title: Arcanobacterium pyogenes: molecular pathogenesis of an animal opportunist.
abstract: Arcanobacterium pyogenes is a commensal and an opportunistic pathogen of economically important livestock, causing diseases as diverse as mastitis, liver abscessation and pneumonia. This organism possesses a number of virulence factors that contribute to its pathogenic potential. A. pyogenes expresses a cholesterol-dependent cytolysin, pyolysin, which is a haemolysin and is cytolytic for immune cells, including macrophages. Expression of pyolysin is required for virulence and this molecule is the most promising vaccine candidate identified to date. A. pyogenes also possesses a number of adherence mechanisms, including two neuraminidases, the action of which are required for full adhesion to epithelial cells, and several extracellular matrix-binding proteins, including a collagen-binding protein, which may be required for adhesion to collagen-rich tissue. A. pyogenes also expresses fimbriae, which are similar to the type 2 fimbriae of Actinomyces naeslundii, and forms biofilms. However, the role of these factors in the pathogenesis of A. pyogenes infections remains to be elucidated. A. pyogenes also invades and survives within epithelial cells and can survive within J774A.1 macrophages for up to 72 h, suggesting an important role for A. pyogenes interaction with host cells during pathogenesis. The two component regulatory system, PloSR, up-regulates pyolysin expression and biofilm formation but down-regulates expression of proteases, suggesting that it may act as a global regulator of A. pyogenes virulence. A. pyogenes is a versatile pathogen, with an arsenal of virulence determinants. However, most aspects of the pathogenesis of infection caused by this important opportunistic pathogen remain poorly characterized.
authors.affiliation: Department of Veterinary Science and Microbiology, University of Arizona, 1117 East Lowell Street, Tucson, AZ 85721, USA. jost@u.arizona.edu
authors.forename: B Helen
authors.initials: BH
authors.lastname: Jost
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Billington
mesh_terms: D000191:Actinomycetaceae / Q000235:genetics / Q000472:pathogenicity*; D000193:Actinomycetales Infections / Q000469:parasitology / Q000662:veterinary*; D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D002415:Cats; D002417:Cattle; D002460:Cell Line; D004285:Dogs; D004847:Epithelial Cells / Q000382:microbiology; D008264:Macrophages / Q000382:microbiology; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009894:Opportunistic Infections / Q000469:parasitology / Q000662:veterinary*; D054353:Perforin; D052899:Pore Forming Cytotoxic Proteins; D037521:Virulence Factors / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D008562:Membrane Glycoproteins; D052899:Pore Forming Cytotoxic Proteins; D037521:Virulence Factors; D054353:Perforin