Describe how viruses and prions can alter cell functions

Viruses and prions can alter cell function because

the prions and viruses have the ability to reproduce.

After they enter a cell they alter something about protein formation.
Prions are being composed of proteins material which folds multiple structurally abstract ways and they have the ability to induce abnormal folding of certain normal proteins which are cellular and they are abundantly found in the brain.
The virus is an infectious agent which replicates only inside living cells. Viruses can infect different types of life forms from plants and animals to microorganisms which include archaea and bacteria.