Epigenetic Roulette in Blood Stream Plasmodium: Gambling on Sex

The well-known and invidious pathology caused by malaria parasites (Plasmodium spp.) stems from the intraerythrocytic developmental cycle (IDC), which is the progressive invasion of erythrocytes by the merozoite form of the parasite followed by parasite growth, asexual replication, and lysis of the host cell liberating logarithmically greater numbers of infectious merozoites. Gene expression during the asexual IDC can largely be viewed as the result of an iterated transcriptional cascade predominantly orchestrated by members of the ApiAP2 family of transcription factors/chromatin regulators that is initiated upon sporozoite transformation in the hepatocyte [1]. However, parasite populations generated during this growth phase are far from homogeneous. Successful (even isogenic) parasite populations superimpose variation upon the basal transcriptional programme through bet hedging [2].