Development of an oral protein subunit COVID-19 vaccine to induce mucosal and systemic immune response

It is widely recognized that mucosal immunization is the most efficient route of delivery to offer protective immunity. Oral administration can boost the economic value of vaccines, make needle-free delivery possible, and allow for safe and convenient self-administration. Despite these critical advantages, there are very few oral or nasal COVID-19 vaccine in development, and none on the market. The main challenge for an efficacious vaccine administered orally is the need for an efficient antigen delivery system into the mucosa. VaxForm has developed a technology that consists of co-adsorbing antigen(s) and a C-type lectin (CTL) receptor agonist to an aluminum delivery particle and encapsulating the vaccine with an enteric polymer to protect it from the stomach acidic environment and enhance stability. Once in the intestines, the protective polymer dissolves, and the CTL agonist targets the microfold (M) cells in the gut associated lymphoid tissues (GALT), allowing efficient delivery of the antigens adsorbed to aluminum particle Please click Download on the upper right corner to see the full abstract

Group A Streptococcus Vaccine Targeting the Erythrogenic Toxins SpeA and SpeB Is Safe and Immunogenic in Rabbits and Does Not Induce Antibodies Associated with Autoimmunity

Group A streptococcus (GAS) is a global pathogen associated with significant morbidity and mortality for which there is currently no licensed vaccine. Vaccine development has been slow, mostly due to safety concerns regarding streptococcal antigens associated with autoimmunity and related complications. For a GAS vaccine to be safe, it must be ensured that the antigens used in the vaccine do not elicit an antibody response that can cross-react with host tissues. In this study, we evaluated the safety of our GAS vaccine candidate called VaxiStrep in New Zealand White rabbits. VaxiStrep is a recombinant fusion protein comprised of streptococcal pyrogenic exotoxin A (SpeA) and exotoxin B (SpeB), also known as erythrogenic toxins, adsorbed to an aluminum adjuvant. The vaccine elicited a robust immune response against the two toxins in the rabbits without any adverse events or toxicity. No signs of autoimmune pathology were detected in the rabbits’ brains, hearts, and kidneys via immunohistochemistry, and serum antibodies did not cross-react with cardiac or neuronal tissue proteins associated with rheumatic heart disease or Sydenham chorea (SC). This study further confirms that VaxiStrep does not elicit autoantibodies and is safe to be tested in a first-in-human trial