Encystation of Giardia lamblia: a model for other parasites

Curr Opin Microbiol. 2007 Dec;10(6):554-9. doi: 10.1016/j.mib.2007.09.011. Epub 2007 Nov 5.


To colonize the human small intestine, Giardia lamblia monitors a dynamic environment. Trophozoites attach to enterocytes that mature and die. The parasites must 'decide' whether to re-attach or differentiate into cysts that survive in the environment and re-activate when ingested. Other intestinal parasites face similar challenges. Study of these parasites is limited because they do not encyst in vitro. Giardia trophozoites were persuaded to encyst in vitro by mimicking physiological stimuli. Cysts are dormant, yet 'spring-loaded for action' to excyst upon ingestion. Giardial encystation has been studied from morphological, cell biological, biochemical, and molecular viewpoints. Yet important gaps remain and the mechanisms that co-ordinate responses to external signals remain enigmatic.

Publication types

  • Research Support, N.I.H., Extramural
  • Review

MeSH terms

  • Animals
  • Cell Wall / metabolism
  • Gene Expression Regulation
  • Giardia lamblia / cytology
  • Giardia lamblia / genetics
  • Giardia lamblia / metabolism
  • Giardia lamblia / physiology*
  • Protozoan Proteins / genetics
  • Protozoan Proteins / metabolism


  • Protozoan Proteins