Chicago Tribune (CT) - WEDNESDAY June 15, 1988 Edition: SPORTS FINAL Section: NEWS Page: 5 Word Count: 891
Jon Van, Chicago Tribune

The full implications of this discovery aren't yet clear to scientists, who say the virus that causes AIDS-human immunodeficiency virus, or HIV-is emerging as one of nature's most complex microbes.

"This virus can fly below the radar of the immune system, and that's something we haven't seen before," Dr. William Haseltine of Harvard University told the conference.

The AIDS virus can turn itself off for years or wrap itself in a coating of sugar molecules so it goes undetected by the body's immune system, Haseltine said.

The tests widely used to determine HIV infection are antibody tests that detect proteins produced by the body in reaction to infection. If an infected person fails to produce antibodies, the tests won't identify an infection.

Scientists long have known there is a "window" between initial infection with HIV and the time when enough antibodies have been produced to be detected by the test. They usually estimated this period at a few weeks to as much as six months.

It now appears the period of silent infection can last for years.

Using a new genetic test called the polymerase chain reaction technique, Dr. Steven Wolinsky of Northwestern University found that the AIDS virus had infected one patient at least 3 1/2 years before he tested positive for the antibodies.

The Northwestern study involved 41 homosexual or bisexual men from four cities. Twenty-five of the men tested positive for HIV on the standard antibody test either at the beginning of or during the 1-year study, Wolinsky reported. But by conducting the new genetic test on stored blood samples of some of the test subjects, researchers found that six of the men had the virus at least two years before they tested positive for HIV on the antibody test.

Haseltine, who summarized the findings that a number of researchers presented at conference workshops, said other studies also showed that the silent infection period can be longer than previously believed.

Wolinsky's group at Northwestern and two others have pioneered testing with the new technique that detects and amplifies very small genetic particles of the virus itself, rather than proteins produced by the body in response to it.

Haseltine said the new technique is providing scientists with a fascinating and frightening look at how complex and clever the AIDS virus is at eluding human immune detection.

It is not yet known whether a person who is infected with HIV in the silent infection state is capable of infecting sexual partners, Haseltine said. It also isn't known how common this silent infection may be.

Haseltine also reported discovery of a new gene, the ninth now known to comprise the AIDS virus. This new gene, like others already discovered, works to slow the growth of the virus.

Several genes have now been identified that regulate HIV replication, Haseltine noted. Many of these genes work to suppress or slow replication, he said. It is likely that most specimens of HIV grown in labs for study actually have damaged genes because of lab requirements for fast replication. In its normal state, the AIDS virus is very slow to grow and reproduce.

One treatment strategy may be to find ways to strengthen the genes that suppress viral replication and block the genes that encourage it, he said. This could extend the "silent infection" phase for years, while delaying symptoms and suffering caused by AIDS.

Another characteristic of the virus emerging from research presented at the conference is the ability of HIV to provoke an initial reaction from the body's immune system and then settle into a long quiet state.

It is possible for people who have tested positive for antibodies to eventually test negative even though they still harbor the virus, he said.

The new complexities make development of a vaccine against AIDS even more difficult, Haseltine said, although it may not be impossible.

In the short term, the most promising strategy against AIDS may be to give small doses of antiviral drugs to healthy people who have been exposed to HIV, such as the spouses of people who have the virus, to protect them from developing symptoms, he said. Studies in mice suggest this is a feasible approach, he said.

Northwestern's Wolinsky also reported using the genetic testing technique to distinguish between babies born with HIV infection and those who are not truly infected but who carry antibodies to the infection passed along by their mothers.

Wolinsky said his work in detecting the AIDS virus in its silent phase is preliminary, but the genetic detection technique could prove useful in dealing with medical problems other than AIDS.

In other studies, he and colleagues have been able to detect virus particles associated with cancer of the cervix in women whose Pap smears were negative.

Dr. Cecil Fox of the National Institutes of Health said the new genetic test, developed by the CETUS Corp., a biotechnology company based in Emeryville, Calif., should provide a valuable tool in the early detection of HIV infection.

"The approach we use now is like trying to understand what an ice cube looks like after it has melted," he said.

CAPTION: Photo: (Published on page 1.) (William) Haseltine.

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