They reveal why some people do not develop COVID despite exposure

A scientific team has discovered new immune responses that help explain how some people, despite being in contact with the coronavirus, avoid contracting and developing the disease. COVID-19.

Using single-cell sequencing, researchers from the Wellcome Trust Sanger Institute, University College (UCL) and Imperial College London studied immune responses against SARS-CoV-2 infection in healthy adult volunteers.

Not all exposed participants developed a COVID-19 infectionallowing the team to discover unique immune responses associated with resistance to sustained viral infections and diseases.

The findings, published in Nature, provide the “most comprehensive timeline” to date of how the body responds to exposure to SARS-CoV-2 or any infectious disease, according to the authors.

Human Cell Atlas

The work is part of the international initiative ‘Human Cell Atlas’which is mapping all cell types in the human body to transform our understanding of health and disease.

The researchers set out to capture immune responses directly from exposure, the Wellcome Trust Sanger Institute reports in a statement.

To do this, 36 healthy adult volunteers with no history of COVID-19 were administered the SARS-CoV-2 virus through the nose. The researchers conducted a Detailed monitoring of blood and lining of the nosetracking the entire infection as well as immune cell activity prior to infection in 16 volunteers.

The teams then used single-cell sequencing to generate a data set of more than 600,000 individual cells.

Subtle innate immune responses

In all participants, the team discovered previously unreported responses involved in immediate detection of the virus. This included the activation of specialized mucosal immune cells in the blood and a reduction of inflammatory white blood cells that normally engulf and destroy pathogens.

Individuals who immediately cleared the virus did not show a typical generalized immune response, but instead developed subtle innate immune responses, never seen before.

The researchers suggest that high levels of activity of a gene called HLA-DQA2 before exposure also helped people prevent prolonged infection.

In contrast, the six individuals who developed a sustained SARS-CoV-2 infection They exhibited a rapid immune response in the blood, but a slower immune response in the nose, allowing the virus to establish itself there.

The researchers also identified common patterns among activated T cell receptors, which recognize and bind to virus-infected cells.

This offers insights into immune cell communication and the potential to develop T-cell targeted therapies not only against COVID-19, but also other diseases.

A much greater understanding

Rik Lindeboom, currently at the Netherlands Cancer Institute, says this was ‘an incredibly unique opportunity’ to see what immune responses are like. when they encounter a new pathogenin an environment where factors such as infection time and comorbidities could be controlled.

For UCL’s Marko Nikolić, there is now a much greater understanding of the full range of immune responses, which could provide a basis for developing potential treatments and vaccines that mimic these natural protective responses.

Sarah Teichmann, lead author of the study and co-founder of the Human Cell Atlas, adds that as this map is built, we will be able to better identify which cells are essential for fighting infections and understand why different people respond to the coronavirus in different ways.

(With information from EFE)