Tuesday, June 01, 2021

Antibody from common cold can neutralise COVID-19 and could lead to vaccine that protects against all coronaviruses, new study suggests

An antibody that develops after people have the common cold can neutralize the virus that causes COVID-19, a new study suggests.

Both the common cold and SARS-CoV-2 fall under a family known as coronaviruses, which cause upper-respiratory tract illnesses.

However, it was believed that antibodies that react to ordinary coronaviruses didn't work against the virus that leads to COVID. 

But in blood samples of COVID survivors, researchers found high levels of immune cells generated during the common cold that 'remember' diseases and are called back into action if the threat returns.

The team, from the Scripps Research Institute, in La Jolla, California, says the findings could help scientists develop a vaccine or antibody treatment that protects against all coronaviruses. 

The team found the antibody is produced by a type of immune system cell known as a memory B cell. Memory B cells lock onto the surface of invading pathogens and mark them for destruction by other immune cells. 

They also can circulate in the bloodstream for years - even decades - and the immune system can call up on them if there is another infection. 

For the study, published in the journal Nature Communications, the team looked at blood samples from participants pre-pandemic and during the pandemic. 

'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,' senior author Dr Raiees Andrabi, an investigator at Scripps' Department of Immunology and Microbiology, told News Medical.

Results showed that levels of memory B cell antibodies were higher in blood samples of people who had been infected with COVID-19 than those who never had been.

The team says this suggests that exposure to a non-serious coronavirus can spur the production of antibodies when infected with a more serious coronavirus.

Tests showed that the antibody also neutralized SARS-CoV-1, the coronavirus that causes Severe Acute Respiratory Syndrome (SARS) and a cousin of COVID-19.

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

Next, researchers examined how the antibody was able to neutralize several different types of coronaviruses. 

They found that the antibody binds to the base of the spike protein (S protein) on coronaviruses, which they use to enter and infect cells.

Co-author Dr Dennis Burton, Chair of Scripps' Department of Immunology and Microbiology, said the discovery is important for understanding how to protect against future coronaviruses.

'Another deadly coronavirus will likely emerge again in the future--and when it does, we want to be better prepared,' Burton told News Medical. 

'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.'


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