Prokaryotes, Eukaryotes, & Viruses Tutorial
Viruses
Basic characteristics of viruses
Simply stated, viruses are merely genetic information surrounded by a protein coat. They may contain external structures and a membrane. Viruses are obligate intracellular parasites--meaning that they require host cells to reproduce. In the viral life cycle, a virus infects a cell, allowing the viral genetic information to direct the
synthesis of new virus particles by the cell.
There are many kinds of viruses. Those infecting humans include polio, influenza, herpes,
smallpox, chickenpox, and human immunodeficiency virus (HIV) causing
AIDS.
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Biology and AIDS
Recent studies show that having low virus levels allow longer life (Science 272, 1124 (1996))
Molecular studies of HIV have led to developing drugs that interfer with viral
biology. Taking a combination of three drugs, indinavir, zidovudine, and
lamivudine caused 85% of patients to have no detectable virus in their blood.
Data being collected will show if these and other drugs will make AIDS
treatable.
Note that that since 1981, there have been 2.5 million deaths by AIDS and 20-40 million deaths by malaria.
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Revised: November 8, 1999
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