Breakthrough in HIV research

Our old friend cholesterol is making medical news again - but this time it has nothing to do with clogged arteries, too much butter, or whether or not eggs are good for you - probably. Researchers at Johns Hopkins University have discovered that cholesterol is crucial for human immunodeficiency virus (HIV) entering and exiting cells.

And of what use is this information in everyday life? Dr. James Hildreth, a member of the research team at Johns Hopkins who made the discovery, explained that cholesterol plays a key role in the biology of the virus. "The most important implication of this discovery is that we can affect the virus's ability to infect," he said.

Like some other viruses, HIV works by stealing proteins from the cell membrane. This allows the virus to bind to many other types of cells, increasing its ability to infect. As it turns out, there is a naturally occurring molecule called cyclodextrin that will remove cholesterol from the virus - it also removes cholesterol from cells. When you expose HIV to this molecule, HIV loses cholesterol and loses its ability to infect.

Scientists are now developing vaginal and rectal creams that contain cholesterol depleting compounds that will, if used before sex, prevent the sexual transmission of HIV. "As there is no vaccine on the immediate horizon, microbicides that can remove cholesterol from cell membranes, rendering HIV noninfectious, may play an important part in controlling the AIDS pandemic," said Dr. Hildreth.

Currently, 39.4 million people are estimated to be living with HIV/AIDS worldwide: 2.2 million of those are children under the age of 15. Since 1981, HIV/AIDS has claimed over 20 million lives.

While the discovery of cholesterol's role in HIV infection, and the subsequent development of chemical condoms - microbicides creams - is extremely good news, it could be argued that the availability of traditional condoms has not managed to stem the increase of HIV infection because people do not always use them. In fact the rate of HIV infection continues to increase, with the most profound rise being among women, so what good will a cream do? Creams or cervical rings containing microbicides would not only chemically prevent infection during intercourse, they could be applied before intercourse, rather than during intercourse, which is when the use of a latex condom is typically initiated.

More people, particularly women who may be reluctant to bring out condoms during intercourse, or who may not have any say in how sex is practiced, may be inclined to use a cream they could apply possibly hours or days in advance.

"One of our primary motivations is to empower women, who have no say over how sex is practiced, to protect themselves," Dr. Hildreth said. "The real challenge for the people who are developing the microbicides is to develop something that is not only safe, but would also be imperceptible. In other words, neither partner would necessarily know that it's there. That would be the ideal chemical condom. We also want to develop something that has a long cycle of protection."

So far experiments in mouse models with human immune systems show that cyclodextrin in saline solution applied to the vagina before the HIV is injected into the vagina, provides more than 90% protection.

"It has great promise," said Dr. Hildreth. "We are very encouraged that with the right formulation and studies, we can create a safe and effective microbicide." A microbicide cream may be available within the next 3 years.

Of course, the question that springs immediately to mind is - regardless of high blood pressure - should we reduce our cholesterol intake?

"We don't yet know whether or not high cholesterol levels in blood translate to high cholesterol levels in cell membrane and therefore higher sensitivity to HIV," said Dr. Hildreth. Cholesterol, in fact, enables cell membranes to transmit signals, so it is essential to a healthy, functioning body. "If people are already practicing safe sex, I don't think they should be worried about their cholesterol levels. People should be much more concerned about not practicing safe sex," Dr. Hildreth said.

So - bring on the eggs Benedict and the condoms.

The contents of this health site are for informational purposes only. Always seek the advice of your physician or other qualified healthcare provider regarding any questions you may have about a medical condition.

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