Cómo funciona la vacuna contra la COVID-19 de Sinopharm
In early 2020, the Beijing Institute of Biological Products created an inactivated coronavirus vaccine called BBIBP-CorV. Clinical studies by the state-owned company Sinopharm showed an effectiveness rate of 79 percent. China approved the vaccine and soon began exporting it to other countries.
A vaccine with coronavirus
BBIBP-CorV teaches the immune system to produce antibodies against the SARS-CoV-2 coronavirus. Antibodies attach to viral proteins such as so-called spike proteins that cover their surface.
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Gene of
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To generate BBIBP-CorV, researchers at the Beijing Institute of Biological Products received three variants of the coronavirus from Chinese hospital patients. They chose one because it could multiply quickly in monkey kidney cells grown in bioreactor tanks.
Virus suppression
After the researchers made large amounts of coronavirus, they doused them with a chemical called beta-propiolactone. The compound inactivated coronaviruses by binding to their genes. Inactivated coronaviruses could no longer replicate. But its proteins, including the tip, remained intact.
The researchers then extracted the inactivated viruses and mixed them with a small amount of an aluminum-based compound called an adjuvant. Adjuvants stimulate the immune system to increase its response to a vaccine.
Inactivated viruses have been used for more than a century. Jonas Salk used them to make his polio vaccine in the 1950s and they are the basis for vaccines against other diseases such as rabies and hepatitis A.
Trigger an immune response
Since the BBIBP-CorV coronaviruses are dead, they can be injected into the arm without causing COVID-19. In the body, some of the inactivated viruses are taken up by a type of immune cell called an antigen-presenting cell.
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CELL
MODERATOR
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Digestion of
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CELL
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Digestion of
Proteins
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The antigen presenting cell tears up the coronavirus and shows some of its fragments on its surface. A helper T lymphocyte can detect the fragment. If the fragment fits into one of its surface proteins, the T lymphocyte is activated and can help recruit other immune cells to respond to the vaccine.
Formation of antibodies
Another type of immune cell called B lymphocytes can also be found with the inactivated coronavirus. B lymphocytes have surface proteins in a variety of shapes, and some may be shaped appropriately to attach to the coronavirus. If a B-lymphocyte becomes stuck, it may carry part or all of the virus and present coronavirus fragments on its surface.
A helper T cell activated against coronavirus can bind to the same fragment. In this case, the B lymphocyte is also activated. It multiplies and secretes antibodies that are the same shape as its surface proteins.
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Stop the virus
Once vaccinated with BBIBP-CorV, the immune system can respond to a live coronavirus infection. B lymphocytes produce antibodies that adhere to invaders. Antibodies directed against the spike protein can prevent the virus from entering cells. Other types of antibodies can block the virus in different ways.
Virus store
Clinical studies with Sinopharm have shown that BBIBP-CorV can protect people from COVID-19. But nobody can say how long this protection will last. The amount of antibodies may decrease over the months. However, the immune system also contains special cells called memory B and T cells that can hold information about the coronavirus for years or even decades.
Sources: National Center for Information on Biotechnology; Science; The lancet; Lynda Coughlan, University of Maryland Medical School; Jenna Guthmiller, University of Chicago.
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