Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 8/9/2009
Publication Date: 8/9/2009
Citation: Hughes, V., Bannantine, J.P., Denham, S., Mcnair, J., Strain, S., Paustian, M., Stevenson, K. 2009. Evaluation of Subspecies-specific Proteins for the Diagnosis of Mycobacterium avium subspecies paratuberculosis Infections [abstract]. Interpretive Summary:
Technical Abstract: Mycobacterium avium subspecies paratuberculosis (Map)-specific proteins (35) were identified by comparing the proteomes of Map isolates with those of the genetically similar subspecies IS901+ Mycobacterium avium subspecies avium or silvaticum. This approach identified subspecies-specific proteins including the products of differential expression that would not have been detected by a comparative genomics approach. The genes encoding the proteins of interest were cloned into pMAL-c2X and expressed in Escherichia coli and the immunogenicity of the recombinant proteins determined to assess their potential as specific immunological reagents for the diagnosis of paratuberculosis and epidemiological studies. Immunogenicity was evaluated using the interferon-gamma enzyme-linked immunosorbent assay (IFN-gamma ELISA), serum ELISA and immunoblotting. Responses to the recombinant Map-specific proteins were compared to those of PPD from M. avium subspecies avium (PPD-A) and Map (PPD-J). Immune responses were evaluated in naturally Map-infected sheep with subclinical and clinical disease and in calves experimentally infected with either Map or IS901+ M.avium. Three proteins were found to have diagnostic potential when incorporated in the IFN-gamma ELISA. Seventeen proteins were detected in at least one of the immunoassays and eleven proteins were detected by serum ELISA with an optical density in excess of the cutoff of 0.1 in four of six sheep sera tested. The immunoreactivity of these proteins indicates their potential as unique diagnostic antigens for the specific immunodiagnosis of paratuberculosis.