Understanding Viruses: Tiny Agents of Disease

Microscopic infectious agents that replicate only inside living cells of organisms.
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Virology | Immunology | Public Health | Influenza | COVID-19 | Vaccination | Antivirals
Prepared by Lee Cheng, reviewed by Dr. Helena Rodriguez

Viruses FAQ

What is a virus in biology?

A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Viruses are found in almost every ecosystem on Earth and are the most numerous type of biological entity.

How do you describe a virus?

You can describe viruses based on a number of features, including: What they look like (their shape and size). Genome properties. Structural proteins and whether or not it has an envelope. Viruses can look very different from each other.

What are some common features of a virus?

Viruses share some common features. Viruses: Are made up of genetic material (RNA or DNA) and a protective protein coating (capsid). Sometimes have another layer called an envelope around the capsid. Viruses without an envelope are called “naked viruses.” Are similar to parasites — they need a host to reproduce.

Viruses References

If you want to know more about Viruses, consider exploring links below:

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