title: Validation and clinical use of a sensitive HIV-2 viral load assay that uses a whole virus internal control.
abstract: BACKGROUND
  Human immunodeficiency virus type 2 (HIV-2) is distantly related to the more widespread HIV-1. Although HIV-2 infection is rare in the U.S., cases are concentrated in the Northeast. No FDA-approved HIV-2 viral load assays exist. A clinically validated laboratory-developed assay is currently available in the U.S., however it is not currently approved for use on New York State patients.
  
  
  OBJECTIVE
  To develop a sensitive viral load assay to quantify HIV-2 RNA in plasma and to validate it for clinical use.
  
  
  METHODS
  The real-time RT-PCR assay simultaneously amplifies HIV-2 and a whole virus internal control, added during the lysis step. Two extraction volumes can be used. Results are reported in HIV-2 RNA International Units (IU).
  
  
  RESULTS
  The assay has a limit of detection of 7 IU/mL and a lower limit of quantification of 29 IU/mL. The assay detects multiple strains of HIV-2 group A and B and generates reproducible results. Samples exchanged with a comparator laboratory produced similar viral load results, with 74% of positives differing by <0.5 log10 IU/mL. To date, we have tested 52 clinical specimens from 25 individuals. Twenty-eight (54%) specimens had measurable HIV-2 viral loads (range: 1.63-5.14 log10 IU/mL), 10 (19%) were positive but not quantifiable, and 14 were negative. HIV-2 RNA was detected in at least one specimen from 19 of 25 (76%) individuals tested.
  
  
  CONCLUSIONS
  We developed a sensitive and accurate HIV-2 viral load assay. Validation data indicate the assay is suitable for clinical use and its availability in New York State will improve clinical monitoring of HIV-2 infected patients.
authors.affiliation: Bloodborne Viruses Laboratory, Wadsworth Center, New York State Department of Health, Albany, NY 12208, United States; Department of Biomedical Sciences, School of Public Health, University at Albany, Albany, NY 12201, United States. Electronic address: lms24@health.state.ny.us.
authors.forename: Linda M
authors.initials: LM
authors.lastname: Styer
authors.affiliation: Bloodborne Viruses Laboratory, Wadsworth Center, New York State Department of Health, Albany, NY 12208, United States.
authors.forename: Thomas T
authors.initials: TT
authors.lastname: Miller
authors.affiliation: Bloodborne Viruses Laboratory, Wadsworth Center, New York State Department of Health, Albany, NY 12208, United States.
authors.forename: Monica M
authors.initials: MM
authors.lastname: Parker
mesh_terms: D001769:Blood / Q000821:virology*; D015658:HIV Infections / Q000821:virology*; D015498:HIV-2 / Q000302:isolation & purification*; D006801:Humans; D025202:Molecular Diagnostic Techniques / Q000379:methods* / Q000592:standards*; D009518:New York; D012367:RNA, Viral / Q000097:blood; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods; D012015:Reference Standards; D015203:Reproducibility of Results; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D012680:Sensitivity and Specificity; D019562:Viral Load / Q000379:methods* / Q000592:standards*
chemical_list: D012367:RNA, Viral
keywords: Clinical assay; HIV-2; Real time RT-PCR; Viral load