title: The Multispot rapid HIV-1/HIV-2 differentiation assay is comparable with the Western blot and an immunofluorescence assay at confirming HIV infection in a prospective study in three regions of the United States.
abstract: BACKGROUND
  A new HIV diagnostic algorithm has been proposed which replaces the use of the HIV-1 Western blot and HIV-1 immunofluorescence assays (IFA) as the supplemental test with an HIV-1/HIV-2 antibody differentiation assay.
  
  
  OBJECTIVE
  To compare an FDA-approved HIV-1/HIV-2 antibody differentiation test (Multispot) as a confirmatory test with the HIV-1 Western blot and IFA.
  
  
  METHODS
  Participants were screened with an HIV-1/HIV-2 combination Antigen/Antibody (Ag/Ab) screening assay. Specimens with repeatedly reactive results were tested with Multispot and either Western blot or IFA. Specimens with discordant screening and confirmatory results were resolved with HIV-1 RNA testing.
  
  
  RESULTS
  Individuals (37,876) were screened for HIV infection and 654 (1.7%) had a repeatedly reactive Ag/Ab assay result. On Multispot, 554 (84.7%) were HIV-1 reactive, 0 (0%) were HIV-2 reactive, 1 (0.2%) was reactive for both HIV-1 and HIV-2 (undifferentiated), 9 (1.4%) were HIV-1 indeterminate, and 90 (13.8%) were non-reactive. HIV-1 RNA was detected in 47/90 Multispot non-reactive (52.2%) specimens. Among specimens confirmed to have HIV infection (true positives), Multispot and Western blot detected HIV-1 antibody in a similar proportion of cases (93.7% vs. 94.4% respectively) while Multispot and IFA also detected HIV-1 antibody in a similar proportion of cases (84.5% vs. 83.4% respectively).
  
  
  CONCLUSIONS
  In this study, Multispot confirmed HIV infections at a similar proportion to Western blot and IFA. Multispot, Western blot, and IFA, however, did not confirm all of the reactive Ag/Ab assay results and underscores the importance of HIV NAT testing to resolve discordant screening and confirmatory results.
authors.affiliation: San Francisco Department of Public Health, San Francisco, CA, United States. Electronic address: Mark_Pandori@sfdph.org.
authors.forename: Mark W
authors.initials: MW
authors.lastname: Pandori
authors.affiliation: New York City Department of Health & Mental Hygiene, New York City, NY, United States.
authors.forename: Emily
authors.initials: E
authors.lastname: Westheimer
authors.affiliation: University of North Carolina at Chapel Hill, Chapel Hill, NC, United States(1).
authors.forename: Cindy
authors.initials: C
authors.lastname: Gay
authors.affiliation: Alameda County Department of Public Health, Oakland, CA, United States.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Moss
authors.affiliation: New York City Department of Health & Mental Hygiene, New York City, NY, United States.
authors.forename: Jie
authors.initials: J
authors.lastname: Fu
authors.affiliation: University of North Carolina at Chapel Hill, Chapel Hill, NC, United States(1).
authors.forename: Lisa B
authors.initials: LB
authors.lastname: Hightow-Weidman
authors.affiliation: ICF International, Atlanta, GA, United States.
authors.forename: Jason
authors.initials: J
authors.lastname: Craw
authors.affiliation: ICF International, Atlanta, GA, United States.
authors.forename: Laura
authors.initials: L
authors.lastname: Hall
authors.affiliation: New York City Department of Health & Mental Hygiene, New York City, NY, United States.
authors.forename: Francesca R
authors.initials: FR
authors.lastname: Giancotti
authors.affiliation: San Francisco Department of Public Health, San Francisco, CA, United States.
authors.forename: Mae Ling
authors.initials: ML
authors.lastname: Mak
authors.affiliation: San Francisco Department of Public Health, San Francisco, CA, United States.
authors.forename: Carmela
authors.initials: C
authors.lastname: Madayag
authors.affiliation: New York City Department of Health & Mental Hygiene, New York City, NY, United States.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Tsoi
authors.affiliation: San Francisco Department of Public Health, San Francisco, CA, United States.
authors.forename: Brian
authors.initials: B
authors.lastname: Louie
authors.affiliation: Centers for Disease Control and Prevention (CDC), Atlanta, GA, United States.
authors.forename: Pragna
authors.initials: P
authors.lastname: Patel
authors.affiliation: Centers for Disease Control and Prevention (CDC), Atlanta, GA, United States.
authors.forename: S Michele
authors.initials: SM
authors.lastname: Owen
authors.affiliation: Centers for Disease Control and Prevention (CDC), Atlanta, GA, United States.
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Peters
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D015153:Blotting, Western / Q000379:methods; D002648:Child; D019411:Clinical Laboratory Techniques / Q000379:methods*; D003955:Diagnostic Tests, Routine / Q000379:methods*; D005260:Female; D005455:Fluorescent Antibody Technique / Q000379:methods; D015483:HIV Antibodies / Q000097:blood*; D015658:HIV Infections / Q000175:diagnosis* / Q000821:virology*; D015497:HIV-1 / Q000145:classification* / Q000276:immunology; D015498:HIV-2 / Q000145:classification* / Q000276:immunology; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012698:Serologic Tests / Q000379:methods; D014481:United States; D014773:Virology / Q000379:methods; D055815:Young Adult
chemical_list: D015483:HIV Antibodies
keywords: Algorithms; HIV; HIV serodiagnosis