Study Shows AIDS Virus May Be Hiding Out
Vaughan, C., Science News
Study shows AIDS virus may be hiding out
A sensitive new genetics test has uncovered traces of AIDS-virus DNA in the few infected people who first tested positive for AIDS antibody in their blood on standard tests and later tested negative, scientists announced this week. In some of these cases, the scientists were unable to detect even that trace of the virus in later runs with the new test, and they question whether this means the virus has gone by deeply into hiding or disappeared completely.
Most standard AIDS tests reveal exposure to the virus, known as HIV, by finding antibodies to it rather than by finding the virus itself. A year ago a research team announced that out of 1,000 homosexual men studied, four who initially showed antibodies to the virus slowly lost those antibodies. This process, called seroreversion, usually occurs only in the last stages of the disease, when the immune system becomes too enfeebled to mount any antibody response to the virus. However, these four men had no symptoms of the disease. The most likely explanations were that the men had managed to conquer the invading virus, or that the virus had entered a latent phase and become undetectable with available blood-screening tests.
The new research provides preliminary evidence that the virus may be going into latency and not provoking an immune response, rather than disappearing altogether in these men, reports a group of medical researchers in the June issue of the ANNALS OF INTERNAL MEDICINE. A test using a newly developed technique called polymerase chain reaction (PCR), which allows scientists to search directly for very small amounts of DNA, led to the discovery of bits of AIDS-virus DNA embedded in the men's own DNA, say the scientists. The team includes researchers from the Johns Hopkins School of Hygiene and Public Health in Baltimore, the National Institutes of Health in Bethesda, Md., Northwestern University in Chicago, the University of California at Los Angeles, the University of Pittsburgh and Cetus Corp. in Emeryville, Calif.
In two of the four cases, the men later lost even the small amounts of HIV DNA detectable with PCR tests. The reason for this disappearance is unclear, and it may be that the viral DNA is present in too low a concentration for even the new test to find, or the virus could be hiding in the brain or spleen, the scientists report. …