14 DAY TRIAL // Oral sex is regarded as safe, both against unwanted pregnancies and sexually transmitted diseases; moreover the unbearable condom is no longer necessary. But after researchers have recently discovered that the human papillomavirus (HPV), a germ that causes cervical (uterine) and throat cancer, can be transmitted through oral cancer, the real bomb has come right now: HIV, the dreadful plague of the 21st century, can use the same entrance to the human body.
The deadly virus can be transmitted through the tonsils. The discovery could also have an impact on preventing HIV from being transmitted from infected mothers to their children through breastfeeding.
A team led by Niki Moutsopoulos at the National Institute of Dental and Craniofacial Research in Bethesda, Maryland, US, investigated gum tissues taken from eight patients.
By employing specially designed antibody molecules, the team identified the level of several proteins within these mouth tissues. About 12% of the tonsil cells were positive for the protein CD4, located on the surface of immune cells that are particularly vulnerable to HIV infection, while less than 4% of the gum cells displayed this protein.
Genetic analysis showed that the CXCR4 gene, encoding a protein that determines vulnerability to HIV in immune cells, was 11 times more active in the tonsils than in the gum samples. Tonsils were much more susceptible to HIV infection than other mouth areas, like the cheek lining and mouth floor.
"The new findings provide biological data to complement clinical and epidemiological evidence suggesting that HIV can - in exceptional cases - spread through oral sex. It's a further piece of the jigsaw puzzle," John Greenspan, director of the AIDS Research Institute at the University of California in San Francisco, US told New Scientist.
HIV transmission by oral sex seems to be less likely than in the case of vaginal sex. Experts give a chance of 1 infection for 2,500 oral sex exposures, while 1 out of 200-1000 vaginal sex contacts can result in infection.
Still, researchers point to the use of condoms for safe oral sex and a tonsillectomy (tonsils removal) would significantly minimize the risk.
"I think that would be a stretch. We can't go taking out every tissue that HIV could pass through. If future studies bear out a link between tonsils and HIV transmission, there could be implications for blocking the spread of the virus from mother to child in parts of the world where infant formula and antiretroviral drugs are in short supply. "said Moutsopoulos.
"Some scientists have started investigating whether probiotic treatments - which promote the growth of healthful bacteria - might reduce the transmission of HIV to very young children through the oral cavity and gastrointestinal tract." said Greenspan.
"The tonsils - which were removed routinely up until the late twentieth century - are now seen as a first line of defense in the immune system, alerting the body to potentially dangerous foreign particles," warns Mousopolous.