merck sp and pfizer hiv drugs

I recently heard some discussion of new HIV therapies on a Naked Scientists podcast.

Apparently Schering Plough, Pfizer and Merck are working on therapies based on studies of people in Africa that have a natural immunity to HIV. These people have been infected over and over again and aren't able to be infected due to a genetic mutation that HIV can't recognise, and so can't take hold.

Have to admit i was a bit worried when i heard this as I hold AVX from levels higher than it is now, and these new therapies sound like they may be particularly effective...

If Merck, SP and Pfizer all have drugs that may be as effective as they sound, why would they look at AVX?

Just a question...

Listen from 7min 45sec for the story on HIV drugs...

http://media.libsyn.com/media/nakedscientists/Naked_Scientists_Show_07.08.05.mp3