A No-nonsense Guide to HIV Drug Resistance Testing

A 22-page booklet on HIV drug-resistance testing, written by well-known AIDS activists Tim Horn and Spencer Cox and edited by resistance expert Douglas Richman, M.D., is available without charge.

HIV resistance tests are used to tell which drugs the patient's virus has developed resistance to, so that a new regimen can be designed by combining drugs which are all likely to work. Similar testing has long been done with antibiotics -- but for technical reasons such tests are much more difficult with HIV, so they are only now coming into widespread use.

The booklet explains the two kinds of resistance testing -- genotypic and phenotypic. Genotypic, the older technology, looks at the genes of the virus to find mutations associated with resistance to particular drugs. Genotypic testing is less expensive and more rapid, but the results are often hard to interpret, because different mutations interact in complex ways, not all of which are known. Phenotypic testing exposes virus to different levels of the drugs being tested -- but is difficult to carry out, because HIV from patients seldom grows well in the laboratory, so a new virus has to be made by inserting part of the genetic material from the patients' virus into a different strain of HIV which can grow in the laboratory. Because of this complexity, phenotypic tests usually cost more and take longer than genotypic tests.

The booklet also explains when and how the tests are used. It also includes a glossary and a resource guide.

You can obtain a free copy of "A No-nonsense Guide to HIV Drug Resistance Testing," updated version, by calling ViroLogic, Inc. customer service, 1-800-777-0177 Monday through Friday 8 a.m. to 5 p.m. Pacific time.

ISSN # 1052-4207

Copyright 2000 by John S. James. Permission granted for noncommercial reproduction, provided that our address and phone number are included if more than short quotations are used.

Back to the AIDS Treatment News June 23, 2000 contents page.