What is the Antigen Used in the Purified Protein Derivative

Question

What is the antigen used in the purified protein derivative (PPD) skin test?
A) A purified protein from the nucleus of Mycobacterium tuberculosis
B) A purified piece of DNA from M. tuberculosis
C) A purified protein from the cell wall of M. tuberculosis
D) A piece of ribosomal RNA from M. tuberculosis

Accepted Answer

The antigen used in the PPD skin test is a purified protein extracted from the cell wall of Mycobacterium tuberculosis. This protein is called tuberculin and it triggers an immune response in individuals who have been previously exposed to or infected with the bacteria. This immune response causes a raised bump or redness at the site of the skin test, indicating a positive result.