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Sponsored by:
This HIV Drug Resistance Resource Center is provided to The Body by Monogram Biosciences, which is solely responsible for the information provided here. Neither The Body nor its publisher, Body Health Resources Corporation, endorses or opposes any particular product, service or treatment option. Instead, you are encouraged to discuss your options with a healthcare provider who specializes in treating HIV. |
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GeneSeq HIV |
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GeneSeq™ HIV is a highly accurate genotypic HIV drug resistance test. The test
is performed using state-of-the-art technology and the results are determined
using the most recently updated HIV mutation information and information from
scientific research and Monogram's resistance experts.
About Genotyping
Genotypic testing looks for the presence of genetic changes, or mutations, in
HIV to predict resistance to antiretroviral drugs. If the mutations found in a
person's virus match the mutations that are known to cause resistance to a
drug, then his or her virus is presumed to be resistant to that drug. The
critical aspect of genotyping, however, is not identifying mutations but
interpreting the results — in other words, making sense of all the different
mutations and how they interact with each other to affect drug susceptibility.
Click on the links below to learn more about genotypic testing.
How Genotypic Testing Is Performed
There are two main types of genotypic resistance testing: sequencing assays and
point mutation assays. Sequencing assays scan the complete sequence of gene,
whereas point mutation assays look for mutations at specific locations, or
codons, in the gene sequence. Though these assays differ in how the genetic
structure is analyzed, they both start by using polymerase chain reaction (PCR)
technology to amplify (copy) the viral RNA or DNA present in a patient's blood
sample. PCR technology allows researchers to amplify specific genetic sequences
in a person's HIV to create a sufficient amount for genotypic testing. The
following example of how genotypic testing is performed is based on GeneSeq
HIV.
Step 1. Sample is taken
Step 2. Copies of the virus are made (using PCR technology, the genetic
material of a person's HIV is copied numerous times)
Step 3. Genes within the virus (most commonly the reverse transcriptase and
protease genes) are evaluated for mutations
Step 4. Mutations found in the virus are compared to known resistance mutations
Results: If the type and pattern of mutations present in a person's virus match
pre-established mutations for a particular drug, the virus has probably
developed resistance to that drug.
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What Genotypic Test Results Mean
If genotypic testing reveals drug resistance mutations in a person's HIV,
certain antiretroviral drugs may be less likely to work. The specific type and
placement of the mutations determine which drugs the virus may be resistant
to. For example, if the "M184V" mutation is discovered in a person's HIV, the
virus is probably resistant to 3TC (lamivudine). Once a healthcare provider
understands which drugs are less likely to work, she/he can develop a treatment
plan that avoids the use of those drugs. This results in a therapy regimen that
is more likely to be effective for a longer period of time.
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How Genotypic Results Are Reported
Once the mutations present in a person's virus are identified, they are organized
and listed on a report form. Mutations are usually listed by the drug category they
pertain to — nucleoside reverse transcriptase inhibitors (NRTIs), non-nucleoside reverse
transcriptase inhibitors (NNRTIs), or protease inhibitors (PIs). Once the mutations are
organized, they must be reviewed and compared to the most recent guidelines explaining
what a given mutation or collection of mutations means; this step can be subjective.
Below is a sample GeneSeq HIV report form to provide a better idea of how the drug resistance
information is reported.
Click on the image below to enlarge the form.
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| Is an HIV drug resistance test right for you? If so, which kind? Click here |
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How to check if you're covered for an HIV resistance test.
Click here or call
1-877-436-6243. |
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