Medicine: AIDS Research Spurs New Interest in Some Ancient Enemies

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In addition to causing AIDS and flu, viruses have brought the scourges of smallpox, yellow fever and polio. They bear responsibility for many of the familiar rashes of youth -- chicken pox, measles, rubella -- as well as such disparate disorders as the common cold, gastroenteritis, herpes, shingles, warts and mononucleosis. Viruses are known to cause at least one form of human cancer and are prime suspects in several other kinds of malignancies. Just last week Dr. Robert Gallo of the National Cancer Institute in Bethesda, Md., announced that he and his team had isolated a new virus that may cause certain kinds of lymphoma and may even play a role in a chronic fatigue illness that seems to strike adults. One prominent virologist, Dr. William Haseltine of Harvard's Dana-Farber Cancer Institute, ventures that "at least 25% of human cancers are caused by viruses." Viruses may even initiate so- called autoimmune diseases by tricking the immune system into attacking its own body tissue.

For all their malevolence and mischief, viruses may have played an important, perhaps crucial, role in evolution. And now, as recombinant DNA technology advances, molecular biologists are engineering viruses that may ! soon benefit rather than devastate humans.

Stripped of their harmful genes, viruses are becoming the stuff of safe and potent vaccines. And within the next few years, scientists hope to gain federal approval to conduct gene therapy. Their goal: the use of viruses as "vectors" to carry healthy genes to the chromosomes of people with genetic diseases, genes that may permanently cure them.

Mankind has long been familiar with the ravages of viruses, if not the creatures themselves. Dried pustules on the mummified face of Ramses V testify to the fact that smallpox killed even the mighty in Egypt 3,000 years ago. In the 16th century, Spanish conquistadors may have unknowingly used viruses in a primitive form of germ warfare; they apparently supplied their intended victims, the Aztecs and the Incas, with blankets taken from houses with smallpox in Europe. Viruses helped cause a fiscal crisis in 17th century Holland, where infections of tulip bulbs produced a new variety of the flower with spectacular, rippling patterns of color. The government was unable to control the resulting speculation, which threatened the economy before tulipomania, as it became known, died down.

Although the agents of all these infections remained a mystery, the first safe vaccine against a viral disease was developed in the 18th century by Edward Jenner, a doctor in rural England. Jenner noticed that farmhands who contracted cowpox, a mild disease related to smallpox, did not develop the more deadly disease. In 1798 he inoculated a boy with material from a milkmaid's cowpox sore, then demonstrated that the lad had developed immunity to smallpox.

It was not until the late 19th century, the "golden age of bacteriology," that scientists began to suspect the existence of some kind of infectious agents even smaller than the bacteria that were clearly visible through their microscopes.