1) Viruses are not considered to be alive or dead. They require a host to replicate.
2) Viruses insert their genes into their host and use their host’s genetic machinery to replicate.
3) The genome of viruses can be made of either DNA or RNA.
4) Many genes inside humans are thought to have originally come from viruses.
5) Different types of viruses infect different types of hosts. Some viruses can only infect plants, while others can only infect animals, and others that only infect bacteria.
6) The word “virus” comes from the Latin, which means poison.
7) Viruses that only infect bacteria and archaea are called “bacteriophages” or “phages”.
8) Bacteriophages can be in the lytic cycle or lysogenic cycle. Bacteriophages in the lytic cycle make many viruses inside the host and are then released when they destroy their host. Bacteriophages in the lysogenic cycle combine their genome with their host and end up replicating whenever their host replicates.
9) Viruses can be used as tools in biological research. They can be used to change the genes of other cells which allows scientists to study what those genes do.
10) Scientists are trying to use viruses to treat diseases, in a field called “virotherapy”. As an example, some scientists are trying to create viruses that can only infect and destroy cancer cells while leaving normal cells intact.