Interferon - A type of protein produced by cells of the immune system that help keep viruses, bacteria, and cancer cells from growing.⏎
Immune System - The system of biological structures and processes that protects the body from foreign substances, including pathogens.⏎
Germ Theory - A theory in medicine stating that microorganisms are the causative agents of infectious, contagious diseases.⏎
Habitat - The specific geographical area or physical environment that is inhabited by an organism or a population of organisms.⏎