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流感特效药可能失效？26 August 2004 /sciencenow.scie
26 August 2004 /sciencenow.sciencemag.org
日本一个小规模的针对儿童流感的研究发现，流感病毒可以轻而易举的骗过相应特效药。这篇论文在8月28号的The Lancet上发表时，一些国家正储存着一批这种特效抗病毒药用来防止流感在全国范围的流行。但流感研究者声称没必要停止储备这种药，因为它还能起一定作用。
最近一次全球范围的流感大流行，在1918年的西班牙导致5000万人丧生。去年冬天在亚洲导致24人丧生的高治病性的H5N1鸟流感病毒如果发生变异，出现人－人传播型，将导致另一场流感全球大流行。由于研制相应抗病毒疫苗需要6个月，当流感全球范围爆发时，抗病毒药将被投放到抗病毒战场第一线。虽然病毒对老一代药物会产生抗药性，但对新一代抗病毒药唾液酸苷酶抑制剂似乎没那么容易，这种药的靶点是病毒生成蛋白质外壳时需要的一种酶。所以一些国家已经开始储备这种药物，比如oseltamivir（商品名是Tamiflu）。
美国联邦流感流行计划相关负责人透露，他们已经储备足够的oseltamivir足以应付100万病人，这个计划包括提高疫苗产量的相应步骤，以及州和地方卫生保健部门的应急方案。
但The Lancet有文章提示流感病毒对oseltamivir产生抗药性的能力比我们想象的容易。日本东京大学的滤过性病原体学者Yoshihiro Kawaoka和同事们在日本和美国两地做了流感的抽样调查，观察50个儿童服用oseltamivir5天后的情况。其中18％，即9个儿童体内的病毒发生突变而对oseltamivir产生抗药性。
Kawaoka说那倒也不能说明抗病毒药就没用了，他还在University of Wisconsin, Madison任职。他说在某些病例，病毒发生抗药性突变可能反而会降低其治病性。在一个附属出版刊物上，即纽约市Anne Moscona of Mount Sinai School of Medicine 有消息说与oseltamivir同一级别的另一类叫zanamivir的药可能相对较不容易产生抗药性。
而且the University of Michigan, Ann Arbor的病毒专家Arnold Monto 说鸟病毒并不一定那么容易产生抗药性。Monto现供职于一个国际委员会，该委员会在今年8月13号Weekly Epidemiological Record上建议储备唾液酸苷酶抑制剂。Monto更是呼吁由政府负责进行药物储备工作。
Influenza Virus Evades Key Drug
A small study of children with flu in Japan finds that the influenza virus can outwit a drug that was thought to be relatively foolproof. The paper, published in the 28 August issue of The Lancet, comes as some countries are stockpiling the same antiviral drug against a flu pandemic. Flu researchers say there's no need to stop stockpiling, however--the drugs should still prove useful.
The last major global influenza pandemic, the 1918 Spanish flu, killed 50 million people. Another big pandemic could be in the works if the highly virulent H5N1 avian flu, which killed at least 24 people in Asia last winter, assumes a form that can be transmitted from person to person. Because preparing a vaccine against such a virus could take 6 months, antiviral drugs would be the first line of defense against pandemic flu. Although the flu virus can develop resistance to some older drugs, newer drugs called neuraminidase inhibitors, which target an enzyme that makes a flu virus coat protein, have seemed more impervious. So some countries have begun stockpiling one of these drugs, oseltamivir (sold as Tamiflu).
The United States is among them, according to a federal pandemic flu plan released today. The United States has stored enough oseltamivir to treat 1 million people, officials said. The plan also describes steps to increase vaccine manufacturing capacity and how state and local health care providers should respond.
The Lancet report, however, suggests that flu virus develops resistance to oseltamivir more readily than was thought. Virologist Yoshihiro Kawaoka of the University of Tokyo and colleagues in Japan and the United States collected virus samples from 50 children taking a 5-day course of oseltamivir for a flu episode. In nine samples, or 18% of the children, the virus developed mutations that made it resistant to the drug.
But that doesn't mean antivirals won't work against a pandemic, says Kawaoka, who is also at the University of Wisconsin, Madison. For one, the changes that make a virus resistant to oseltamivir may make it less pathogenic, he says. In an accompanying editorial, Anne Moscona of Mount Sinai School of Medicine in New York City notes that another drug in this class, zanamivir, may be less prone to becoming resistant.
Moreover, adds flu expert Arnold Monto of the University of Michigan, Ann Arbor, avian flu strains won't necessarily become resistant to oseltamivir as easily. Monto, who serves on an international committee that recently recommended stockpiling neuraminidase inhibitors in the 13 August Weekly Epidemiological Record, concludes: "The message for most of us is, governments should stockpile."
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作者:admin@医学,生命科学 2011-03-05 17:23
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