Researchers Revise Finding on AIDS Detection Testing : Disease: Evidence indicates men originally studied may have only been partially infected.

A controversial suggestion that the standard AIDS test might fail to detect the AIDS virus in nearly one in four “high risk” gay men has been revised in light of evidence that the men originally studied may never have been completely infected.

In a letter published today in The New England Journal of Medicine, two researchers at UCLA reported that they had continued to follow many of the men examined earlier and were no longer able to find the virus in their blood.

The new findings suggest that at the time of the original study the men may have been partially or incompletely infected--that is, that the virus was present in certain cells but was never incorporated into their genetic material, the researchers said.

If that were the case, the virus could have been cleared from their systems. David Imagawa, a UCLA professor of pediatrics and microbiology-immunology, said such a phenomenon has been seen in monkeys exposed to a virus like the one that causes AIDS. Other researchers have suggested it may also occur in humans.

“It appears now that maybe it wasn’t a latent infection,” said Imagawa, who wrote the letter with Dr. Roger Detels. “It may have been more of an abortive infection or a transient infection. It’s not a complete infection.”

The issue arose in June, 1989, when Imagawa and others reported in the journal that, using a highly sensitive test, they had found the virus in the blood of nearly one-quarter of the high-risk, gay men they had studied, even though the standard AIDS test had found nothing.

They said their findings suggested that the virus was “latent” or the infection “silent”--a hypothesis that raised the specter of inadvertent contamination of the blood supply or spread of the virus from one person to another.

Other researchers were skeptical about the conclusions. Some later studies seemed to confirm the results; others did not. Imagawa and his group explored, then rejected, the possibility that their samples might have become contaminated in the lab.

They then took new blood samples from 27 of the men in whom they had found the virus and analyzed them using polymerase chain reaction--the same test they had first used and which is known to be much more sensitive than the standard AIDS test.

According to their letter, they found the virus in only one of the 27 men.

Imagawa said the new finding does not negate the idea of latent infection since other studies by other researchers support that notion. He said researchers intend to continue to explore the possibility and implications of incomplete infection.