1.   PMPA, he said, attacks the human immunodeficiency virus in the same way that AZT does by blocking a crucial viral enzyme called reverse transcriptase.

2.   The new results are from studies with protease inhibitors, drugs that block a key viral enzyme.

3.   The protease inhibitor blocks a key viral enzyme called protease, and the older drugs block a different enzyme.

4.   They work by jamming a viral enzyme known as reverse transcriptase which enables HIV to replicate itself.

5.   Unlike existing drugs, it does not inhibit specific viral enzymes.

6.   Existing AIDS drugs generally work inside cells, targeting viral enzymes involved in the replication of the virus.

7.   Protease is an essential viral enzyme necessary for the virus to commandeer human cells, forcing them to make new copies of HIV.