Stochastic Expression of Invasion Genes in Plasmodium falciparum Schizonts

Abstract

Genetically identical cells are known to exhibit differential phenotypes in the same environmental conditions. These phenotypic variants are linked to transcriptional stochasticity and have been shown to contribute towards adaptive flexibility of a wide range of unicellular organisms. Here, we investigated transcriptional heterogeneity and stochastic gene expression in P. falciparum by performing single cell RNA sequencing on blood stage schizonts. Our data reveals significant transcriptional variations in the schizonts stage with a distinct group of highly variable invasion gene transcripts being identified. Moreover, our data reflected several diversification processes including putative developmental “checkpoint”; transcriptomically distinct parasite sub-populations and transcriptional switches in variable gene families (var, rifin, phist). Most of these features of transcriptional variability were preserved in isogenic parasite cell populations (albeit with a lesser amplitude) suggesting a role of epigenetic factors in cell-to-cell transcriptional variations in human malaria parasites. Lastly, we applied quantitative RT-PCR and RNA-FISH approach and confirmed stochastic expression of merozoites surface proteins encoding msp1, msp3, msp7, rhoptry protein encoding rhopH2 and erythrocyte binding antigen encoding eba181, some of which represent key candidates for invasion blocking vaccines.

High-throughput analysis of the transcriptional patterns of sexual genes in malaria

“…Particularly, we concentrated on profiling the expression of known sexual marker genes in up to hundreds of samples simultaneously at high resolution. Since gametocytogenesis is essential for malaria transmission, in this study we focused on the early transcriptional regulation of gametocytogenesis, as an example of the plethora of processes in Pf biology where transcriptional regulation of gene expression is crucial, to include for example monitoring virulence var gene expression [55], invasion gene expression [56], sex determination and stage transition [57].…”