Effect of cholesterol on the growth and virulence of Acanthamoeba castellanii

M. M. Mitra, R. E. Silvany, H. F. Leher, H. Alizadeh, J. Y. Niederkorn

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Purpose. To examine the effect of cholesterol on the growth and virulence of Acanthamoeba castellanii. Methods. A soil isolate (#30234) and an ocular isolate (#30868) of A. castellanii were cultured for 4 days in peptone-yeast extract-glucose (PYG) medium in the presence and absence of cholesterol (0.05 mg/ml). Trophozoite size was determined microscopically using an ocular micrometer and proliferation was assessed by direct cell counts. Trophozoite virulence was evaluated spectrophotometrically by the production of cytopathic effects (CPE) on corneal epithelial cell monolayers. Results. Propagation in cholesterol resulted in a significant increase in the size of both soil isolate (#30234) and ocular isolate (#30868) trophozoites. Mean diameter of soil isolate trophozoites increased from 15.5 μm to 19.2 μm while the ocular isolate trophozoites increased from 18.7 μm to 21.6 μm. Cultivation in cholesterol-containing PYG did not significantly (P>0.05) affect the growth rate of the ocular isolate, but did produce a significant (P<0.01) increase in the proliferation of soil isolate (#30234) trophozoites. Although cholesterol did not influence in vitro virulence of the ocular isolate, it induced a 43% increase in the cytopathogenicity of soil isolate trophozoites. Conclusions. Cholesterol can significantly alter the growth, proliferation, and virulence of at least one environmental isolate of A. castellanii and thus, might act as a virulence and risk factor in Acanthamoeba keratitis.

Original languageEnglish (US)
Pages (from-to)S871
JournalInvestigative Ophthalmology and Visual Science
Issue number3
StatePublished - Feb 15 1996

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience


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