Summary:
- A virus is a sub-microscopic particle that can infect living cells.
- Because viruses do not consist of cells, they also lack cell membranes, cytoplasm, ribosomes, and other cell organelles.
- Viruses can replicate only by infecting a host cell.
- They cannot reproduce on their own.
- Antibiotics have no effect on viruses and only a few antiviral drugs are available for some diseases.
- One of the best ways to prevent viral diseases is with a vaccine, which produces immunity.