A phagocytosis mutant of Entamoeba histolytica is less virulent due to deficient proteinase expression and release

Exp Parasitol. 2007 Feb;115(2):192-9. doi: 10.1016/j.exppara.2006.08.004. Epub 2006 Sep 20.


Cysteine proteinases are key virulence factors of Entamoeba histolytica that are released during the process of invasion. We used a chemical mutant of E. histolytica strain HM-1:IMSS, clone L6, which is deficient in virulence, phagocytosis, and cysteine proteinase activity to help define the mechanisms of cysteine proteinase release. All cysteine proteinase genes of wild type HM-1 were present in the L6 mutant genome, but three of the major expressed proteinases, ehcp1, ehcp2, and ehcp5 were both transcribed, translated, and released at lower levels in L6. We hypothesized that a central protein such as the calcium binding protein 1, EhCaBP1, which is required for both phagocytosis and exocytosis might be deficient in this mutant. We found that both mRNA and proteinase levels of EhCaBP1 were decreased in L6. These findings provide an important link between phagocytosis, passive release of multiple cysteine proteinases, and attenuated virulence of this E. histolytica mutant.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium-Binding Proteins / biosynthesis
  • Calcium-Binding Proteins / genetics
  • Cysteine Endopeptidases / genetics
  • Cysteine Endopeptidases / metabolism*
  • Entamoeba histolytica / enzymology*
  • Entamoeba histolytica / genetics
  • Entamoeba histolytica / pathogenicity*
  • Enzyme-Linked Immunosorbent Assay
  • Gene Expression Regulation, Enzymologic / genetics*
  • Microarray Analysis
  • Microspheres
  • Mutation
  • Phagocytosis / genetics*
  • RNA, Messenger / analysis
  • RNA, Protozoan / genetics
  • Reverse Transcriptase Polymerase Chain Reaction
  • Transcription, Genetic
  • Virulence / genetics
  • Virulence / physiology
  • Virulence Factors / genetics
  • Virulence Factors / metabolism


  • Calcium-Binding Proteins
  • RNA, Messenger
  • RNA, Protozoan
  • Virulence Factors
  • Cysteine Endopeptidases
  • Ca2+-binding protein-1