Investigating the relationship between two unique apicomplexan parasite organelles: the Eimeria refractile body and Plasmodium crystalloid

Principal Supervisor: Dr Virginia Marugan-Hernandez (RVC)

Co-Supervisor: Dr Johannes Dessens and Professor Fiona Tomley (LSHTM)

Project Description

Apicomplexan parasites are widespread protozoan parasites of animals. The phylum Apicomplexa contains thousands of species and includes major pathogens of humans, domestic animals and livestock. For example, malaria (caused by Plasmodium spp.) causes nearly half a million human deaths per annum globally, while chicken coccidiosis (caused by Eimeria spp.) has an estimated global economic cost of >10 billion US$ per annum through losses in poultry production and treatment.

Plasmodium and Eimeria have evolved very different life cycles, nonetheless, their monophyletic ancestry has conserved many Apicomplexa-specific cellular structures and molecular processes involved in cell division, invasion, and motility, as well as two unique parasite structures: the ‘crystalloid’ of Plasmodium and the ‘refractile body’ (RB) of Eimeria. The crystalloid and RB share similar features such as their size and number: two crystalloids and RBs are found, which merge into a single organelle during transition into oocyst and schizont, respectively In recent years, studies in P. berghei have provided strong evidence for a spatial and functional link between the crystalloids and a family of LCCL domain-containing proteins (LAPs) that are essential for sporogony. The RBs are found exclusively in the sporozoite and young primary schizont life cycle stages of Eimeria and their roles in parasite development remain unresolved. Eimeria spp. encode several LAP orthologues and this project will test the hypothesis that Eimeria LAPs localise in the RB and are involved in the function of this organelle.

Subject Areas/Keywords

Molecular parasitology, Cell biology, Apicomplexa, Plasmodim, Eimeria, Organelle function, Crystalloid body, Refractile body, Cell division

Key References

[1] Saeed S, Tremp AZ, Dessens JT (2018). The Plasmodium LAP complex affects crystalloid biogenesis and oocysts cell division. International Journal for Parasitology 48: 1073-1078.

[2] Burrell A, Tomley FM, Vaughan S, Marugán-Hernández V (2020). Life cycle stages, specific organelles and invasion mechanisms of Eimeria species. Parasitology 147: 263–278.

[3] Saeed S, Tremp AZ, Sharma V, Lasonder E, Dessens JT (2020). NAD(P) transhydrogenase has vital non-mitochondrial functions in malaria parasite transmission. EMBO Reports 21: e47832.

[4] Pastor-Fernández I, Pegg E, Macdonald SE, Tomley FM, Blake DP, Marugán-Hernández V (2019). Laboratory growth and genetic manipulation of Eimeria tenella. Current Protocols in Microbiology 53: e81.

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