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　　Each year, scientists work to develop a unique influenza¹ vaccine² to protect people against the strain expected in the coming flu season. Mutations in the virus mean that last year's vaccine probably won't protect against this year's flu variety. Now, a team of U.S. scientists think they're on track to developing a "universal" vaccine that will protect people against all kinds of influenza.
每年，科学家们都根据下一个流感季节的流感类型预测来研发一种专门的流感疫苗。流感病毒不断发生变异，去年的流感疫苗很可能无法对抗今年的流感类型。现在，一些美国科学家正在研发一种广谱疫苗，帮助人们预防任何类型的流感。
The standard flu vaccine causes the body to produces antibodies, which target parts of the virus that frequently mutate. But in a new study, researchers used a vaccine aimed at a different part of the virus.
典型的疫苗可以促使人体产生抗体，抵御病毒经常发生变异的那部分。现在，在一项新的研究中，研究人员使用了一种针对病毒不同部分的疫苗。
"There are parts of the flu virus that could be the target of what we would hope eventually could be a universal influenza vaccine," said Gary Nabel, who heads the U.S. government's Vaccine Research Center at the National Institute of Allergy³ and Infectious Diseases of the National Institutes of Health and was the study's lead author.
美国国家卫生院所属国家过敏及传染病研究所的疫苗研究中心主任盖瑞·内伯尔说：“流感病毒中有些部分是我们的突破口，我们希望最终能够研发出一种广谱疫苗。病毒的这部分不会变异。”
"They don't mutate, and the reason they don't mutate is that if they try to, the virus can't survive if you have mutations in these sites."
To get at these non-mutating parts of the virus, Nabel and his colleagues used a two-step vaccination⁴ process, called "prime-boost." The first step uses a bit of influenza DNA⁵ to get the patient's immune system to begin fighting off the flu, and then the protection is given a "boost" some time later by the second step, which can be either another bit of DNA or a conventional flu vaccine.
为了在病毒中分离这种“非变异”成分，内伯尔和他的同事们使用一个两步接种过程。第一步是使用少量流感NDA，使病患的免疫系统开始与流感对抗。稍过一阵，再采取第二步，通过再使用少量流感DNA或者一般的流感疫苗，来加强抵御能力。
In his paper, which was published online by the journal Science, Nabel describes the results of animal tests in ferrets and mice using the 1999 vaccine for the boost.
内伯尔的研究报告发表在《科学》杂志网络版上。他介绍了用1999年的疫苗在白鼬和老鼠身上进行试验的结果。
"The antibodies that we were able to elicit⁶ could neutralize⁷ [varieties of flu virus] as far back as 1934 and as recently as 2007. So it really gave a broad coverage⁸ against a range of seasonal⁹ viruses that wouldn't be covered by the traditional flu vaccine," he said.
“我们分离出来的抗体，能够抑制1934至2007年间各种流感的病毒。因此，它的确可以作用于传统疫苗无法抑制的多种季节性流感。”
Preliminary phase one tests of this new type of flu vaccine have already started in humans, but in an interview, Nabel said that even if all goes well, it will still be years before a universal flu vaccine is widely available.
新疫苗第一阶段的初步试验已经在人体进行。但是，内伯尔表示，即使一切顺利，也还需要几年的时间，才能推广这种广谱流感疫苗。
"So it's certainly not going to be with us in anything less than three years, and I think it's more likely that we're in a five to ten year time frame."
“3年之内肯定还不行。我想大概应该是5年至10年的样子吧。”
Gary Nabel of the U.S. Vaccine Research Center points out that his universal flu vaccine would have another benefit. A DNA-based vaccine wouldn't have to be grown in chicken eggs, doing away with the time-consuming and finicky manufacturing process of the current flu vaccine.
内伯尔说，广谱流感疫苗还有另外一个好处。一种以遗传因子为基础的疫苗，不必像传统疫苗那样在鸡蛋里培养，所以避免了费时且费神的制造过程。