Nearly everyone has been exposed to the highly prevalent seasonal coronaviruses responsible for the common cold. But could this exposure induce antibodies that also recognize certain proteins of the SARS-CoV-2 virus? A CITF-funded study led by University of Ottawa researcher Dr. Marc-André Langlois, questioned if these antibodies could influence COVID-19 disease severity. In this pre-print, not yet peer reviewed, the team proposes that some individuals previously infected with certain seasonal coronaviruses may have pre-existing protective immune responses against SARS-CoV-2, which could lessen the severity of COVID-19 symptoms.

Key points:

  • Researchers used samples collected prior to 2019, ensuring no exposure to SARS-CoV-2. The majority of these samples were positive for IgG antibodies against proteins from seasonal coronaviruses OC43, NL63, and 229E (83%, 75%, and 82% respectively).
  • While less than 5% of these samples also reacted against the SARS-CoV-2 spike protein, close to 11% reacted to the SARS-CoV-2 nucleocapsid protein. This can be explained by antibody ‘cross-reactivity’ as these individuals were not exposed to the SARS-CoV-2 virus at the time of sample collection. Antibody cross-reactivity is due to antibodies recognizing areas that are similar between proteins from different coronaviruses.

The authors concluded that of the many different seasonal coronaviruses, previous exposure to NL63 seems to be associated with a greater ability to neutralize the interaction between the SARS-CoV-2 spike and its receptor, ACE2. Aside from antibodies, other variables (cell mediated immunity from prior exposures) yet to be identified may also be involved protection against SARS-CoV2.

 

Galipeau Y, Siragam V, Laroche G, Marion E, Greig M, McGuinty M, Booth RA, Durocher Y, Cuperlovic-Culf M, Bennett SAL, Crawley AM, Giguère P, Cooper C, Langlois M-A. Relative Ratios of Human Seasonal Coronavirus Antibodies Predict the Efficiency of Cross-Neutralization of SARS-CoV-2 Spike Binding to ACE2. MedRxiv 2021.07.16.21260079; doi: https://doi.org/10.1101/2021.07.16.21260079