Experimental new vaccine blocks COVID-19 and other coronavirus variants

May 11, 2021
COVID-19

A pan-coronavirus vaccine developed by members of the Duke Human Vaccine Institute (DHVI), from the Duke University School of Nursing, NC, has proven effective in protecting monkeys and mice from a variety of coronavirus infections such as SARS-CoV-2, the original SARS-CoV-1 and related bat coronaviruses. Its success in primates is highly relevant to humans and could potentially “prevent, rapidly temper, or extinguish a pandemic.”

The new vaccine triggers the release of neutralising antibodies via a coronavirus-based nanoparticle and a small molecule adjuvant that boosts the body’s immune response.

“We began this work last spring with the understanding that, like all viruses, mutations would occur in the SARS-CoV-2 virus, which causes COVID-19,” said Dr. Barton F. Haynes, director of DHVI. “The mRNA vaccines were already under development, so we were looking for ways to sustain their efficacy once those variants appeared.

“This approach not only provided protection against SARS-CoV-2, but the antibodies induced by the vaccine also neutralised variants of concern that originated in the United Kingdom, South Africa and Brazil – the antibodies reacted with quite a large panel of coronaviruses.”

The Achilles heel for the coronaviruses is their receptor-binding domain, located on the spike that links the viruses to receptors in human cells. This binding site enables it to enter the body and cause infection; it can also be targeted by antibodies.

Haynes and colleagues managed to identify one particular receptor-binding domain site that is present on SARS-CoV-2, its circulating variants and SARS-related bat viruses that makes them highly vulnerable to cross-neutralising antibodies and then designed a nanoparticle displaying this vulnerable spot.

In tests on monkeys, the experimental pan-coronavirus vaccine blocked COVID-19 infection by 100%, eliciting significantly higher neutralising levels in the animals than current vaccine platforms or natural infection in humans.

“Basically what we’ve done is take multiple copies of a small part of the coronavirus to make the body’s immune system respond to it in a heightened way,” said Kevin Saunders, director of research at DHVI. “We found that not only did that increase the body’s ability to inhibit the virus from causing infection, but it also targets this cross-reactive site of vulnerability on the spike protein more frequently. We think that’s why this vaccine is effective against SARS-CoV-1, SARS-CoV-2 and at least four of its common variants, plus additional animal coronaviruses.”

Category: Features, Pharmaceuticals

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