Question

How does a person build a line of defense against a pathogen? What is the difference in antigenic drift and antigenic shift?

Answer 1

All animals have innate immune defenses against common pathogens. These first lines of defense include outer barriers like the skin and mucous membranes. When pathogens breach the outer barriers, for example through a cut in the skin or when inhaled into the lungs, they can cause serious harm.

Some white blood cells (phagocytes) fight pathogens that make it past outer defenses. A phagocyte surrounds a pathogen, takes it in, and neutralizes it.

Both antigenic drift and antigenic shift are terms used to describe ways in which the flu virus changes over time. A drift is a minor change while a shift is a major one.

Antigenic drift is a term used to describe one of the ways that influenza (flu) viruses change and mutate. It describes a minor change in the flu virus.

Antigenic shift is a more major change in the influenza virus. This shift occurs typically when a human flu virus crosses with a flu virus that usually affects animals (such as birds or pigs).