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PhenoSense HIV Technology
PhenoSense™ HIV utilizes the most advanced technology for a rapid and precise measure of susceptibility to antiretroviral drugs. This not only means strong science in the performance of the assay itself, but also the most expert data analysis available. Years of development in the Monogram Clinical Laboratory, extensive commercial use, and utilization in antiretroviral drug research have made PhenoSense HIV the industry standard in phenotypic resistance testing technology.
Click on the links below to learn more about the technology behind PhenoSense HIV.
Performing the test
- Patient blood sample is received
- Virus is isolated —
Protease and reverse transcriptase genetic sequences are isolated from patient sample and then amplified using Polymerase Chain Reaction (PCR)
- Vector is constructed —
Protease and reverse transcriptase segments plus luciferase indicator gene are inserted into a resistance test vector. Luciferase indicator is inserted into a deleted portion of the HIV-1 envelope (env) gene
- Virus is produced —
Resistance test vector introduced into host cells along with amphotrophic murine leukemia virus (A-MLV) envelope vector. Host cell is co-transfected. A-MLV envelope vector will serve to assemble the resulting virus particles. (when testing Protease Inhibitors, they are introduced here)
- Virus is tested —
Virus particles collected during transfection step (step 4.) are used to infect the target cells. A single round of viral replication results in the production of luciferase. (when testing Reverse Transcriptase Inhibitors, they are introduced here)
- Results are measured —
Drug susceptibility is measured by comparing luciferase activity produced in the presence and absence of drugs.
Low levels of luciferase activity — susceptible virus
High levels of luciferase activity — virus with reduced susceptibility
Analyzing the data
- Data are analyzed by plotting percent inhibition of luciferase activity vs log10 concentration of drug
- The drug susceptibility curve is used to calculate the concentration of drug required to inhibit viral replication by 50% (IC50)
- The IC50 of the patient's virus is compared to the IC50 of a drug-sensitive reference virus control to calculate fold change in susceptibility
- Reduced drug susceptibility is indicated by a shift in the patient inhibition curve toward higher drug concentrations (to the right)
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