Toxoplasma invasion of mammalian cells is powered by the actin cytoskeleton of the parasite

Cell. 1996 Mar 22;84(6):933-9. doi: 10.1016/s0092-8674(00)81071-5.


Toxoplasma gondii is an obligate intracellular parasite that invades a wide range of vertebrate host cells. We demonstrate that invasion is critically dependent on actin filaments in the parasite, but not the host cell. Invasion into cytochalasin D (CD)-resistant host cells was blocked by CD, while parasite mutants invaded wild-type host cells in the presence of drug. CD resistance in Toxoplasma was mediated by a point mutation in the single-copy actin gene ACT1. Transfection of the mutant act1 allele into wild-type Toxoplasma conferred motility and invasion in the presence of CD. We conclude that host cell invasion by Toxoplasma, and likely by related Apicomplexans, is actively powered by an actin-based contractile system in the parasite.

Publication types

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

MeSH terms

  • Actin Cytoskeleton / physiology
  • Actins / drug effects
  • Actins / physiology*
  • Animals
  • Base Sequence
  • Blotting, Western
  • Bone Marrow Cells
  • Cell Adhesion / drug effects
  • Cell Adhesion / physiology
  • Cell Line / parasitology
  • Cell Movement / drug effects
  • Cell Movement / physiology*
  • Cytochalasin D / pharmacology
  • Cytoskeleton / parasitology
  • Cytoskeleton / physiology
  • Macrophages / parasitology
  • Mice
  • Mice, Inbred BALB C
  • Molecular Sequence Data
  • Mutation / physiology
  • Toxoplasma / cytology
  • Toxoplasma / genetics
  • Toxoplasma / parasitology*


  • Actins
  • Cytochalasin D