Scientists are planning to use human immunodeficiency（免疫缺陷)virus（HIV), one of mankind's most feared viruses, as a carrier of genes which can fight cancer and a range of diseases that cannot be cured. The experts say HIV has an almost perfect ability to avoid the body’s immune（免疫的)defenses, making it ideal for carrying replacement genes into patients' bodies, according to the Observer.
A team at the California-based Salk Institute, one of the world's leading research centers on biological sciences, has created a special new breed of HIV and has started negotiations with the U>S> Food and Drug Administration（FDA)to begin clinical gene therapy（治疗) trials this year. The first trials are expected to involve patients suffering from cancers that cannot be cured by surgery although project leader Professor Inder Verma said the HIV technique would have“ far wider applications”。
The plan remains very likely to cause controversy since it involves making use of a virus which has caused more than 22 million deaths around the world in the past two decades. Verma said that the idea of using HIV for a beneficial purpose was “shocking” but the fierce nature of HIV had disappeared by having all six of the potentially deadly genes removed.
Illnesses such as various cancers are caused when a gene in a patient's body fails to work properly. In the past two years, breakthroughs in genetics（遗传学)have led gene therapy scientists to try and replace the genes that do not function normally.
Unfortunately, the body's immune defenses have been known to attack the modified genes and make them lose their effects before they can start their task and progress in the field has been held up by the lack of a suitable carrier.
The HIV virus has the ability to escape from, and then destroy, the immune defense cells designed to protect our bodies and this makes it attractive to scientists as a way of secretly conveying replacement genes into patients' bodies.
16 FDA has approved the plan of using HIV to cure cancer in humans.
A Right
B Wrong
C Not mentioned
17 The idea of using HIV for a beneficial purpose has been widely accepted.
A Right
B Wrong
C Not mentioned
18 HIV can be safely used to cure cancer only if the deadly genes have been removed.
A Right
B Wrong
C Not mentioned
19 The HIV virus is an excellent warrior to fight the body's immune cells.
A Right
B Wrong
C Not mentioned
20 Other countries are also expected to begin clinical gene therapy trials soon.
A Right
B Wrong
C Not mentioned
21 It is the lack of money that has held up the progress in using replacement genes to cure cancer.
A Right医.学.全.在.线网站www.med126.com
B Wrong
C Not mentioned
22 The HIV virus has caused more deaths in developed countries.
A Right
B Wrong
C Not mentioned
答案：16.B 17.B 18.A 19.A 20.C 21.B 22.C
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