25501 HIV-1 Genotypic Protease and Reverse Transcriptase Inhibitor Drug Resistance, Plasma (HIVPR)

Identification of genotypic variants associated with viral resistance to HIV-1 nucleotide reverse-transcriptase inhibitors, non-nucleotide reverse-transcriptase inhibitors, and protease inhibitors.

Guiding initiation or change of combination antiretroviral therapy in individuals, including children, living with HIV. 

Test is intended to be used to monitor known HIV-positive infections. It is not intended for primary detection of HIV infections.

Centrifuge sample within one hour of collection and transfer plasma into plastic transfer tube. Freeze plasma immediately and ship frozen on dry ice. If shipment is delayed >24 hours, freeze specimen at -70 degrees C (up to 35 days).

Additional Information:  Specimens submitted for HIV-1 genotyping should contain > or = 500 copies/mL of HIV-1 RNA. 

Detectable HIV-1 genotypic mutations conferring resistance to an antiviral drug are reported as amino acid codon changes (eg, M184V) resulting from the alterations, according to the interpretative algorithm of the Stanford HIV Database program.  Genotypic variant codons are categorized and interpreted in relation to previously performed phenotypic antiviral susceptibility tests.  Each variant is assigned a drug penalty score and the total score generated from all of the variants relevant to the specific antiviral drug is used to estimate the level of resistance to that drug.  These interpretive rules may be updated periodically by the Stanford HIV Database Team after reviewing newly published data on HIV-1 genotypic drug resistance variants. 

Susceptible (Susc) indicates that the genotypic variants present in patient's HIV-1 strain have not been associated with resistance to the specific drug (Stanford HIVdb total score 0 to 9).

Potential Low-Level Resistance (PLR) indicates that genotypic variants detected have been associated with possible reduction in susceptibility to the specific drug (Stanford HIVdb score 10 to 14).

Low-Level Resistance (LR) indicates that genotypic variants detected have been associated with reduction in susceptibility to the specific drug (Stanford HIVdb score 15 to 29).

Intermediate Resistance (IR) indicates that genotypic variants detected have been associated with reduction in susceptibility to the specific drug (Stanford HIVdb score 30 to 59).

High-level Resistant (HR) indicates that genotypic variants detected have been associated with maximum reduction in susceptibility to the specific drug (Stanford HIVdb > or = 60). 

Unable to genotype indicates that the sequence data obtained are of poor quality to determine the presence or absence of genotypic resistant variants in the patient's HIV strain. Probable causes of such poor sequence data include polymorphism in the region of the sequencing primers interfering with primer binding and subsequent sequencing reaction or low viral load (ie, <500 copies/mL).

Inconclusive indicates inability of the assay to reliably determine antiviral resistance because of the presence of PCR inhibitors or ambiguous or incomplete viral target sequences generated from the assay.