Word: infectivity
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...tend to worry a lot more about the health hazards of anal sex than oral. Everybody knows, after all, that it's much easier for the virus that causes AIDS to cross the lining of the rectum than to infect someone through the mouth. Or is it? The surprising results of a study on rhesus monkeys published last week in Science not only suggest otherwise but also underscore how little scientists know about how, at the microscopic level, HIV spreads from one person to the next...
...study, scientists from Boston's Dana-Farber Cancer Institute and Tulane University tried to infect 15 sedated monkeys with SIV, the simian cousin of the AIDS virus. To simulate oral sex, researchers dribbled an SIV solution onto the tongues of seven animals. Then, for comparison, they carefully placed SIV in the rectums of eight other monkeys. Much to their surprise, they found that it took less of the viral solution to infect a monkey orally than rectally--6,000 times less...
...believed to stimulate viral replication. In fact, the virus is missing so much of this particular gene--known as nef, for negative factor--that it is hard to imagine how the gene could perform any useful function. And sure enough, while the Sydney virus retains the ability to infect T cells--white blood cells that are critical to the immune system's ability to ward off infection--it makes so few copies of itself that the most powerful molecular tools can barely detect its presence. Some of the infected Australians, for example, were found to carry...
...scientists are enthusiastic about testing the proposition by injecting HIV--however weakened--into millions of people who have never been infected. After all, they note, HIV is a retrovirus, a class of infectious agents known for their alarming ability to integrate their own genes into the dna of the cells they infect. Thus once it takes effect, a retrovirus infection--unlike those of viruses that cause measles, smallpox and any number of other diseases--is permanent. While some retroviruses are benign, others can strike without warning. Some remain hidden for years, only to trigger disease later in life when...
...Patten and the British government realize that a more independent legislature would be a powerful bulwark against Chinese political interference after the takeover. And perhaps they hope that a bit of democracy can find its way into the China-bound cash flow. If Hong Kong's capitalist ideals can infect the mainland, why can't democratic ones...