Identification of novel Listeria monocytogenes serotype 4h with specific antisera against wall teichoic acid

Listeria monocytogenes (Lm) strains are serotyped based on their somatic (O) and flagellar (H) antigens. The newly designated serotype (ST) 4h exhibits a greater ability to colonize organs than well-characterized hypervirulent strains. Therefore, simple and rapid identification methods for Lm ST 4h are urgently needed for effective monitoring and prevention. Here, we report the development of rabbit polyclonal antibodies against the O-antigen of Lm ST 4h, targeting its unique galactosylated wall teichoic acid (WTA) structure. These antisera exhibit high titers and enable the rapid and accurate identification of ST 4h isolates via slide agglutination and ELISA assays, demonstrating their specificity in labeling Lm ST 4h. The WTA-antisera provide a valuable tool for investigating the pathogenic mechanisms of hypervirulent strains and enhancing existing methods for Lm ST identification.