Treatment for Dengue Fever
There is no vaccine to prevent dengue and no specific medicine to treat it, so the only defense is eradication of the mosquitoes that carry it and measures to protect people from mosquito bites.
But hope is offered by research being carried out at the Southwest Foundation for Biomedical Research in San Antonio, which relies on very special mice.
The small white animals with pink eyes are kept in a special isolated room so that they will not be exposed to any bacteria or germs that might infect them. They have been altered to be susceptible to human diseases.
Lead researcher Rebecca Rico-Hesse says the mice have been modified or humanized by an infusion of stem cells taken from human umbilical cords that were discarded at local hospitals. We have basically reconstituted the human immune system in these mice and it is only because they have these immune system cells that they can get infected and show symptoms of dengue fever, she said.
By infecting these humanized mice with strains of the dengue virus, investigators can study how the disease takes hold and what factors might cause the more serious and often deadly dengue hemorrhagic fever.
A recent report co-authored by Rico-Hesse and her colleague Javier Mota shows for the first time why some strains of dengue virus are more severe than others. In this report, we present results of eight different virus strains and we show that the ones that have been associated with the more severe epidemics and the ones that cause hemorrhagic fever in patients are actually of a specific genetic variant, she said.
Lab workers infect the mice artificially with the virus, keeping precise records of how much virus and what type of virus is used. But natural transmission of dengue by mosquitoes involves certain proteins the insects inject into the skin, something that Rico-Hesse says is missing when mice are artificially infected in the lab.
If you are just, you know, injecting it in with a syringe, you are missing out on all those salivary gland factors and all the things that happen during a natural infection that might either speed up the infection rate or decrease the infection rate. And we also need to know how many mosquitoes it takes to infect a humanized mouse, she said.
Rico-Hesse and her colleagues are breeding mosquitoes in the laboratory to test various strains of the dengue virus transmitted to the mice by mosquitoes.
Although effective vaccines or antiviral drugs for dengue may still be a long way off, researchers here say they are making important steps that they hope will one day minimize the suffering and death caused by the illness
1.Which statement is correct according to Paragraph 1
A.Dengue fever can be eradicated by mosquitoes.
B.Strong effect of certain medication can cure dengue fever.
C.By killing all the mosquitoes in the world, we can prevent dengue fever.
D.Scientists have invented a vaccine that can prevent dengue fever
正确答案:C
解析:问题问的是：根据第一段，正确的是哪一项?第一段中提到，没有疫苗和药物能预防或治愈登革热，只有消灭所有携带病毒的蚊子才能防止被感染。由此可见，C选项正确
2.The special mice used in the lab test
A.have red eyes.
B.are kept in an ordinary open room.
C.are put in the room with lots of mosquitoes.
D.have been altered so that they can easily infected by human diseases
正确答案:D
解析:问题问的是：试验中用到的特别的老鼠是怎样的?A选项错误，第三段第一句提到老鼠眼睛是粉色的;B选项错误，第三段提到，老鼠被置于特殊的与病菌隔离的房间里，与选项中说的普通的开放的房间矛盾;C选项错误，文中提到老鼠体内的病菌是研究人员注射植入的，老鼠并没有与蚊子放在一起。而D中的easily infected正是第三段最后一句中susceptible的同义词，意为易感染的。因此，D正确
3.According to the report, the virus strains that cause the more severe dengue and hemorrhagic fever are actually
A.of a specific genetic variant..
B.from a special mosquito.
C.invented in the lab.
D.killable with a specific genetic variant
正确答案:A
解析:问题问的是：能够导致更加严重的登革热和出血热的病毒株实际上是什么?第六段最后一句中提到这两种病毒株其实是属于同一种基因变异体。因此选A。容易引起混淆的是D选项，其中提到了特殊变异体，只是该选项的意思是说病毒可以被病毒的特殊变异体杀死，显然不对。注意killable，是kill和able组成的合成词，意为可杀死的
4.Which statement is true according to the passage
A.Lab workers inject into the mice the fever virus with a syringe .
B.The umbilical cords used in modifying the immune system of the mice are from live humans.
C.The artificial infection of virus has exactly the same effect as the natural one.
D.Rico-Hesse and her colleagues are raising mosquitoes as their pets.
正确答案:A
解析:问题问的是：关于短文，哪个观点是正确的?文中第八段第一句就提到了A中的观点，其中的it实际上就是指the virus，也就是病毒。B中说改变老鼠免疫系统式脐带来自活人，这与原文中提到的来自医院不要的脐带不符，注意discard一词意为丢弃C中说人工植入的病毒与蚊子植入的病毒效果完全相同，而文中说的是人工植入的病毒缺乏唾液腺的因素，达不到自然植入的病毒的效果;D中说养蚊子做宠物显然与原文中研究蚊子直接对老鼠传播的病毒引发的登革热的说法不符
5.What is the authors attitude to the future of the researchers work
A.Optimistic.
B.Pessimistic.
C.Objective.
D.Sarcastic
正确答案:C
解析:问题问的是：作者对该项研究的前景持何种态度?纵观全文，作者始终非常客观的叙述试验的细节及进展情况，包括最后对前景的展望都是引用研究人员的原话。因此，他的态度应该是客观的。C选项正确