title: Kinetics of conversion of Neisseria gonorrhoeae to resistance to complement by cytidine 5'-monophospho-N-acetyl neuraminic acid.
abstract: Freshly isolated gonococci upon subculture are readily lysed by normal human serum although a few strains remain inherently resistant to the complement activity. The sensitive gonococci can be converted to serum resistance by incubation with a host derived factor referred to as cytidine 5'-monophospho-N-acetylneuraminic acid (CMP-NANA). These gonococci resist complement mediated killing due to their sialylation of an epitope structure on a component of lipo-oligosaccharide (LOS). In the present study, the kinetics of conversion to serum resistance by the action of sialyltransferase (STase) in Neisseria gonorrhoeae was followed with very low concentrations of CMP-NANA. This conversion could not be perceived at 2 x 10(-3) nmol.ml-1 but was fully attainable from 8 x 10(-3) to 2 x 10(-2) nmol.ml-1 CMP-NANA. When pretreated up to 100 min in presence of the very low concentration of 2 x 10(-3) nmol.ml-1, a potentiating effect on the conversion of gonococci by 2 x 10(-2) nmol.ml-1 was observed in relation to the time of preincubation. This action was abolished after exposure to a subinhibitory concentration of chloramphenicol (0.5 microgram.ml-1). The gonococci recovered their ability to convert to serum resistance following adequate washing. The potential for increase in STase activity should be of interest for understanding the conversion from a serum sensitive to a serum resistance state.
authors.affiliation: Centre Hospitalier Intercommunal de Villeneuve-Saint-Georges, France.
authors.forename: J P
authors.initials: JP
authors.lastname: Emond
authors.forename: A
authors.initials: A
authors.lastname: Dublanchet
authors.forename: M
authors.initials: M
authors.lastname: Goldner
mesh_terms: D001770:Blood Bactericidal Activity; D002701:Chloramphenicol / Q000494:pharmacology; D003165:Complement System Proteins / Q000494:pharmacology*; D003569:Cytidine Monophosphate N-Acetylneuraminic Acid / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D008070:Lipopolysaccharides / Q000378:metabolism; D009344:Neisseria gonorrhoeae / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D012799:Sialyltransferases / Q000378:metabolism
chemical_list: D008070:Lipopolysaccharides; C023023:lipid-linked oligosaccharides; D003569:Cytidine Monophosphate N-Acetylneuraminic Acid; D002701:Chloramphenicol; D003165:Complement System Proteins; D012799:Sialyltransferases