Roanoke Times
                 Copyright (c) 1995, Landmark Communications, Inc.

DATE: THURSDAY, May 17, 1990                   TAG: 9005170567
SECTION: NATIONAL/INTERNATIONAL                    PAGE: A/10   EDITION: EVENING 
SOURCE: Associated Press
DATELINE: WASHINGTON                                LENGTH: Medium

STUDY FINDS TESTS OFTEN FAILED TO DETECT AIDS CASES

Dr. Tab Ansari of Emory University in Atlanta said his laboratory tested the blood of 165 people who had tested negative for the AIDS virus and found that 30 were, in fact, infected.

He said in an interview that the study raises the possibility that there are people who are chronically infected with the human immunodeficiency virus, which causes AIDS, but who never get sick or develop easily found antibodies.

In a study published in the Proceedings of the National Academy of Science, Ansari said his team used a new type of test to find HIV antibodies that had escaped detection by routine hospital laboratory blood tests.

"All of the ones that they found positive, we found positive," Ansari said. "But in addition, there were quite a few that were negative in their assay that were picked up as positive."

Ansari said the experiment began with 165 blood samples tested using ELISA, or enzyme-linked immunosorbent assay, the AIDS test most commonly used in hospitals and clinics. The samples then were additionally tested using the Western Blot assay, a test routinely used to confirm the ELISA finding.

All of the samples tested in that traditional way were found negative for the HIV virus, according to the study.

Meanwhile, unlabeled blood from the same samples, along with blood specimens from healthy volunteers, were provided to Ansari and his team. His team did not know which samples came from a high-risk population - mostly drug users - and which came from healthy volunteers.

The specimens were subjected to a test called the pokeweed mitogen assay, a procedure that forces specialized cells in the blood to expel antibodies into the blood serum. The serum then was tested using the ELISA and Western Blot assays.

Thirty of the samples, or 18 percent, were found to contain antibodies to the HIV virus, an indication of infection. Each of those 30 samples were previously found by the two standard tests to be free of virus antibodies.

Ansari said the routine tests would give positive results only if HIV antibodies are in the blood serum. The pokeweed mitogen assay, he said, shows that there may be infected people who don't develop serum antibodies to the AIDS virus.

"For some reason there are blood cells that have the antibody, but do not secrete it," Ansari said, adding that the ELISA and Western Blot tests would not be able to detect the antibodies.

The study, similar findings by other researchers and studies of viral infections in monkeys suggest that some people may contract the HIV infection but never progress to the actual AIDS disease, he said.

"We need to follow up these people and study their immunity and then perhaps we could understand how that happens," he said.

Ansari, however, emphasized that the possible existence of hidden, chronic HIV infections that never progress to disease is only speculation.