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Every fall, you need a new flu shot. That’s because today’s vaccines² train your immune system to recognize specific strains of flu, indentified by two proteins on the virus’s coat, / and /. That’s where the H and N come from in H1N1.

Problem is those proteins are moving target. They mutate quickly. Once they do, your immune system can’t recognize them, and you’ve got something like the 2009 swine flu. A strain the flu shot never primed us to fight.

To make a more universal vaccine¹ that would work year after year, researchers focused on a smaller, more stable protein, called M2. In human’s strains, the protein has hardly changed since 1930s.

Researchers engineered the M2 vaccine and gave it to mice. Then they exposed the mice to lethal³ dose of human, swine and bird flu. All the vaccinated⁴ mice survived, their unlucky counterparts did not. The research appears in journal Molecular⁵ Therapy.

A good seasonal⁶ flu vaccine will still beat the M2 vaccine, but if the M2 give us insurance against a surprise strain, well, it might be worth a shot.

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收听单词发音

1 vaccine
n.牛痘苗，疫苗；adj.牛痘的，疫苗的
参考例句：
The polio vaccine has saved millions of lives.脊髓灰质炎疫苗挽救了数以百万计的生命。 She takes a vaccine against influenza every fall.她每年秋季接种流感疫苗。

2 vaccines
疫苗，痘苗( vaccine的名词复数 )
参考例句：
His team are at the forefront of scientific research into vaccines. 他的小组处于疫苗科研的最前沿。 The vaccines were kept cool in refrigerators. 疫苗放在冰箱中冷藏。

3 lethal
adj.致死的；毁灭性的
参考例句：
A hammer can be a lethal weapon.铁锤可以是致命的武器。 She took a lethal amount of poison and died.她服了致命剂量的毒药死了。

4 vaccinated
[医]已接种的，种痘的，接种过疫菌的
参考例句：
I was vaccinated against tetanus. 我接种了破伤风疫苗。 Were you vaccinated against smallpox as a child? 你小时候打过天花疫苗吗？

5 molecular
adj.分子的；克分子的
参考例句：
The research will provide direct insight into molecular mechanisms.这项研究将使人能够直接地了解分子的机理。 For the pressure to become zero, molecular bombardment must cease.当压强趋近于零时，分子的碰撞就停止了。

6 seasonal
adj.季节的，季节性的
参考例句：
The town relies on the seasonal tourist industry for jobs.这个城镇依靠季节性旅游业提供就业机会。 The hors d'oeuvre is seasonal vegetables.餐前小吃是应时蔬菜。