Scientists are Looking for people with "Natural Immunity" of COVID-19

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Scientists are Looking for people with “Natural Immunity” of COVID-19.

Why do some people who have not been vaccinated, have no history of infection, stay in a high-risk environment every day, but are not infected with the COVID-19?

“Nature” magazine recently published a study saying that this “innate protection” may originate from a previous infection with the common cold virus, which causes the immune system to produce memory T cells, thereby generating a cross-immune response to the COVID-19.

In other words, these lucky people who are close to the COVID-19 but are not infected may already have defensive capabilities before the pandemic.

“I have never seen anything like this.” Shane Crotty, an immunologist at the La Jolla Institute of Immunology in California, USA, reviewed the previous study and said that this type of specific T cells can quickly recognize and eliminate the COVID-19, so that “natural immunity” “A person’s nucleic acid test will not be positive, and antibodies against the COVID-19 will not be produced in the body.

However, the research team in the article “Nature” emphasized that not all people who have suffered from the common cold have a golden bell shield. “We propose the possibility of T cell immunity, or propose a new direction for vaccine development. But it is too early to assert that people can prevent infection.”

1/10 of the “lucky ones”

In the article “Nature”, University College London and St. Bartholomew’s Hospital formed a team with 58 subjects as the research group.

These subjects are all medical staff, come from many hospitals in London, England, and have all experienced the first wave of epidemics in the UK in April 2020.

At that time, the daily average number of new diagnoses in the UK was about 5,000, and people living in nursing homes and hospitalized patients were severely affected. As a result of a medical run, a large number of medical staff and nursing home staff were found to be infected.

Research and analysis showed that within 4 months of the outbreak, the nucleic acid test and antibody test of the COVID-19 of these 58 people were always negative.

However, compared with the medical staff who were diagnosed with COVID-19 infection in the control group, the immune response of these 58 people was “somewhat different,” and their specific memory T cell responses were stronger. Among them, there are 20 people whose specific memory T cells doubled.

Scientists are Looking for people with "Natural Immunity" of COVID-19

In addition, 19 people have increased levels of the immune system protein IFI27. This is an immune marker that suggests viral infection.

According to the researchers, this shows that people who seem to be “naturally immune” are not “invincible”. The greater possibility is that they have briefly experienced a very low level of infection after being exposed to the COVID-19. But the immune system quickly subdued the virus.

Therefore, the virus does not multiply in large numbers, and these people will not be detected as infected, have no symptoms, and have not produced COVID-19 antibodies in their bodies.

Leo Swadling, one of the study authors and an immunologist at University College London, explained that about 1 in 10 people have experienced such “abortive infections.”

Shane Crotty, who was not involved in the study, cited an earlier review by the British Medical Journal that multinational studies have shown that about 20%-50% of healthy people have targeted T cell immunity before the emergence of the COVID-19. .

The “misoperation” of memory T cells just kills the COVID-19

Here comes the question: why some people’s immune systems can naturally resist and eliminate the COVID-19?

“Nature”, “British Medical Journal”, “Science-Immunity”, etc. have all published articles pointing out that the key lies in memory T cells. It is a “special force” that will have memories of specific viruses or virus components. When you meet again, you can launch a targeted attack.

“Science-Immunity” once published a Stanford University study saying that after comparing the COVID-19 with four common coronaviruses, it found that it has 24 similar protein sequences. Tested with 19 blood samples taken before the outbreak (that is, those who were determined to have not been infected with the COVID-19), it was found that T cells in the blood could target the 24 similar protein sequences mentioned above.

Moreover, compared with the unique protein sequence of the COVID-19, the sequence shared with the coronavirus is easier to activate T cells and induce immune responses.

Leo Swadling said that his research revealed the mechanism of action: Memory T cells “remember” the “transcriptional replication complex” (RTC) protein inside the coronavirus. “The coronavirus family has some commonalities. For example, the RNA polymerase in the RTC protein is very conservative and has the same sequence.

In other words, when the COVID-19 enters the human body, the immune system recognizes the RTC protein inside and mistakes it for the previous The pathogens encountered, proactively launch defensive attacks.”

Researchers say this partly explains why children are less severely ill and die less after being infected with the COVID-19. Because they are people with a high incidence of common colds and flu, they have rich experience in preparing memory T cells in their bodies.

“Natural Immunity” may be helpful to develop new vaccines

“Nature” interpreted the aforementioned research and stated that this may guide the development of a new generation of vaccines against T cell immune responses.

T-cell vaccines are not a novel idea. In the past decade or so, a team at Oxford University has been researching related vaccines against influenza viruses.

Scientists are Looking for people with "Natural Immunity" of COVID-19

“At this stage, the main principle of the COVID-19 vaccine is to induce human cells to produce neutralizing antibodies to fight the virus.” Eleanor Riley, an immunologist at the University of Edinburgh in the United Kingdom, pointed out that there is sufficient evidence that protective antibodies will weaken over time, so vaccination is required. Strengthen the needle.

Compared with antibody vaccines, T cells have a very long lifespan and can provide longer-lasting immunity. In August of this year, the research team of Professor Lu Hongzhou and Associate Professor Chen Jun of the Shanghai Public Health Clinical Center found that 7 months after infection, the patient’s immune response to neutralizing antibodies decreased, but T lymphocyte immunity continued.

In addition, the antibody vaccine may become invalid due to the mutation of the COVID-19. But for T cell vaccines, as long as the RTC protein inside the virus does not change, it will work. At the same time, this protection also applies to other coronaviruses that rely on similar RTC proteins to replicate.

At present, the British vaccine manufacturer Emergex has obtained the approval of the Swiss drug regulatory authority to carry out a phase I clinical trial of the T cell COVID-19 vaccine in Lausanne, the capital of the canton of Vaud, Switzerland on January 3, 2022. It is expected that 26 volunteers will participate in the trial. .

Reference:

1.Pre-existing polymerase-specific T cells expand in abortive seronegative SARS-CoV-2. Nature. doi.org/10.1038/s41586-021-04186-8

2.How do people resist COVID infections? Hospital workers offer a hint. Nature. doi.org/10.1038/d41586-021-03110-4

3.Decline in neutralising antibody responses, but sustained T-cell immunity, in COVID-19 patients at 7 months post-infection. Clinical & Translational Immunology. 26 July 2021. doi.org/10.1002/cti2.1319

Scientists are Looking for people with “Natural Immunity” of COVID-19

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