Chemical Synthesis of Lipid A and Its Development as a Vaccine Adjuvant

Lipopolysaccharide, an outer membrane component of Gram-negative bacteria, is known as a representative immune activator, and its active principle is the terminal glycolipid, lipid A. LPS is thus a potential adjuvant candidate. However, canonical Escherichia coli LPS is known as an endotoxin, since it can induce lethal sepsis due to hyperinflammatory immune response. Therefore, to apply them as adjuvants, it is necessary to structurally modify LPS and lipid A to minimize their toxic effects while maintaining their adjuvant effects.