title: Performance characteristics of the COBAS AmpliScreen HIV-1 test, version 1.5, an assay designed for screening plasma mini-pools.
abstract: BACKGROUND
  The COBAS AmpliScreen HIV-1 test, version 1.5 (v1.5) (Roche Molecular Systems), is designed for screening pools composed of samples from 24 individual units of blood or plasma. A specimen-processing procedure (Multiprep) simultaneously concentrates and extracts HIV-1, HCV, and HBV particles from plasma and incorporates an HIV-1 internal control (IC) RNA. Processed samples are amplified by RT-PCR using HIV-1-specific primers and detected by hybridization of the amplified products to HIV-1- and IC-specific oligonucleotide probes.
  
  
  METHODS
  Plasma samples containing known quantities of HIV-1 were used to evaluate analytical sensitivity and precision and to validate a pool testing algorithm. Analytical specificity was evaluated by adding various viruses and bacteria to HIV-1-negative plasma. Seroconversion panels were tested to estimate the window-period reduction achieved by RNA testing.
  
  
  RESULTS
  The analytical sensitivity of the test (concentration that yields > or = 95% positive results in a set of replicate tests) was 25 copies of HIV-1 RNA per mL of pooled plasma. Representative strains from all HIV-1 group M subtypes were reproducibly detected (> 95% positive results) at concentrations of 20 to 200 viral particles per mL. The test did not cross-react with a set of 31 viral and 5 bacterial isolates, and it yielded negative results on a panel of 500 blood samples from HIV-1-seronegative donors. Plasma samples containing abnormally high levels of Hb, albumin, triglycerides, or bilirubin did not interfere with the test. HIV-1 RNA was detected 2 to 14 days before HIV-1 antibody and 0 to 28 days before p24 antigen. The test specifically detected pools containing a single positive unit with 2400 HIV-1 RNA copies per mL and correctly identified the positive unit.
  
  
  CONCLUSIONS
  The COBAS AmpliScreen HIV-1 test, v1.5, has sufficient sensitivity to detect a single infected unit containing 600 copies of HIV-1 per mL in a pool with 23 uninfected units and should reduce the window period between infection and seroconversion by at least 2 to 14 days.
authors.affiliation: Roche Molecular Systems, Inc., Pleasanton, California, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Yang
authors.forename: M H
authors.initials: MH
authors.lastname: Lamendola
authors.forename: M
authors.initials: M
authors.lastname: Mendoza
authors.forename: D
authors.initials: D
authors.lastname: Xu
authors.forename: M
authors.initials: M
authors.lastname: Nguyen
authors.forename: S
authors.initials: S
authors.lastname: Yeh
authors.forename: Y
authors.initials: Y
authors.lastname: Wu
authors.forename: J
authors.initials: J
authors.lastname: Ku
authors.forename: M
authors.initials: M
authors.lastname: Rosenstraus
authors.forename: R
authors.initials: R
authors.lastname: Sun
mesh_terms: D000163:Acquired Immunodeficiency Syndrome / Q000175:diagnosis*; D006679:HIV Seropositivity; D015497:HIV-1 / Q000302:isolation & purification*; D006801:Humans; D012367:RNA, Viral / Q000032:analysis*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D012367:RNA, Viral