Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: WEDNESDAY, December 15, 1993 TAG: 9312150038
SECTION: NATIONAL/INTERNATIONAL PAGE: A-6 EDITION: METRO
SOURCE: Associated Press
DATELINE: WASHINGTON LENGTH: Medium
The tests, when they reach the market, should help doctors monitor the effects of AIDS treatment and also may provide earlier diagnosis of AIDS infections, particularly in newborns.
Widely used tests available since the mid-1980s reveal only the presence of AIDS antibodies, which are the body's reaction to an AIDS infection. But those tests do not directly detect HIV, the AIDS virus.
Two new generations of tests are under development, both based on greatly streamlined versions of polymerase chain reaction, a sophisticated lab technique that expands tiny amounts of genetic material so it can be easily detected. The technique has been used in sophisticated research to search for the HIV virus in humans.
The AIDS virus, unlike most other forms of life, carries its genes as RNA rather than DNA, both of which are acids found inside cells and help produce the proteins that build and regulate the body.
To make new copies of itself, the AIDS virus first must convert its genes from RNA into DNA and then stitch them into the genetic material of infected blood cells.
Furthest along are tests that will spot viral genes that have become part of blood cells this way. These tests, which look for viral DNA, will reveal whether or not someone is infected with the AIDS virus.
The latest innovation, outlined at a scientific meeting Tuesday, are tests that reveal viral RNA. The tests will spot genes that are inside the virus but are not part of cells' genetic machinery. Developers say this gives them a way to assess the quantity of individual viruses inside the body.
The most sensitive of these tests discussed at the meeting was developed by Roche Molecular Systems of Alameda, Calif. Dr. John Sninsky of Roche said their test is only slightly more complicated than the antibody tests that are already broadly used to test blood samples for AIDS exposure.
Both tests may be useful for diagnosing infections in their earliest stages. For instance, they may be able to reveal soon after an accidental AIDS exposure, such as a hospital needle injury, whether someone is infected.
Other potential uses include testing babies born to infected mothers and pinning down whether infection actually exists in adults who have gotten ambiguous results from antibody screening.
by CNB