What is genotypic resistance test?
HIV genotypic antiretroviral resistance testing is used to help select a drug regimen that will likely be effective in treating your HIV infection. The test is used to determine whether the HIV strain infecting you is resistant or has developed resistance to one or more drugs used to treat HIV.
Which assay can be used to detect resistance in HIV?
Two methods are used to determine drug resistance for HIV: genotyping, which detects treatment-resistant genetic mutations; and phenotyping, which assesses the viral response to ART agents. Genotyping is the preferred test in most clinical situations.
How is an HIV genotyping done?
Genotypic resistance testing examines the genetic structure (genotype) of a patient’s HIV. A blood sample is taken from the patient, and the HIV is analyzed for the presence of specific genetic mutations that are known to cause resistance to specific drugs.
What are the two types of HIV resistance?
Two types of resistance to HIV infection have been recognized: 1) resistance due to mutations in co-receptors used by HIV to establish infection; 2) when HIV infection does become established, there are some individuals who appear to be able to mount a particularly vigorous and effective immune response which is able …
How do you test resistance?
To measure resistance:
- Turn power to circuit OFF.
- Turn digital multimeter dial to resistance, or ohms, which often shares a spot on the dial with one or more other test/measurement modes (continuity, capacitance or diode; see illustration below).
- First insert the black test lead into the COM jack.
What is a phenotypic test?
Phenotypic assays measure the drug susceptibility of the virus by determining the concentration of drug that inhibits viral replication in tissue culture. Genotypic assays determine the presence of mutations that are known to confer decreased drug susceptibility.
Can you be tested for CCR5 Delta 32?
Genetic testing can be done on several genes that affect HIV and the course of the infection. For example, a genetic mutation causing a protein defect called CCR5 delta 32 has been shown to be resistant to the HIV virus.
What tool should be used to check resistance?
Resistance is measured using an instrument such as an analog multimeter or digital multimeter. Both types of instrument can measure not only resistance, but also current, voltage, and other parameters, so they can be used in a variety of situations.
Why do we measure resistance?
Why measure resistance? To determine the condition of a circuit or component. The higher the resistance, the lower the current flow, and vice versa.
What is phenotypic resistance?
However, in some situations resistance can be achieved without any genetic alteration; this is called phenotypic resistance. Non-inherited resistance is associated to specific processes such as growth in biofilms, a stationary growth phase or persistence.
When is resistance testing indicated for HIV infection?
Resistance testing can guide therapy selection to optimize virologic response in people with acute or recent (early) HIV infection, in pregnant people with HIV, or in people who will initiate ART on the day of or soon after HIV diagnosis. Therefore, resistance testing in these situations is recommended (AII).
What is a next-generation sequencing Genotypic resistance assay for HIV?
A next-generation sequencing genotypic resistance assay that analyzes HIV-1 proviral DNA in host cells is now commercially available. This test aims to detect archived resistance mutations in patients with HIV RNA below the limit of detection or with low-level viremia.
What is included in genotypic drug-resistance testing in ARV-naive persons?
Standard genotypic drug-resistance testing in ARV-naive persons involves testing for mutations in the reverse transcriptase (RT) and protease (PR) genes. If transmitted integrase strand transfer inhibitor (INSTI) resistance is a concern, providers should ensure that genotypic resistance testing also includes the integrase gene (AIII).
How fast do HIV resistance-associated mutations revert to wild-type virus?
The rate at which transmitted resistance-associated mutations revert to wild-type virus has not been completely delineated, but mutations present at the time of HIV transmission are more stable than those selected under drug pressure.