A new type of test can detect a person’s immune response to coronovirus, compared to a widely used antibody test, according to research released on Tuesday.
The test, if authorized by the Food and Drug Administration, will be the first commercial product to detect a T cell response – a type of immune cell – to the virus. Antibodies have been dominated in immune interactions since the onset of the epidemic, but scientists believe it may be important in preventing T cells from regenerating.
The test was developed by Adaptive Biotechnology, a Seattle-based company. The company used small blood samples from 1,000 people in 25 metropolitan areas in the United States as well as another 3,500 participants from Europe to create tests that could detect recent or previous infections of the coronavirus Huh.
The company’s data has not yet been reviewed for publication in a scientific journal, but experts say work has been promised to assess the role of T cells in disease caused by coronovirus.
Pathogens are exposed to multiple arms of the immune system: antibodies, but also immune cells that can marshal the fight against the intruder.
“What we are developing is essentially a way of looking at that cellular part of the immune,” Chief Medical Officer of Adaptive Biotechnology, Dr. Lance Baldo said.
Antibodies have attracted a lot of attention so far – because testing for them is quick and easy. But after solution of active disease the level of antibody decreases and Can be inexplicable Within a few months.
Several studies have suggested that T cells that remember the virus persist. At least six months. “There is an increasing belief that T cells are more important than antibodies and may even be a better indicator of clinical outcome”, said Alessandro Sette, an immunologist at the La Jolla Institute for Immunology in California.
But differentiating T cells is an elaborate and serious process, severely limiting information about their role.
Each trillion present at birth of T cells carries a unique receptor on its surface that can detect a different molecule, or antigen, from potential invaders. This huge diversity among T-cell receptors enables the human body to recognize almost any new pathogen that it can withstand (although a vast majority may never meet their match.) But it is not the case of scientists. Makes it even better to painstakingly identify 20 or 30 T. Trillary cells Identify fragments Of a specific pathogen like coronavirus.
“One of the cruel things about immunology is that all white blood cells look alike,” said Shane Crotti, a virologist at the La Jolla Institute for Immunology. “You can’t even tell B cells from T cells, let alone T cells to be specific to a virus.”
To find T cells specific to a virus, researchers must first separate the bulk of immune cells from a few milliliters of blood, which takes time. They then wash and count the cells, and stimulate them with virus fragments to identify small pools of T cells. Activated cells release a molecule called gamma interferon that acts as a signal of their activity.
“The better the assay, the more complex it is,” Dr. Said Cretty. “You get more and more information, but it gets more and more complicated.”
A single researcher cannot process more than five blood samples in another day and a half.
Dr. a virologist from Duke NUS Medical School, Singapore. Antonio Bertolletti said, “This is why every single paper on T cells that is studied never exceeds 100 in those subjects.” “There has never been a great demand to wake up to the intricacies of T cell tests.”
Adaptive biotechnology is completely different approach: Instead of looking at cells, the company focused on the sequencing of proteins on the surface of cells.
Confused by the terms about coronavirus testing? Let us help:
- Antibodies: A protein produced by the immune system Which can properly identify and engage specific types of viruses, bacteria or other invaders.
- Antibody Testing / Serology Testing: A test that detects antibodies to coronovirus. Antibodies appear in the blood approximately one week after the coronavirus is infected with the body. Because antibodies take so long to develop, An antibody test can not do Reliably diagnose ongoing infection. But it can identify those who were exposed to coronovirus in the past.
- Antigen test: This test detects bits of coronavirus virus called antigens. Antigen tests are faster, take five minutes less, but are less accurate Testing that detects genetic material from the virus.
- Coronavirus: Any virus that belongs to the orthocoronavirina family of viruses. The cornivirus that causes Kovid-19 is known as SARS-CoV-2.
- COVID-19: Disease caused by the new coronavirus. Name is short for Coronavirus disease 2019.
- Isolation and Quarantine: Isolation is the isolation of those who know they are ill with an infectious disease that is not sick. Quarantine A refers to restricting the movement of people exposed to the virus.
- Nasopharyngeal Swab: A long, flexible rod, stuck with a soft broom, inserted from the nose to take the specimen deep into the place where the nasal cavity meets the throat. Can take samples for coronovirus testing Must also be collected with swab that does not go deep into the nose – Sometimes called nasal inflammation – or oral or throat swelling.
- Polymerase chain reaction (PCR): Scientists use PCR to make millions of copies of genetic material in a sample. Tests using PCR enable researchers to detect coronaviruses When it is rare.
- Viral Load: The amount of virus in a person’s body. In people infected with coronavirus, Symptoms of viral load may begin before they appear, If symptoms appear at all.
Trillions of T cell receptors, known as TCRs, have different performance for each individual. But at least some of those TCRs are similar to others. “We call those public T cell receptor sequences, because, theoretically, many people in the population would deflect those reactions,” Dr. Baldo said.
When the epidemic began, Adaptive Technologies was already working with Microsoft to design a TCR-based diagnostic test for Lyme Disease, a project made possible by the advent of faster and cheaper sequencing technologies.
To pivot CoronavirusThe team identified 135,000 public TCRs that recognize 545 fractions of the virus. Of these 545 antigens, about 11 assume the largest immune response, researchers said Reported in september. (Only one of these antigens, the spike protein, is being used to develop vaccines.)
In the new work, the team analyzed samples from 2,200 people from VO, Italy, who tested all 2,900 of their residents for the presence of coronovirus in March, when cases were growing there. A test by researchers called T-Detect correctly identified 97 percent of people whose diagnosis was confirmed, compared to 77 percent from a commercial antibody test called Dysorin. Results are freely available in a database called ImmuneCode.
The company is building a point-of-care test for the general public that can diagnose pre-infection, as well as a sophisticated version for vaccine companies interested in tracking T cell responses to their candidates.
Experts not involved in the work praised the company’s innovative approach, but said they wanted to see evidence that the test was specific to coronavirus.
“There is not a general consensus that you can now take TCR from one person to a specific person and tell that another person is infected with the virus in a consistent manner,” Dr. Said Cretty. “If they figured out a way to do it that’s great, but it’s a very good novel.”
A commercial trial also would not offer information to people beyond the evidence of previous infections, warned Akiko Iwasaki, an immunologist at Yale. But if the test is specific to the new coronovirus, he said, “it would give us a more sensitive way of measuring whether a person has been exposed.”
Can also test Insight into Kovid-19. And about 5 percent of patients who are seriously ill show a “tremendous decline” in their T cell response, Drs. Baldo said. But in the majority of people, the T cell response seems to peak around day 10 and persist for several months, he said, “We are already seeing, as a more robust and a more durable T cell response.” Opposed. To the antibody response. “