The diagnostic targeting of a carbohydrate virulence factor from M.Tuberculosis

The current clinical management of TB is complicated by the lack of suitable diagnostic tests that can be employed in infrastructure and resource poor regions. The mannose-capped form of lipoarabinomannan (ManLAM) is unique to the surface envelope of slow-growing, pathogenic mycobacteria such as M.tuberculosis (M.tb) and facilitates passive invasion of mononuclear phagocytes. The detection of this virulence factor in urine, sputum and serum has engendered interest in its employment as a biomarker for M.tb infection. In this study, we utilize a subtractive screening methodology to engineer the first high affinity recombinant antibody (My2F12) with exquisite specificity for the α1-2 mannose linkages enriched in ManLAM from M.tb. My2F12 binds to pathogenic mycobacterial species but not fast growing non-pathogenic species. Testing on matched urine and serum samples from TB patients indicates that My2F12 works in patient cohorts missed by other diagnostic methodologies.