Human saliva may contain unidentified substances that help prevent the AIDS virus from infecting white blood cells. Researchers at the National Institute of Dental Research in Bethesda, Maryland, combined saliva from healthy volunteers with blood cells and the virus. None of the cells became infected, a finding that is in keeping with evidence of how AIDS spreads: Though some studies have found minute levels of the virus in the saliva of AIDS patients, there has never been a case reported of a patient who contracted the disease through kissing or through other contact with saliva.
