Lipooligosaccharidic antigens from Mycobacterium kansasii and Mycobacterium gastri.

A set of Lipooligosaccharides (LOSs) has previously been characterized in M. gastri W471. The structure of the highly antigenic LOS (LOS-III) was elucidated and this molecule can unambiguously distinguish M. gastri from the opportunistic pathogen M. kansasii. In the present study, the structures of three other M. gastri W471 LOSs were determined by one-dimensional 1H-NMR spectroscopy and gas liquid chromatography. They differ by the number of Xylp units and by the structure of the distal monosaccharide. The two dimensional (2D) NMR approach was successfully applied to the LOS antigen of M. kansasii to locate the acetyl and acyl substituents and to determine the anomeric configuration of the alpha-D-Fucp unit. The molecular specificity of anti-LOS-III antibodies was investigated and the LOS-III epitope was defined as the distal disaccharide: 3,6-dideoxy-4-C-(1,3-dimethoxy-4,5,6,7-tetrahydroxy- heptyl)-alpha-xylohexp-(1-->3)-beta-L-Xylp.