title: Use of human immunodeficiency virus (HIV) type 1 and 2 recombinant strip immunoblot assay to resolve enzyme immunoassay anti-HIV-2-repeatably reactive samples after anti-HIV-1/2 combination enzyme immunoassay screening.
abstract: BACKGROUND
  With the implementation of combination human immunodeficiency virus types 1 and 2 (HIV-1/2) antibody enzyme immunoassay (EIA) in donor screening in 1992, the supplemental testing algorithm changed to require the use of a Food and Drug Administration (FDA)-licensed HIV-1 Western blot (WB) or immunofluorescence assay, as well as an FDA-licensed HIV-2 EIA. When HIV-2 EIA-reactive specimens are identified, further testing to confirm HIV-2 infection is recommended. Currently, a licensed HIV-2 supplemental assay is not available.
  
  
  METHODS
  The sensitivity of an HIV-1/2 recombinant strip immunoblot assay (SIA) for HIV-2 was determined on the basis of the analysis of 65 HIV-2-positive samples identified by the Centers for Disease Control and Prevention (CDC). Anti-HIV-1/2 combination EIA-repeatably reactive (RR) specimens from seven blood centers and their affiliated hospitals were tested in parallel by HIV-1 WB and HIV-2 EIA. Anti-HIV-2 EIA-RR specimens were further tested by HIV-1/2 SIA. Specimens interpreted as positive for HIV-2 or HIV-1/2 were referred to the CDC for final resolution of antibody status.
  
  
  RESULTS
  Ninety-seven percent (63/65) of known HIV-2-positive samples tested positive for HIV-2 only or HIV-1/2 on the HIV-1/2 SIA. A total of 1048 anti-HIV-1/2 combination-EIA-RR specimens were evaluated. Sixty-nine percent (75/109) of the WB-positive specimens were HIV-2 EIA-RR, while only 9 percent (84/939) of WB-indeterminate or WB-negative specimens tested HIV-2 EIA-RR. The HIV-1/2 SIA resolved 91 percent of HIV-2 EIA-RR samples as negative. Four HIV-2 EIA-RR specimens (all HIV-1 WB-positive) were classified as positive for HIV-1 and HIV-2 in the HIV-1/2 SIA. Final interpretation of these specimens by CDC was that they were reactive for HIV-1 with cross-reactivity to HIV-2.
  
  
  CONCLUSIONS
  No confirmed HIV-2-positive specimens were detected. The HIV-1/2 SIA is currently useful for resolving HIV-2 EIA-RR specimens.
authors.affiliation: Irwin Memorial Blood Centers, San Francisco, California, USA.
authors.forename: L H
authors.initials: LH
authors.lastname: Tobler
authors.forename: E
authors.initials: E
authors.lastname: Kaufman
authors.forename: N
authors.initials: N
authors.lastname: Gefter
authors.forename: C
authors.initials: C
authors.lastname: Schable
authors.forename: M P
authors.initials: MP
authors.lastname: Busch
mesh_terms: D015492:AIDS Serodiagnosis / Q000379:methods*; D001782:Blood Donors; D015153:Blotting, Western; D015483:HIV Antibodies / Q000032:analysis; D015658:HIV Infections / Q000175:diagnosis*; D015497:HIV-1 / Q000276:immunology*; D015498:HIV-2 / Q000276:immunology*; D006801:Humans; D007124:Immunoenzyme Techniques; D011933:Reagent Kits, Diagnostic; D011934:Reagent Strips; D011994:Recombinant Proteins; D012680:Sensitivity and Specificity
chemical_list: D015483:HIV Antibodies; D011933:Reagent Kits, Diagnostic; D011934:Reagent Strips; D011994:Recombinant Proteins