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HIV and mothers ’ milk —— As luck would have it
艾滋病病毒與母乳：真不巧
One of the proteins in milk protects infants against HIV infection
母乳中的一種蛋白質可保護嬰兒免受艾滋病病毒感染
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BAD though it has been, the AIDS epidemic would have been a great deal worse but for a strange and unexplained quirk. Infected mothers, it was feared, would transmit HIV, the AIDS-causing virus, to their children when suckling them. Mothers ’ milk carries the virus, and suckling may last two years — which is plenty of time for transmission to happen. And indeed it does, but not nearly as often as was originally suspected. Less than 10% of infants suckled by untreated infected mothers ( those not on antiretroviral drugs, which suppress the virus ’ s reproduction ) pick up HIV.
盡管情況很糟糕瞭，但是由於一種奇怪的無法解釋的現象，艾滋病的流行程度沒有更糟。很多人擔心受感染的母親會在哺乳時將艾滋病病毒傳播給自己的孩子。母乳攜帶有艾滋病病毒，哺乳期可能達到兩年，這給傳染提供瞭足夠長的時間。而事實上傳染也發生瞭，但是跟最初所懷疑的有出入。隻有不到 10% 的嬰兒會從未接受治療的母親那裡感染艾滋病 ( 未接受治療是指沒有使用抑制病毒繁殖的抗逆轉錄藥物 ) 。
Why that should be has remained mysterious. But Genevieve Fouda of Duke University, in North Carolina, and her colleagues think they have the answer. If they are right, many children have been spared AIDS by a fluke — but a fluke that could be used to develop a new weapon to attack it.
上述問題一直是未解之謎。但是北卡羅來納州杜克大學的吉納維夫 · 富達和她的同事認為他們找到瞭答案。如果他們是正確的，這意味著許多兒童僥幸逃過艾滋病，這種僥幸能用來開發一種對抗艾滋病的新武器。
Clearly, something in milk disables HIV. Previous experiments had identified proteins that do this to a certain extent, but nowhere near enough to explain all the data. Those earlier searches must therefore have missed something crucial. Dr Fouda, as she describes in the Proceedings of the National Academy of Sciences, set out to find what it was.
很明顯，母乳中的某種物質會阻止艾滋病病毒。先前的實驗確定瞭蛋白質能在一定程度上阻止艾滋病病毒，但是不足以解釋所有的數據。那麼，先前的研究肯定錯過瞭一些關鍵的東西。富達博士在美國國傢科學院院刊上表示她試圖發現錯過的東西。
Milk is a complex mixture of chemicals, so her problem was how to isolate one of them without knowing in advance which was responsible. That meant running raw milk through a series of processes, each of which divided it into smaller and smaller fractions, and testing each fraction for its HIV-neutralising quality on the way. That quality, it turns out, is concentrated in a single protein called tenascin-C. Further experiments showed that this protein disables HIV by locking onto a protein on the virus ’ s surface, and that it is as effective at doing so as antibodies generated by the immune system for that specific purpose.
牛奶是一種復雜的混合物，因此問題在於在事先不知道的情況下如何找出它們中起作用的那種物質。這意味著將生牛奶通過一系列過程，每次將生牛奶分成更小的成分，測試每個成分對艾滋病病毒的作用。使艾滋病病毒無效的特性屬於一種被稱作黏蛋白 C 的蛋白質。更進一步的實驗表明這種蛋白質通過附著在病毒表面的一種蛋白質上而阻止艾滋病病毒，效果跟免疫系統產生的抗體一樣。
This was a surprise, because tenascin-C is not an antibody, nor had it been suspected of having any antiviral function. Its known jobs are to help the development of the fetal brain and to assist in wound healing. That it is also the right shape to attach itself to HIV ’ s envelope protein seems a complete coincidence — which, indeed, it must be because AIDS is such a recent disease that evolution could not have had time to throw up a novel ( and also ubiquitous ) anti-HIV protein of this sort.
這很意外，因為黏蛋白 C 既不是抗體，也沒有任何抗病毒功能。已知的功能是幫助胎兒大腦的發育和傷口愈合。黏蛋白 C 與艾滋病病毒的信使蛋白相吻合也純屬巧合，肯定是這樣的，因為艾滋病是最近才出現的疾病，進化沒有足夠的時間產生這種新型 ( 無處不在的 ) 抗艾滋病蛋白。
Whether tenascin-C, or something derived from it, can be deployed against HIV by doctors, rather than just by nature, remains to be seen. As far as possible, infected mothers are now given antiretroviral drugs — both for their own health and for the health of their suckling infants — so Dr Fouda ’ s discovery will probably not affect them directly.
黏蛋白 C，或者它的衍生物，排除其原始性質，能否被醫生用於對抗艾滋病仍需要進一步研究。最可能的是，受感染的母親們現在接受抗逆轉錄藥物，為瞭她們自己以及孩子的健康，因此富達博士的發現可能不會對她們產生直接影響。
For the wider campaign against AIDS, however, it could be of great importance. The generals running that campaign are now shifting their approach from defence to attack, and are talking of ways to bring about an AIDS-free world. For them, a natural human protein that neutralises the virus will be interesting indeed.
然而，對防治艾滋病運動來說，這個發現可能至關重要。運動的領導者們現在改變方法，從防守變為進攻，正在討論消滅艾滋病。對他們來說，一種人類天生具有的對抗艾滋病病毒的蛋白質真的很有趣。
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