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  3. The realization that colds can kill has renewed interest in finding vaccines and treatments. The trouble is that the common cold

The realization that colds can kill has renewed interest in finding vaccines and treatments. The trouble is that the common cold

admin2015-10-20  58
问题     The realization that colds can kill has renewed interest in finding vaccines and treatments. The trouble is that the common cold is caused not by one virus but by hundreds of different ones. This means a vaccine or drug that works a-gainst one of these viruses, or one family of viruses, is usually ineffective against all the others. What’s more, because colds are usually so mild, if treatments cause even minor side effects they can be worse than the disease. Such treatments will never get approval for general use, which is why most companies instead focus on drugs that relieve symptoms.
    Nevertheless, some drugs and vaccines are being developed against the cold viruses most likely to turn nasty. A vaccine against Respiratory Syncytial Virus(RSV), a virus which can cause serious illness in young children and the elderly, is going through clinical trials. It consists of a weakened strain of the virus given as a nasal spray.
    A treatment for RSV infections, based on RNA interference, is also in development. However, treatments for specific viruses are useless unless your cold is caused by the virus in question—and doctors have no quick way to work out which virus is to blame for a cold. Systems to do this are under development, mostly based on looking for specific DNA or RNA sequences, but none are near to reaching the market.
    An alternative approach would be to keep taking drugs that prevent infection throughout the cold season, such as a derivative of the anti-smallpox drug cidofovir which has been shown to combat adenoviruses, viruses that can cause upper respiratory infections. But again, as adenoviruses are only responsible for a few percent of colds, the benefits hardly justify the expense and risk of side effects from remaining on a drug permanently.
    Short of everyone on the planet isolating themselves for two or three weeks, so existing cold viruses run out of hosts and die out, it is hard to see how we can ever defeat the common cold. Even then, new cold viruses would evolve in time from animal viruses. Some even question whether it is desirable to try to eliminate colds. "It’s blind speculation," says Joel Weinstock of Tufts University in Boston in the US, "but the common cold may protect us from more serious viruses." An occasional sniffle might be a price worth paying if it keeps our immune defenses primed.
It could be inferred from the third paragraph that
选项 A、specific DNA or RNA sequences are developed to detect the viruses.
B、it is not a quick way to look for DNA sequences.
C、systems to detect viruses are working to enter the market.
D、treatments for some specific virus are successful.
答案D
解析 推理判断题。根据题干定位到第三段。其中讲到治疗特定病毒的药物丝毫不起作用。除非感冒是由被怀疑病毒所致，故D项正确，表示针对某些特定病毒的治疗是有效的。
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