title: Cellular Microbiology of Mycoplasma canis.
abstract: Mycoplasma canis can infect many mammalian hosts but is best known as a commensal or opportunistic pathogen of dogs. The unexpected presence of M. canis in brains of dogs with idiopathic meningoencephalitis prompted new in vitro studies to help fill the void of basic knowledge about the organism's candidate virulence factors, the host responses that it elicits, and its potential roles in pathogenesis. Secretion of reactive oxygen species and sialidase varied quantitatively (P < 0.01) among strains of M. canis isolated from canine brain tissue or mucosal surfaces. All strains colonized the surface of canine MDCK epithelial and DH82 histiocyte cells and murine C8-D1A astrocytes. Transit through MDCK and DH82 cells was demonstrated by gentamicin protection assays and three-dimensional immunofluorescence imaging. Strains further varied (P < 0.01) in the extents to which they influenced the secretion of tumor necrosis factor alpha (TNF-α) and the neuroendocrine regulatory peptide endothelin-1 by DH82 cells. Inoculation with M. canis also decreased major histocompatibility complex class II (MHC-II) antigen expression by DH82 cells (P < 0.01), while secretion of gamma interferon (IFN-γ), interleukin-6 (IL-6), interleukin-10 (IL-10), and complement factor H was unaffected. The basis for differences in the responses elicited by these strains was not obvious in their genome sequences. No acute cytopathic effects on any homogeneous cell line, or consistent patterns of M. canis polyvalent antigen distribution in canine meningoencephalitis case brain tissues, were apparent. Thus, while it is not likely a primary neuropathogen, M. canis has the capacity to influence meningoencephalitis through complex interactions within the multicellular and neurochemical in vivo milieu.
authors.affiliation: Department of Infectious Diseases and Pathology, College of Veterinary Medicine, University of Florida, Gainesville, Florida, USA.
authors.forename: Dina L
authors.initials: DL
authors.lastname: Michaels
authors.affiliation: Department of Infectious Diseases and Pathology, College of Veterinary Medicine, University of Florida, Gainesville, Florida, USA.
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Leibowitz
authors.affiliation: Department of Infectious Diseases and Pathology, College of Veterinary Medicine, University of Florida, Gainesville, Florida, USA.
authors.forename: Mohammed T
authors.initials: MT
authors.lastname: Azaiza
authors.affiliation: Department of Infectious Diseases and Pathology, College of Veterinary Medicine, University of Florida, Gainesville, Florida, USA.
authors.forename: Pollob K
authors.initials: PK
authors.lastname: Shil
authors.affiliation: Department of Infectious Diseases and Pathology, College of Veterinary Medicine, University of Florida, Gainesville, Florida, USA.
authors.forename: Suzanne M
authors.initials: SM
authors.lastname: Shama
authors.affiliation: Department of Pathobiology and Veterinary Science and Center of Excellence for Vaccine Research, University of Connecticut, Storrs, Connecticut, USA.
authors.forename: Gerald F
authors.initials: GF
authors.lastname: Kutish
authors.affiliation: Department of Microbiology, Miami University, Oxford, Ohio, USA.
authors.forename: Steven L
authors.initials: SL
authors.lastname: Distelhorst
authors.affiliation: Department of Microbiology, Miami University, Oxford, Ohio, USA.
authors.forename: Mitchell F
authors.initials: MF
authors.lastname: Balish
authors.affiliation: Department of Biomedical Sciences, College of Osteopathic Medicine, University of New England, Biddeford, Maine, USA.
authors.forename: Meghan A
authors.initials: MA
authors.lastname: May
authors.affiliation: Department of Infectious Diseases and Pathology, College of Veterinary Medicine, University of Florida, Gainesville, Florida, USA drbrown@ufl.edu.
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Brown
mesh_terms: D000818:Animals; D000942:Antigens, Bacterial / Q000235:genetics / Q000276:immunology*; D001253:Astrocytes / Q000276:immunology / Q000382:microbiology; D001921:Brain / Q000276:immunology / Q000382:microbiology; D017242:Complement Factor H / Q000235:genetics / Q000276:immunology; D004283:Dog Diseases / Q000276:immunology / Q000382:microbiology* / Q000473:pathology; D004285:Dogs; D019332:Endothelin-1 / Q000235:genetics / Q000276:immunology; D005786:Gene Expression Regulation; D006644:Histiocytes / Q000276:immunology / Q000382:microbiology; D000949:Histocompatibility Antigens Class II / Q000235:genetics / Q000276:immunology; D054884:Host-Pathogen Interactions; D007371:Interferon-gamma / Q000235:genetics / Q000276:immunology; D016753:Interleukin-10 / Q000235:genetics / Q000276:immunology; D015850:Interleukin-6 / Q000235:genetics / Q000276:immunology; D061985:Madin Darby Canine Kidney Cells; D008590:Meningoencephalitis / Q000276:immunology / Q000382:microbiology / Q000473:pathology / Q000662:veterinary*; D009174:Mycoplasma / Q000235:genetics / Q000276:immunology* / Q000472:pathogenicity*; D009439:Neuraminidase / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000276:immunology; D014774:Virulence
chemical_list: D000942:Antigens, Bacterial; D019332:Endothelin-1; D000949:Histocompatibility Antigens Class II; D015850:Interleukin-6; D017382:Reactive Oxygen Species; D014409:Tumor Necrosis Factor-alpha; D016753:Interleukin-10; D017242:Complement Factor H; D007371:Interferon-gamma; D009439:Neuraminidase