Why they have been preserved in humans is unclear and no infectious viral particles have been discovered to date. But the gene portions can apparently make viral parts. A protease is like a pair of protein scissors. HIV-1's genetic machinery churns out long protein chains from which its protease makes specific cuts to create functional parts.
Protease inhibitors block the cutting.
But, even in the presence of multiple inhibitors, HIV-1 often seems to find a way to get the job done. This is due, at least in part, to the virus developing mutations that make the protease resistant to multiple drugs. A nonprofit organization with a membership of more than 155,000 chemists and chemical engineers, the American Chemical Society publishes scientific journals and databases, convenes major research conferences, and provides educational, science policy and career programs in chemistry. Its main offices are in Washington, D.C., and Columbus, Ohio.