Clinical Trial Starts On Needle-free COVID Shot

A Single dose of a virus-based COVID-19 shot developed by Ottawa researchers has generated a strong, durable immune response in mice and monkeys.

The vaccine is based on a strain of the replicating virus used to inoculate people against smallpox in the 1950s and 60s.

TOH-Vac 1, made-in-Ottawa, offers a versatile and potentially important new tool in the global fight against COVID-19 and its variants, said Dr. John Bell, senior scientist at The Ottawa Hospital and a senior author of the study recently published in the journal Molecular Therapy.

‘TOH-Vac 1 vaccine may offer a versatile and potentially important new tool in the global fight against COVID-19 and its variants.’

Bell, whose work has previously focused on leveraging the power of viruses to fight cancer, said a virus-based COVID-19 vaccine offered potency, versatility, and safety.

"Viruses have been used to vaccinate people for many, many years, so they have a great safety record," Bell said.

"The other thing that's nice about them, particularly ones like this that are can replicate, is that they generate a much more potent immune response: A single dose will be able to give you long-lasting immunity."

The TOH-Vac1 vaccine employs a weakened strain of the Vaccinia virus, which was used in the global campaign to eradicate smallpox.

Dr. Stephen Boulton, a postdoctoral fellow, working at The Ottawa Hospital's Cancer Centre, is one of the researchers who helped conceive and develop TOH-Vac1. "When the pandemic hit, everyone wanted to help: This is why we get into science," he said.

Boulton and his colleagues compared the efficacy of two vaccines made from different Vaccinia virus strains. The replicating version proved more potent than the non-replicating one, he said, producing three to four times more antibodies and activating more T-cells.

Monkeys, given the virus, suffered no adverse effects other than minor swelling or lesions at the injection site. Protective antibody levels remained high six months later.

Bell said the weakened virus infects several host cells when the vaccine enters the body. "That whole process of hopping from cell to cell generates an inflammatory response, which gives you a great immune response," he explained.

The vaccine confers COVID-19 immunity by neutralizing the coronavirus' ability to infect the host cells it needs to survive and reproduce.

The initial work on the vaccine was funded by a grant from the Thistledown Foundation, a charity established by the founder of Shopify and his wife, Tobi Lutke and Fiona McKean, along with support from The Ottawa Hospital Foundation and the Canadian Institutes of Health Research.

The research team is now searching for a research grant of $1 million, so the vaccine can move into clinical trials with people.

Bell said TOH-Vac1 might prove to be particularly important in the drive to improve global levels of vaccination since it's inexpensive, easy to manufacture, and can be used against multiple variants.

As a vaccine platform, the virus offers scientists a "large coding capacity," Bell said, meaning it can be genetically engineered with different proteins from the coronavirus that causes COVID-19. With that information, he said, the immune system can produce more of the antibodies and T-cells it needs to fight a coronavirus infection - possibly even one from a new variant.

"You can target parts of the virus that are invariant, that just don't change," explained Bell, who is also a professor at the University of Ottawa.

The messenger RNA (mRNA) vaccines produced by Pfizer/BioNTech and Moderna target a single coronavirus protein, the spike protein.

The problem now is that the coronavirus has mutated, changing the spike protein that mRNA vaccines target. It means COVID-19's Omicron variant is less sensitive to the protective antibodies of vaccinated people.

The TOH-Vac1 vaccine can be stored at room temperature, unlike the mRNA vaccines, and requires only a single shot for a robust immune response.

It also confers smallpox immunity since it's built on the same viral platform as the smallpox vaccine.

Around the world, there are about 190 COVID-19 vaccine candidates still in development. Work continues apace because of the ongoing mutations of the coronavirus that causes COVID-19.

"We're very fortunate that we have good access to safe and effective vaccines in Canada," Bell said, "but this pandemic isn't over."

The Ottawa researchers have not patented their vaccine, so it can be manufactured anywhere in the world.



Source: Medindia