‘Pan-coronavirus’ vaccine shows early promise in monkeys and mice, research finds

A universal vaccine that could offer protection against Covid variants, along with a variety of other coronavirus infections, including Sars and Mers, has been found to be effective in monkeys and mice, scientists say.

Across the globe, research is underway to develop a “pan-coronavirus” vaccine which will retain its efficacy in the face of new and emerging variants, and also provide some level of immunity against the distant viral cousins of Sars-CoV-2.

Scientists, including Oxford’s Professor Sarah Gilbert, have been attempting to design a universal flu vaccine for years – but attention is now turning to the coronaviruses, which are similarly capable of mutating and escaping parts of the body’s immunological response.

One team at the Duke Human Vaccine Institute (DHVI), in the US, has reported encouraging early results after testing its vaccine candidate on macaques and mice.

The research showed the vaccine generated antibodies that not only provided protection against Sars-CoV-2 but also neutralised the variants of concern that were first detected in the UK, South Africa and Brazil.

Alongside this, the scientists said, the induced antibodies were also partly capable of neutralising the coronaviruses that caused the severe acute respiratory syndrome (Sars) and Middle East respiratory syndrome (Mers) outbreaks.

The vaccine uses a nanoparticle that features multiple copies of a receptor-binding domain (RBD) site that is present in the spike protein of Sars-CoV-2, its circulating variants and other bat-related animal coronaviruses. 

The RBD is a key part of the virus that allows it to dock and gain entry to human and primate cells.

In targeting a RBD site that is common to all the viruses, the vaccine ensures that cross-neutralising antibodies are generated when it’s presented to the host’s immune system. A chemical booster called an adjuvant is also used to enhance the response to the vaccine.

The research, published in the journal Nature, was led by Professor Barton Haynes, director of the Duke DHVI.

“We began this work last spring with the understanding that, like all viruses, mutations would occur in the Sars-CoV-2 virus,” Prof Haynes said.

“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. And the induced antibodies reacted with quite a large panel of coronaviruses.”

Prof Haynes and colleagues built on earlier studies involving Sars, the respiratory illness caused by Sars-CoV-1. They found a person who had been infected with Sars developed antibodies capable of neutralising multiple coronaviruses.

According to the DHVI research, the nanoparticle vaccine blocked Covid-19 infection by 100 per cent in the five inoculated macaques. The new vaccine also elicited 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,” Prof 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.”

Three coronavirus epidemics have now occurred in the past 20 years, highlighting the need to develop an effective universal vaccine that will better protect humanity against the next significant outbreak.

Earlier this year, Dr Anthony Fauci, chief Covid-19 adviser to the White House, told the American Association for the Advancement of Science: “It’s clearly the time to start now to develop a universal coronavirus vaccine.”

In the UK, scientists from the University of Nottingham and a company called Scancell are working to develop a mRNA-based jab specific to all Covid variants.

Their vaccine targets the conserved core of Sars-CoV-2, called the nucleocapsid, as well as the spike protein, which is the main site of the mutations that have been detected to date.

Dr Gillies O’Bryan-Tear, Scancell chief medical officer, told The Independent: “What’s been mutating in the pandemic has been the spike protein, which alters the transmissibility of the virus and can alter its ability to resist either the immunity acquired by natural infection or vaccination.

“The difference between our technology and most others is that as well as targeting the spike protein, we have another specificity in our vaccine which targets the nucleocapsid protein. This is the body of the virus.

“We don’t think it mutates as much as the spike does, so there’s a chance it could work across different variants irrespective of the spike protein mutations.”

Human trials of the vaccine will begin in the second half of this year after testing on mice returned positive results.