Scientists look beyond antibodies with viral immune hunts

Paris-Will previous ghosts of cold help protect you from COVID-19 even if you have never been infected with the new global coronavirus?

Scientists are investigating a poorly understood immune system in the body, hoping that they can help efforts to control pandemics.

At this time, people suspected of having the virus may undergo serology for antibody testing.

These proteins can help fight infections and prevent them from getting sick again in the future-but with COVID-19, there are signs that they will disappear within a few weeks.

This leaves another tool, the T lymphocyte, in the body’s toolkit. It is a type of white blood cell that is responsible for the second part of the immune response.

Little is known about how they behave against COVID-19, so scientists are competing to fill our knowledge gap.

One hypothesis is that these T cells “remember” previous infections by other viruses of the same family, four of which cause a cold, thus providing a level of cross-immune protection from COVID-19. It can be useful.

“The immune system is complex,” Andreas Thiel co-authored a study investigating the presence of T cells that respond to the new coronavirus in both confirmed and healthy individuals.

A study published last week in Nature magazine found that at least one-third of adults without COVID-19 have these T cells.

“These are probably derived from previous infections by the epidemic coronavirus,” Professor Tiel of the Berlin Brandenburg Center for Regenerative Therapy told AFP.

But he warned that more research is needed to find out whether his presence necessarily implies immunity.

Virus family

This study follows a study by a Singaporean team published in Nature in early July and reached similar conclusions.

Another US study, published Tuesday in Science, found a large number of T cells that respond to both the new virus SARS-CoV-2 and the cold-causing coronavirus.

“This explains why some people have milder symptoms of the disease and others are more seriously ill,” Daniella Weyskoff, a co-author of the La Jolla Immunology Institute, said in a statement. May help you.”

The study builds on a study published by Cell in May in the same team that detects these SARS-CoV-2-reactive T cells in 40-60% of people who have never experienced COVID-19. did.

Persistent immunity?

The vaccine currently being developed for the new coronavirus seeks to elicit both types of immune responses.

However, in the past, the main focus has been on the immunity conferred by antibodies.

“But don’t assume there’s nothing else,” Yonathan Freund told AFP, professor of emergency medicine at the Paris Piti Salpetriere Hospital.

Studies have shown that antibody levels in patients with COVID-19 are likely to fall rapidly, probably within weeks.

“It might mean two things: one is catastrophic, one that is unsustainable immunity to COVID,” Freund said, adding he doubts this is true.

The second possibility is that there is potential immunity, but it is “not detectable” by antibody serology.

That is, calculations on the proportion of the population that may be immune to coronaviruses, based on antibody detection, may be underestimated worldwide.

A recent study at the Karolinska University Hospital in Sweden showed that many people with mild or asymptomatic COVID-19 showed a T cell immune response to the virus, even if the antibody test was negative. It was.

But Freund emphasized that the T-cell debate is mostly “hypothesis” for now.

And scientists are keen to emphasize the need for thorough and extensive research before any impact on the pandemic effort.

“Pet’s theory is okay in academic debate, but dangerous when it comes to policy advice,” said Devi Sridard, professor of global public health at the University of Edinburgh, on Twitter this week.

She added that she was “happy” if there was clear evidence of wider public immunity or if the virus was weakened.

“That’s what we all want, but we must plan and prepare for the latest evidence and observational studies around the world,” she said.