The effectiveness of people’s immune system against SARS-CoV-2 may depend on antibodies produced from previous coronavirus infections responsible for common colds, a study has found.
This is not the first time that humans have battled a coronavirus; before COVID-19, mankind has faced six types of coronaviruses, at least.
The name coronavirus is given to these viruses because their surface is full of crown-like (corona) spike proteins.
The research team wanted to know how coronaviruses flare up our immune system and how human adaptive immunity works after being exposed to the virus for the first time.
Dr John Altin, the study’s senior author, said:
“Our results suggest that the COVID-19 virus may awaken an antibody response that existed in humans prior to our current pandemic, meaning that we might already have some degree of pre-existing immunity to this virus.”
This understanding can help scientists to develop efficient vaccines or monoclonal antibody treatments to protect humans from novel coronavirus mutations.
The research team used PepSeq, a tool to map antibody responses against any coronavirus infecting humans.
Dr Jason Ladner, the study’s first author, said:
“The data generated using PepSeq allowed for broad characterization of the antibody response in individuals recently infected with SARS-CoV-2 compared with those of individuals exposed only to previous coronaviruses that now are widespread in human populations.”
As well as SARS-CoV-2, the team studied the antibody responses to life threatening SARS-CoV-1, the first pandemic coronavirus responsible for the 2003 outbreak and Middle East Respiratory Syndrome (MERS) responsible for the 2012 outbreak.
All three viruses were initially found in animals but evolved to infect humans and make them sick.
The team also tested the antibody responses to four older coronaviruses causing mild infection: betacoronavirus OC43, betacoronavirus HKU1, alphacoronavirus 229E, and alphacoronavirus NL63, which are responsible for common colds.
They found that SARS-CoV-2 summons those antibodies produced in response to pervious coronavirus infections.
Dr Altin said:
“Our findings highlight sites at which the SARS-CoV-2 response appears to be shaped by previous coronavirus exposures, and which have potential to raise broadly-neutralizing antibodies.
We further demonstrate that these cross-reactive antibodies preferentially bind to endemic coronavirus peptides, suggesting that the response to SARS-CoV-2 at these regions may be constrained by previous coronavirus exposure.”
This might explain why COVID-19 patients react differently to the virus as some show no symptoms, some have mild symptoms, and some have severe infections causing hospitalization or death.
Dr Ladner said:
“Our findings raise the possibility that the nature of an individual’s antibody response to prior endemic coronavirus infection may impact the course of COVID-19 disease.”
The study was published in the journal Cell Reports Medicine (Ladner et al., 2020).