Intranasal Subunit Vaccine Shows Promising Protection Against COVID-19: Study
In a recent study published in Scientific Reports, researchers working at Ohio State University in the United States of America (USA) have developed a promising intranasal subunit vaccine for COVID-19. The vaccine, named NARUVAX-C19/Nano, is based on the receptor-binding domain (RBD) of the spike protein of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It is entrapped in mannose-conjugated chitosan nanoparticles (NP) and includes a toll-like receptor 9 (TLR-9) agonist, CpG55.2, as an adjuvant to enhance cellular immune responses.
The study aimed to assess the immunogenicity, efficacy, and ability of the NARUVAX-C19/Nano vaccine to prevent transmission from vaccinated to naive animals. Researchers used the standard ionic gelation method to prepare the vaccine formulation using mannose-conjugated chitosan nanoparticles. They administered the vaccine intranasally to mice and observed its effects on serum and lung antibodies, as well as cellular immune responses. Additionally, they tested the vaccine on hamsters to evaluate its protective efficacy against SARS-CoV-2 infection.
Results showed that a single or double dose of the intranasal NP-vaccine induced detectable levels of receptor-binding domain-specific secretory immunoglobulin A (sIgA) in the serum and lungs of mice. On the other hand, the vaccine did not induce the production of specific antibodies in serum. However, it did trigger type 1 T helper (Th1) cells that secreted interferon-gamma (IFN-γ), interleukin-2 (IL-2), and tumor necrosis factor-alpha (TNF-α) in response to receptor-binding domain stimulation. In hamsters, the NP-vaccine provided adequate protection against SARS-CoV-2 infection by reducing viral load in the upper and lower respiratory tract and lung damage.
The researchers acknowledge that more studies are needed to further optimize the NP-vaccine’s formulation and increase its immunogenicity and protective efficacy. They suggest investigating the efficacy of the NARUVAX-C19/Nano vaccine against the Omicron variant, as current intramuscular-delivered vaccines may offer suboptimal protection against this highly transmissible variant.
Overall, the study shows promising results for an intranasal subunit vaccine against COVID-19. Though this particular vaccine did not induce serum-neutralizing antibodies, it demonstrated protective efficacy through the elicitation of cellular immune responses. Further research and development in this area may lead to new vaccine approaches that can enhance mucosal immunity and provide improved protection against COVID-19.
Disclaimer: This article is meant for informational purposes only and is not intended to endorse or promote any specific vaccine. Please consult with a healthcare professional for personalized medical advice.
