Having previously been in contact with infections caused by other coronaviruses may determine that some people respond better to the SARS-Cov-2 coronavirus infection. The only requirement is to have developed neutralizing antibodies before that virus of the past.
According to a study published in “Cell Reports Medicine”, the response of the immune system of people with covid-19 may depend on these antibodies created to previous coronaviruses.
SARS-Cov-2 is not the first coronavirus to which humanity has been exposed. Previously, at least 6 other types of coronavirus have ‘visited’ us. And, depending on the job, if there is memory in the immune system, in the form of antibodies, a better defense against covid-19 can be produced.
“Our results suggest that SARS-Cov-2 19 can trigger a ‘historical’ antibody response present in the body, which means that we could have some degree of pre-existing immunity to this pandemic virus,” explains John Altin, lead author of the study.
This This information is very valuable because it could be used to design new diagnoses, assess the healing powers of convalescent plasma, develop new treatments and, most importantly, to help shape future vaccines or monoclonal antibody therapies capable of protecting us against future mutations of the coronavirus.
The researchers used a sophisticated tool –PepSeq– to accurately map antibody responses to all coronaviruses that infect humans.
«The data generated with PepSeq allowed a thorough characterization of the antibody response in people recently infected with SARS-CoV-2 compared to others exposed only to previous coronaviruses spread among the population, ”writes Jason Ladner, lead author of the study.
In addition to SARS-CoV-2, the researchers examined the antibody responses of two other life-threatening coronaviruses: MERS-CoV, which caused the 2012 outbreak of Middle East respiratory syndrome in Saudi Arabia, and the SARS-CoV-1, the first pandemic coronavirus to cause the severe acute respiratory syndrome outbreak in Asia in 2003. All three are examples of coronaviruses that infect animals, but evolved to infect humans and became new human pathogens.
In addition to characterizing the antibodies that recognize SARS-CoV-2, they also examined the antibody responses of other four coronavirus más antiguos: alfacoronavirus 229E, alfacoronavirus NL63, betacoronavirus OC43, y betacoronavirus HKU1.
These so-called ‘common’ coronaviruses are endemic in the world’s population, but they are not fatal and cause mild upper respiratory infections, similar to those of the common cold.
By comparing the patterns of reactivity to all these different coronaviruses, the researchers demonstrated that SARS-CoV-2 could ‘invoke’ immune system antibodies generated in response to previous coronavirus infections.
And this cross-reactivity occurred in two areas of the SARS-CoV-2 spike protein, the protein on the surface of virus particles that binds to ACE2 proteins in human cells to facilitate cell entry and infection.
“Our results highlight locations where the response to SARS-CoV-2 appears to be determined by previous exposures to the coronavirus and which have the potential to generate broadly neutralizing antibodies,” Altin emphasizes.
The study also shows that these cross-reactive antibodies are «preferentially bind to endemic peptides of the coronavirus“Suggesting that the response to SARS-CoV-2 in these regions may be” limited by previous exposure to coronavirus, “he adds.
The findings could also help explain the variable responses of COVID-19 patients, from mild or asymptomatic to severe infections that require hospitalization and often lead to death.
It is also possible that the differences in the pre-existing antibody response identified by this study may help explain some of the differences in the severity of the manifestation of covid-19 disease in older and younger people, due to their history of infections with common coronaviruses.