title: Evaluation of supplemental testing with the Multispot HIV-1/HIV-2 Rapid Test and APTIMA HIV-1 RNA Qualitative Assay to resolve specimens with indeterminate or negative HIV-1 Western blots.
abstract: BACKGROUND
  The use of Western blot (WB) as a supplemental test after reactive sensitive initial assays can lead to inconclusive or misclassified HIV test results, delaying diagnosis.
  
  
  OBJECTIVE
  To determine the proportion of specimens reactive by immunoassay (IA) but indeterminate or negative by WB that could be resolved by alternative supplemental tests recommended under a new HIV diagnostic testing algorithm.
  
  
  METHODS
  Remnant HIV diagnostic specimens that were reactive on 3rd generation HIV-1/2 IA and either negative or indeterminate by HIV-1 WB from 11 health departments were tested with the Bio-Rad Multispot HIV-1/HIV-2 Rapid Test (Multispot) and the Gen-Probe APTIMA HIV-1 RNA Qualitative Assay (APTIMA).
  
  
  RESULTS
  According to the new testing algorithm, 512 (89.8%) specimens were HIV-negative, 55 (9.6%) were HIV-1 positive (including 19 [3.3%] that were acute HIV-1 and 9 [1.6%] that were positive for HIV-1 by Multispot but APTIMA-negative), 2 (0.4%) were HIV-2 positive, and 1 (0.2%) was HIV-positive, type undifferentiated. 47 (21.4%) of the 220 WB-indeterminate and 8 (2.3%) of the 350 WB-negative specimens were HIV-1 positive.
  
  
  CONCLUSIONS
  Applying the new HIV diagnostic algorithm retrospectively to WB-negative and indeterminate specimens, the HIV infection status could be established for nearly all of the specimens. IA-reactive HIV-infected persons with WB-negative results had been previously misclassified as uninfected, and HIV diagnosis was delayed for those with WB-indeterminate specimens. These findings underscore the limitations of the WB to confirm HIV infection after reactive results from contemporary 3rd or 4th generation IAs that can detect HIV antibodies several weeks sooner than the WB.
authors.affiliation: Division of HIV/AIDS Prevention, Centers for Disease Control and Prevention, United States. Electronic address: LLinley@cdc.gov.
authors.forename: Laurie
authors.initials: L
authors.lastname: Linley
authors.affiliation: Division of HIV/AIDS Prevention, Centers for Disease Control and Prevention, United States.
authors.forename: Steven F
authors.initials: SF
authors.lastname: Ethridge
authors.affiliation: ICF International, United States.
authors.forename: Emeka
authors.initials: E
authors.lastname: Oraka
authors.affiliation: Division of HIV/AIDS Prevention, Centers for Disease Control and Prevention, United States.
authors.forename: S Michele
authors.initials: SM
authors.lastname: Owen
authors.affiliation: Division of HIV/AIDS Prevention, Centers for Disease Control and Prevention, United States.
authors.forename: Laura G
authors.initials: LG
authors.lastname: Wesolowski
authors.affiliation: Association of Public Health Laboratories, United States.
authors.forename: Kelly
authors.initials: K
authors.lastname: Wroblewski
authors.affiliation: Association of Public Health Laboratories, United States.
authors.forename: Kenneth M
authors.initials: KM
authors.lastname: Landgraf
authors.affiliation: Wadsworth Center, New York State Department of Health, United States.
authors.forename: Monica M
authors.initials: MM
authors.lastname: Parker
authors.affiliation: North Carolina State Laboratory of Public Health, United States.
authors.forename: Myra
authors.initials: M
authors.lastname: Brinson
authors.affiliation: Division of HIV/AIDS Prevention, Centers for Disease Control and Prevention, United States.
authors.forename: Bernard M
authors.initials: BM
authors.lastname: Branson
mesh_terms: D000465:Algorithms; D015153:Blotting, Western / Q000379:methods; D019411:Clinical Laboratory Techniques / Q000379:methods*; D015658:HIV Infections / Q000175:diagnosis* / Q000821:virology*; D015497:HIV-1 / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D015498:HIV-2 / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D006801:Humans; D025202:Molecular Diagnostic Techniques / Q000379:methods*; D012189:Retrospective Studies; D012698:Serologic Tests / Q000379:methods; D014773:Virology / Q000379:methods
keywords: Acute HIV infection; Algorithm; HIV testing; HIV-1 NAT; HIV-1/HIV-2 Rapid Test; IA; WB; Western blot; immunoassay