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A virus is a small collection of genetic code, either DNA or RNA, surrounded by a protein coat. A virus cannot replicate alone. Viruses must infect cells and use components of the host cell to make copies of themselves. Often, they kill the host cell in the process, and cause damage to the host organism. Viruses have been found everywhere on Earth. Researchers estimate that viruses outnumber bacteria by 10 to 1. Because viruses don’t have the same components as bacteria, they cannot be killed by antibiotics; only antiviral medications or vaccines can eliminate or reduce the severity of viral diseases, including AIDS, COVID-19, measles and smallpox.

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Narration



Viruses are submicroscopic, which means that you cannot see them in the microscope. What's interesting about viruses is that they have two or three components. Starting from the inside, you will have a nucleic acid, which can be either RNA or DNA, and in both cases the nucleic acid can be either single-stranded or double-stranded. Then surrounding the nucleic acid will be a protein coat that's in the form of capsid, or little small units that are assembled in a certain way. That is what all viruses have. Now, some viruses will also have an envelope which they obtain as they emerge from the cell. Viruses are very interesting in that they can only survive inside a living cell. So they must have a living cell in order to survive and replicate. Antibiotics are not effective against viruses, but vaccines are, as well as some antivirals.

Bettie J. Graham, Ph.D.

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