When exposed to high levels of human immunodeficiency virus (HIV), the cells from the lining of the mouth can develop a low-level infection, according to research from Charles R. Drew University and the University of California, Los Angeles published in the March 2003 issue of the Journal of Virology.
In the study, the researchers tested the ability of HIV to infect oral mucosal cells known as normal human oral keratinocytes (NHOK) in the test tube. They found that when exposed to high concentrations of the virus, the cells established a low-level, productive infection that could subsequently transfer to activated lymphocytes.
“Human saliva contains several types of anti-HIV activity that may help protect an individual against a small virus inoculum. However, if individuals are exposed to inocula containing a heavy viral load, it is conceivable that the oral epithelium could be infected and thus serve as a beachhead for HIV-1 infection,” say the researchers.
Editorial comment
Several recent studies have suggested that the risk of HIV transmission through oral sex is low, but health educators have consistently proposed that the risk of contracting HIV through oral sex may be increased if:
- semen comes into contact with damaged tissue in the mouth
The findings published in the Journal of Virology shed further light on how HIV transmission may occur under the second and third conditions.
Although the findings explain how HIV transmission might occur in some cases, they do not alter the basic message widely supported by health educators around the world: oral sex carries less risk of HIV transmission than unprotected anal or vaginal intercourse.
Further information on this website
Factsheet on oral sex and HIV transmission
Oral sex has near-zero HIV risk according to new San Francisco study - news story Nov 2002
References
Liu X, et al. Human immunodefiency virus type 1 infection and replication in normal human oral keratinocytes. Journal of Virology, 77: 3470-3476, 2003.