Abstract: Leishmania spp. are flagellated eukaryotic parasites that cause leishmaniasis, a neglected tropical disease with a range of different pathologies. Leishmania has a complex life cycle with multiple developmental forms as it cycles between a sand fly vector and a mammalian host. Within the sand fly, Leishmania parasites have two major morphological forms, a motile promastigote and a haptomonad, which is attached to the stomodeal valve through a shortened and modified flagellum. Dissecting haptomonad development and attachment is critical to understanding parasite transmission; however, studies of haptomonads are limited, as this is a technically challenging life cycle form to investigate. To gain an in-depth understanding of the in vivo haptomonad cellular architecture and organisation, we combined two volume electron microscopy techniques – serial block face-scanning electron microscopy (SBF-SEM) and serial electron microscopy tomography – generating high resolution 3D models of haptomonads attached to the stomodeal valve. Haptomonads were densely packed around the valve and were attached through the tip of a shortened flagellum. The attachment interface was filled, on the flagellum side, with an electron-dense plaque that connected to abundant filaments and filament bundles. Next, we generated attached L. mexicana haptomonads in vitro and confirmed that the fine ultrastructure of these forms was comparable to that of haptomonads found in vivo. Using comparative proteomic approaches, we identified proteins locating to the attachment interface and a number of these proteins are present in other kinetoplastid parasites. Deletion analysis using CRISPR/Cas9 compromised Leishmania attachment both in vitro and in the sand fly, confirming that we have identified critical components of the attachment interface. This provides the first molecular insights into a kinetoplastid parasite vector attachment interface, which will underpin our understanding of this crucial interaction.

Biography: I am a molecular cell biologist and microscopist by training who is fascinated by the ability of parasites to subvert their host organism enabling them to thrive. I studied Biochemistry at the University of Cambridge, before spending nearly a year working at the International Livestock Research Institute in Nairobi. I then returned to Cambridge where I did my PhD supervised by Professor Mark Carrington studying the cell biology of the parasite Trypanosoma brucei. I then switched to the University of Oxford for my post-doc with Professor Keith Gull. In 2017, I took the opportunity to come to Oxford Brookes University to establish my own research group. In my lab, we use the flagellated eukaryotic parasites Trypanosoma brucei and Leishmania mexicana to understand the fundamental processes that define the cell organisation underlying parasite interactions with their hosts and vectors. The distinctive shape of trypanosomes and Leishmania is formed by a corset of cross-linked microtubules that are just beneath the cell membrane and both have a flagellum that provides the propulsive force enabling them to move. We focus on understanding the morphogenesis of cytoskeletal-membrane interfaces that contribute to i) cell and substrate attachments, ii) interaction with the insect vector and mammalian host.