How do viruses infect cells?
How viruses multiply in the body and how to deal with them
Nikolay Nikitin, Post-science
What's it?
Diagram: it shows how the virus infects cells and how the immune system fights the uninvited guest. Let's look at how it works, using the example of the coronavirus.
In order for a person to get sick, the coronavirus must "attach" S-protein, its "crown", to a receptor on the cell surface – angiotensin converting enzyme 2 (APF2). After successful docking, the cell membrane and the viral envelope merge: this is how the virus penetrates into the cell.
In a cell, the virus uses its resources and organelles to copy its RNA and synthesize proteins. New copies of the virus – daughter virions - are formed from structural proteins and RNA. They exit the cell by exocytosis to infect new ones.
How does the immune system react to the virus? T-helper cells of the immune system identify the virus or its particles (antigens) and attract the attention of the immune system: "Guard, the enemy is inside!" After receiving a signal from T-helpers, the immune system triggers a defense mechanism: it produces B- and T-immune cells. B cells produce antibodies that bind to the virus and neutralize it, and T cells find and destroy virus-infected cells, preventing them from producing the pathogen.
Vaccines cause an immune response to virus particles or its components that are safe for the body. They "introduce" the body to a future infection: vaccines contain an antigen for which antibodies are produced. Thus, a person develops immunity even before meeting with a real pathogen.
Why is this interesting for science?
Sometimes there are outbreaks of previously unknown infections. For example, in December 2019, Wuhan, a city in the Chinese province of Hubei, became a hotbed of a new coronavirus infection – three months later, WHO announced the beginning of a pandemic. In such cases, doctors throw all their efforts into the manufacture of vaccines and antiviral drugs that can stop the infection. But it is impossible to do this without knowledge of the immune response and the biology of the virus.
Why should I know about it?
To develop effective antiviral drugs that prevent the spread of the virus in the body. To create safe vaccines that will form a stable adaptive (acquired) immunity. And also to find the source of a new infection in time.
About the author: Nikolay Nikitin – Doctor of Biological Sciences, Head of the Department of Virology, Faculty of Biology, Lomonosov Moscow State University.
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