To boost vaccine effectiveness molecules known as adjuvants are often included in the vaccine formulation. Adjuvants are most commonly used to increase the magnitude of vaccine-induced immune responses, specifically T cell immune responses. However, the quality of a T cell response can be more important than its quantity, and a team of researchers, at the National Institutes of Health, has now identified a way to increase the quality but not the quantity of a vaccine-induced T cell response in mice.
TLRs are a family of microorganism-sensing proteins that represent potential new vaccine adjuvants, as stimulating certain pairs of TLRs has a synergistic effect on the magnitude of immune responses in preclinical models. The team, led by Jay Berzofsky, found that when mice were immunized with an HIV peptide together with three molecules that bound different TLRs they mounted a more effective protective T cell response than did mice immunized with the HIV peptide together with any two of the ligands.
Further analysis determined that the increased protection correlated with T cell responses of enhanced quality, rather than enhanced quantity.
The authors therefore suggest that select TLR ligand combinations could be used to separately manipulate the quality and quantity of vaccine-induced T cell responses.
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