title: Interferon gamma responses to proteome-determined specific recombinant proteins: potential as diagnostic markers for ovine Johne's disease.
abstract: Johne's disease (JD), or paratuberculosis is a fatal enteritis of animals caused by infection with Mycobacterium avium subspecies paratuberculosis (Map). There may be a long subclinical phase with no signs of clinical disease. Diagnosis of JD is problematic and no test can reliably detect sub-clinical disease. Th1 responses to Map are believed to be activated first with a later switch to Th2 responses and progression to clinical disease. Detection of a cell-mediated response, indicated by interferon gamma (IFN-γ) produced in response to mycobacterial antigens, may give an early indication of infection. Crude extracts of Map (PPDj) have been used to detect the cell-mediated response, but more specific, quantifiable antigens would improve the test. Thirty Map-specific proteins were screened for their ability to raise a cell-mediated response in subclinically infected sheep. Four proteins were selected and tested using blood from subclinical animals and controls from a JD-free flock. Three proteins elicited IFN-γ levels which were higher in the subclinical group than in the control group, two were statistically significant. Thus these proteins have the ability to discriminate groups of infected and uninfected animals and may have use in diagnosis of JD.
authors.affiliation: Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik EH26 0PZ, United Kingdom. Val.Hughes@moredun.ac.uk
authors.forename: Valerie
authors.initials: V
authors.lastname: Hughes
authors.forename: Susan
authors.initials: S
authors.lastname: Denham
authors.forename: John P
authors.initials: JP
authors.lastname: Bannantine
authors.forename: Francesca
authors.initials: F
authors.lastname: Chianini
authors.forename: Karen
authors.initials: K
authors.lastname: Kerr
authors.forename: Linda
authors.initials: L
authors.lastname: May
authors.forename: Joyce
authors.initials: J
authors.lastname: McLuckie
authors.forename: Mintu
authors.initials: M
authors.lastname: Nath
authors.forename: Karen
authors.initials: K
authors.lastname: Stevenson
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000276:immunology*; D007371:Interferon-gamma / Q000096:biosynthesis*; D010283:Paratuberculosis / Q000175:diagnosis*; D020543:Proteome / Q000378:metabolism; D011994:Recombinant Proteins / Q000276:immunology; D012756:Sheep; D012757:Sheep Diseases / Q000175:diagnosis*
chemical_list: D001426:Bacterial Proteins; D020543:Proteome; D011994:Recombinant Proteins; D007371:Interferon-gamma
keywords: Cell-mediated diagnosis; IGRA; Interferon gamma release assay; JD; Johne's; Johne's disease; Mycobacterium avium subspecies paratuberculosis; interferon gamma release assay