1 For the virus to enter a cell, it must first attach to two receptors, or docking ports, on the cell. A drug delivered straight to such sites might thwart the virus before it docks. One type of drug in development seeks to block a receptor called CCR5. Another is aimed at the CD4 receptor.
2 If the virus attaches to the cell, it uncoils a harpoon-like device that plunges into the cell wall to force entry. So-called fusion inhibitor drugs keep the uncoiling from taking place.
3 After the virus gets in, it replicates by inserting its genes into the cell's chromosomes. This requires an enzyme called integrase. Drugs that disable integrase could prevent replication.