The secrets of the malaria parasite skeleton revealed by expansion microscopy


Plasmodium is the parasite causing malaria, one of the deadliest parasitic disease. The parasite requires two hosts - the Anopheles mosquito and the human- to complete its life cycle and goes through different forms at each stage of its life cycle. Transitioning from one form to the next involves a massive reorganization of the cytoskeleton. Two teams from the department have shed new light on the cytoskeleton organisation in Plasmodium. Their research, published in PLOS Biology, details the organisation of the parasite's skeleton at an unprecedented scale, adapting a recently developed technique called expansion microscopy. Cells are “inflated” before imaging, providing access to more structural details, at a nanometric scale. The study identifies traces of an organelle called “conoid”, which was thought to be lacking in this species despite its crucial role in host invasion in closely related parasites. 


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Expansion microscopy applied to malaria-causing parasites unveils novel cytoskeletal features including a remnant conoid, a tubulin structure that was presumed to be lost in these organisms despite its crucial role in host cell invasion by related apicomplexan parasites.


Microbes are not visible to the naked eye. Nevertheless, they represent approximately 98% of the total biomass and it is estimated that our world is colonized by more than 1030 bacteria and even more viruses. In addition to bacteria and viruses, Archaea, fungi and Protozoa complete this microbiological universe. To coexist with these ubiquitous microbes, the human body has developed a sophisticated immune system, not only to defend itself against harmful organisms, but also to tolerate the presence of an astonishingly large number of bacteria. Indeed, the healthy human body requires the presence of a highly diverse microflora to digest certain nutrients, produce vitamins, stimulate the immune system, and defend its host against invading pathogens. The genetic heritage of human beings, the environment, and the ever-present microorganisms therefore shape our health. Thus the threat of infectious diseases may vary from individual to individual and, at a larger scale, presents very different pictures in the industrial and the developing world.

Several years ago, the Faculty of Medicine of the University of Geneva made research on “Host-Pathogen Interactions” one of its priorities. Research in Microbiology and Immunology encompasses a very broad field, from basic to clinical research, including the development of new powerful and rapid diagnostic tools. In addition to fostering translational research amongst clinical and fundamental research groups, the Faculty of Medicine is long known for its strength in Humanitarian Medicine, a field that faces also challenges related to microbes.

Research in our Department includes a variety of microorganisms studied in different contexts; several different bacteria, different  classes of viruses, two apicomplexa parasites and yeast, are actively investigated from different perspectives. Several research groups approach the subject from the side of the host, either in fundamental research or in a clinical context. Inherent to this diversity is a wide range of approaches from classical genetics to molecular techniques including state-of-the-art nucleic acid analysis, proteomics, and imaging.

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