Nature papers read in detail! In some healthy people, SARS-CoV-2 reactive T cells exist.

!--:page title"----- In a new study, researchers from the SchallitSchool School of Medicine in Berlin, Germany, and the Max Planck Institute for Molecular Genetics found that some healthy people have immune cells that recognize the new coronavirus SARS-CoV-2.
may be affected by previous infections that trigger the "common cold" coronavirus (the common cold coronavirus).
whether this cross-reaction is protective of the clinical process estabic process escant in SARS-CoV-2 infections, it will be answered by the Charit? Corona Cross Study at the Scharet School of Medicine in Berlin.
related findings published online July 29, 2020 in the journal Nature, with the title "SARS-CoV-2-reactive T cells in healthy donors and patients with COVID-19".
color-scanned electron microscopy of MERS-CoV virus particles attached to the surface of infected cells, pictured from NIAID-Frederick.
Why do some people develop severe symptoms after contracting SARS-CoV-2, while others are barely aware of the infection? The answer to this question is multi-layered and is a subject worthy of in-depth study.
in the new study, the authors now identify a potential key factor: previous exposure to harmless common cold coronavirus.
this insight is based on research involving auxiliary T cells (T-helper cell, Th), a specific type of white blood cell that is essential to regulate our immune response.
the authors found that one-third of people who had not previously been exposed to SARS-CoV-2 still had Th cells that could recognize the virus.
may be due to the structural similarities between SARS-CoV-2 and the common cold coronavirus.
in the study, the authors isolated immune cells from the blood of 18 patients who were treated at the Schallitt School of Medicine in Berlin and tested positive for PCR for SARS-CoV-2.
they also isolated immune cells from the blood of 68 healthy people who had never been exposed to the new coronavirus.
they then stimulate these immune cells with small synthetic fragments of SARS-CoV-2 "sting proteins", in which the stingproteinis is a characteristic coronal protrusion on the outer surface of the coronavirus and allows the virus to enter human cells.
they then tested whether th cells were activated by exposure to these protein fragments.
they found that 15 out of 18 COVID-19 patients (85%) were in the same situation. "That's exactly what we're looking for," explained Dr. Claudia Gieske-Thiel, co-author of the
paper and head of the flow cytometer facility at the Max Planck Institute for Molecular Genetics.
these patients' immune systems are in the process of fighting the new coronavirus, so the same reaction is shown in vitro.
," she added, "not all PATIENTs with COVID-19 exhibit this th cell response to viral fragments, most likely because T cells cannot be activated outside the body during the acute or particularly severe stage of the disease."
" However, the authors were surprised to find memory Thcells in the blood of healthy people that could identify fragments of SARS-CoV-2 stingproteins.
in 68 healthy people tested, the cells were found in 24 (35%) of them.
in fact, they noted that immune cells in patients with COVID-19 respond edited to these viral envelope fragments differently from those in healthy humans.
Although patient Th cells are able to identify full-length sting proteins, the Th cells isolated from healthy people are mainly activated by similar SARS-CoV-2 sting protein fragments associated with the corresponding fragments of the harmless common cold coronavirus. "This suggests that healthy people's Th cells respond to SARS-CoV-2 because they have been exposed to the popular common cold coronavirus before," said Dr. Giesecke-Thiel,
.
," she continued, "one of the characteristics of Th cells is that they are activated not only by 'perfectly consistent' pathogens, but also by 'sufficiently similar' pathogens."
", they were able to find that Th cells isolated from healthy participants who responded to SARS-CoV-2 were also activated by various common cold coronaviruses, which showed so-called "cross-reactivity."
the new study does not mention how this cross-reaction may affect healthy people who have previously contracted SARS-CoV-2. "In general, cross-reactive Th cells have the potential to have protective effects, for example by helping the immune system accelerate the production of antibodies against this new coronavirus," said Professor Leif Erik Sander of the Department of Infectious Diseases and Respiratory Medicine at the Scharet School of Medicine in Berlin,
.
in this case, a recent common cold may cause less severe COVID-19 symptoms.
however, this cross-reactive immunity can also lead to incorrect immune responses and potentially negative effects on the clinical process of COVID-19.
for example, we know this could happen to dengue fever.
"a prospective study is needed to determine whether previous infections of the common cold coronavirus will protect against subsequent SARS-CoV-2 infections and whether this may address higher differences in clinical performance."
a prospective study led by the Schallitt School of Medicine in Berlin and conducted in collaboration with the Technical University of Berlin and the Max Planck Institute for Molecular Genetics has just begun.
the "Cross-Study of Coronavirusins at the Scharet Medical School in Berlin", funded by the German Federal Ministry of Health and the German Federal Institute for Medicines and Medical Devices, will explore the effects of cross-reactive Th cells on the course of COVID-19 disease. In Germany, coronaviruses cause up to 30 percent of seasonal cold cases, said Andreas Thiel, co-author of the
paper and a researcher at the Schallitt School of Medicine in Berlin. "Current estimates suggest that, in general, adults are infected with one of four endemic coronaviruses about every two to three years, " explains Professor Thiel
.
If we assume that these common cold coronaviruses can give a certain level of immunity against SARS-CoV-2, then this means that people who have been exposed to such infections regularly in the past, as well as people who have tested positive for cross-reactive Th cells, should be better protected.
, therefore, this population will be a particular focus of the 'Berlin Charit School of Medicine's cross-study of coronaviruses'.
" the authors will also follow people at risk for COVID-19 for months.
finally, the study was designed to help predict the clinical progressofcin of COVID-19, including people who have previously been infected with SARS-CoV-2 and who have not been infected. "This is crucial, both for people's daily lives and for patients, " explains Professor
thiel.
"!--/ewebeditor:!--:page" - the study includes a comprehensive immunology survey of child day care workers, paediatric practitioners and nursing home residents, which will continue into next year.
, for swabs collected from participants, PCR-based tests will be used to detect SARS-CoV-2.
further tests will include testing of antibodies and T-cell reactions to the virus.
if the study participants were subsequently infected with SARS-CoV-2, the authors would be able to establish a link between the course of the disease and the immunological parameters of the patient.
the authors also plan to collect blood samples from at least 1,000 recovered COVID-19 patients.
the authors will then test these samples for a series of immunological factors to study their correlation with symptoms.
they hope to be able to identify other potential parameters that affect the severity of COVID-19 and the clinical process.
they are currently looking for someone who has been diagnosed with THE COVID-19 case and subsequently recovered.
they also want to know about people who have developed infections at some point in the past few years that have been later confirmed to be caused by common cold coronaviruses such as 229E, OC43, NL63 or HKU1.
(bioon.com) References: 1. Julian Braun et al. SARS-CoV-2-reactive T cells in healthy donors and patients with COVID-19. Nature, 2020, doi: 10.1038/s41586-020-2598-9.2.Can exposure to common cold viruses affect the severity of SARS-CoV-2 symptoms?