A vaccine that AIDS has had more success in monkey experiments that any other approach has never been tested in humans. The reason: Many researchers believe the vaccine based on weakened - or attenuated - live virus, would be too risky.
The International based in Chicago Now, a group of doctors involved in AIDS care, convinced that the potential benefits outweigh the risks, leads an unusual campaign to recruit hundreds of volunteers for a study this security approach. Association of Physicians in AIDS Care (IAPAC) uses a live attenuated HIV test in the August issue of his newspaper and posted a registration form for the trial on its website (www.iapac.org) . IAPAC said more than a dozen people have already stepped forward.
Ronald Desrosiers, Central New England Regional Primate Research in Southborough, Massachusetts, first showed the power of live attenuated approach in a monkey study published in science there are nearly 5 years (December 18, 1992, p. 1938). Monkeys who received the vaccine are infected later, when administered a lethal strain of SIV, simian cousin of HIV. Desrosiers has spent the last few years to eliminate various genes of SIV and HIV to find a weakened form that is as safe as possible, but still be able to protect animals against pathogenic isolates of the virus.
A live attenuated vaccine AIDS would have three potential pitfalls, however. The weakened virus is still able to replicate and can cause AIDS after, say, 30 years. It is also possible that the virus could mutate into a virulent form, although Desrosiers think that this risk can be virtually eliminated by removing enough genes. Finally, the weakened HIV would still incorporate the DNA of a host cell, which could theoretically trigger cancer.
Leading the drive to register is voluntary AIDS clinician Charles Farthing, medical director of the AIDS Healthcare Foundation in Los Angeles, California. Farthing said he hopes the trial will show that people, like monkeys, can control the replication of the virus and weakened immune comes to no harm. Yet AIDS experts say a short trial would not answer some key questions of security. "We are really concerned about what happens when you vaccinate 20 million people and 10 years later, 5% or 10% get lymphoma," said Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases. "You're not going to know [IAPAC's proposed test]."
0 Komentar