Which compound, when conjugated to polysaccharides in a vaccine, is likely to enhance antibody response?

• A. Dinitrophenol
• B. Palmitic acid
• C. Flagellin
• D. Lipopolysaccharide

Answer: (C)

The enhancement of antibody response in vaccines is often achieved by using certain compounds that act as adjuvants, which help to boost the immune response to the vaccine's antigens. In this context, flagellin is notable because it is a potent immunostimulatory compound derived from bacterial flagella. It can activate the immune system via Toll-like receptor 5 (TLR5), which is present on various immune cells.

When flagellin is conjugated to polysaccharides in a vaccine, it acts as an adjuvant that enhances the immune response. This is particularly important for polysaccharide antigens, which by themselves may not elicit a strong immune response, especially in young children. The conjugation of flagellin can result in improved antibody production and a more robust and sustained immune response against the polysaccharide antigen.

This mechanism of action is significant for designing effective vaccines, particularly against pathogens that feature polysaccharide capsules, as the conjugation with flagellin can lead to the generation of T-dependent responses, enabling a stronger and longer-lasting immunity. This is why flagellin is the correct choice for enhancing antibody response upon conjugation with polysaccharides in vaccines.