infection. These data showed that L.aethiopica trafficking is depend on the parasite stage and this is the first study to compare trafficking of those three stages. The data clearly showed differences in internalization which relate to the type of infection and indicate that intracellular parasites might spread to uninfected hosts within the PV of previously infected cells.