How do cells protect themselves from viruses?

Viruses | Tebu Bio

More than two years ago, the whole planet got impacted by COVID-19. Over time, and with the help of our dedicated worldwide scientific research community, we have learnt how to prevent its spread and to protect ourselves from getting infected and ill.

Different vaccines have been developed, using various scientific approaches. Scientists worked hard to provide efficient vaccines that could be suited to every part of the population.

But the thing is, even if you are very careful, you might be contaminated at a certain point. And your body must fight the virus. Your immune system and immune cells will help you combat the infection and recover from it. But how do cells work to eradicate virus infected cells?

Fight infections with MxB protein

A group of researchers from Mayo Clinic, led by Hong Cao, M.D. decided to give explanations regarding the mechanism that occurs when our body cells encounter a virus. In other words, how the cells defend themselves from invading viruses.

In the study published in the Journal “Nature Communication”, they declare that they have identified an essential protein called myxovirus resistance mx protein. It is meant to support cells into defending themselves against infections and to regulate a crucial element: the mitochondria. These are cell organelles whose main function is to generate the energy needed by the cells to realize their function.

The study was conducted on patients delivering an immune response to the Human Immunodeficiency Virus (HIV) and Herpes virus. These two viruses have been selected because they are known to affect the mitochondria during the infection. The study revealed that MxB protein was present within the mitochondria as well as on their surface. When scientists removed the protein from where it was, the team observed that the mitochondria were no longer producing energy and that they kicked out their DNA genome into the cytoplasm.

Facing a viral infection

When a virus gets into someone’s system, it needs to find a host cell, able to infect the other cells and spread to as many cells as possible. This is what a viral infection is, it is the proliferation of the viral cells.

Naturally, while the infection is spreading, the infected cells release proteins called interferons. Thanks to these, the neighboring cells increase the production of  MxB proteins in and on the surface of mitochondria, allowing them to fight the infection. The researchers were very surprised when they discovered that MxB were present both on the surface and inside the mitochondria, not only to help defend the cells but also to help stabilize and preserve mitochondria.

The team concluded that MxB proteins were both “induced in the response to infection and vital to mitochondrial integrity”, said Doctor Cao.

Keeping mitochondrial integrity

The mitochondrion is a vital element for each and every cell in the body. Its primary function is to keep the cell alive. Mitochondria act as energy processors.

They absorb nutrients in the cells, and they transform them into energy so that the cells can keep functioning and defend the body against potential viral infections. When a cell is not receiving enough energy in order to function properly, it will die, and the body will lose some of its defensive tools.

The MxB affects the mitochondria in a way that if there is no active MxB protein, the mitochondria malfunctions, unable to produce energy. The various tests the team executed during the study, showed that when manipulating MxB protein expression, the size, the shape, and the distribution of mitochondria was affected. Indeed, depending on the level of manipulation, mitochondria were clustered or fragmented, preventing them from functioning properly.

On another note, the study also proved that MxB proteins were able to condense in several points or to diffuse themselves in the mitochondria, to dissolve themselves and to regenerate into larger structures.

A complex mechanism

In other words, it clearly appears that the cells’ defense machinery is quite complex. We know that our body triggers an immune response when being under virus attacks. The immune response is partly being held by defensive cells or T cells.

These cells are activated or made functional thanks to the presence of mitochondria. Without them, they don’t have the energy to combat viral infections.

This mechanism can be pictured as a chain. If one of the chain links breaks, the others will not be able to function, and the viral infection will spread within the system.

But this chain still has some secrets to reveal. The next steps for the group of scientists are first to investigate how MxB proteins are assigned to the mitochondria. The second is to discover how and why these proteins can affect their integrity in such a dramatic way.

Mx proteins help cells to fight virus or cancer cells, without using antibodies or white blood cells. MxB has revealed itself to be essential as they stabilized mitochondria to make the cells function properly. Without them, cells would not have the sufficient energy to help the body fight the attack.


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