AIDS therapies and vaccines Treating the Virus There are several
reasons why AIDS is difficult to treat. HIV is a retrovirus (a
virus made up of ribonucleic acids, or RNA, instead of
deoxyribonucleic acids, or DNA). All retroviruses use a special
enzyme, called reverse transcriptase, to copy their genetic
material directly into a host cell. HIV is lytic, meaning that
it kills the cells it invades. The virus can then become
inactive for long periods of time. Researchers are trying to
learn how and why the virus reactivates. Treatment must either
kill the virus or stop it from multiplying. The ideal treatment
would kill the virus without harming the HIV host cells.
Developing such an antiviral drug is extremely difficult,
because viruses use a cell's own genetic machinery to reproduce.
This makes it hard for scientists to distinguish between viral
and host cell protein molecules. In 1984 scientists began
testing more than 300 drugs to learn their effectiveness against
HIV. The researchers knew that a good drug