A Plasmodium phospholipase is involved in disruption of the liver stage parasitophorous vacuole membrane

PLoS Pathog. 2015 Mar 18;11(3):e1004760. doi: 10.1371/journal.ppat.1004760. eCollection 2015 Mar.

Abstract

The coordinated exit of intracellular pathogens from host cells is a process critical to the success and spread of an infection. While phospholipases have been shown to play important roles in bacteria host cell egress and virulence, their role in the release of intracellular eukaryotic parasites is largely unknown. We examined a malaria parasite protein with phospholipase activity and found it to be involved in hepatocyte egress. In hepatocytes, Plasmodium parasites are surrounded by a parasitophorous vacuole membrane (PVM), which must be disrupted before parasites are released into the blood. However, on a molecular basis, little is known about how the PVM is ruptured. We show that Plasmodium berghei phospholipase, PbPL, localizes to the PVM in infected hepatocytes. We provide evidence that parasites lacking PbPL undergo completely normal liver stage development until merozoites are produced but have a defect in egress from host hepatocytes. To investigate this further, we established a live-cell imaging-based assay, which enabled us to study the temporal dynamics of PVM rupture on a quantitative basis. Using this assay we could show that PbPL-deficient parasites exhibit impaired PVM rupture, resulting in delayed parasite egress. A wild-type phenotype could be re-established by gene complementation, demonstrating the specificity of the PbPL deletion phenotype. In conclusion, we have identified for the first time a Plasmodium phospholipase that is important for PVM rupture and in turn for parasite exit from the infected hepatocyte and therefore established a key role of a parasite phospholipase in egress.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Disease Models, Animal
  • Fluorescent Antibody Technique
  • Hepatocytes / enzymology
  • Hepatocytes / microbiology*
  • Malaria / enzymology*
  • Mice
  • Phospholipases / metabolism*
  • Plasmodium berghei / enzymology
  • Plasmodium berghei / pathogenicity
  • Protozoan Proteins / metabolism*
  • Reverse Transcriptase Polymerase Chain Reaction
  • Transcriptome
  • Vacuoles / enzymology
  • Vacuoles / microbiology

Substances

  • Protozoan Proteins
  • Phospholipases

Grant support

This work was supported by grants from the Swiss National Foundation to VTH (grant 310030_140691/1) and the EVIMalaR EU consortium. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.