Treatment Action Group is a US-based HIV/AIDS activist organization formed in 1991 involved with worldwide efforts to increase research on treatments for HIV and for deadly co-infections that affect people with HIV, such as hepatitis C

Hepatitis C

Hepatitis C is an infectious disease primarily affecting the liver, caused by the hepatitis C virus . The infection is often asymptomatic, but chronic infection can lead to scarring of the liver and ultimately to cirrhosis, which is generally apparent after many years...

 and tuberculosis

Tuberculosis

Tuberculosis, MTB, or TB is a common, and in many cases lethal, infectious disease caused by various strains of mycobacteria, usually Mycobacterium tuberculosis. Tuberculosis usually attacks the lungs but can also affect other parts of the body...

. The group also monitors research on HIV vaccines and fundamental science aimed at understanding the pathogenesis of HIV/AIDS.
The Treatment Action Group had its origins in the AIDS activist organization, ACT UP New York.