英语六级阅读备考：快速阅读练习(7)_大学英语阅读

英语六级阅读备考：快速阅读练习(7)

　　Health authorities are focusing on prevention as a key method to limit the spread of the epidemic. Educational programs preach abstinence from sex, monogamy and safer sex using condoms, as ways to protect against infection. Many countries give away free condoms and offer needle exchange programs to try and limit transmission among injecting drug users. Microbicides in the form of creams that prevent transmission of HIV may soon offer another method of protection.

　　A vaccine, as an alternative method to prevent HIV infection, may still be many years away. This is partly because the virus mutates so rapidly. A vaccine may not only have to prime antibodies to attack the virus but might also need to increase T-cell production. Vaccine trial; have been undertaken in South Africa, Kenya, the US and Thailandthough most have yet to yield promising results. Controversial vaccines made from the blood of HIV carriers, have been tested is Nigeria and Thailand.

　　Anti-retroviral Cocktails

　　There is no cure for AIDS, but a range of drugssome of which have unpleasant side-effectsare available to slow its progress. Other drugs are used to treat opportunistic infections or AIDS symptoms Even some herbal treatments have been investigated.

　　Most anti-HIV drugs aim at stalling viral replication. Nucleoside analogues such as AZT and also non-nucleoside reverse transcriptase inhibitors , attack the action o! the viral enzyme reverse transcriptase. This prevents it from creating functional DNA which would otherwise integrate into the DNA of infected cells.