在艾滋病爆发中心试验疫苗

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在艾滋病爆发中心试验疫苗康纳•梅沃尔德（CONOR MYHRVOLD） 研究人员将在南非的一个地区测试4个实验疫苗，那里五分之一的成年人被感染了HIV。一个国际研究联盟计划于2014年开始在南非的一个省测试4种新的艾滋病疫苗。那里是世界上艾滋病感染率最高的地区之一。

哈佛医学院的教授布鲁斯•沃克（Bruce Walker）是夸祖鲁-纳塔尔省（KwaZulu-Natal）德班市（Durban）一家本月即将建成的研究机构的创始科学家之一。而对新疫苗的检测也将在那里进行。沃克说，为了测试一些疫苗所付出的不同寻常的努力几乎立即可以反映出找到预防HIV感染方法的难度。

夸祖鲁-纳塔尔省五分之一的成年人携带HIV。在那里，对疫苗的希望“让我们非常有效地进行疫苗试验，非常有效地得到答案，”沃克说。因为感染率极高，也许只要短短两年，就能知道某种疫苗是否有效。

沃克估计，只需要200个接受所有四种疫苗的病人，就能发现每种疫苗能否提供保护。“同样的研究在泰国也许需要16000个病人，因为那里的发病率要低很多，”沃克说。“你需要大约90到100个病人才能知道疫苗是否会有影响。”

目前已经有三次HIV疫苗的大规模试验，但是没有一次试验在保护人们不受感染上获得成功。几次大的失败出现在2003年，2007年和2009年，药物公司赛诺菲（Sanofi）制造的疫苗在16000个志愿者参与的研究中被发现无效。

“在我们的领域，实际上只测试过三种不同的[疫苗]概念，而且每次我们或多或少地结束一个概念，然后开始另外一个，”沃克说，“我们的计划是平行而非依次朝前推进。”

一般来说，疫苗的作用原理是将死去或减活病毒，或是病毒表面特异的分子注射到人体内。这样会教会免疫系统识别并攻击这些微生物。研发HIV疫苗已被证实非常困难，因为HIV这种逆转录病毒可以迅速突变，并逃避疫苗的保护效果。

沃克提到了4个即将进入测试阶段的疫苗。其中一个是利用改造过的金丝雀痘病毒（canarypox virus）表达HIV的两个表面蛋白，这是根据病毒弱点的计算研究选出的。另外一个蛋白被扭曲以模拟HIV的形状。还有和遗传物质一起包装的脂质纳米颗粒制成的合成疫苗，这也是新的待测疫苗中最不同寻常的一个。沃克相信合成疫苗相对其他疫苗，可以更快地获得管理机构的批准，而且一旦最初结果不好，也更容易被修改。

在发达国家，因为反转录病毒药物能抑制病毒和预防艾滋病，所以HIV感染已经很大程度上变成了可治的疾病。但在非洲，这些药物被证实过于昂贵，很难得到广泛应用。

利用药物，“我不认为就能治好目前的大流行，”沃克警告说，他还是波士顿的疫苗研究中心拉根研究所（Ragon Institute）的主任。拉根研究所已经收到了超过1亿美元的研究经费和捐献资助，目前正有效地领导全球的HIV疫苗测试。

根据联合国艾滋病规划署（UNAIDS program），全球超过3000万人携带艾滋病病毒，每年有100万人死亡，大部分出现在像南非这样的地方。南非的艾滋病案例占全世界的17%。沃克表示，仅南非的流行规模，就足以成为1亿美元疫苗花费的理由。“类似艾滋病的疾病会袭击处于生命壮年期的人们，给整个社会带来的危害非常巨大，”他说。“母亲死了，孩子就成了孤儿。这些问题还会持续恶化。”

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HIV Vaccines to be Tested at the Disease's Epicenter
Researchers will test four experimental vaccines in a region in South Africa where one in five adults is infected with HIV.
By Conor Myhrvold on October 9, 2012


An international research consortium plans to begin testing four new HIV vaccines in 2014 in a province of South Africa where the infection rate is among the highest in the world.
The unusual effort to test several vaccines nearly simultaneously reflects the difficulty of finding a way to prevent HIV infection, says Bruce Walker, a Harvard Medical Scho­­ol professor and one of the founding scientists of a new research center opening this month in Durban, in KwaZulu-Natal province, where the tests will occur.


More than a fifth of KwaZulu-Natal's adult population carries HIV, and basing the vaccine effort there "allows us to very efficiently do vaccine trials and very efficiently get answers," says Walker. Because the infection rate is so high, it could take as little as two years to determine if a given vaccine works.
Walker estimates that only 2,000 patients will need to receive each vaccine to discover whether it offers protection against the virus. "The same study in Thailand might take 16,000 patients, because the incidence is so much smaller," says Walker. "You figure you need about 90 to 100 infections in your cohort to see if there's an impact."
There have been three large tests of HIV vaccines so far, but none succeeded in protecting people from becoming infected. Major disappointments came in 2003, 2007, and 2009, when a vaccine manufactured by drug firm Sanofi showed inconclusive results in a study involving 16,000 volunteers.
"We as a field have only ever actually tested three different concepts [for vaccines], and each time we've sort of finished one concept and then started another one," says Walker. "Our plan is to take things forward in parallel and not in sequence."
Vaccination typically works by inoculating people with dead or attenuated forms of a virus, or with specific molecules present on the virus's surface. That teaches the immune system to recognize and attack the microörganism. Developing a vaccine against HIV, a retrovirus, has proved difficult because it can mutate quickly and evade the protective effects of a vaccine.
Of the four new vaccines Walker says will enter testing, one is a canarypox virus engineered to express two surface proteins of HIV, which were chosen based on computational studies of the virus's weaknesses. Another is a protein that's been twisted to mimic HIV's shape. The most unusual of the new candidates is a synthetic vaccine made from fatty nanoparticles packed with genetic material. Walker believes a synthetic vaccine could get regulatory approval more quickly than others, and might be easier to alter if the initial results are disappointing.
In developed nations, HIV infection has become a largely treatable condition because of anti-retroviral drugs, which can suppress the virus and prevent AIDS. In Africa, however, those medications have proved too expensive and difficult to use widely.
"I don't think we can treat our way out of this epidemic" with drugs, warns Walker, who is also director of the Ragon Institute, a vaccine research center in Boston that has received more than $100 million in grants and donations (see "Three New Initiatives") and now effectively directs HIV vaccine tests globally.
According to the United Nations' UNAIDS program, over 30 million people worldwide carry HIV, and a million die from it each year, mostly in places like South Africa, which has more than 17 percent of the world's HIV cases. Walker says the size of the epidemic in South Africa alone is reason enough to spend $100 million on a vaccine. "The damage to society in general from a disease like this, that hits people in the prime of their lives, is just enormous," he says. "A mother dies and a child is orphaned. These problems just continue to swell."

嘟利6

内容很丰富，希望能早日攻克HIV

樵夫

艾滋病的问题确实需要全人类共同努力攻克，我国也在相关的领域做了大量的研究，http://www.aids.org.cn/

琪琪5

路过学习了，谢谢老师的分享