DFG project: The egress of malaria gametocytes from the red blood cell following parasite transmission to the mosquito


Sub-project of SPP 1580: Intracellular compartments as places of pathogen-host-interactions

Duration: 2x 3 years

Application period: 2012-2018

Doctorates: Dr. Christine Wirth, Dr. Tim Weißbach, Dr. Sandra Bennink


Malaria parasites are obligate intracellular pathogens that replicate in human red blood cells harbored by a protective membrane-bound vacuole. In order to pass through sexual reproduction, the parasites have to leave the shelter of the enveloping erythrocyte. Sexual reproduction is initiated by the uptake of dormant sexual precursor cells, the intraerythrocytic gametocytes, by blood-feeding Anopheles mosquitoes. In the mosquito midgut, the gametocytes become activated by environmental stimuli signalling the change of host. Within less than 15 minutes following activation, malaria parasites egress from the erythrocytes to form gametes. Erythrocyte egress is crucial for the parasite to undergo gametogenesis and to continue its life cycle in the mosquito. The underlying molecular mechanisms of erythrocyte egress by the gametocytes, however, are up to date not well understood.Plasmodium falciparum gametocytes egress from the erythrocyte via an inside-out mode, during which the parasitophorous vacuole membrane ruptures prior to the erythrocyte membrane. Gamete formation is accompanied by drastic membrane rearrangements, including the relocation of components of the inner membrane complex to the plasma membrane. The project aimed at unveiling the molecular mechanisms of membrane ruptures during gametocyte egress with particular focus on 1) the detailed biochemical and biophysical characterization of the mode of action of PPLP2 during erythrocyte membrane permeation and its possible interaction with other perforin molecules; 2) the functional studies on plasmodial proteases involved in the disruption of the vacuolar compartment and the destabilization of the erythrocyte cytoskeleton; and 3) investigating the involvement of plasmodial phospholipases during membrane disintegration.