Another universal coronavirus vaccine is ready for human trials

As scientists desperately hunt for a rapidly mutating SARS-CoV-2 virus by attempting to update current COVID vaccines to better target circulating variants, a massive project simmers in the background. The goal is to develop a universal coronavirus vaccine designed to generate broad enough immunity to protect humans from all currently circulating strains of SARS-CoV-2, as well as any future variants that may yet arise. And there are several compelling candidates in the pipeline.

A new study published in the journal Science reports promising results from preclinical studies led by researchers at Caltech. The vaccine uses novel mosaic nanoparticle technology to protect not only against SARS-CoV-2, but also against the original SARS and several common cold coronaviruses.

The experimental vaccine focuses on a specific genus of coronaviruses called betacoronaviruses. These are the most clinically relevant types of coronaviruses for humans, including SARS, MERS, SARS-CoV-2 and two coronaviruses associated with the common cold – OC43 and HKU1.

Pamela Bjorkman, a Caltech researcher leading the project, said creating broad immunity against the entire betacoronvirus group should provide protection against new viruses that may emerge in the future. And considering that three dangerous viruses from the betacoronavirus family have emerged in the last 20 years, anticipating the possible next pandemic is crucial.

“We’re trying to make an all-in-one vaccine that protects against SARS-like betacoronaviruses, regardless of what animal viruses might evolve to allow infection and spread in humans,” Bjorkman said. “This type of vaccine would protect against current and future SARS-CoV-2 variants even without an update.”

The Caltech vaccine uses nanoparticle scaffolds to attach a number of different betacoronavirus fragments. The vaccine targets eight different betacoronaviruses: SARS-CoV-2 and seven other betacoronaviruses that currently only circulate in animals but all have the potential to mutate into a form that could infect humans in the future.

The vaccine does not focus on the traditional coronavirus spike protein, instead using viral fragments called receptor-binding domains (RBDs). These are parts of the virus that act as a kind of interface between the spike protein and the ACE2 receptors in human cells. RBDs are like the anchor that connects the virus to the human receptor.

And recent animal studies testing this novel vaccine, called Mosaic-8, have produced impressive results. In a series of studies in mice and primates, the researchers found that the vaccine successfully protected against most betacoronavirus strains.

Interestingly, the researchers tested the Mosaic-8 design against a nanoparticle loaded solely with a SARS-CoV-2 RBD. When mice were exposed to the original SARS virus, only the animals given the Mosaic-8 vaccine survived. This suggests that the combination of eight different antigens may generate broad cross-protective immunity against different types of betacoronavirus.

“Animals vaccinated with the Mosaic-8 nanoparticles elicited antibodies that recognized virtually every SARS-like betacoronavirus strain we examined,” noted study co-author Alexander Cohen. “Some of these viruses could be related to the strain causing the next SARS-like betacoronavirus outbreak. So what we really want would be something that targets this entire group of viruses. We think we have that.”

Thanks to a major funding injection from The Coalition for Epidemic Preparedness Innovations (CEPI), Mosaic-8 is on track to advance to Phase 1 human trials very soon. As it is 2022 and most of the world’s people have either already received a COVID-19 vaccine or have previously been infected with SARS-CoV-2, researchers are first conducting animal testing to try to administer the novel vaccine to previously exposed animals testing.

“In the twenty-first century there have already been three major coronavirus epidemics or pandemics – and COVID-19 continues to have a devastating impact on the world’s health, society and economy,” said Richard Hatchett, CEO of CEPI. “Creating vaccines that could provide comprehensive protection against emerging COVID-19 variants and future coronavirus threats would not only help mitigate the damaging effects of another COVID-19-like pandemic, but also help reduce the time and resources required to continually update vaccine formulations.”

Mosaic-8 is certainly not the only universal coronavirus vaccine currently in development. There are no fewer than 10 different research groups working with different strategies to produce a coronavirus vaccine that protects against current and future variants.

The US Army, for example, earlier this year reported successful preclinical results testing a unique ferritin nanoparticle with the ability to hold 24 different coronavirus antigens. This research has already entered the first phase of human trials and results are expected soon.

The new study was published in the journal Science.

Source: Caltech