Scientists and physicians continue to learn more about COVID-19, and a new study found something remarkable: more than one-third of people who have never contracted the virus have immune cells capable of recognizing SARS-CoV-2.
“Scientists suggest that these cells could be the result of prior infection with other ‘common cold’ viruses,” StudyFinds.com reported on Tuesday.
The study, led by scientists at Charité – Universitätsmedizin Berlin and the Max Planck Institute for Molecular Genetics, looked “at the presence of an immune cell called a T-helper cell in the blood of 18 coronavirus patients and 68 healthy individuals with no exposure to the virus. T-helper cells are critical for the development and maintenance of protective antibody responses in humans. Scientists believe these cells may play an important role in the immune response to SARS-CoV-2.”
After isolating immune cells from the blood of each patient, the authors stimulated these cells in petri dishes with small, synthetic fragments of the SARS-CoV-2 “spike protein.” This is the viral component that forms characteristic, crown-like protrusions on its surface.
Specifically, the researchers designed two pools of these protein fragments, or peptides, each spanning a different section of the spike protein. One peptide pool designated “S-I” contained fragments from the part of the protein involved in viral entry into human cells. Researchers note that this section of the protein represents a major target of human antibodies that are able to block SARS-CoV-2. The other peptide pool, dubbed “S-II,” contains fragments derived from the part of the spike protein that is similar to spike proteins from common cold human coronaviruses.
The study showed that those T-helper cells from COVID-19 patients react strongly to both peptide pools, with 67% of patients reacting to S-I, and 85% reacting to S-II.
“This was exactly what we had expected. The immune system in these patients was in the process of fighting this novel virus, and therefore showed the same reaction in vitro,” explains one of the study’s three lead authors, Claudia Giesecke-Thiel, in a statement. “The fact that not all patients with COVID-19 showed this T-helper cell response to viral fragments is probably due to fact that T cells cannot be activated outside the human body during an acute or particularly severe phase of an illness.”
The study was published in Nature.
