It is more important than ever to have new drugs to suppress the AIDS virus since the virus almost always does mutate eventually, AIDS experts told the 12th Annual Retrovirus Conference in Boston.

It is more important than ever to have new drugs to suppress the AIDS virus since the virus almost always does mutate eventually, AIDS experts told the 12th Annual Retrovirus Conference in Boston.

Combinations of HIV drugs called highly active antiretroviral therapy or HAART work very well to suppress HIV and keep it from damaging the immune system so badly that patients develop AIDS. But resistance develops eventually in many if not most patients.

Then new drugs are needed, and they must be different enough from the old drugs to avoid what is called cross-resistance.

One drug, still called by its experimental name TMC-114 by Tibotec, a subsidiary of drugs and personal products giant Johnson & Johnson, suppresses the virus well in patients who have been taking HAART for a while and who have developed resistance, the conference heard.

Dr. Richard Haubrich of the University of California, San Diego and colleagues tried a new cocktail in 497 patients, all but 100 or so of whom got varying doses of TMC-114, a new member of a drug class called protease inhibitors, with various other drugs.

The highest dose suppressed the virus back down to desirable levels, he told the meeting.

A second Tibotec drug called TMC 278 is in a class called non-nucleoside reverse transcriptase inhibitors or NNRTIs.

An international team tested 47 men who had never taken any HIV drugs with varying doses of TMC 278 for a week.

It suppressed the virus and allowed immune system cells to recover, they reported.

Another experimental drug was tested in a new class of HIV drugs called integrase inhibitors. The result shows they prevent the virus from infecting new cells.

After being tested in 30 HIV-infected patients, the drug, called L-000810810, worked effectively and safely both in patients who had taken HAART and stopped and those who had never taken any drugs, according to Dr. Susan Little of the University of California San Diego and colleagues.

Editor: Catherine