VOA标准英语2010年-Researchers Seek Genetic Clues to Dead

An international team of researchers looking for the cause of severe bacterial¹ epidemics² has deciphered the genome of group A streptococcus, a normally harmless sore throat pathogen that occasionally turns deadly.   Experts say the breakthrough could speed the development of a vaccine³ to prevent the leading cause of heart disease in children. 

The scientists mapped the genetic⁴ material of nearly 100 samples of strep-A bacteria involved in three severe epidemics in Ontario, Canada, during the past 17 years.

The focus of their interest was strep A's ability to transform itself from a relatively⁵ benign⁶ microbe into a potent⁷ pathogen responsible for the lethal⁸ disease known as necrotizing fasciitis, which causes widespread skin destruction.  It can also lead to a deadly blood infection, according to Jim Musser, co-director of the Methodist Research Institute in Houston, Texas. 

Musser says patients may be extremely sick before seeking medical help because severe strep-A infections may at first mimic⁹ other milder diseases like the flu.  Musser says lethal forms of strep A often go undetected by physicians, because such infections occur infrequently and many doctors fail to recognize them.

"Many of these patients show up at their doctor or the hospital too late in the course of their disease to be adequately treated," he explained.  "There is too much tissue destruction; the disease has progressed too far to be able to really save the patient."

Musser led the team of researchers that deciphered the genetic make-up of bacteria responsible three successive epidemics in Canada, hoping to learn the molecular¹⁰ underpinnings of the bacteria.

"This has permitted us for the first time to have a precise molecular portrait of how the organisms change over this time, which organisms have the propensity¹¹ to cause a more severe type of illness and the exact molecular changes in the pathogen that are responsible," he added.

Musser says having the bacterial genome helps researchers understand how the flesh-eating pathogen takes advantage of people who become infected with it so better diagnostics and treatments can be developed. 

Musser is hopeful the work also leads to the development of a vaccine against group-A streptococcus to prevent rheumatic fever, the leading cause of childhood heart disease in developing countries, where poverty is widespread.  Strep A causes inflammation of the heart muscle and damages the internal valves. 

According to the World Health Organization, the infection is responsible for more than three million cardiovascular deaths each year.

"Rheumatic fever, followed by rheumatic heart disease remains¹² the most common cause of preventable childhood heart disease globally," he added.  "So we really need to develop vaccines¹³ not against for rheumatic fever and rheumatic heart disease caused by streptococcus but also sore throat and the invasive disease."

An article on the genetics of aggressive streptococcus, by Methodist University's Jim Musser and colleagues, is published this week in Proceedings¹⁴ of the National Academy of Sciences.
 

1 bacterial   

a.细菌的

参考例句：

• Bacterial reproduction is accelerated in weightless space. 在失重的空间，细菌繁殖加快了。
• Brain lesions can be caused by bacterial infections. 大脑损伤可能由细菌感染引起。

2 epidemics   

n．流行病

参考例句：

• Reliance upon natural epidemics may be both time-consuming and misleading. 依靠天然的流行既浪费时间，又会引入歧途。
• The antibiotic epidemics usually start stop when the summer rainy season begins. 传染病通常会在夏天的雨季停止传播。

3 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。

4 genetic   

adj.遗传的，遗传学的

参考例句：

• It's very difficult to treat genetic diseases.遗传性疾病治疗起来很困难。
• Each daughter cell can receive a full complement of the genetic information.每个子细胞可以收到遗传信息的一个完全补偿物。

5 relatively   

adv.比较...地，相对地

参考例句：

• The rabbit is a relatively recent introduction in Australia.兔子是相对较新引入澳大利亚的物种。
• The operation was relatively painless.手术相对来说不痛。

6 benign   

adj.善良的，慈祥的；良性的，无危险的

参考例句：

• The benign weather brought North America a bumper crop.温和的气候给北美带来大丰收。
• Martha is a benign old lady.玛莎是个仁慈的老妇人。

7 potent   

adj.强有力的，有权势的；有效力的

参考例句：

• The medicine had a potent effect on your disease.这药物对你的病疗效很大。
• We must account of his potent influence.我们必须考虑他的强有力的影响。

8 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。

9 mimic   

v.模仿，戏弄；n.模仿他人言行的人

参考例句：

• A parrot can mimic a person's voice.鹦鹉能学人的声音。
• He used to mimic speech peculiarities of another.他过去总是模仿别人讲话的特点。

10 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。

11 propensity   

n.倾向；习性

参考例句：

• He has a propensity for drinking too much alcohol.他有酗酒的倾向。
• She hasn't reckoned on his propensity for violence.她不曾料到他有暴力倾向。

12 remains   

n.剩余物，残留物；遗体，遗迹

参考例句：

• He ate the remains of food hungrily.他狼吞虎咽地吃剩余的食物。
• The remains of the meal were fed to the dog.残羹剩饭喂狗了。

13 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。

14 proceedings   

n.进程，过程，议程；诉讼(程序)；公报

参考例句：

• He was released on bail pending committal proceedings. 他交保获释正在候审。
• to initiate legal proceedings against sb 对某人提起诉讼