Adjuvants can prolong the protection afforded by protein-based vaccines and impact adaptive immune responses
Enhanced CD4 T cell responses, helper and effector, correlate with duration of protection
Durable protection from ma-EBOV is associated with Tfh frequency, Th1 antibody titers, and effector CD4 T cells
Protein-based vaccines are extremely safe, but they sometimes require the addition of adjuvants to enhance immunogenicity. In this study, we compared the impact of multiple adjuvants on immunogenicity, focusing on the duration of vaccine-mediated protection in mice. We then looked at how each adjuvant impacted the immune response in order to identify correlates of that long lasting immunity. The most effective adjuvant/vaccine combinations elicited multifunctional CD4 T cell responses and a Th1-skewed antibody response. By transferring antigen-experienced CD4 T cells and serum into naïve animals, we demonstrated that both CD4 T cells and serum were critical for durable vaccine-mediated protection.