Figure 3. A hypothetical model for immunity dependent regulation of PfEMP1 expression.

The black, blue and grey circles represent PfEMP1 variants expressed on the surface of the infected erythrocytes. (a–c) represents the response of parasites to partial immunity; (a) shows a hypothetical PfEMP1 expression profile within a naïve host where multiple PfEMP1 are expressed at high level to explore the host cytoadhesive space. Dominant variants are those which have a growth advantage due to their optimal cytoadhesion ability (b) antibody are raised first against the dominant variants (in this case the black type) (c) another variant (blue) previously expressed at lower frequency dominates the population. (d,e) represents the response of the parasite population in an individual carrying antibodies to a broad range of variants; (d) the pre-existing naturally acquired antibody clears all variants carrying high levels of PfEMP1, (e) A population of parasites expressing a previously recognised PfEMP1 but expressed at low levels of PfEMP1 survive and establish chronic infections.