Host cell cytosolic immune response during Plasmodium liver stage development

Area of Science:

• Malariology
• Cell Biology
• Immunology

Background:

• Significant knowledge gained on Plasmodium parasite-host cell interactions during the liver stage.
• A substantial proportion of sporozoites invading hepatocytes do not develop into infectious merozoites.
• The parasitophorous vacuole membrane (PVM) is the critical interface between the parasite and hepatocyte.

Purpose of the Study:

• To elucidate the molecular mechanisms governing parasite elimination and survival during the Plasmodium liver stage.
• To understand the role of autophagy and the PVM/tubovesicular network (TVN) in controlling parasite development.
• To identify potential targets for new antimalarial strategies.

Main Methods:

• Observation of Plasmodium liver stage parasites within hepatocytes.
• Analysis of autophagy marker protein localization on the PVM.
• Investigation of PVM dynamics and interaction with the TVN during parasite development.

Main Results:

• Autophagy marker proteins decorate the PVM, leading to the elimination of a proportion of parasites via an autophagy-like mechanism.
• Successfully developing Plasmodium berghei parasites shed PVM material into the TVN.
• The TVN, an extension of the PVM, releases vesicles into the host cell cytoplasm, aiding parasite survival.

Conclusions:

• Parasite elimination during the Plasmodium liver stage is mediated by an autophagy-like host defense mechanism.
• Plasmodium parasites can evade elimination by manipulating the PVM and TVN.
• Understanding PVM/TVN molecular events offers a basis for novel antimalarial interventions.