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Scientists Discover 'Natural Barrier' to HIV

By RobotGod     Mar 5, 2007 in Health
Researchers have discovered that cells in the mucosal lining of human genitalia produce a protein that "eats up" invading HIV -- possibly keeping the spread of the AIDS more contained than it might otherwise be.
Even more important, enhancing the activity of this protein, called Langerin, could be a potent new way to curtail the transmission of the virus that causes AIDS, the Dutch scientists added.
Langerin is produced by Langerhans cells, which form a web-like network in skin and mucosa. This network is one of the first structures HIV confronts as it attempts to infect its host.
But they did observe that Langerin is able to scavenge viruses from the surrounding environment, thus preventing infection. And since in general all tissues on the outside of our bodies have these cells, they think that the human body is equipped with an antiviral defense mechanism, destroying incoming viruses.
This is fascinating news and as the doctor in the article states It may explain part of the relative inefficiency of HIV in being transmitted. Though HIV has killed an estimated 22 million people since it was first found over 25 years ago, it is actually not very good at infecting humans. An example would be, the human papillomavirus (HPV), which causes cervical cancer, and is nearly 100 percent infectious. That means that every encounter with the sexually transmitted virus will end with an infection.
"On the other hand, during one episode of penile-vaginal intercourse with an HIV-infected partner, the chance that you are going to get HIV is somewhere between one in 100 and one in 200," Laurence said.
Experts had wondered why HIV is relatively tough to contract, compared to other pathogens and this would explain why.
When HIV comes in contact with genital mucosa, its ultimate target -- the cells it seeks to hijack and destroy -- are immune system T-cells. However T-cells are far away (in lymph tissues), so HIV uses nearby Langerhans cells as "vehicles" to migrate to the T-cells.
After looking more closely at the interaction of HIV and Langerhans cells, they found that the cells "do not become infected by HIV-1, because the cells have the protein Langerin on their cell surface. Langerin captures HIV-1 very efficiently, and this Langerin-bound HIV-1 is taken up (like eating it) by the Langerhans cells and destroyed."
In essence, Geijtenbeek said, "Langerhans cells act more like a virus vacuum cleaner."
They found that only in certain circumstances, such as when levels of invading HIV are very high, or if Langerin activity is particularly weak -- are Langerhans cells overwhelmed by the virus and then infected.
Talk about making progress. This is amazing news. I can't wait to see more on this. This could be the very key that people have long hoped for. By minipulating these cells they should be able to make great strides.
More about Discover, Barrier, HIV