title: Structural and biochemical alterations in Giardia lamblia cysts exposed to ozone.
abstract: Because of its efficacy in inactivating waterborne protozoan cysts and oocysts, ozone is frequently used for disinfection of drinking water. The effect of ozone on cysts of Giardia lamblia was investigated in gerbils (Meriones unguiculatus), using an infectivity assay by scanning electron microscopy, immunoblotting, and flow cytometry. Cysts recovered from experimentally infected gerbils were exposed to an initial ozone concentration of 1.5 mg/L for 0, 30, 60, and 120 sec. This treatment resulted in a dose-dependent reduction in cysts concentration, loss of infectivity in gerbils, and profound structural modifications to the cyst wall. Exposure for 60 sec or longer resulted in extensive protein degradation and in the disappearance of a cyst wall and a trophozoite antigen.
authors.affiliation: Tufts University School of Veterinary Medicine, Building 20, 200 Westboro Road, North Grafton, Massachusetts 01536, USA. giovanni.widmer@tufts.edu
authors.forename: Giovanni
authors.initials: G
authors.lastname: Widmer
authors.forename: Tim
authors.initials: T
authors.lastname: Clancy
authors.forename: Honorine D
authors.initials: HD
authors.lastname: Ward
authors.forename: Dan
authors.initials: D
authors.lastname: Miller
authors.forename: Glenda M
authors.initials: GM
authors.lastname: Batzer
authors.forename: Christine B
authors.initials: CB
authors.lastname: Pearson
authors.forename: Zia
authors.initials: Z
authors.lastname: Bukhari
mesh_terms: D000818:Animals; D000953:Antigens, Protozoan / Q000032:analysis / Q000187:drug effects; D004202:Disinfectants / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005434:Flow Cytometry; D005849:Gerbillinae; D016829:Giardia lamblia / Q000737:chemistry / Q000187:drug effects* / Q000648:ultrastructure; D015151:Immunoblotting; D008855:Microscopy, Electron, Scanning; D010083:Oxidants, Photochemical / Q000494:pharmacology*; D010126:Ozone / Q000494:pharmacology*; D015800:Protozoan Proteins / Q000187:drug effects / Q000378:metabolism
chemical_list: D000953:Antigens, Protozoan; D004202:Disinfectants; D010083:Oxidants, Photochemical; D015800:Protozoan Proteins; D010126:Ozone