AIDS virus developing resistance to drugs; Study shows spread of mutant forms in 1 percent of infected


DALLAS -- The AIDS virus is quickly developing an ability to outmaneuver the potent drug cocktails that have helped many patients return to their daily routines, evidence from five cities suggests.

According to the research, about one in every 100 people who become infected with the human immunodeficiency virus will contract a disease that may defy all types of known medicines. The research represents the first broad tests of the spread of resistant infection in the United States.

People who contract these mutant HIV strains may not benefit from dramatic recent gains in AIDS treatment. They may also amplify the problem by passing this armored virus to others. And, given that drug resistance seems only to worsen once it gets a foothold, these less treatable forms of AIDS will probably be diagnosed in more and more patients.

"You put everything together, it's all very concerning," said Dr. Susan Little of the University of California, San Diego, who presented the data last week in Chicago during the sixth Conference on Retroviruses and Opportunistic Infections. The annual gathering is one of the country's premier AIDS research meetings.

Little's study also found that about 4 percent of people infected within the last year -- and who have not taken anything for their condition -- have caught virus strains that appear invulnerable to at least one of the three types of AIDS drugs available to patients. An additional 20 percent harbor viruses with a dulled sensitivity to treatment.

HIV can become resistant when drugs don't restrain the infection properly and the virus most able to withstand treatment is allowed to thrive. The transmission of a drug-resistant virus was expected, Little said, but researchers have not had an accurate sense of how widespread the problem might be. Most previous estimates have relied on small numbers of patients or have simply looked to see whether the virus had genetic mutations.

"Now we can assign a believable number to it," Little said of the resistance problem. Her study contains data from 79 newly infected patients, including 12 from Dallas, one of whom was found to have a resistant virus. Little's presentation reported data from the first 69 subjects. The research also included patients from Boston, Denver, Los Angeles and San Diego.

A second study presented in Chicago, of U.S. military personnel, reported similar numbers. Of 114 newly infected people, about 1 percent caught a virus that was resistant to all three classes of AIDS drugs, and 2 percent had infections that resisted two classes. The three types of drugs -- nucleoside reverse transcriptase inhibitors, nonnucleoside reverse transcriptase inhibitors and protease inhibitors -- attack the virus on different fronts.

About 40,000 new HIV infections occur in the United States each year.

Pub Date: 2/08/99

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