VOA标准英语2014--New Vaccine Research Aimed at Cattle Killer 新疫苗研究意在对付牧牛杀手

 

New Vaccine¹ Research Aimed at Cattle Killer² 新疫苗研究意在对付牧牛杀手

New research is underway to develop an advanced vaccine against East Coast fever – a parasitic³ disease that killed more than one-million cattle in Africa last year. Researchers say the project also could lead to better treatments for malaria⁴ and cancer in humans.

International Livestock⁵ Research Institute says East Coast fever was found in 11 African countries in 2013. It caused $300-million in losses. The Nairobi-based institute warns the disease is spreading rapidly and poses a threat to 28-million cattle.

Vish Nene says the disease is caused by a parasite⁶ that’s transmitted by a tick bite.

“East Coast fever is described as a cancer-like disease of cattle. And the reason for that is there is a huge expansion of infected white blood cells that occurs post-infection. And these infected white blood cells behave like cancer cells. So they proliferate⁷ in an uncontrolled fashion. They spread throughout the body of an infected animal. Eventually, you can get depression of immune responses.”

Nene, who heads the institute’s Vaccine Biosciences Program, said East Coast fever can eventually cause pulmonary edema -- a potentially fatal build-up of fluid in the lungs.

“The disease is very acute. It’ll kill an animal within three to four weeks of infection. All the signs and symptoms, et cetera – because of that scientists describe this as a lymphoproliferative disease. And that’s the link with human cancers,” he said. 

A lymphoproliferative disease is one in which white blood cells are produced in excessive amounts. Also, the fact it’s caused by a parasite makes East Coast fever similar to malaria.

Despite the risk it poses to millions of cattle, the disease has not received as much attention as might be expected.

“It’s a huge problem,” he said, “Part of the reason for perhaps not having a wider awareness⁹ of this disease is that it occurs only in sub-Saharan Africa. And so it hasn’t really reached the dimensions of where it’s got the attention of other people.”

There is a treatment and a current vaccine available. Both are very expensive for African farmers – eight to 12 dollars a dose. The drug must be used very early in the disease and may leave cattle weaker and less productive.

The current vaccine has been available for many years. It’s made in part by grinding up ticks infected with the parasites¹⁰.

Nene said, “It was made based on the observation that if an animal recovered from an infection it was solidly immune to reinfection. So scientists started to work on that observation and what they started to do was to deliberately¹¹ infect an animal and then treat it so that it recovered. That is the basis of what is called the infection and treatment method of immunization. And that is what the live vaccine is. That’s the current vaccine that’s being used.”

Some cattle spontaneously recover from East Coast fever, while others respond to treatment. The reason, he said, appears to be the same – killer T-cells produced by the immune system.

“These killer T-cells can identify the infected white blood cells and they kill those cells. And that is what gives rise to immunity¹².”

The International Livestock Research Institute has received an $11 million grant from the Bill & Melinda Gates Foundation to develop an advanced vaccine for the disease. Nene said that researchers hope to accomplish two things.

“In addition to the killer T-cells that I mentioned, we also know that antibodies play a role in immunity. So we have two prongs that we are trying to address. One is: can we raise a potent⁸ antibody response that protects the animal? And can we raise a potent killer T-cell response that also protects the animals? Either one alone may work -- either one alone and then both combined to see if that’s more efficacious,” he said.

If successful, Nene said, the vaccine would be cheaper, safer and much more available. And, unlike the current vaccine, would not have to be stored in extreme cold, namely liquid nitrogen.

Nene added that developing the new vaccine will take time – possibly 10 to 15 years barring any research breakthroughs. Researchers are expected to share their findings with those trying to develop a malaria vaccine and vice-versa.

Besides East Coast fever, the institute is helping¹³ to develop vaccines¹⁴ for African swine fever, goat plague, contagious¹⁵ bovine¹⁶ lung plague and Rift¹⁷ valley fever.

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 killer   

n.杀人者，杀人犯，杀手，屠杀者

参考例句：

• Heart attacks have become Britain's No.1 killer disease.心脏病已成为英国的头号致命疾病。
• The bulk of the evidence points to him as her killer.大量证据证明是他杀死她的。

3 parasitic   

adj.寄生的

参考例句：

• Will global warming mean the spread of tropical parasitic diseases?全球变暖是否意味着热带寄生虫病会蔓延呢？
• By definition,this way of life is parasitic.从其含义来说，这是种寄生虫的生活方式。

4 malaria   

n.疟疾

参考例句：

• He had frequent attacks of malaria.他常患疟疾。
• Malaria is a kind of serious malady.疟疾是一种严重的疾病。

5 livestock   

n.家畜，牲畜

参考例句：

• Both men and livestock are flourishing.人畜两旺。
• The heavy rains and flooding killed scores of livestock.暴雨和大水淹死了许多牲口。

6 parasite   

n.寄生虫；寄生菌；食客

参考例句：

• The lazy man was a parasite on his family.那懒汉是家里的寄生虫。
• I don't want to be a parasite.I must earn my own way in life.我不想做寄生虫，我要自己养活自己。

7 proliferate   

vi.激增，(迅速)繁殖，增生

参考例句：

• We must not proliferate nuclear arms.我们决不能扩散核武器。
• Rabbits proliferate when they have plenty of food.兔子有充足的食物就会繁衍得很快。

8 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。

9 awareness   

n.意识，觉悟，懂事，明智

参考例句：

• There is a general awareness that smoking is harmful.人们普遍认识到吸烟有害健康。
• Environmental awareness has increased over the years.这些年来人们的环境意识增强了。

10 parasites   

寄生物( parasite的名词复数 )； 靠他人为生的人； 诸虫

参考例句：

• These symptoms may be referable to virus infection rather than parasites. 这些症状也许是由病毒感染引起的，而与寄生虫无关。
• Kangaroos harbor a vast range of parasites. 袋鼠身上有各种各样的寄生虫。

11 deliberately   

adv.审慎地；蓄意地；故意地

参考例句：

• The girl gave the show away deliberately.女孩故意泄露秘密。
• They deliberately shifted off the argument.他们故意回避这个论点。

12 immunity   

n.优惠；免除；豁免，豁免权

参考例句：

• The law gives public schools immunity from taxation.法律免除公立学校的纳税义务。
• He claims diplomatic immunity to avoid being arrested.他要求外交豁免以便避免被捕。

13 helping   

n.食物的一份&adj.帮助人的，辅助的

参考例句：

• The poor children regularly pony up for a second helping of my hamburger. 那些可怜的孩子们总是要求我把我的汉堡包再给他们一份。
• By doing this, they may at times be helping to restore competition. 这样一来, 他在某些时候,有助于竞争的加强。

14 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。

15 contagious   

adj.传染性的，有感染力的

参考例句：

• It's a highly contagious infection.这种病极易传染。
• He's got a contagious laugh.他的笑富有感染力。

16 bovine   

adj.牛的；n.牛

参考例句：

• He threw off his pack and went into the rush-grass andand munching,like some bovine creature.他丢开包袱，爬到灯心草丛里，像牛似的大咬大嚼起来。
• He was a gentle,rather bovine man.他是一位文雅而反应迟钝的人。

17 rift   

n.裂口，隙缝，切口；v.裂开，割开，渗入

参考例句：

• He was anxious to mend the rift between the two men.他急于弥合这两个人之间的裂痕。
• The sun appeared through a rift in the clouds.太阳从云层间隙中冒出来。