Cross-reactive antibody could form basis of broad coronavirus vaccine

In a new study, scientists from Scripps Research, US, have investigated how the immune system’s previous exposure to cold-causing coronaviruses can impact immune response to COVID-19. In doing so, they discovered one cross-reactive coronavirus antibody that is triggered during infection from SARS-CoV-2.

According to the team, the findings will help in the pursuit of a vaccine or antibody treatment that works against most or all coronaviruses. 

“By examining blood samples collected before the pandemic and comparing those with samples from people who had been sick with COVID-19, we were able to pinpoint antibody types that cross reacted with benign coronaviruses as well as SARS-CoV-2,” said senior author of the study, Dr Raiees Andrabi. 

Using electron microscopy, the team investigated how the cross-reactive antibody is able to neutralise a range of coronaviruses. They saw that it mostly binds to the base of the virus’s Spike (S) protein, an area that does not change much from strain to strain. 

In later tests, the researchers found that the antibody also neutralised SARS-CoV-1, the coronavirus that causes severe acute respiratory syndrome (SARS). 

“We were able to determine that this type of cross-reactive antibody is likely produced by a memory B cell that is initially exposed to a coronavirus that causes the common cold and is then recalled during a COVID-19 infection,” said Andrabi.

The team say that memory B cells are an essential part of the immune system as they “remember” initial disease threats and can circulate in the bloodstream for decades. These cells are responsible for producing targeted antibodies.

“Another deadly coronavirus will likely emerge again in the future and when it does, we want to be better prepared,” said Professor Dennis Burton, whose lab the research was conducted in. “Our identification of a cross-reactive antibody against SARS-CoV-2 and the more common coronaviruses is a promising development on the way to a broad-acting vaccine or therapy.”

Burton’s lab is also investigating broadly neutralising antibodies that can be harnessed to protect against many forms of influenza, another virus likely to cause a pandemic in the future.

The study is published in Nature Communications.