Medicine: AIDS Research Spurs New Interest in Some Ancient Enemies

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Recent research also shows a link between papillomavirus and cervical cancer, which annually strikes 15,000 women in the U.S. The human papillomavirus (HPV) family is a large one, including 46 types capable of causing everything from common plantar warts (HPV-1 and 4) to choking growths in the throat (HPV-11) to a bizarre warty rash found almost exclusively on the hands of butchers and meat handlers (HPV-7). So far, six types of HPV, all responsible for benign genital lesions, have also been associated with malignant cervical growths. Says Dr. Harald zur Hausen of the German Cancer Research Center in Heidelberg: "At least 80% of all cervical cancers are linked to papilloma."

But infection with these viruses does not always lead to malignant growth. In fact, that happens infrequently. Explains M.I.T. Biologist Nancy Hopkins: "Cancer arises from a number of insults to the DNA. Viruses are one insult. They start the process rolling." Years usually elapse between infection and the development of a related cancer. When liver cancer strikes a hepatitis carrier, for example, it generally does so 30 to 50 years after the victim was first infected. These long delays, Zur Hausen observes, "suggest the need for other events besides infection to occur in order to progress to cancer."

Several such events or "co-factors" have been suggested in the papillomavirus-cervical cancer connection. They include smoking (which appears to increase risk of this cancer fourfold), poor hygiene and concurrent infection with the herpes simplex virus type 2. Says Dr. Carlos Lopez of the Centers for Disease Control: "Maybe one virus is the instigator and the other is the promoter."

A growing amount of evidence suggests that whenever viral infection leads to cancer or chronic disease, some sort of breakdown or weakness of the immune system plays a contributing role. For instance, organ-transplant patients whose immune systems have been suppressed by antirejection drugs have a greatly increased risk of developing virus-related malignancies. "There is a very intimate relationship between viruses and immunity," says Dr. Thomas Merigan of Stanford's school of medicine. "If our immunity is a little deficient for one reason or another, then we are more likely to have progressive disease."

This may be true of AIDS. One of the great mysteries surrounding the disease is why only some of those infected get sick while others have carried the virus in their cells for several years and have so far remained healthy. Dr. Jay Levy, an AIDS researcher at the University of California, San Francisco, cites the possible role of other infections, use of drugs, poor nutrition, stress and lack of sleep, any of which may weaken the immune system. "If the person's immune system is not compromised by such events," he says, "I believe they will be able to fight off the virus and not develop the disease."

Other researchers have their doubts. They point out that although the immune systems of most AIDS victims make antibodies to the virus, the antibodies do not seem to halt the progression of the disease. There are several apparent explanations: