Secret behind pre-existing immunity in individuals unexposed to COVID-19

Kolkata: In a study published in the Nature journal, Scientific Reports recently, an international team of researchers from MedGenome, India & USA suggest robust pre-existing T-cell immunity against the SARS-CoV-2 virus in individuals unexposed to COVID-19.

The presence of high-quality cross-reactive TCRs against common CMV and flu antigens can protect individuals by mounting an early CD8 T-cell response and clearing the virus. This finding is in contrast with the multiple published studies where pre-existing T-cell immunity has been suggested to arise from shared epitopes between SARS-CoV-2 and other common cold-causing coronaviruses.

Additionally, the findings also raise a possibility that many individuals carrying antigen-experienced T-cells against other viruses may be naturally protected against COVID-19 without prior SARS-CoV-2 infection.

The study identified immunodominant CD8 T-cell epitopes from the SARS-CoV-2 spike antigen using a novel TCR-binding proprietary algorithm OncoPeptVAC.

“The strong immunological basis of our findings may help vaccine designs for emerging respiratory viruses which need consideration and rational inclusion of CD8 epitopes to confer long-term resistance. Identifying additional immunodominant epitopes in SARS-CoV-2 and their cognate TCRs can become a powerful immune monitoring tool for assessing protective immunity against SARS-CoV-2 in the global population,” said Dr Amitabh Chaudhuri, Vice President, R&D, MedGenome and a lead study author.

The COVID-19 pandemic has revealed a range of disease phenotypes in infected patients with asymptomatic, mild, or severe clinical outcomes, but the mechanisms that determine such variable outcomes remain unresolved. Uncovering the immunological responses to COVID-19 infection will help in designing and developing next-generation therapies and manage the treatment of critical COVID-19 patients.

“Vaccinating the population being one of the major weapons in fighting the pandemic, and our primary focus is building immunity against the virus, identifying robust pre-existing immunity against SARS-CoV-2 in the healthy population will be a useful measure to assess the mode of recovery and viral spread in the global population. These findings will help in the development of efficacious targeted vaccines with long-term therapeutic benefits.”, said Sam Santhosh, Founder & Chairman, MedGenome. (UNI)