Use of Mycobacterium avium subsp paratuberculosis specific coding sequences for serodiagnosis of bovine paratuberculosis

Department of Proteomic and Protein Biochemistry, University of Mons-Hainaut, Av. du Champs de Mars, 6, B-7000 Mons, Belgium.
Veterinary Microbiology (Impact Factor: 2.51). 10/2008; 135(3-4):313-9. DOI: 10.1016/j.vetmic.2008.09.065
Source: PubMed


In this study, the finished complete genome of Mycobacterium avium subsp. paratuberculosis (Map) was screened for specific coding sequences that could be very valuable in the design of a sensitive and specific Map detection serological assay. Eighty-seven Map-specific sequences were retained. Among these, three candidate antigens have been analysed for their serodiagnostic potential. These antigens were selected on the basis of their putative immunogenicity as predicted by in silico analysis. The antigens were cloned in Escherichia coli, expressed, and purified before testing in an antibody detection ELISA test, using a well characterized panel of 18 and 48 sera from Map infected and uninfected cattle, respectively. Two of these antigens, antigen 6 and MAP1637c, yielded in our conditions a sensitivity of 72% and 82%, respectively, for a specificity of 98%. It is particularly noticeable that, when probed with the same serum panel, the most widely used European paratuberculosis commercial seroassay (Pourquier test) yielded a sensitivity of 72% for a specificity of only 92%.

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    • "MAP1693c has also been identified by Cho et al. (2007, 2006) to be a good candidate for an indirect antibody detection ELISA. The selection of Ag5, Ag6, MAP1637c, MAP0388 and MAP3743 was based on an in silico analysis of Map genome performed in 2003 (Leroy et al., 2009). Briefly, genomic sequences with no significant homologies in other mycobacterial genomes as analyzed by BLASTn and BLASTp/nr were identified and three different T cell epitope prediction programs for MHC class II (Feller and de la Cruz, 1991) and MHC class I (Parker et al., 1994; Rammensee et al., 1999) were used to select five antigens, predicted to be strongly immunogenic, among eighty-seven in silico predicted MAP-specific ORF. "
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    • "Environmental mycobacteria are abundant in the Irish environment and known to cause non-specific sensitisation to tuberculins [16]. Leroy et al. [27] further report that if M. bovis exposed cattle are used as a negative control, Sp of the MAP Pourquier test was only 91.6%, i.e., four sera among 48 were detected as false-positive. Although M. bovis is quite prevalent in the Irish environment, the M. bovis status of the ELISA-positive herds or animals were not determined in this study. "
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