title: Acanthamoeba isolates belonging to T1, T2, T3, T4 but not T7 encyst in response to increased osmolarity and cysts do not bind to human corneal epithelial cells.
abstract: Acanthamoeba is an opportunistic protozoan that is widely distributed in the environment and can cause human infections. The life cycle of Acanthamoeba consists of an infective trophozoite form. However under harsh environmental conditions trophozoites differentiate into a double-walled, metabolically inactive and resistant cyst form. Research in Acanthamoeba has mostly focussed on the infective trophozoite form and its pathogenic mechanisms. In this study, we used Acanthamoeba isolates belonging to T1, T2, T3, T4, T7 genotypes and studied their cysts properties. We determined that food deprivation stimulates encystment in Acanthamoeba isolates belonging to T1, T2, T3, T4 and T7 genotypes in a sodium dodecyl sulfate (SDS)-resistant manner. In addition, increase in osmolarity triggered encystment in T1, T2, T3, T4 isolates (SDS-resistant) but T7 failed to encyst (SDS-labile). Adhesion assays revealed that Acanthamoeba cysts belonging to T1, T2, T3, T4, and T7 genotypes exhibited no and/or minimal binding (<5%) to the host cells. Fluorescein-labelled lectins showed that all Acanthamoeba isolates tested exhibited binding to concanavalin A, indicating the expression of mannosyl- and/or glucosyl-residues. Role of cysts in the transmission of infection is discussed further.
authors.affiliation: School of Biological and Chemical Sciences, Birkbeck, University of London, London WC1E 7HX, UK.
authors.forename: Ricky
authors.initials: R
authors.lastname: Dudley
authors.forename: Abdul
authors.initials: A
authors.lastname: Matin
authors.forename: Selwa
authors.initials: S
authors.lastname: Alsam
authors.forename: James
authors.initials: J
authors.lastname: Sissons
authors.forename: Amir Hossein
authors.initials: AH
authors.lastname: Maghsood
authors.forename: Naveed Ahmed
authors.initials: NA
authors.lastname: Khan
mesh_terms: D000048:Acanthamoeba / Q000145:classification* / Q000235:genetics / Q000254:growth & development; D000818:Animals; D002448:Cell Adhesion; D002478:Cells, Cultured; D019573:Epithelium, Corneal / Q000166:cytology* / Q000469:parasitology; D005838:Genotype; D006801:Humans; D008018:Life Cycle Stages; D009994:Osmolar Concentration