Shigella sonnei O-specific polysaccharide-core (Ss O-SP) (Ss O-SP)

The Shigella sonnei O-specific polysaccharide-core is a critical antigenic component of the lipopolysaccharide (LPS) found on the outer membrane of the Gram-negative bacterium Shigella sonnei [1]. This molecule consists of a unique repeating disaccharide unit composed of 2-acetamido-2-deoxy-L-altruronic acid and 2-acetamido-2,6-dideoxy-L-galactose [2]. As a primary virulence factor, the O-specific polysaccharide (O-SP) shields the bacterium from the host's innate immune system, particularly complement-mediated lysis, and is essential for the invasion of the colonic epithelium [3]. Because S. sonnei is monotypic, meaning it possesses only one serotype, its O-SP is a highly attractive target for vaccine development [4]. Current therapeutic approaches involve the creation of glycoconjugate vaccines, where the O-SP is chemically linked to a carrier protein to stimulate a robust T-cell dependent immune response [5]. These vaccines aim to elicit high titers of protective IgG and IgA antibodies that neutralize the pathogen and prevent shigellosis, a major cause of global diarrheal morbidity [4]. Clinical evaluation of candidates like Flexyn2a has shown that targeting this polysaccharide can induce significant bactericidal activity in human subjects [3].

Other names

Shigella sonnei O-antigenS. sonnei O-SPShigella sonnei lipopolysaccharide O-side chainS. sonnei LPS core-OPSShigella sonnei O-polysaccharide

Induction of serotype-specific bactericidal antibodies (IgG and IgA) that target the O-antigen to prevent bacterial colonization and invasion of the intestinal mucosa.