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Covid-19 Nasal Vaccine Produces Antibodies, Cuts Viral Load

Nasal spray

(Wikimedia Commons)

3 Mar. 2022. Tests with lab animals show a vaccine given as a nasal spray produces high antibody volumes against SARS-CoV-2 infections and reduces viral loads. Results of tests by biotechnology companies Oragenics Inc. in Tampa, Florida and Inspirevax in Laval, Quebec with National Research Council of Canada, appear yesterday on the bioRxiv pre-publication server, and are not yet peer-reviewed.

Oragenics creates vaccines and treatments for infectious diseases, focusing recently on the Covid-19 pandemic, but also multi-drug resistant microorganisms. For Covid-19, the company is developing a next-generation vaccine called Terra CoV-2 with a synthetic protein technology licensed from National Institutes of Health and National Research Council of Canada. Oragenics says its platform enables design of new vaccines targeting the SARS-CoV-2 spike protein in six to eight weeks, making it possible to respond quickly to future variants.

The company enhances Terra CoV-2 with an adjuvant for stimulating more immune response in mucosal surfaces in the nose and lungs. That adjuvant, developed by Inspirevax — known until recently as Biodextris — is also licensed to Oragenics. The company envisions Terra CoV-2 as an easy-to-use booster vaccine to protect against Covid-19 after initial immunity wanes from today’s injected vaccines.

“Intranasally delivered SARS-CoV-2 vaccines,” says Oragenics executive chairman Frederick Telling in a company statement, “could provide increased protection in the nose and throat where viral entry occurs. This could lead to lower transmission of the virus compared to the currently available intramuscularly delivered vaccines as well as offering a needle-free delivery option.”

Higher antibody concentrations in vaccine recipients

A team from Oragenics, Inspirevax, and National Research Council tested immune responses of its Covid-19 nasal spray vaccine and protection against illness in lab mice and hamsters. Researchers gave two doses of vaccine or a placebo to mice, 21 days apart, with blood samples taken on days 21 and 35 after the first dose, as well as nasal swabs on day 35.

Blood samples show higher concentrations of immunoglobulin G and A antibodies in active vaccine than placebo recipients, which neutralize both the ancestral SARS-CoV-2 strain and beta variant, which prevents binding to receptor proteins in host cells. Nasal swab tests likewise show higher immunoglobulin A antibodies in mucous tissue among active vaccine recipients, compared to placebo.

The team then conducted a challenge test of the vaccine with hamsters that have a high susceptibility to Covid-19 infections. Animals received two doses of the nasal spray vaccine at either high or low levels, or a placebo, 21 days apart, with blood tests taken after 35 days. As with mice, hamsters receiving the active vaccine produce more neutralizing immunoglobulin G antibodies than placebo recipients after 35 days. Seven days later, the animals were exposed to SARS-CoV-2 viruses in ancestral, beta, and delta variant forms.

After five days, placebo recipient hamsters lose about 10 percent of their body weights, indicating development of illness, while vaccinated hamsters at both high and low dosage levels, experience no weight loss. Post-mortem analysis of the hamsters show no evidence of virus in nose or lung tissue retrieved from high- and low-dose vaccine recipients, while placebo recipients have high virus levels in nose and lung tissue. The authors do not report any indicators of adverse effects from the vaccine experienced by either mice or hamsters.

The authors believe the findings support continued development of the nasal spray vaccine. Oragenics says the results will be part of the company’s investigational new drug application with FDA, in effect a request to begin clinical trials.

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