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Cofactor in AIDS?

A large number of homosexual men have been infected with the AIDS-associated virus, yet most of them haven't contracted AIDS. The hidden cofactor in developing AIDS, suggest W. Lawrence Drew Of Mt. Zion Hospital in San Francisco and his colleagues, could be cytomegalovirus, one of the herpesviruses.

In a study of homosexual men without overt signs of AIDS, 33 of 67 men who showed signs fo recent cytomegalovirus infection had an abnormal ratio between two types of white blood cells called T lymphocytes. This immunological disorder can presage AIDS. But only two of 42 men without cytomegalovirus antibodies had the abnormal ratio, the researchers report in the July ANNALS OF INTERNAL MEDICINE.

Until the researchers have completed long-term observation to see if only the cytomegalovirus-infected men go on to get AIDS--which can take years to develop--the study only suggests a relationship. But it brings cytomegalovirus a little close to identification as the cofactor, says Drew. "It might be that the primary event is cytomegalovirus infection, which does something detrimental to the lymphocytes."

A cytomegalovirus factor could explain the AIDS-homsexual connection, says Drew. A Study several years ago showed that over 95 percent of the homosexual community in San Francisco showed evidence of past cytomegalovirus infection, compared with only 50 percent of the heterosexuals. In addition, cytomegalovirus is absorbed rectally much more readily than vaginally. What could be happening, says Drew, is that during an active cytomegalovirus infection the exhausted immune system might not put up as strong a defense against the AIDS virus; with homosexuals encountering the virus more often, they would be more vulnerable to the AIDS retrovirus.

What would strengthen the cytomegalovirus case is more epidemiological studies, as well as laboratory studies showing that preinfecting lymphocytes with cytomegalovirus makes them more receptive to the retrovirus, says Drew.
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Publication:Science News
Date:Aug 3, 1985
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