Role of Vpma phase variation in Mycoplasma agalactiae pathogenesis.
Compared with other bacterial pathogens, the molecular mechanisms of mycoplasma pathogenicity are largely unknown. Several studies in the past have shown that pathogenic mycoplasmas are equipped with sophisticated genetic systems that allow them to undergo high-frequency surface antigenic variations. Although never clearly proven, these variable mycoplasma surface components are often implicated in host immune evasion and adaptation. Vpma surface lipoproteins of the ruminant pathogen Mycoplasma agalactiae are encoded on a genomic pathogenicity island-like locus and are considered as one of the well-characterized model systems of mycoplasma surface antigenic variation. The present study assesses the role of these phase-variable Vpmas in the molecular pathogenesis of M. agalactiae by testing the wild-type strain PG2 in comparison with the xer1-disrupted Vpma 'phase-locked' mutants in sheep infection models. The data clearly illustrate that although Xer1 recombinase is not a virulence factor of M. agalactiae and Vpma phase variation is not necessary for establishing an infection, it might critically influence the survival and persistence of the pathogen under natural field conditions, mainly due to a better capacity for dissemination and evoking systemic responses. This is the first study where mycoplasma 'phase-locked' mutants are tested in vivo to elucidate the role of phase variation during infection.
Institute of Bacteriology, Mycology and Hygiene, Department of Pathobiology, University of Veterinary Medicine, Vienna, Austria. rohini.chopra-dewasthaly@vetmeduni.ac.at
Rohini
R
Chopra-Dewasthaly
Martina
M
Baumgartner
Erika
E
Gamper
Carmen
C
Innerebner
Martina
M
Zimmermann
Franz
F
Schilcher
Alexander
A
Tichy
Petra
P
Winter
Wolfgang
W
Jechlinger
Renate
R
Rosengarten
Joachim
J
Spergser
D000818:Animals; D000940:Antigenic Variation; D004195:Disease Models, Animal; D044404:Genomic Islands; D008074:Lipoproteins / Q000235:genetics / Q000276:immunology; D008565:Membrane Proteins / Q000276:immunology; D016254:Mutagenesis, Insertional; D009154:Mutation; D009175:Mycoplasma Infections / Q000382:microbiology* / Q000473:pathology*; D045644:Mycoplasma agalactiae / Q000235:genetics / Q000276:immunology* / Q000472:pathogenicity*; D012756:Sheep; D012757:Sheep Diseases / Q000382:microbiology / Q000473:pathology; D014774:Virulence
D008074:Lipoproteins; D008565:Membrane Proteins