The vaccine protects against members of the COVID family of viruses

Long before COVID-19 changed everyday life, scientists were aware of the possibility that the coronavirus could make the jump from an animal species to a human population.

How different the last few years would be if a vaccine capable of blocking the SARS-CoV-2 virus were administered to workers at the Huanan Market in Wuhan, China. where, according to scientistsraccoon dog infected the seller and caused a pandemic that more than 6.3 million people died around the world.

A new type of vaccine developed at Caltech aims to protect against new coronaviruses before health officials even know they exist. When tested in mice and monkeys, the animals’ immune systems learned to recognize eight viruses at once and induced immunity to viruses they had never encountered.

resultspublished Tuesday in the journal Science could lead to a powerful tool against a virus that mutates too fast to be detected. found in modern vaccines. The International Vaccine Fund has pledged $30 million to begin human clinical trials of an experimental vaccine.

“Over the past 20 years, we have had three pandemics or epidemics: first SARS, then MERS, then SARS-CoV-2,” the Caltech biochemist said. Pamela Bjorkmanwho led the new work. New outbreaks caused by “secondary events” are inevitable, she said, and “we want to protect now from future side effects.”

Dr. Anthony FauciPresident Biden’s chief adviser on the COVID-19 pandemic, called the study “an important conceptual step towards a coronavirus vaccine.”

“This is a very, very important proof of concept,” he said, noting that it remains to be seen if it works as well in humans as it does in lab animals. “That’s why you’re doing the experiment.”

The new vaccine does not block all coronaviruses, and the ambitious goal is not yet achievable by science. Instead, he focuses on a group known as betacoronaviruses, which includes those that cause COVID-19, severe acute respiratory syndrome, and Middle East respiratory syndrome, among other diseases.

Instead of using a piece of an inactivated virus or a lab-created molecule that mimics a naturally occurring molecule, Caltech researchers created a microscopic piece of matter that they could decorate as they saw fit. Their nanoparticles are made up of proteins with sticky bits on the surface, to which researchers can attach even tiny virus particles.

The team tested three versions of the nanoparticle. One was covered in pieces of SARS-CoV-2. The “mosaic” version contained SARS-CoV-2 plus samples of seven other coronaviruses, including the one that causes MERS and other strains found in bats and pangolins. The latter was naked to serve as a control.

When looking for fragments of viruses that can be cut and attached, the team focused on a region of the spike protein called the receptor-binding domain, or RBD. This is the part that the immune system normally targets. neutralizing antibodieswhether they were created in response to a vaccine or a previous infection.

Given that the RBDs of the betacoronaviruses share many characteristics, the researchers hoped that the mosaic version would encourage the immune system to focus on parts common to all eight viruses. They also suggested that if these parts were common to most or all betacoronaviruses, the vaccine would elicit an immune response when exposed to any member of the viral group, even those not present in the samples.

They were right.

By creating their mosaic nanoparticle, they deliberately excluded SARS-CoV, the virus that causes severe acute respiratory syndrome. If the vaccine had worked properly, animals vaccinated with mosaic nanoparticles and then exposed to SARS-CoV would have developed an immune response.

They did. In fact, the vaccinated mice and monkeys had virtually no detectable virus, despite attempts to infect them with either SARS-CoV or SARS-CoV-2.

“We are very excited about this,” Bjorkman said.

This did not happen with animals that were injected with naked nanoparticles – they could not fight any virus and died. Animals vaccinated with only pieces of SARS-CoV-2 were protected against this virus, but had no protection against any other coronavirus, and most also died.

If the mosaic vaccine works as well in humans as it does in animals, it could provide protection against the betacoronaviruses we know about and related ones that haven’t yet made it to humans.

This prospect is promising, but far from certain.

The next step is a Phase 1 human clinical trial, the first hurdle to overcome when bringing a new drug or vaccine to market in the US. at least a year.

Coalition for Epidemic Preparedness Innovation said on Tuesday it would pay the bill for an initial trial to establish evidence that the vaccine is safe for humans.

“Of course it’s reassuring,” he said. Dr. Paul Offit, virologist and immunologist at the University of Pennsylvania. “But this is animal research, and as is well known among scientists, mice lie and monkeys exaggerate.”

“It’s hard to do universal vaccines work,” Offit added. “It’s not for lack of money. It is not due to lack of desire or effort. It’s just very hard to do.”

This is not the only team in the US studying nanoparticle vaccines against coronaviruses. Researchers in Duke University and Walter Reed Army Research Institute research them too.

“These general approaches all use the receptor binding domain to elicit a strong antibody response that can neutralize the virus, so they all hold some promise,” he said. Dr. Stanley Perlmanvirologist and immunologist at the University of Iowa specializing in betacoronaviruses.

“This is a good approach based on what we know,” he said, “and it is to be hoped that it will be useful for viruses that we have not yet identified.”