Viruses don't actually "live" or "breed" in the way that living organisms do. They are not made of cells and cannot reproduce on their own. They can only replicate inside living cells.

Here's how it works:

* Viruses invade cells: A virus attaches to a specific type of cell, called a host cell, and enters it.

* Hijacking the cell: Once inside, the virus uses the host cell's machinery (enzymes, ribosomes, etc.) to create copies of itself.

* Replication: The virus replicates its genetic material (DNA or RNA) and then assembles new virus particles.

* Release and spread: The new virus particles are released from the host cell, often killing it in the process, and go on to infect other cells.

So, while viruses don't live in cells in the same way living organisms do, they rely on cells to replicate. The specific type of cell a virus can infect depends on the virus's surface proteins and the receptors on the host cell. For example:

* Influenza virus targets cells in the respiratory system.

* HIV virus targets cells of the immune system.

* Hepatitis B virus targets liver cells.

It's important to remember that viruses are not alive in the traditional sense. They are essentially packages of genetic material that need a host cell to survive and multiply.