Latent transcriptional variations of individual Plasmodium falciparum uncovered by single-cell RNA-seq and fluorescence imaging

PLoS Genet. 2019 Dec 19;15(12):e1008506. doi: 10.1371/journal.pgen.1008506. eCollection 2019 Dec.

Abstract

Malaria parasites follow a complex life cycle that consists of multiple stages that span from the human host to the mosquito vector. Among the species causing malaria, Plasmodium falciparum is the most lethal, with clinical symptoms manifesting during the intraerythrocytic developmental cycle (IDC). During the IDC, P. falciparum progresses through a synchronous and continuous cascade of transcriptional programming previously established using population analyses. While individual parasites are known to exhibit transcriptional variations to evade the host immune system or commit to a sexual fate, such rare expression heterogeneity is largely undetectable on a population level. Therefore, we combined single-cell RNA-sequencing (scRNA-seq) on a microfluidic platform and fluorescence imaging to delineate the transcriptional variations among individual parasites during late asexual and sexual stages. The comparison between asexual and sexual parasites uncovered a set of previously undefined sex-specific genes. Asexual parasites were segregated into three distinct clusters based on the differential expression of genes encoding SERAs, rhoptry proteins, and EXP2 plus transporters. Multiple pseudotime analyses revealed that these stage-specific transitions are distinct. RNA fluorescent in situ hybridization of cluster-specific genes validated distinct stage-specific expression and transitions during the IDC and defined the highly variable transcriptional pattern of EXP2. Additionally, these analyses indicated huge variations in the stage-specific transcript levels among parasites. Overall, scRNA-seq and RNA-FISH of P. falciparum revealed distinct stage transitions and unexpected degrees of heterogeneity with potential impact on transcriptional regulation during the IDC and adaptive responses to the host.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Gene Expression Profiling
  • Gene Expression Regulation, Developmental
  • In Situ Hybridization, Fluorescence / methods*
  • Life Cycle Stages
  • Microfluidic Analytical Techniques
  • Multigene Family
  • Plasmodium falciparum / genetics
  • Plasmodium falciparum / growth & development*
  • Protozoan Proteins / genetics*
  • Sequence Analysis, RNA / methods*
  • Single-Cell Analysis / methods*

Substances

  • Protozoan Proteins

Grants and funding

This work was supported by the Burroughs Wellcome Fund; Duke MGM Chair Pilot Funding; Duke Microbiome Center; Duke Chancellor Pilot Project funds; the National Science Foundation Graduate Research Fellowship Program [to K.A.W.]; and the Deans’ Summer Research Fellowship of Duke University [to L.Y.E.]. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.