New Clues About AIDS

Among the mysteries of the AIDS epidemic is why certain people seem to be less susceptible than others. Why do the sex partners of some AIDS patients remain free of infection? Why are Africans more likely to contract the disease than American heterosexuals?

Two new reports yield some clues. Anthony Pinching and colleagues at St. Mary's Hospital Medical School in London found evidence of a genetic factor in AIDS vulnerability. They examined blood samples from more than 200 individuals for a protein called group-specific component, which has three genetically determined variants. People with one Gc type seemed to be protected against AIDS infection; those with another type had a high incidence of AIDS.

A study led by Thomas Quinn of the National Institutes of Health suggests a link between AIDS susceptibility and the presence of other infections. Both Africans and homosexual American males were found to have higher levels of antibodies against syphilis, hepatitis B, herpes and four other microbes than did U.S. heterosexuals. Those high levels of exposure apparently cause a "chronically activated" immune state, which may increase vulnerability to AIDS.