‘Gene Probe’ AIDS Test Seen in 2 Years
A newly developed “gene probe” may be available in two years to detect the presence of an active AIDS virus long before signs of the disease become evident, scientists report.
Using synthetically produced genes, researchers at Cetus Corp. in Emeryville have manufactured a highly responsive probe that hones in on the virus and quickly reveals its presence.
“A gene probe is a stretch of DNA that is complementary to a region on the genes you’re looking for,” said bioengineer Fred Faloona who helped develop the system that tags the AIDS virus with radioactive phosphorus.
The synthetic probe attaches itself to specific sites on genes that exist only inside the core of the AIDS virus and reveals the virus to scientists.
“With this kind of technique you have to label the probe with something radioactive or with chemicals that emit color or fluorescence so that the genes you’re looking for will show up, allowing them to be easily detected,” he said.
Tested Only in Lab So Far
So far researchers at the biotechnology firm have only tested the new detection system in the laboratory using AIDS-infected human cells.
They predict that the method will eventually replace the sometimes inaccurate AIDS antibody tests currently used by hospitals and blood banks when screening people for blood donations.
Faloona said that, because the test reveals “the chromosomal DNA of the virus,” it is a much more accurate measure of detecting the deadly virus.
“Antibody tests just reveal the presence of proteins mounted in response to infection,” Faloona explained, adding that such tests cannot reveal whether the AIDS virus is active in a person who has positive evidence of the proteins.
The antibody tests currently are the only method available to doctors who must test and inform people who are at risk. Sometimes people with active AIDS viruses in their systems fail to show any antibody activity at all, Faloona said.
Wide Variation of Proteins
He added that the picture has been complicated by the wide variation of AIDS viral proteins with each culture dish showing different protein structures when the virus is examined under the microscope.
But Faloona said that, by using computer programs to compare the plethora of possible protein segments produced by the virus, researchers were able to identify sequences that showed no change whatsoever inside the viral core.
