The more severe the symptoms at the time of infection, the "deeper" the new crown immune memory
Can the immune system in our body "remember" after resisting the attack of the new coronavirus?
If so, is there a chance of life-long immunity after being infected with the new crown?
If not, then how long should I boost my immunity afterwards.
The immune memory problem of the human body after the new coronavirus infection has always been the focus of response to the epidemic.
On October 5th, researcher Liu Jun from the Institute of Viral Diseases of the Chinese Center for Disease Control and Prevention, together with the team of academician Gao Fu and researcher Wu Guizhen, published a study in the authoritative journal "Clinical Infectious Diseases" showing that the human body's immune memory against the new coronavirus can be maintained More than one year, the proportion of recovered patients who still have new crown-specific neutralizing antibodies and T cell immune memory one year after infection is 95% and 92%, respectively.
"We conducted a half-year and one-year return visit to 101 patients who had recovered from new coronary pneumonia, and detected immune antibodies through multiple tests of serum samples, including neutralization of live viruses, and virus-specific tests of immune memory T cells. And whether immune memory T cells still exist.” On October 7, Liu Jun, one of the corresponding authors of the paper and a researcher at the Institute of Viral Disease Control and Prevention of the Chinese Center for Disease Control and Prevention, told a reporter from Science and Technology Daily.
"Pursuing" Immune Memory
How can immune memory be pursued?
If you want to know if a person has memory, just ask: Do you remember?
"If you want to know whether the immune system has memory after being infected with the new crown, you have to find out whether there are related T cells and B cells." Liu Jun introduced that acquired immune factors such as T cells and B cells are the key to immune memory.
Therefore, to "fish" cells related to immune memory in research work, we must first create special "memory fragments" that can match the memory cells related to the new coronavirus as "bait".
This "memory fragment" is the "small fragment" polypeptide of the new coronavirus protein. They will cause the "memory flashback" of the T cells in the blood cells of the new coronary pneumonia survivors, which will stimulate the immune response again, and finally be discovered through the color reaction.
Therefore, the design of "bait" is very important, it must have specificity and sensitivity.
In response to the S protein, M protein, and N protein on the new coronavirus particles, the team designed specific peptide pools for S1, S2, M, and N proteins to "hunt" the "hunting" of immune memory cells.
In order to improve specificity, the research team also specially synthesized a tetramer complex for the new crown-specific peptides to conduct a "stereo" search for immune memory T cells.
In 1 year, there was no sign of "fading" in immune memory
After conducting a comprehensive and three-dimensional memory cell search on the blood cells of 101 survivors, the research team found that 93% of the survivors had neo-coronavirus-specific T cell immune memory 6 months after the onset of the disease. This specificity T cell immune memory can last up to 12 months after the onset of 92% of recovered patients.
"We found that compared with 6 months after the onset, the percentage of virus-specific memory T cells in recovered patients did not decrease significantly." Liu Jun said, this means that immune memory will continue.
There are different types of immune memory cells. The team also classified and searched for central memory T cells and effector memory T cells, and the results showed that the latter accounted for the majority.
"This means that the T cell immune memory specific to the virus still exists and can be used to resist re-infection." Liu Jun said.
What's more interesting is that the level of T cell immune response is positively correlated with the severity of the disease.
In other words, the more severe the symptoms of the survivors at the time of infection, the "deeper their immune memory".
At the same time, the level of T cell memory against the S protein is positively correlated with the level of new coronavirus-specific antibodies, that is, the higher the antibody level, the more significant the T cell immune memory.
It shows that the two memory "lines of defense" of the human body against the new crown are complementary.
After 1 year, specific antibodies persisted
The researchers also tested specific antibodies and conducted regular analysis.
Studies have shown that in more than 95% of recovered patients, specific IgG antibodies and neutralizing antibodies can persist from 6 months to 12 months after the onset of disease, and their titer is positively correlated with the severity of the acute phase.
At 6 months and 12 months after the onset, the neutralizing antibodies showed no obvious signs of regression.
"Specific T cell immune memory and antibodies can last for at least one year, which has a very positive effect on individuals avoiding re-infection with the new coronavirus." Liu Jun said that the research on immune memory characteristics and the improvement of related mechanisms will also help The formulation of vaccine strategy provides theoretical basis.