AIDS: You Haven't Heard Anything Yet

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Unfortunately, AZT is not a cure and has a number of serious drawbacks. It must be taken every four hours around the clock to be effective, and can cause severe bone-marrow damage and anemia in some patients. "It's not an answer, and it's very toxic," says Polk, of Johns Hopkins. "Probably half of our patients on AZT will require weekly or bimonthly blood transfusions."

Perhaps the most promising of the dozens of other AIDS drugs under development is dideoxycytidine (DDC), which belongs to the same category of drugs as AZT. Like AZT, it works by interfering with viral reproduction, but researchers hope it will prove to be less toxic. Hoffmann-La Roche expects to receive a license to manufacture the drug within the next few months.

Doctors generally agree that they will need a two-pronged approach in order to treat AIDS effectively. In addition to eliminating the virus, they must rebuild the patient's ravaged immune system. That may turn out to be the most difficult goal to achieve; researchers have had little success so far with such natural immune boosters as alpha and gamma interferon. Indeed, AIDS therapy may ultimately prove to be most effective in patients whose immune systems are not yet destroyed -- those who show only early symptoms of the disease or perhaps are symptomless carriers. With drugs like AZT, says Broder, "it might be possible to prevent the onset of AIDS. That's a possibility."

Protecting those who have not yet become infected has an equally high priority, and research on vaccines for AIDS is proceeding at an unprecedented pace. Of the many groups at work on a vaccine, Genentech, of South San Francisco, Calif., appears to be one of the furthest along and may begin tests of a prototype vaccine on humans as early as this year. But vaccinemakers face several daunting obstacles. Perhaps the most formidable is the fact that the virus mutates and changes its outer coat so rapidly that no single vaccine is likely to be effective against all strains. Researchers are seeking a section of the viral coat that remains unchanged despite the mutations, hoping to use it as a basis for a vaccine.

Another potential solution is being explored by Dr. Allan Goldstein at George Washington University. Goldstein has found that it is possible to use a protein from the core of the AIDS virus to immunize laboratory animals. This protein, unlike those in the outer coat, does not vary much from one strain of the virus to the next. Says Goldstein: "We think we've overcome the problem of a constantly changing virus." Even if he has, it remains to be shown that this or any other vaccine preparation can actually protect people from infection. Predicts Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases: "It is very unlikely that we will see a vaccine available for widespread use any earlier than the mid-1990s."