Location: Infectious Bacterial Diseases ResearchTitle: Antigenicity of recombinant maltose binding protein-Mycobacterium avium subsp. paratuberculosis fusion proteins with and without factor Xa cleaving) Author
Submitted to: Clinical and Vaccine Immunology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/26/2013
Publication Date: 12/1/2013
Publication URL: http://handle.nal.usda.gov/10113/58861
Citation: Gurung, R.B., Begg, D.J., Purdie, A.C., Bannantine, J.P., Whittington, J. 2013. Antigenicity of recombinant maltose binding protein-Mycobacterium avium subsp. paratuberculosis fusion proteins with and without factor Xa cleaving. Clinical and Vaccine Immunology. 20(12):1817-1826. Interpretive Summary: Johne’s disease in livestock such as dairy cattle and sheep is caused by the bacterium Mycobacterium avium subspecies paratuberculosis (MAP). A major obstacle to controlling this disease is detecting infection using antibody-based assays shortly after infection but before the animal begins shedding the bacterium. Once shedding occurs on the farm, it thus provides a source for infecting herd mates. In this manuscript, we examined the antibody reactivity (antigenicity) of MAP recombinant proteins using sera from sheep with Johne’s disease. We found that over half of the proteins tested were antigenic. However, these recombinant proteins all have a protein tag associated with them that help to purify the protein. This protein tag can also be responsible for some of the antibody reactivity we observed. Therefore, we removed the tag with a protease enzyme called factor Xa. A reanalysis of proteins without the tag showed enhanced antigenicity. Thus, we conclude that slight modifications to the recombinant proteins can serve to create an improved protein for diagnosis of Johne’s disease. This research is of primary interest to veterinarians, stakeholders and other researchers in the field.
Technical Abstract: Mycobacterium avium subsp paratuberculosis (MAP) causes Johne’s disease (JD) in ruminants. Proteomic studies have shown that MAP expresses certain proteins when exposed to in vitro physiological stress conditions similar to the conditions experienced within a host during natural infection. Such proteins were hypothesised to be expressed in vivo, are recognised by the host immune system and may be of potential use in diagnosis of JD. In this study, 50 maltose binding protein (MBP) fusion MAP proteins were evaluated using serum samples from sheep infected with MAP and 58% of them (29/50) were found to be antigenic. Among 50 MBP fusion MAP proteins 10 proteins were evaluated in MBP fusion and Factor Xa cleaved forms. Antigenicity evaluation after cleaving (and removal of) MBP tag appeared to enhance antigenicity (62%, 31/50).