Topical Adjuvants to Enhance the Efficacy of Influenza Vaccines

DESCRIPTION (provided by applicant): An adequate medical response to the threat of pandemic influenza includes surveillance and isolation, a sufficient supply of antiviral drugs, and rapid development of a protective vaccine. Under optimal circumstances, production of enough vaccine to protect the US population would take 6 months. A lag time of 6 months between identification of a pandemic strain and an adequate supply of vaccine could result in devastating morbidity, mortality, and economic loss. A dose-sparing adjuvant that enabled a limited supply of vaccine to protect more people would diminish this problem. We have identified small lipophilic molecules that penetrate the intact stratum corneum and activate the dendritic cells (DCs) in normal mouse skin. They enable resident DCs to process antigens injected into the skin without endogenous adjuvants, and cause the DCs to mature and migrate to the draining lymph node where they activate nave T cells. The speed with which these topical adjuvants promote protective T cell immunity, their low cost, and physical independence of the vaccine antigen, suggest that they might be ideal adjuvants for enhancing the protection afforded by a limiting supply of influenza vaccine. We will test whether our topical adjuvants 1) accelerate the development of T-dependent antibody responses to influenza vaccine injected into mouse skin; 2) elicit the same concentration of influenza-specific antibodies using lower doses of vaccine in mice; 3) enable lower doses of vaccine to protect mice against a lethal challenge with influenza virus; and 4) exhibit a transdermal transport rate across human skin ex vivo sufficient to permit activation of human skin DCs in vivo. If our efforts are successful, the product will be an inexpensive small molecule, applied to the skin over a vaccine injection site that will make vaccines more effective. As stand-alone adjuvants, if our topical DC activators are found to be safe and effective in humans, they should enhance the efficacy of any vaccine that can be delivered into the skin. The best public health response to pandemic influenza is an effective vaccine, but with current vaccine manufacturing capabilities it could take years to produce enough vaccine to protect the US population. We need vaccine additives that can extend the effective dose of a vaccine to cover more people. That is the goal of the proposed research.