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The researchers suggest that inducing a mucosal immune response may be crucial in protecting against SARS-CoV-2 infection and that the tablet formulation could overcome several major challenges associated with injectable vaccines.
A biotech company developing a recombinant oral vaccine against SARS-CoV-2 delivered in tablets announced the pre-publication of a manuscript detailing how its COVID-19 vaccine candidate performed in preclinical trials.
The study evaluated the relative immunogenicity of four candidate vaccines expressing multiple combinations of SARS-CoV-2 peak (S) and nucleocapsid (N) proteins in a standard mouse model. Vaxart, Inc. said that the inclusion of protein N, along with protein S in its vaccine candidate, may prevent the vaccine from becoming ineffective due to accumulation of mutations in the SARS-CoV-2 protein S.
The company based the recombinant adenoviral mucosa vaccine on its oral adenovirus platform that has been developed to deliver vaccines in a tablet formulation that is at room temperature and can be stored and shipped without refrigeration. The company has shown that the vaccine delivery platform is suitable for delivering recombinant vaccines, such as those reported.
“Vaxart is developing an oral COVID-19 vaccine that will address many of the key challenges of injectable vaccines,” said Andrei Floroiu, CEO of Vaxart. “Cold room distribution and the need for medical personnel, in addition to having to travel to vaccination sites and dislike for needles, pose significant barriers to the absorption of the vaccine necessary for successful mass vaccination campaigns. We believe that our easy to administer, room temperature stable oral vaccine provides a unique solution that overcomes these significant challenges. We look forward to advancing our COVID-19 candidate vaccine to the clinic. ”
The organization highlighted four key findings from its preclinical studies:
- Immunization with the candidate vaccine induced an IgA response (indicative of a mucosal immune response) in the lungs of the animals, a high percentage of the total antibody response being neutralizing antibodies.
- While all candidates demonstrated the ability to elicit a strong immune response, the vaccine expressing the full-length S and N proteins was the most successful IgG response and induced in a dose-dependent manner.
- Antigen-specific CD4 + and CD8 + T cells were induced at both low and high doses of vaccine.
- Administration of the vaccine induced only low levels of IL-4 production, suggesting a small risk of vaccine-dependent disease improvement.
Dr. Sean Tucker, Vaxart Chief Scientific Officer, commented: “The data from these studies suggest that our candidate vaccine is capable of inducing immunogenicity at three levels: first, to induce potent neutralizing serum antibodies against viral protein S, second to induce a mucosal immune response and third to induce T cell responses.
“As we continue to learn more about COVID-19, there is a growing body of evidence that mucosal immunity may become a key factor in the development of an effective vaccine. Both mucosal IgA and mucosal T cells have been shown to help sterilize immunity in other respiratory diseases. Importantly, while systemic immunity is important in controlling the development of the disease, it has been suggested that mucosal immunity may be essential in blocking transmission, which will be crucial for an effective vaccination campaign. We believe this will be essential to reduce infection rates and ultimately eradicate COVID-19 globally. “
