THE VIRGINIAN-PILOT
Copyright (c) 1994, Landmark Communications, Inc.
DATE: Monday, August 8, 1994 TAG: 9408080053
SECTION: FRONT PAGE: A5 EDITION: FINAL
SOURCE: LOS ANGELES TIMES
LENGTH: Medium: 55 lines
The human immunodeficiency virus, like all viruses, is a wispy organism that is neither inanimate nor fully alive. Strictly speaking, viruses are not alive because they do not consume food for energy and cannot reproduce without assistance.
Viruses are simply a small bundle of genetic information encapsulated in a protective protein coat and a viral membrane stolen from the last cell they visited. They are extremely simple, containing as few as four genes or perhaps as many as a dozen, compared with the estimated 100,000 genes necessary to describe a human.
But their power is disproportionate to their size. They attack by sneaking into cells and hijacking the host's protein- and gene-producing machinery, proliferating until their sheer numbers force the cells to break open in a death spasm, freeing the newly made viruses to infect other cells and other hosts. Because viruses use a cell's own machinery to reproduce, it has been almost impossible to develop anti-viral drugs that do not kill healthy cells as well.
Sore throats occur, for example, when the influenza virus kills cells lining the throat. Paralysis occurs when the polio virus destroys muscle cells. Dementia occurs when the rabies virus short-circuits brain cells. Death occurs when the hantavirus destroys lung cells.
Although HIV shares broad characteristics with other viruses, it falls into a special category, called retroviruses, which makes it especially unpredictable and, therefore, deadly.
Viruses can have two types of genetic material, DNA or RNA. DNA viruses share the same deoxyribonucleic acid that encodes the genes of all living organisms. Most DNA viruses cause relatively harmless infections, ranging from warts to colds, but one family, the herpes viruses, causes illnesses ranging from cold sores to cancer.
Most serious diseases, including measles, mumps, encephalitis, polio, hepatitis and rabies, are caused by RNA viruses. Ribodeoxynucleic acids, which are chemically similar to DNA, are used for carrying messages inside cells of all living organisms, but in viruses they store genetic information.
HIV and other retroviruses are RNA viruses, but they are unusual because they contain an enzyme called reverse transcriptase, or RT, that makes a DNA copy of the virus's RNA genes. This DNA ``transcript'' can then be used as a pattern for making more viruses. Reverse transcriptase is the sloppy housekeeper in HIV, introducing genetic errors and then failing to correct them.
KEYWORDS: AIDS VIRUSES
by CNB