COVID-19 spike proteins could evolve against immune responses

A new study suggests that COVID-19 spike proteins could evolve to disguise themselves from the human immune system – if they behave like seasonal human coronaviruses

Scientists believe that two species of seasonal human coronavirus related to SARS-CoV-2 can evolve in certain proteins to escape recognition by the immune system.

This means that if COVID-19 evolves in the same way as these seasonal human viruses, current vaccines against the virus may become outdated. This would require new ones to be made to match future strains – the horror story that politicians and healthcare professionals are attempting to avoid.

In the UK, a new consortium hopes to answer these questions. The G2P-UK consortium will be led by Professor Wendy Barclay, who is currently Head of the Department of Infectious Disease at Imperial College London. She describes the UK as fantastic in “sequencing viral genomes” and “identifying new variants”, which stands in stark contrast to the lack of Nationally available data on variants in the US.

How possible is it for COVID-19 to evolve a disguise?

“Some coronaviruses are known to reinfect humans but it is not clear to what extent this is due to our immune memory fading or antigenic drift,” says first author Kathryn Kistler, a PhD student at the Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, US.

“We wanted to investigate whether there is any evidence of coronaviruses related to SARS-CoV-2 evolving to evade our immune responses.”

Mutations made the virus faster, not stronger

Currently, there are three variants of COVID-19 that appear to be causing the virus to be more easily transmitted. One of those is the notorious B117 variant, which appears to have originated in Kent, UK.

The virus is doing its job the only way it can – understanding human defences, and trying to confuse those same defences. The question that scientists are now trying to answer, is how exactly will these changes impact the vaccine?

Professor Barclay, with a separate team, further commented: “We are already working to determine the effects of the recent virus variants identified in the UK and South Africa and what that means for the transmission of SARS-CoV-2 and vaccine effectiveness.”

The team studied something that was not COVID-19

The research team looked at the four seasonal human coronaviruses (HCoVs) which are related to SARS-CoV-2 but typically cause milder symptoms, such as the common cold. HCoVs have been circulating in the human population for 20-60 years, meaning their antigens would likely have faced pressure to evolve against our immune system.

The researchers found a high rate of evolution in the spike proteins of two of the four viruses, OC43 and 229E. Nearly all of the beneficial mutations appeared in a specific region of the spike proteins called S1, which helps the virus infect human cells.

This finding suggests that reinfection by these two viruses can occur as a result of antigenic drift as they evolve to escape recognition by the immune system.

‘It is not entirely clear’

“Due to the high complexity and diversity of HCoVs, it is not entirely clear if this means that other coronaviruses, such as SARS-CoV-2, will evolve in the same way,” explains senior author Trevor Bedford, Principal Investigator and Associate Member at the Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center.

“The current vaccines against COVID-19, while highly effective, may need to be reformulated to match new strains, making it vital to continually monitor the evolution of the virus’ antigens.”

Read the full study here.