Isolation of an Antigenic Oligosaccharide Fraction from Leptospira interrogans serovar canicola with a Monoclonal Antibody

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Abstract
An oligosaccharide fraction containing the antigenic determinant of lipopolysaccharide antigen (TM antigen) from L. interrogans serovar canicola, recognized by a monoclonal antibody (CT3) which agglutinates serovars canicola and broomi, was isolated by formic acid and successive sulfuric acid hydrolyses. Separation of the antigenic compounds was done by Bio-Gel P-2 Sephadex G-25 gel filtration, and high-performance liquid chromatography with 2 different columns. The fraction finally obtained was a mixture of 2 oligosaccharides, both of which migrated as a single spot having a slightly higher mobility than an authentic tetrasaccharide (stachyose) on TLC. The fraction contained rhamnose, arabinose and 2 major and 2 minor unknown sugars which were shown to be N- or O-acetylated and/or O-methylated sugars by NMR. The fraction inhibited the binding of CT3 antibody with TM antigen in enzyme-linked immunosorbent assay and microscopic agglutination of serovar canicola with the antibody. The inhibitory activity was destroyed by periodate oxidation or mild alkaline treatment, but was resistant to NaBH reduction.