title: Comparison of in vivo and in vitro properties of capsulated and noncapsulated variants of Mycoplasma mycoides subsp. mycoides strain Afadé: a potential new insight into the biology of contagious bovine pleuropneumonia.
abstract: Mycoplasma mycoides subsp. mycoides (Mmm) strain Afadé had previously been shown to undergo spontaneous phase variations between an opaque capsulated variant and a translucent (TR) variant devoid of a capsule but able to secrete cell-free exopolysaccharides. This phase variation is associated with an ON/OFF genetic switch in a glucose permease gene. In this study, in vivo and in vitro assays were conducted to compare the virulence of the two variants and their abilities to resist host defence. Capsulated variants were shown, in a mouse model, to induce longer bacteraemia that was correlated with better serum resistance in vitro. In contrast, TR variants displayed better ability to adhere to an inert support, linked to the absence of a capsule, changes in cell surface hydrophobicity and increased resistance to antimicrobial peptide and hydrogen peroxide. The switch from one variant population to another, which was observed both in vivo and in vitro under stress conditions, is further discussed as a means for Mmm to modulate its interactions with animal hosts during different stages of the disease.
authors.affiliation: Laboratoire de Lyon, UMR Mycoplasmoses des Ruminants, Agence Nationale de Sécurité Sanitaire, Lyon, France; VetAgro Sup, UMR Mycoplasmoses des Ruminants, Université de Lyon, Marcy-L'étoile, France.
authors.forename: Patrice
authors.initials: P
authors.lastname: Gaurivaud
authors.forename: Latifa
authors.initials: L
authors.lastname: Lakhdar
authors.forename: Dominique
authors.initials: D
authors.lastname: Le Grand
authors.forename: François
authors.initials: F
authors.lastname: Poumarat
authors.forename: Florence
authors.initials: F
authors.lastname: Tardy
mesh_terms: D000818:Animals; D016470:Bacteremia / Q000382:microbiology / Q000473:pathology; D001422:Bacterial Adhesion; D016667:Bacterial Capsules / Q000378:metabolism; D002417:Cattle; D002418:Cattle Diseases / Q000382:microbiology*; D004195:Disease Models, Animal; D005260:Female; D008810:Mice, Inbred C57BL; D009176:Mycoplasma mycoides / Q000276:immunology / Q000472:pathogenicity / Q000502:physiology*; D011002:Pleuropneumonia, Contagious / Q000382:microbiology*; D011019:Pneumonia, Mycoplasma / Q000382:microbiology / Q000662:veterinary*; D013499:Surface Properties; D014774:Virulence
keywords: bacteria-host interactions; capsule; exopolysaccharide; mycoplasma