艾滋研究新进展：HIV新疫苗&ARV治疗对异性恋间的传播的预防作用

iavjssssmqee · 发表于 2011-5-13 20:04:03

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本帖最后由 iavjssssmqee 于 2011-5-13 20:05 编辑

Unusual AIDS Vaccine Shows Promising Results in Monkeys

A new study gives a much-needed booster shot to the beleaguered AIDS vaccine field. The experiment, led by immunologist and pathologist Louis Picker of the Oregon Health & Science University in Beaverton, showed that an unusual approach to vaccinating against SIV (a simian cousin of HIV) protected 12 of 24 monkeys from a “challenge” with a particularly virulent strain of that virus. Specifically, all monkeys became infected, but in half of the animals, their immune systems drove the virus down to undetectable levels for more than a year.

“It’s the best result I’ve seen against the worst SIV known,” says the University of Wisconsin’s David Watkins, an immunologist who tests AIDS vaccines in monkeys and was not involved with the work. “I’m very excited by this approach.”

The vaccine contains SIV genes stitched into cytomegalovirus (CMV), a herpesvirus that harmlessly infects many humans and serves as the delivery vehicle, or vector, for the AIDS virus proteins. Typically, AIDS vaccines use vectors that quickly die, but CMV stays alive indefinitely and constantly confronts the immune system with the mock version of the enemy. As a result, Picker contends, the immune system stays on high alert and can respond to an attack by SIV much more quickly. “The whole game changes when you talk about early interception of the virus,” he says.

AIDS researchers have long debated which specific immune responses correlate with protection, and this study—published online today in Nature—is reigniting that discussion. Picker contends that a novel type of T cell response plays a critical role in why the vaccine works, but others find the evidence for that less than compelling. “I’m not sure what the protective mechanism is in these experiments,” Watkins says.

Most vector-based AIDS vaccines train what are known as central memory T cells to recognize the virus. Upon a real infection, these cells expand and mount an attack. But, Picker says, “it’s too late and too little to handle [AIDS] viruses.” With the CMV vector, monkeys developed high levels of so-called effector memory T cells, which do not go through an expansion phase and remain ready to do battle at all times. Other experiments suggested that these cells were key and that only CMV rouses them. Picker’s team vaccinated monkeys with a variety of vectors bearing SIV genes, but none of them triggered effector memory cells. Monkeys receiving these other vaccines and challenged with the same highly pathogenic SIV (known as mac239) handled the virus little better than control animals that did not receive any vaccine. “Our vaccine is completely different than all the other vaccines and works completely differently,” Picker says.

Picker suspects that the monkeys that received CMV vaccines but failed to control the challenge virus did not generate high enough levels of effector memory cells in their tissues. He’s looking for ways to augment the effector memory response and would like to combine the CMV vaccine with one that elicits antibodies against SIV and, ultimately, HIV.

Currently, Picker’s team has no plans to move the vaccine into human studies because of safety concerns about CMV. The virus causes no harm in healthy people and is widespread, infecting nearly half of the U.S. population and more than 90% of people in sub-Saharan African and India. Still, it can hurt fetuses, leading to vision and hearing loss as well as mental retardation, and, in an ironic twist, can cause blindness in immune-deficient children and adults who have diseases like HIV infection. Picker’s group is now trying to make a weakened CMV that cannot cause disease under any circumstance. “We’re fairly far along on it,” he says. “But we’re going to have to prove that it’s safe and still protective.”

http://news.sciencemag.org/scien ... y-preve.html?ref=hp

iavjssssmqee · 发表于 2011-5-13 20:06:47

HIV Treatment Dramatically Prevents Heterosexual Transmission

A multicountry study has found that HIV-infected people who start antiretroviral (ARV) treatment at earlier stages of the disease lowered their risk of transmitting the virus to their sexual partners by 96%. The results have major policy implications and “add yet again to the armamentarium of data that indicate the multifaceted benefits of early treatment,” said Anthony Fauci, head of the U.S. National Institute of Allergy and Infectious Diseases (NIAID), which sponsored the 6-year study.

