Okay, kids, here's a quick HIV 101 lesson. HIV is a retrovirus. This means several things, but the most important for us are that: +It holds its code in RNA, not the usual DNA of normal viruses. +It uses a special enzyme, RNA reverse transcriptase, to convert its RNA into DNA, which is then incorporated in the host cell's DNA. This effectively makes the host a virus factory. Normal viruses use normal transcriptase to reproduce inside the host. +It breaks the "central dogma" of Biology by allowing information to travel from RNA to DNA. The "central dogma" states that information goes DNA -> (through transcriptase) RNA -> (with the help of ribosomes) protein. So, eg, Lemarckian evolution is impossible, but we now know that the truth is much more complex. +Since its viral code is part of the cell's DNA, the cell can continue living and even multiplying while carrying the code with it. Indeed, analysis of "dead" genetic sequences in our genomes shows evidence of several sites coding for RNA reverse transcriptase, suggesting that we were historically infected by many retroviruses which failed to spawn correctly. It could also be possible that we copied DNA from other individuals and even organisms by being infected by retroviruses which had spawned with some of their previous host's code. +As alluded to in the last point above, one of the reasons why retroviruses (such as flu, IIRC) change so quickly is because they often accidently copy some of their host's DNA when spawning. So, with the above in mind, it seems logical that the best way to tackle HIV is to antagonise (neutralise by changing its shape so it can't work properly, according to the lock-and-key hypothesis) the RNA reverse transcriptase, right? Well, I'm afraid, that's exactly how AZT and Naviropine work, and we all know how successful they are(n't)... Class dismissed.
