HIV病毒会规避人体免疫系统 疫苗开发艰难
HIV病毒
日、英、美等国科学家报告称，开发艾滋病毒(HIV)疫苗可能比想象中更加困难。因为HIV不仅会对抗病毒药产生抗性，而且会进化产生规避人类免疫系统的方法。相关论文2月25日在线发表于《自然》(Nature)杂志。
之前有科学家曾在单个患者身上研究过HIV进化与人类免疫系统之间的交互作用，结果发现，携带人类白细胞抗原(HLA)某些突变的人能更有效地控制HIV的感染。
美国国立癌症研究所从事病毒进化研究的Colm O'hUigin认为，过去的研究仅为揭示这些谜团开启了“一小扇窗口”。他说：“此次的研究则不同凡响，因为它提出了一种长期的观点，即HLA正开始在人群中塑造病毒。”
新研究在来自9种人群、共2875名HIV感染者身上检查了HLA突变体与HIV之间的交互作用。研究人员最初聚焦的是已知能减轻患者感染的HLA-B51，但研究人员发现，在携带HLA-B51的患者身上，HIV发展了一种“逃避突变”，能够规避HLA-B51的保护效应。
研究人员发现，具有HLA-B51的HIV感染者中96%体内都存在这种逃避突变。在HLA-B51常见的区域，逃避突变也很常见，表明HIV正在进化规避免疫系统。对另外13种逃避突变的研究也显示了相同的模式。
既然HIV能够设法规避人类免疫系统，那么很可能它也能规避相关疫苗。因此，O'hUigin表示，针对HLA能够识别的病毒抗原位(epitope)的疫苗“最初可能会收到效果，但病毒很快将会适应疫苗策略，并开始形成独特形态规避疫苗”。
不过，论文作者之一、美国哈佛大学、MIT及麻省陆军总医院(MGH)联合组建的Ragon艾滋病研究所主任Bruce Walker强调，这一结果可能并不像它看起来那么可怕。他说：“乍一看，你会想，噢，天哪，这太糟糕了。但在另一方面，随着病毒的改变，这有可能为疫苗暴露了其它的靶标。”他同时表示，病毒的一些区域较少发生突变，当这些区域发生突变时，病毒会变得较为“虚弱”，所以我们有可能鉴别并标靶这些区域。
他说，总体来说，这一研究强调了，我们需要在世界范围的人口中追踪HIV，而不能仅仅限于美国国内，“它帮助解释了为什么HIV在世界不同的地方存在如此的差异，因为它不得不适应不同的世界”。
Source: Internet 2009-02-27
HIV virus
Japan, Britain, the United States scientists reported that the development of HIV (HIV) vaccines may be more difficult than expected. HIV antiviral drugs because not only will generate resistance, but will also circumvent the evolution of human immune system. Related papers online February 25, published in "Nature" (Nature) magazine.
Before scientists have had in a single study in patients with HIV evolution and human interaction between the immune system, was found to carry human leukocyte antigen (HLA) certain mutations in people can more effectively control the HIV infection.
The United States National Cancer Institute study of virus evolution Colm O'hUigin think, past studies only reveal these mysteries to open a "window of one small fan." He said: "The research is extraordinary, because it presents a long-term view that the HLA is beginning to shape the virus in the crowd."
New study from nine kinds of people, a total of 2875 HIV-infected persons who examined the HLA mutant with the interaction between HIV. The researchers initially focused are known to reduce infection in patients with HLA-B51, but the researchers found that, in carrying the HLA-B51 patients, HIV has developed a kind of "escape mutants", be able to circumvent the HLA-B51 protective effect.
The researchers found, with HLA-B51 HIV-infected persons in 96% of the body are to avoid the existence of such mutations. HLA-B51 in common areas, escape mutation is also common, indicating that the evolution of HIV is to circumvent the immune system. The other 13 kinds of escape mutation study has also shown a similar pattern.
Now that HIV can try to evade the human immune system, then it could probably also be able to circumvent the relevant vaccine. Therefore, O'hUigin said that for HLA can recognize virus antigen epitopes (epitope) of the vaccine "may receive the initial effect, but the virus will quickly adapt to the vaccine strategy, and began to take shape a unique form of circumvention of the vaccine."
However, the author of the thesis, Harvard University, MIT and Massachusetts General Hospital of the Army (MGH) to form the United Ragon AIDS Institute Director Bruce Walker stressed that the results may not be so terrible as it looks. He said: "At first glance, you would think, Oh, my God, this is a bad thing. But on the other hand, as the virus changes, which may have exposed other vaccine target." He also said that virus in some regions fewer mutations, when mutations in these regions, the virus will become more "weak", so we may have to identify and target these areas.
He said that the whole, this study emphasizes the importance, we need to track the worldwide population of HIV, and not merely confined to the United States, "It helps explain why HIV in different parts of the world places such differences exist, because it have to adapt to a different world. "
