HIV may spread through oral sex

Recent laboratory studies of mouth tissue suggest that unprotected oral sex does have the potential to transmit HIV but it is still less risky than other routes of transmission. The results of this study has helped researchers understand how HIV is transmitted and suggested that even oral tissue that is intact, without any tears or sores, can become infected with HIV under the right circumstances.Researchers from the University of Medicine and Science in Los Angeles, California obtained oral tissue samples from over 50 healthy, HIV-negative patients and exposed the tissue to three different subtypes of HIV.They found that two of the types could infect and reproduce within cells called keratinocytes that line the surface of the mouth and that these cells can then transfer the infection to adjacent white blood cells. However, the level of infection in the mouth cells was much lower than that seen in white blood cells, approximately one-fourth to one-eighth lower. The researchers said that HIV is able to get into keratinocytes, but it reproduces less than it would in blood cells because saliva contains an HIV inhibitor. Under certain circumstances keratinocytes are able to release the virus to blood cells, which proliferate much faster than keratinocytes. Thus, the transfer of the infection from keratinocytes to white blood cells may provide a 'foothold' for HIV in the body. In the study, the researchers examined three receptors found on cells that HIV uses to latch onto and infect cells. The receptors they looked at did not include CD4, a receptor found on white blood cells that is the most common target of HIV. No exchange of infected bodily fluids is absolutely safe, but kissing has been shown to be of no risk, and oral sex is of much lower risk than the other traditional factors known to spread HIV. However, research is necessary to determine if the laboratory results mimic what actually happens in a living patient.