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HIV Drug Resistance

August 17, 2015

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Resistance Testing

According to guidelines put out by the US Department of Health and Human Services (DHHS), resistance testing is recommended for:

  • People who have just become infected with HIV, whether or not they are going to take HIV drugs right away
  • People who have never taken HIV drugs and are starting to receive medical care, whether or not they are going to take HIV drugs right away
  • People who have never been on HIV drugs and are planning to start
  • People who are on HIV drugs and see their viral load go up (usually over 1,000 copies/mL)
  • People who have recently started HIV drugs and their viral load is not coming down enough
  • Pregnant women living with HIV

Resistance testing is not usually recommended for:

  • People who have stopped HIV drugs for four weeks or more
  • People with a viral load below 500 copies

There are several ways to test for resistance:

  • Genotype test
    This test uses HIV from your blood to check for mutations -- changes in the virus' genetic sequence or genetic code -- associated with drug resistance. This is the preferred test for those who are new to HIV treatment, whose HIV drugs fail to bring their viral load down enough, and for pregnant women with detectable virus while on treatment.
  • Phenotype test
    This test exposes your virus to many HIV drugs in a test tube to determine which ones still work against your HIV. This is the preferred test for people with complex drug-resistance patterns.
  • Virtual phenotype test
    This is a genotype test that goes one step further -- it takes your genotype, finds similar genotypes in a database, and uses their phenotypic test results to predict which drugs will be effective against your virus (and its mutations)

In most cases, the genotype is the preferred test. For people who have been on HIV treatment before and may have HIV that is resistant to a number of different drugs, including protease inhibitors, the phenotype test may be done in addition to the genotype. Resistance tests are helpful when choosing a drug regimen. The tests are only a guide, however. Other factors, such as past medications, side effects, and adherence should be taken into account as well.

Preventing Resistance

The best way to avoid resistance is to take your medications daily as prescribed. It is important not to skip doses. Also, try to take your medications at the same time every day. If you maintain good adherence, you give your HIV drugs the best chance to work and yourself the best chance to live in good health.

Although resistance may seem overwhelming, remember that you have the power to help prevent it. If you follow your medication schedule, the virus will not reproduce as quickly. And if it is not reproducing, it can not make the changes that lead to resistance.

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This article was provided by The Well Project. Visit The Well Project's Web site to learn more about their resources and initiatives for women living with HIV. The Well Project shares its content with to ensure all people have access to the highest quality treatment information available. The Well Project receives no advertising revenue from or the advertisers on this site. No advertiser on this site has any editorial input into The Well Project's content.

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