English 中文網 漫畫網 愛新聞iNews 翻譯論壇
    中國網站品牌欄目(頻道)
    當前位置: Language Tips > Normal Speed News VOA常速

    Scientists seek HIV vaccine using monkey model

    [ 2012-09-18 10:57] 來源:中國日報網     字號 [] [] []  
    免費訂閱30天China Daily雙語新聞手機報:移動用戶編輯短信CD至106580009009

    Get Flash Player

    Download

    Traditional vaccine methods have been unsuccessful in preventing infection by HIV, the virus that causes AIDS. New techniques are being studied to boost antibodies or other parts of the immune system. But researchers are also working on a method to keep the immune system constantly on guard against HIV.

    There are two traditional methods for creating a vaccine. One uses a weakened or attenuated version of a live virus to generate an immune response. The other uses a dead virus. Both methods are proven safe and effective, except when it comes to HIV. Vaccine candidates using these methods simply have not been successful in people when it comes to the AIDS virus.

    “HIV has been a very difficult target for a vaccine for a variety of reasons. It’s designed to evade the immune response by evolution,” said Dr. Louis Picker, associate director of Oregon Health and Science University.

    While attempts to make an HIV vaccine from a dead virus have failed, Picker said, using a weakened virus holds clues and possibilities when used in primates.

    “The live attenuated approach actually was shown to work 20 years ago. But the problem with it was the live attenuated vaccines that actually worked were actually still pathogenic. So they weren’t safe and they could not be moved into humans. This was demonstrated in the non-human primate models – monkey model of AIDS using the virus SIV,” he said.

    SIV stands for simian immunodeficiency virus.

    “These SIVs that were attenuated, that prevented subsequent infection with the full pathogenic virus, still could cause disease. And people found that if you attenuated them anymore, they didn’t work anymore,” he said.

    Picker and his colleagues wanted to understand why the weakened virus offered protection from infection. But at the same time, they needed to prevent it from itself causing disease. They found the answer has to do with T cells, which attack viruses. The weakened, but persistent virus vaccines somehow caused T cells to be ever vigilant. But if the virus was weakened too much, the T cells were not triggered to attack. They concluded that an “effective HIV vaccine might have to persist in the body.”

    Picker said, “The unique aspect of the live attenuated vaccines that seem to work was that they were persistent. They weren’t cleared by the host immune system, but they were able to stick around. Of course in the case of HIV/SIV that’s a bad thing, because eventually those live attenuated vaccines would gain strength and cause disease. But probably the fundamental reason, at least what I hypothesized, that they would be able to elicit protection was because of that persistence.”

    So, they looked for another persistent virus that was not pathogenic, which might generate T cell immune response.

    “The virus that we selected was a virus called cytomegalovirus (CMV), which is actually a virus from a different family of viruses altogether, but it’s one that most people in the world are infected with. But it’s unique in that you can re-infect these people with a virus that now has within its genes HIV genes and then the body would make immune responses to those HIV genes,” he said.

    The HIV genes that would be placed in the harmless virus, he said, would not cause disease.

    “When they’re introduced into the vaccinee, the immune response recognizes these HIV bits as if they’re part of CMV and raises immune response to it,” he said.

    That’s the plan, anyway. The difficult part is making a version of the vaccine that’s safe and effective for humans. That requires an approved vaccine candidate and years of clinical trials.

    Meanwhile, in Thailand, a follow-up study is getting underway of the RV 144 vaccine candidate. Several years ago, a study showed that it did indeed provide some measure of protection against HIV, but not enough, being only 31 percent effective. A clinical study called RV 305 will use the same vaccine components as RV 144, but will attempt to boost and extend the immune response through antibodies.

    相關閱讀

    Tensions rising again over Iran's nuclear program(視頻)

    Mideast protests spark debate over free speech, religion(視頻)

    The Occupy Movement turns one

    American's first exchange students from China

    (來源:VOA 編輯:Julie)

     
    中國日報網英語點津版權說明:凡注明來源為“中國日報網英語點津:XXX(署名)”的原創作品,除與中國日報網簽署英語點津內容授權協議的網站外,其他任何網站或單位未經允許不得非法盜鏈、轉載和使用,違者必究。如需使用,請與010-84883631聯系;凡本網注明“來源:XXX(非英語點津)”的作品,均轉載自其它媒體,目的在于傳播更多信息,其他媒體如需轉載,請與稿件來源方聯系,如產生任何問題與本網無關;本網所發布的歌曲、電影片段,版權歸原作者所有,僅供學習與研究,如果侵權,請提供版權證明,以便盡快刪除。
     

    關注和訂閱

    人氣排行

    翻譯服務

    中國日報網翻譯工作室

    我們提供:媒體、文化、財經法律等專業領域的中英互譯服務
    電話:010-84883468
    郵件:translate@chinadaily.com.cn
     
     
    亚洲av成人无码久久精品| 大地资源中文第三页| 最近高清中文字幕免费| 国产av永久无码天堂影院| 亚洲一区日韩高清中文字幕亚洲| 久久久久成人精品无码| 无码免费一区二区三区免费播放| 天堂新版8中文在线8| 亚洲成?Ⅴ人在线观看无码| 久久久久亚洲AV无码网站| 无码人妻一区二区三区一| 久久人妻无码中文字幕| 久久伊人中文无码| 国产精品无码无卡在线播放| 免费无码又爽又刺激网站直播| 亚洲AV中文无码乱人伦下载| 亚洲精品无码99在线观看| 久久久久久久人妻无码中文字幕爆 | 亚洲AV无码乱码在线观看牲色| 人妻少妇乱子伦无码视频专区| 伊人久久无码中文字幕| 欧美亚洲精品中文字幕乱码免费高清 | 一本久中文视频播放| 中文字幕人成人乱码亚洲电影| 久久精品无码一区二区三区免费| 久久午夜无码鲁丝片| 亚洲AV日韩AV永久无码绿巨人| 中国无码人妻丰满熟妇啪啪软件| 最近中文字幕高清免费中文字幕mv | 亚洲AV无码1区2区久久| 亚洲精品无码MV在线观看| 国产成人综合日韩精品无码不卡| 合区精品中文字幕| 中文字幕精品无码久久久久久3D日动漫 | 免费无码中文字幕A级毛片| 亚洲AV无码久久精品成人| 亚洲一区爱区精品无码| 亚洲2022国产成人精品无码区| 无码人妻少妇色欲AV一区二区| 久久久久亚洲精品无码蜜桃| 极品粉嫩嫩模大尺度无码视频|