O-specific polysaccharide of Vibrio cholerae O1 Inaba lipopolysaccharide (OSP-Inaba)

The O-specific polysaccharide (OSP) of Vibrio cholerae O1 Inaba is a critical surface antigen and a primary component of the lipopolysaccharide (LPS) found in the outer membrane of the bacterium (Chatterjee & Chaudhuri, 2003). It consists of a homopolymer of 4-amino-4-deoxy-D-mannose (perosamine) units linked by α(1→2) glycosidic bonds (Kasper et al., 1994). In the Inaba serotype, the terminal perosamine unit lacks the 2-O-methyl group found in the Ogawa serotype, a structural difference that defines its immunological specificity (Villeneuve et al., 2000). This molecule is the principal target for protective immunity against cholera, as antibodies directed against OSP are vibriocidal and can prevent the bacteria from colonizing the small intestine (Johnson et al., 2012). Consequently, OSP is a key component in both killed whole-cell oral cholera vaccines and experimental conjugate vaccines (Wierzba et al., 2015). Targeting this polysaccharide helps elicit a robust mucosal immune response, primarily through secretory IgA, which neutralizes the pathogen before it can cause the characteristic secretory diarrhea of cholera (Grandjean et al., 2016). The OSP-specific immune response is often measured via vibriocidal antibody titers, which serve as a surrogate marker for protection in clinical trials (Leung et al., 2004). Structural variations in OSP, such as those between Inaba and Ogawa, necessitate the inclusion of both serotypes in most vaccine formulations to ensure broad protection (Shin et al., 2011).

Other names

Vibrio cholerae O1 Inaba O-antigenInaba O-antigenV. cholerae O1 Inaba LPS O-chainInaba O-specific polysaccharide

Induction of protective vibriocidal antibodies and intestinal secretory IgA that prevent bacterial colonization and toxin production.