Evaluation of Immunity in Hamsters Vaccinated with Oral COVID-19

Thu immunogenicity and immunoprotection of the Esperovax COVID-I9 circular RNA VLP vaccines administered orally as whole yeast or purified RNA-VLPs will be performed in a Syrian hamster model developed by and at UTMB-Galveston. The objective of these experiments is co demonstrate whether the yeast-derived COVID-19 vaccines elicit (i) -systemic and mucosal antibodies specific 10 the SARS-CoV-2 viral Spike protein and (ii) afford immunoprotection across three contemporary SARS-CoV-2

virus variants; the challenge viruses will include SARS-CoV-2 virus variant Bl,1,529. XB8L5, XBA,5 (Omicron), B.1.617.2 (Delta), and 81. 1.7 (Alpha). A successful outcome will be the demonstration that the yeast-derived COVID-19 vaccines afford 1mmun()protection against Omicron and Delta virus variants in 95% of the vaccinated and virus-challenged hamsters at least 2 months post-vaccination.

The hamster model for COVIS-19 ls qualified as the best surrogate for human disease pathogenesis and is permissive for SARS-CoV-2 virus infection Hamsters (N=6/Cohort) will receive orally vaccine dosages of whole yeast harboring the COVID-l9 circular RNA (2 different dosages) or a control licensed COVID-19 mRNA vaccine as a two-dose regimen spaced 21 days apart. Sera from vaccinated hamsters will be collected at 14-, 35- and 56-days post-vaccination and analyzed for IgG and lgA virus-specific antibodies by ELISA and microneutralization assays. Vaccinated and unvaccinated hamsters will be infected at 35 days post-vaccination with SARS-Cov-2 viruses (10⁵ pfu} and followed for changes in clinic31 signs (e.g., lethargy, ruffled fur, rapid breathing, and body weight), virJI burden, and cytokines in serum und lung secretions (i.e. trachea, nasal turbinate, and lung) over 2, 4, and 7 days before sacrificing. The success of these experiments will be the demonstration of high titers of virus-specific and neutralizing systemic  IgG, and mucosal lgA antibodies and protection of at least 90% of the vaccinated animals against the targeted SARS-CoV-2 challenge viruses.

Further studies may be conducted at UTMB to assess the duration of immunity, safety, and immunogenicity of the Esperovax circular RNA vaccines shown to afford Immunoprotection the SARS-CoV-2 Omicron virus variants.  Additionally, we may test the Esperovax circular RNA vaccines formulated with the adjuvant CpG (Cytosine-phosphate-guanine) in hamsters to determine whether enhanced and broader immunity is afforded.  Additional funds would be provided by Esperovax to UTMB/Galveston to

conduct these additional studies.