Core-plus-O-polysaccharide of invasive nontyphoidal Salmonella serovar LPS (COPS)

The core-plus-O-polysaccharide (COPS) is a key structural element of lipopolysaccharide (LPS) in the outer membrane of Gram-negative Salmonella enterica, particularly nontyphoidal serovars like Enteritidis and Typhimurium. It consists of a conserved core oligosaccharide (linked to lipid A via KDO) extended by the serovar-specific repeating O-polysaccharide (OPS) chain, such as the group D trisaccharide backbone with tyvelose in Enteritidis. This structure provides virulence by conferring resistance to complement-mediated killing, phagocyte uptake, and host immune recognition, while influencing innate immunity and bacterial survival in systemic infections. COPS is poorly immunogenic alone but highly targeted in glycoconjugate vaccines, where it is covalently linked to carrier proteins like flagellin to elicit protective antibodies against invasive nontyphoidal Salmonella.

Other names

core O polysaccharideSalmonella core-OPScore-linked O-polysaccharideO-antigen polysaccharide (when linked to core)