Prion - A causative agent of infectious disease that is composed primarily of protein.⏎
Parasitism - A close relationship between two organisms in which one organism, the parasite, benefits at the expense of the host organism.⏎
Respiratory Tract - The part of the anatomy that has to do with the passage of air and includes the nose, larynx, trachea, and lungs.⏎
Replication - The process of producing a copy of a strand of DNA.⏎