title: Comparison of alternative interpretive criteria for the HIV-1 Western blot and results of the Multispot HIV-1/HIV-2 Rapid Test for classifying HIV-1 and HIV-2 infections.
abstract: BACKGROUND
  HIV-1 Western blot (WB) may be positive in specimens from persons with HIV-2 infection due to cross-reactive antibodies. HIV-1 and HIV-2 infections may be identified using assays designed to differentiate HIV-1 and HIV-2 antibody reactivity.
  
  
  OBJECTIVE
  To evaluate the ability of the current CDC WB criteria, alternative more stringent HIV-1 WB criteria (2 env plus one gag or pol band) and the Multispot HIV-1/HIV-2 Rapid Test to accurately differentiate HIV-1 and HIV-2 infections.
  
  
  METHODS
  Two panels were used to determine the ability of each method to properly classify HIV-1 and HIV-2 infections: an HIV-2 panel (n=114) determined to be HIV-2 antibody-positive by both Multispot and by a validated HIV-2 WB, and 2135 HIV-1/HIV-2 immunoassay repeatedly reactive (IA-RR) specimens from the New York State Department of Health Laboratory (NYS).
  
  
  RESULTS
  By CDC WB criteria, 53 (46.5%) HIV-2 panel specimens were HIV-1 WB positive, 60 (52.6%) were indeterminate, and 1 (0.9%) was negative; the alternative WB criteria re-classified 75.5% of the positives as indeterminate. Among 2135 NYS IA-RR specimens, the alternative WB criteria increased the proportion of indeterminates by 0.8%. Only 6 (0.3%) of the NYS specimens were determined to be HIV-2 infections; all 6 were classified either as HIV-1 positive or indeterminate by both WB criteria, but were classified as HIV-2 (n=4) or HIV-1/2 undifferentiated (n=2) by Multispot.
  
  
  CONCLUSIONS
  The alternative WB criteria classified most of the HIV-2 specimens that were HIV-1 positive by CDC criteria as indeterminate, but also slightly increased the proportion of HIV-1 specimens classified as indeterminate. The WB indeterminate specimens would require further testing or follow-up to resolve the infection status, whereas Multispot directly distinguished HIV-1 from HIV-2.
authors: Division of HIV/AIDS Prevention, National Center for HIV, Hepatitis, STD and TB Prevention, Centers for Disease Control and Prevention, Mailstop E46, Atlanta, GA 30333, USA. snasrullah@cdc.gov
authors: Muazzam
authors: M
authors: Nasrullah
authors: Steven F
authors: SF
authors: Ethridge
authors: Kevin P
authors: KP
authors: Delaney
authors: Laura G
authors: LG
authors: Wesolowski
authors: Timothy C
authors: TC
authors: Granade
authors: Joe
authors: J
authors: Schwendemann
authors: Robert D
authors: RD
authors: Boromisa
authors: James D
authors: JD
authors: Heffelfinger
authors: S Michele
authors: SM
authors: Owen
authors: Bernard M
authors: BM
authors: Branson
mesh_terms: D015153:Blotting, Western; D002487:Centers for Disease Control and Prevention, U.S. / Q000592:standards; D003429:Cross Reactions; D015483:HIV Antibodies / Q000276:immunology; D015658:HIV Infections / Q000145:classification* / Q000175:diagnosis* / Q000276:immunology / Q000821:virology; D015497:HIV-1 / Q000276:immunology / Q000472:pathogenicity; D015498:HIV-2 / Q000276:immunology / Q000472:pathogenicity; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D011933:Reagent Kits, Diagnostic; D012680:Sensitivity and Specificity; D014481:United States; D054301:gag Gene Products, Human Immunodeficiency Virus / Q000235:genetics; D054302:pol Gene Products, Human Immunodeficiency Virus / Q000235:genetics
chemical_list: D015483:HIV Antibodies; D011933:Reagent Kits, Diagnostic; D054301:gag Gene Products, Human Immunodeficiency Virus; D054302:pol Gene Products, Human Immunodeficiency Virus