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Rapid elastic ejection of malaria parasites from erythrocytes
The culminating step of the intra-erythrocytic development of P.
falciparum, the causative agent of malaria, is the spectacular release of
multiple invasive merozoites upon rupture of the infected erythrocyte
membrane, and remains up to now an intriguing and controversial process
because of its ephemeral nature [1]. This work reports for the first time
that the whole process, taking place in time scales as short as 400 ms, is
the result of an elastic instability of the infected erythrocyte membrane.
Using high-speed DIC video-microscopy and epifluorescence, we demonstrate that the release occurs in three main steps following osmotic swelling of the infected erythrocyte : a pore opens in about 100 ms, ejecting 1-2 merozoites, an outward curling of the erythrocyte membrane is then
observed, ending by a fast snap-buckling eversion of the infected erythrocyte membrane, pushing the parasites forward. We rationalize our
observations by considering that during the parasite development the
infected red blood cell membrane acquires a spontaneous curvature and we
present a subsequent model describing the dynamics of the curling rim. Our
results show that sequential red blood cell membrane curling and buckling
is necessary for the parasites efficient angular dispersion and might be
biologically primordial for fast and numerous invasions of new
erythrocytes [2].
[1] V. Lew, Malaria : endless fascination with merozoite release, Curr.
Biol., 15, R760-1 (2005)
[2] M. Abkarian, G. Massiera, L. Berry, M. Roques, and C. Braun-Breton,
Blood, in press (2011)
Séminaires du laboratoire Physique et mécanique des milieux hétérogènes : consulter le programme