2016年12月大学英语六级模拟题及答案(7）_第4页

　　The third prong of cellular attack is a protein called integrase(整合酶), which experts say has been harder to block. Once HIV fools host cells by changing its genetic information so it can enter them, integrase acts like a cut and paste operation in a word processor, deleting an immune cell's genetic material and replacing it with its own.

　　An integrase inhibitor would give doctors a third line of attack against HIV infection, according to virologist Daria Hazuda of the division of Virus and Cell Biology at Merck.

　　"This would offer a third class of anti-retroviral medications that can be combined with reverse transcriptase inhibitors and protease inhibitors. And since it is a new mechanism of action, these compounds are active against multi-drug resistant variants. So variants that are resistant to all current therapies have been selected in HIV-patients," she said.

　　Current anti-AIDS drugs eventually become resistant to therapy, or stop working, because the virus changes its shape.

　　While researchers are encouraged by the success with the compound's effectiveness in monkey trials, developing a drug that is equally effective in humans can be difficult.

　　Steven Young is executive director of the Department of Medicinal Chemistry at Merck. He says, if scientists find a compound that is equally effective in people, the company would ask U.S. regulators to speed approval of the drug.

　　"Yeah, I really think that's what we're hoping for," he said. "I mean, we need to get data that show it has robust anti-viral effects in people. And if we're able to get that data, I think we would petition for fast track status."

　　Dr. Young says an integrase inhibitor has the potential to prevent drug resistance.

　　"To ensure our best chance of preventing resistance, we would give this as part of a cocktail therapy," he added. "And I think it's really our plan that we would test this with reverse transcriptase inhibitors and protease inhibitors, as well."

　　47. If the drug proves effective in human trials, it could enhance the effectiveness of existing AIDS drugs in ________.

　　48. What has become standard cocktail therapy?

　　49. While integrase deletes an immune cell's genetic material and replaces it with its own, it acts like ________ in a word processor.

　　50. Why would anti-AIDS drugs stop working?

　　51. According to Steven Young, if scientists get the data that ________, they would petition for fast track status.

　　Section B

　　Directions: There are 2 passages in this section. Each passage is followed by some questions or unfinished statements. For each of them there are four choices marked [A], [B], [C] and [D]. You should decide on the best choice and mark the corresponding letter on Answer Sheet 2 with a single line through the center.

　　Passage One

　　Questions 52 to 56 are based on the following passage.

　　Occasional self-medication has always been part of normal living. The making and selling of drugs have a long history and are closely linked, like medical practice itself, with the belief in magic. Only during the last hundred years or so has the development of scientific techniques made it possible for some of the causes of symptoms to be understood, so that more accurate diagnosis has become possible. The doctor is now able to follow up the correct diagnosis of many illnesses with specific treatment of their causes. In many other illnesses, of which the causes remain unknown, it is still limited, like the unqualified prescriber, to the treatment of symptoms. The doctor is trained to decide when to treat symptoms only and when to attack the cause: this is the essential difference between medical prescribing and self-medication.