Parasite Genetics and Adaption - Project B3

Characterisizing Plasmodium protein function at the parasite-host interface during both liver and blood infection stages

Host lab: Alyssa Ingmundson (Humboldt University Berlin)

Partner labs: Melanie Rug (Australian National University) and Alexander Maier (Australian National University)

Additional interaction partners: Ian Cockburn (Australian National University), Christina Spry (Australian National University) and Giel van Dooren (Australian National University)

Background: While protein export and host cell membrane remodeling are processes conserved across Plasmodium species, their influence on the ability of parasites to thrive in their hosts has been primarily studied in Plasmodium falciparum. While P. falciparum is the deadliest malaria species, it is evolutionarily distinct from the other human-infecting species, such as P. vivax and P. knowlesi. We have been studying P. berghei proteins that are conserved in most human- or rodent-infecting species, but absent from P. falciparum. These proteins are expressed in both the liver and blood stages of infection and are exported into the host red blood cell where they localize to membranes formed in the host cytoplasm and influence the ability of infected red blood cells to sequester in the microvasculature.

Central goals: We aim to better understand the parasite-host interactions in non-falciparum Plasmodium species, and P. knowlesi blood-stage culture and P. berghei mouse infections provide complementary systems for this investigation. We will further characterize the proteins described above as well as other exported proteins common to these species using genetic and biochemical methods together with advanced microscopy. We will also focus on the role these proteins play in the liver stage of infection. Identification of potential protein-interaction partners may indicate protein function, and use of correlative light and electron microscopy can reveal how the parasite and host interact at the ultra-structural level.

Outline of 3-Year Plan:

Year 1 (Berlin)

• Identify potential interaction partners of candidate parasite proteins.
• Characterize liver-stage development of parasites lines deficient for candidate proteins, including preparation of samples for microscopy.

Year 2 (Canberra)

• Characterize exported proteins in Plasmodium knowlesi.
• Use correlative light and electron microscopy to investigate the influence of these proteins on liver-stage and blood-stage infected cells.

Year 3 (Berlin)

• Characterize potential interaction partners or additional candidate proteins through localization and genetic targeting.

Keywords: parasite-host interactions, liver-stage development, proximity-dependent protein labeling, parasite genetics, correlative light and                               electron microscopy.