Our vaccines are composed of three basic elements:
The Vaxart vaccine delivery platform consists of a vector-adjuvant combination that can be used with many recombinant antigens to create vaccines for oral administration.
The foundation of Vaxart’s platform is a non-replicating adenovirus type 5 vector (Ad5). Adenoviruses, some types of which cause the common cold, have a long history of use in vaccines and a proven safety profile. Circumventing pre-existing immunity is especially important for Ad5-based vaccines because a majority of the human population has circulating antibodies against adenovirus, with a significant proportion having neutralizing antibodies. When natural immunity exists, the resulting neutralizing antibodies can block viral uptake upon vector administration or re-admission in the case of multiple vaccinations.
Vaxart is working to address this problem by using the vector in a new way—delivering the Ad5-vectored vaccine via tablet directly to the gut, an organ that doesn’t induce the same sort of anti-vector immunity, thus avoiding any neutralization by blood- or muscle tissue-based immune cells.
This approach requires the use of an adjuvant, as protein vaccines are generally not effective in the gut. Vaxart has developed a patented adjuvant that works through a toll-like receptor (TLR). TLRs have been applied in vaccines and are well-accepted as effective immune stimulators. Vaxart uses a TLR known to be fully effective in the gastrointestinal tract and has “coupled” the adjuvant to the target antigen. The end result is a demonstrable immune response when administered orally.
Modular Vaccine Creation
Vaxart has demonstrated the ability to use the same non-replicating Ad5 vector platform to vaccinate against multiple diseases, using a series of different oral vaccines.
By using the same vector with different antigens, Vaxart intends to pursue a modular, standardized approach to vaccine development. We believe this approach supports rapid and low-cost development, key factors in the event of an emerging pathogen. Further, it may reduce regulatory risk, as safety data from one vaccine will directly support others created with the same platform, making it possible for the FDA to evaluate a “master file” for the platform.