However, injecting people with a virus similar to AIDS is not the only kind of vaccine possible. In another approach, doctors insert part of the HTLV-III virus, like the virus' envelope or shell, onto the harmless portion of another virus. When that new half-breed virus grows, will have the HTLV-III shell without the virus' deadly properties. Then the human immune system may be able to develop protective antibodies to the AIDS virus by coming into contact with a harmless, "dummy" AIDS virus created in the lab.

"I think that approach is what will be done first," Haseltine says.

Drug Treatments

AIDS researchers haven't put all of their eggs in the vaccine basket, however. Some doctors, Haseltine among them, are also trying to design a drug treatment program for AIDS patients.

Haseltine's discovery of the tat-gene may prove to be extremely important in the drug development process. Without the tat-gene the virus can't grow, so if researchers can find a chemical which interferes with the workings of that gene, or any other essential virus process, they are well on their way toward finding a drug treatment program.

"The ideal drug stops some virus enzyme from working but doesn't interfere with normal cells," Haseltine says. So, the more doctors know about how the virus works, the more opportunities they have to stop it from functioning properly.

"This virus presents a plethora of targets because it's not a simple retrovirus. The more we know about it, the more complicated it is," Haseltine says. "It's like the difference between a cowboy's coffee not and an expresso maker: they both make coffee, but one comes with all those bells and whistles, so it's a lot easier to mess up. [The AIDS virus] comes with a lot of genetic baggage which might provide theraputic targets."

Chemically creating a drug which stops a specific viral function, a method called rational drug design, is not the only way researchers go about looking for a chemical cure for AIDS. Haseltine's lab is also helping to design a drug screening program.

Drug screening programs test tens of thousands of chemicals, first in the lab, and then in animals, to find a drug which might cure or arrest AIDS. The possiblities are gradually narrowed down as a chemical meets or fails to meet a set of criteria.

Even after scientists find drugs which can cure or arrest the AIDS virus, they face additional challenges. In order for the drugs to work patients will probably have to take a lot of them over a long period of time. Therefore researchers have to worry whether the chemicals could harm the body over the longterm. "We must imagine lifelong high dose therapy to keep the virus continually suppressed. We have to think about what those chemicals will do to the liver and kidneys," Haseltine says.

However, the outlook is not completely grim. Although Haseltine says he thinks finding drugs to treat AIDS will take time, he remains optimistic. "We are where cancer chemotherapy was in the 1950s. We have drugs that are beginning to work."

Finding Out Who Has It

But in order for the drugs to work, doctors have to be able to determine who has AIDS as soon as possible. "It's like the early detection of cancer. If we were to use the drugs at the very earliest stages of the disease, the chances of success are greater," Essex says.

So workers in his laboratory spend a great deal of time trying to apply their knowledge of the viral proteins to developing better diagnostic and screening tests for AIDS.

And these diagnostic tests will be in use quite soon, according to Essex. "We already have some tools to categorize whether people are likely to be sick. It's a question of polishing. Within a year we'll have them tested and polished," he says.

Essex's lab is also working to develop a more sensitive AIDS screening test. The test currently in use screens the blood for antibodies to the AIDS virus. That procedure presents certain difficulties; there is a lag time "between infection and the presence of antibodies of two to three months, but the individual still has the virus," Essex says. "We need to look for earlier markers."

Haseltine predicts that this venture will be a success. "Within a year there will be more sensitive, more accurate tests," he says.