Returning Fire Against AIDS

By Christine Gorman

Even if an effective AIDS vaccine were discovered tomorrow, its development would presumably be of little benefit to the 3 million to 5 million people around the globe who already harbor the virus in their body. Most vaccines work to prevent an infection, not to eliminate it after it has taken hold. Now, however, a group of scientists from the Walter Reed Army Institute of Research in Rockville, Md., believe they may have found a retroactive vaccine. In a study published in last week's New England Journal of Medicine, the team announced that repeated immunizations with a genetically engineered AIDS vaccine appeared to stabilize and perhaps even boost the beleaguered immune system of some infected people.

The results are preliminary: only 30 patients took part in the experiment, which lasted a scant 10 months. All the subjects appeared healthy to begin with and had been host to the virus for less than seven years. Yet even if this vaccine never helps a single person with full-fledged AIDS, the Walter Reed team has sketched out a blueprint for a potential new weapon against the disease. "This is the first time anyone has proved that you can change the immune system in a chronically infected person," says Dr. Robert Redfield, research-group leader. "Now we have to find out whether or not this makes a difference."

Scientists know that the body puts up a pretty good fight against the AIDS virus (HIV) in the early years of infection. But the great mystery has always been why the body cannot knock HIV out completely. One possibility is that the body has trouble "seeing" all of the virus. Like a Stealth fighter plane, HIV may have hidden parts that do not show up on the immune system's radar screen. As a result, the body may not manufacture all the different kinds of antibodies that could attack the virus. "We thought that if we could make the virus in a slightly different way, the immune system could see it better and mount a more effective response," Redfield says. "In other words, we'd be augmenting Mother Nature's own strategy."

To achieve that goal, the researchers chose a vaccine, manufactured by MicroGeneSys of Meriden, Conn., that consists of genetically engineered pieces of the virus. The vaccine makers took strands of DNA that code for the outer covering of HIV and put them into another kind of virus, one that infects only moths and butterflies. The insect virus then produced AIDS proteins in addition to its own.

The researchers injected these artificial AIDS proteins into 30 human test subjects. In 19 of the volunteers, the proteins apparently looked different enough from what their immune systems had already seen so that additional defensive reactions were triggered against HIV. Not only did these patients produce entirely new antibodies, but the number of their T cells, the key immune defenders the virus normally destroys, remained steady.

"From a conceptual standpoint, the study is quite interesting," says Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases. But he cautions that any dangerous side effects from the vaccine could take years to show up. Even so, the preliminary effects were intriguing enough that Redfield has begun a second trial -- with results expected in 18 months -- to see if the vaccine can produce long-lasting benefits.