The AIDS Questions That Linger. What we still don’t know, on the eve of the upcoming international conference:

Why does AIDS predispose infected persons to certain types
of cancer and infections and not others?

What route does H.I.V. take after it enters the body to
destroy the immune system?

How does H.I.V. subvert the immune system?

What is the precise function of H.I.V.’s nine genes?

What is the most effective anti- H.I.V. therapy?

Is a vaccine possible?

In the absence of a vaccine, how can H.I.V. be stopped?

Why do most babies born to infected mothers escape
infection?

Why do H.I.V. rates differ so greatly among regions in Africa
and elsewhere?

How many people are infected in the United States and has
the rate changed in recent years?

Where did AIDS come from?

New York Times