Protease inhibitor drugs are one of the major weapons in the fight against HIV, the virus that causes AIDS, but their effectiveness is limited as the virus mutates and develops resistance to the drugs over time. Now a new tool has been developed to help predict the location of the mutations that lead to drug resistance. First discovered in 1995, protease inhibitor drugs have dramatically reduced the number of AIDS deaths. Taken in combination with two other anti-HIV drugs, protease inhibitors work by halting the action of the protease enzyme, a protein produced by HIV that is necessary for replication of the virus.