NIAID, which spent $73 million on the trial, had planned to fund it for another 4 years, but an interim analysis by an independent monitoring group led the institute to pull the plug early and announce the results. Run by the HIV Prevention Trials Network (HPTN) at 13 sites in nine countries, the study recruited 1763 couples (97% heterosexual) in which only one partner was infected with the AIDS virus at the start. None of the HIV-positive people had taken ARVs, and all had CD4 counts that ranged from 350 to 550 per milliliter (normal is above 600). Half the participants received immediate treatment, and the other half did not start ARVs until their CD4 count dropped to 250 or they developed an AIDS-related symptom. Everyone received free condoms, safe sex counseling, and treatment for other sexually transmitted diseases.

The interim analysis found that 39 people had become infected, and 28 cases were linked by genetic tests to their regular partners. Of those 28, all but one had a partner in the group that waited to start treatment. Earlier observational studies had shown a similar impact of ARVs reducing sexual transmission in heterosexual couples, but this was the first to demonstrate the prevention power of the drugs in a randomized, controlled clinical trial. “This applies exclusively to heterosexual couples,” cautioned Mike Cohen, a researcher at the University of North Carolina, Chapel Hill, who headed the so-called HPTN 052 study. Cohen noted that they had hoped to include men who have sex with men in the study, but few volunteered to participate.

Although the finding was largely expected—ARVs, after all, reduce the level of HIV in infected people—the prevention power of the drug was greater than the study designers initially anticipated, and policymakers hope it will have a major impact. “It’s information that is not really taking me by surprise, but it’s a game-changer in the AIDS response,” says Michel Sidibé, who heads the Joint United Nations Programme on HIV/AIDS. Sidibé says the results should help put to rest debates about the worthiness of spending money on ARVs as prevention when only one-third of the 15 million HIV-infected people in the world who need treatment for their own immediate health have access to drugs. “The divorce between treatment and prevention is not real,” he says. “Treatment can reduce the number of new infections, which can increase the value of treatment.”

Current treatment guidelines issued by the World Health Organization call for offering treatment to everyone at CD4 counts of 350 or below. Most guidelines in developed countries recommend starting treatment between 350 and 500, but in reality, people who have health insurance or their own money can start at any CD4 count. Sidibé says he hopes the new results will compel pharmaceutical companies to lower the price of ARVs as the demand for the drugs expands. He also anticipates that new partnerships will form to advocate for increased funding and that the findings will be prominently discussed next month at the United Nations High Level Meeting on AIDS in New York City.

But some HIV/AIDS advocates question whether the world will respond appropriately to this good news. Matthew Kavanagh, director of U.S. advocacy for Health GAP (Global Access Project) in Washington, D.C., notes that the U.S. government’s PEPFAR program—which supplies about half the ARVs to people in developing countries—has no plans to scale up. “It’s crazy to me that we’re hearing out of PEPFAR and other places there is not a strategy to roll this out,” Kavanagh says. “The U.S. could be stepping up and saying, 'We have an amazing finding and let’s galvanize the world around this.' ”

Kavanagh notes that the Global Fund to Fight AIDS, Tuberculosis and Malaria—which provides the other half of HIV treatment for the poor countries—also has far less money than it needs. “If there’s not a renewed emphasis that, at all costs, we have to scale up treatment for both life-saving and prevention benefits, we’re going to see a reversal of fortunes and we’ re not going to be able to make use of what the science is telling us,” he says.

http://news.sciencemag.org/scien ... monkeys.html?ref=hp

g655462635 · 发表于 2011-5-14 23:00:46

看着有点蒙啊 ~~~~~

visisi · 发表于 2011-5-15 11:20:47

哪位大侠翻译一下，看的我头疼，好长时间没看英文字母了。

ranhua008 · 发表于 2011-7-21 09:33:27

\(^o^)/需要时间慢慢看看

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[分享] 艾滋研究新进展：HIV新疫苗&ARV治疗对异性恋间的传播的预防作用

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