title: Development and performance of conventional HIV-1 phenotyping (Antivirogram®) and genotype-based calculated phenotyping assay (virco®TYPE HIV-1) on protease and reverse transcriptase genes to evaluate drug resistance.
abstract: OBJECTIVE
  A wide array of monitoring tests is commercially available to gauge HIV-1 disease progression and the overall health status of an HIV-1-infected patient. Viral load tests provide a picture of viral activity, while CD4 cell counts shed light on the immune status and can help physicians to prevent the development of opportunistic infections in patients. On the other hand, genotypic and phenotypic resistance testing and therapeutic drug monitoring help to optimize HIV-1 antiretroviral therapy. Resistance testing is currently recommended within the standard of care guidelines to aid the choice of new drug regimens following treatment failure(s).
  
  
  METHODS
  Genotypic testing described here is based on the amplification and sequencing of an HIV-1 protease (PR) and reverse transcriptase (RT) region from a patient sample to identify resistance mutations associated with PR and RT inhibitor resistance. A genotypic test takes a week to perform and the results are reported as a list of detected mutations. The virco®TYPE HIV-1 report uses genotypic data to predict phenotypic susceptibility by linear regression modeling that uses a large correlative database of genotype-phenotype pairs. Phenotypic testing measures the ability of the virus to replicate in the presence of a drug and provides a direct measurement of drug susceptibility in vitro. Since phenotypic analysis is laborious and time consuming (28 days), genotypic resistance testing is currently the standard reference method used for HIV-1 resistance testing. However, a phenotypic test is important when a patient harbors virus with complex genetic patterns, or when the mutational resistance profile for a particular drug is not well-characterized.
  
  
  CONCLUSIONS
  Some of the currently used resistance tests are partially automated enabling laboratories to increase overall efficiency. However, maximum automation and standardization of the process, instruments and software that we have described here can overcome many of the problems encountered with current tests and aims at having a compliant, high-throughput, diagnostic laboratory, which can guarantee sample integrity from sample reception to result reporting. We also describe in detail the development and performance of virco®TYPE HIV-1 (genotype) and Antivirogram® (phenotype) assay on PR and RT genes to evaluate antiretroviral resistance.
authors.affiliation: Virco BVBA, Beerse, Belgium. tpattery@its.jnj.com
authors.forename: Theresa
authors.initials: T
authors.lastname: Pattery
authors.forename: Yvan
authors.initials: Y
authors.lastname: Verlinden
authors.forename: Hans
authors.initials: H
authors.lastname: De Wolf
authors.forename: David
authors.initials: D
authors.lastname: Nauwelaers
authors.forename: Kurt
authors.initials: K
authors.lastname: Van Baelen
authors.forename: Margariet
authors.initials: M
authors.lastname: Van Houtte
authors.forename: Paula
authors.initials: P
authors.lastname: Mc Kenna
authors.forename: Jorge
authors.initials: J
authors.lastname: Villacian
mesh_terms: D019380:Anti-HIV Agents / Q000494:pharmacology*; D016903:Drug Monitoring / Q000379:methods*; D024882:Drug Resistance, Viral; D005838:Genotype; D015658:HIV Infections / Q000821:virology*; D016333:HIV Protease / Q000235:genetics; D054303:HIV Reverse Transcriptase / Q000235:genetics; D015497:HIV-1 / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics* / Q000302:isolation & purification; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000379:methods; D058889:Molecular Typing / Q000379:methods*; D020125:Mutation, Missense; D010641:Phenotype
chemical_list: D019380:Anti-HIV Agents; C514824:reverse transcriptase, Human immunodeficiency virus 1; D054303:HIV Reverse Transcriptase; D016333:HIV Protease; C514803:p16 protease, Human immunodeficiency virus 1