How does the immune system fight nCoV?

The immune system mobilizes the T-cell army and macrophages in the fight with nCoV, but if overworked, it will bounce back to the body.

When the virus enters the human body, they start a race against time to "abduct" cells, reproduce, spread and occupy to survive. The same is true for nCoV, the pandemic virus Covid-19.

Time passes very quickly for viruses because when their existence is detected by the chemical alert system in the body, an all-out battle broke out with the human immune system, which evolved millions. years to fight pathogens under the guidance of the T-cell killer army. The immune system is one of the reasons humanity still exists. Upon detecting the threat of a signal sent by chemical scouts throughout the body, the immune system reacted aggressively to completely destroy the invading object. In some cases, the result is that everything in the conflict area is compromised, including the body itself.

The immune system does not arrest prisoners. Once they find the cells that have become the factories of the virus, the immune system destroys them by grabbing and shooting molecules through the membrane, destroying the cell and everything inside. Before the start of the full-scale battle on a cellular scale, the virus had mixed into the body, finding its way through the defenses of mucus in the nose and throat to hunt for targets they could control. At the same time, the virus tries to disguise their existence to avoid waking the immune system.

For the first few hours after the pathogen enters the body, the virus tries various tricks to evade the immune system's detection tools, according to Gene Olinger, an immunologist at the MRIGlobal Institute in the United States. It is time to start the "arms race between the virus and the immune system," said Marjolein Kikkert, associate professor at Leiden University Medical Center in the Netherlands.

Because nCoV is a newly discovered virus, researchers have not had enough time to find out exactly how this war plays out. Questions such as why some healthy people with nCoV infection are seriously ill while others do not have answers yet. The scientists' knowledge is based mainly on previous research on the body's immune response to corona virus strains closely related to nCoV such as SARS and MERS, as well as clinical records of Covid patients. -19. The data shows that every part of the immune system needs to be mobilized to eradicate the virus, according to Stanley Perlman, a professor of immunology at the University of Iowa.

When the body's immune response is so strong and overwhelming, the fight against the virus will be extremely destructive, which can have deadly consequences. In particular, nCoV attacks the lungs, a vulnerable battleground. While trying to fight a virus it has never encountered before, the immune system can work too hard, damaging nearby cells and tissues.

According to Kikkert, the system's early warning system for invading pathogens consists of several layers. An abnormality within the cell usually triggers a signal, leading to the production of an alarming protein around the cell about the presence of the virus, while activating the immune molecule, creating an "antiviral state". In the meantime, nCoV is rushing to spread and attack more and more cells. Lungs become battlegrounds filled with immune cells.

The T cell pulls up after detecting the virus, enters the pleura to hunt, capture and kill the infected cell. They will stick to and shoot molecules through the target to eliminate, Olinger explained.

At the same time, antibodies are Y-shaped proteins. They flood the virus, covering the spines that the virus attaches to healthy cells. Later, larger white blood cells called macrophages overflow, devouring large clusters of viral particles. The massacre spread, leading to dead cells piling up in the lungs.

" Dead cells block the airway and reduce oxygen flow ," said Ashley St John, assistant professor at the National University of Singapore School of Medicine. " You need the dilated tissue to contain oxygen, but it is now being filled with immune cells and body fluids. This may prevent patients from breathing in enough oxygen ."

In some patients who have gone through this stage and recover, their lungs may heal. Others may recover but are permanently injured. Chinese data released in late February showed that about 80% of nCoV infections were mild to moderate, about 14% were severe and the remainder were serious cases. 6% of critically ill patients may suffer from respiratory failure, septic shock, and organ failure.

Researchers are still investigating the exact mechanism of action of nCoV in the body, but Covid-19 clearly affects the elderly and people with weakened immune systems. More than 20% of patients over 80 years of age are at risk of death. The death rate in people with cardiovascular disease, diabetes and chronic respiratory disease is twice as high as the average, according to data released by the Covid-19 WHO-China cooperative working mission at the end of the month. 2.

Some researchers suspect that in the "hide and seek" phase, nCoV is harmful to the initial immune response by multiplying so quickly that the system does not keep up or disrupting the way the immune system coordinates itself. There is some evidence that this can boost the overworked immune system, leading to the release syndrome (cytokine storm), which causes tissue inflammation. "With the release syndrome, you go into a state of no brakes, every immune component becomes out of control, the cell invades the tissue, breaks the blood vessel," St John said.

When the body alerts the cells to the lungs to fight, the wrong combination may appear, causing more damage. "The lungs become the worst place for that to happen. The cells are there to kill, surround and control inflammation. Excessive reaction will lead to lung damage. Cells in the area are not." oxygen transport, "Olinger explained. Finally, instead of being damaged by the virus, the immune response itself becomes a burden to the lungs and other internal organs.