Detection of proviral sequences in saliva of patients infected with human immunodeficiency virus type 1

Single samples of saliva collected from 20 human immunodeficiency virus type I (HIV-1) seropositive patients were tested by the polymerase chain reaction for HIV-1 proviral sequences using primers from the long terminal repeat (LTR), gag, and env regions of the virus. Proviral sequences were detected in the saliva of 50% of the patients. Sequential samples of saliva, collected at four different times, from each of six additional patients led to the detection of proviral sequences in 100% of the patients. Since, however, the detection of HIV-1 required not only the highly sensitive polymerase chain reaction, but also multiple samples, it appears that under ordinary circumstances infected cells are present in saliva in low numbers. Although this may explain the lack of transmission of HIV-1 by casual contact through the salivary route to household members and health-care workers, the presence of infected cells in the saliva of a high percentage of patients argues for avoidance of sexually intimate situations involving prolonged and repeated contact with saliva.