This study describes the development and characterization of monoclonal antibodies (mAbs) against xanthan, an exopolysaccharide produced by Xanthomonas campestris. Researchers immunized BALB/c mice with xanthan 646 and generated four hybridomas secreting antibodies designated A6, B3, D1, and D3 with different immunoglobulin isotypes. Competition studies using chemically modified xanthan variants revealed that antibodies A6, D1, and D3 recognize the unsubstituted trisaccharide side-chain, with the inner mannose-glucuronic acid unit being immunodominant. Antibody B3 showed different specificity, requiring the fully acylated side-chain with pyruvylated terminal mannose as the critical epitope. None of the antibodies cross-reacted with cellulose, the glucose backbone of xanthan. Dot-blot immunodetection assays demonstrated that pooled monoclonal antibodies and polyclonal ascitic fluid could detect approximately 0.1 μg of xanthan. These findings indicate that the side-chains rather than the backbone are the primary immune targets, and the results establish these antibodies as useful tools for xanthan detection and structural characterization.

Key findings

• Four monoclonal antibodies (A6, B3, D1, D3) were successfully generated against xanthan exopolysaccharide with high specificity for the side-chain rather than the cellulose backbone
• Antibodies A6, D1, and D3 recognize the unsubstituted trisaccharide side-chain with the inner mannose-glucuronic acid as the immunodominant epitope
• Antibody B3 uniquely requires the fully acylated side-chain with pyruvylated terminal mannose for binding
• Monoclonal antibodies and polyclonal ascitic fluid detected xanthan at approximately 0.1 μg using dot-blot assays on nitrocellulose