Some Uninfected People Have T-Cell Immunity To COVID-19



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Date: July 20, 2020

Researchers were surprised to find memory T-cells in people with no history of SARS, COVID-19, or contact with SARS or COVID-19 patients.

AsianScientist (Jul. 20, 2020) – A Singapore study published in Nature has uncovered the presence of T-cell immunity in people who recovered from SARS 17 years ago, as well as in healthy individuals who had never been infected by either virus.

Memory T-cells induced by viral infections are an integral part of the human immune response, due to their ability to directly target and kill infected cells. These T-cells shape the susceptibility to, and clinical severity of, subsequent infections, and are a useful starting point for the development of vaccines against COVID-19.

A research team led by Professor Antonio Bertoletti from Duke-NUS Medical School, in collaboration with colleagues at the National University of Singapore’s Yong Loo Lin School of Medicine, Agency for Science, Technology and Research, Singapore General Hospital and National Centre for Infectious Diseases, set out to investigate which groups of people had T-cell immunity against SARS-CoV-2.

They tested 36 patients who recovered from COVID-19 and found the presence of SARS-CoV-2-specific T-cells in all of them, which suggests that T-cells play an important role in this infection.

Importantly, the team showed that 23 patients who recovered from the 2003 outbreak of severe acute respiratory syndrome (SARS) 17 years ago still possess long-lasting memory T-cells and displayed robust cross-reactivity to SARS-CoV-2.

What was surprising was the discovery of SARS-CoV-2-specific T-cells in 37 individuals with no history of SARS, COVID-19, or contact with SARS or COVID-19 patients. The virus-specific T-cells in uninfected people exhibited a different pattern of immunodominance, frequently targeting the NSP7 and 13 proteins as well as the nucleocapsid protein.

“Our team also tested uninfected healthy individuals and found SARS-CoV-2-specific T-cells in more than 50 percent of them. This could be due to cross-reactive immunity obtained from exposure to other coronaviruses, such as those causing the common cold, or presently unknown animal coronaviruses,” said Bertoletti.

Scheduled next is a larger study of exposed, uninfected subjects to examine whether T-cells can protect against COVID-19 infection or alter the course of infection. The researchers will also explore the potential therapeutic use of SARS-CoV-2-specific T-cells in vaccine development.

“We have also initiated follow-up studies on the COVID-19 recovered patients, to determine if their immunity as shown in their T-cells persists over an extended period of time. This is very important for vaccine development and to answer the question about reinfection,” said Associate Professor Tan Yee Joo, a senior author on the study.

The article can be found at: Bert et al. (2020) SARS-CoV-2-specific T cell Immunity in Cases of COVID-19 and SARS, and Uninfected Controls.

Credit: Asian Scientist