title: A simple and inexpensive particle agglutination test to distinguish recent from established HIV-1 infection.
abstract: OBJECTIVE
  We sought to modify the Serodia HIV-1/HIV-2 particle agglutination assay (PA), a simple and cost-effective HIV assay that is used globally for the detection of HIV antibodies, as a sensitive/less sensitive test (S/LS) to identify recently infected individuals and to estimate HIV incidence.
  
  
  METHODS
  The Serodia PA test was modified as an S/LS test (PA-LS) by using HIV antigen-coated gelatin particles at a dilution of 1:68 and a specific diluent, and calibrated using 37 HIV clade B seroconversion panels (309 samples) from Trinidad and from a commercial source that were tested at dilution intervals from 1:10 to 1:80,000. The greatest sensitivity for correctly classifying samples from recent and established infections was determined by receiver operator curve (ROC) analysis.
  
  
  RESULTS
  At a 1:40,000 sample dilution and a days post-seroconversion cutoff of 190 days, the PA-LS test yielded a 97% sensitivity for classifying recent and established infection samples. Furthermore, at a 1:20,000 dilution, the positive predictive value for correctly identifying recently infected individuals was 99%. The PA-LS test offers a 30-44-fold cost saving over currently available S/LS tests.
  
  
  CONCLUSIONS
  A modified, low cost and simple-to-perform PA test is appropriate for use in resource-limited countries, and has exhibited excellence in distinguishing recent from established HIV infection.
authors: The China Scholarship Council, Yunnan CDC, Kunming, Yunnan, China.
authors: Hong
authors: H
authors: Li
authors: Fassil
authors: F
authors: Ketema
authors: Anne M
authors: AM
authors: Sill
authors: Kristen M
authors: KM
authors: Kreisel
authors: Farley R
authors: FR
authors: Cleghorn
authors: Niel T
authors: NT
authors: Constantine
mesh_terms: D000372:Agglutination Tests / Q000379:methods*; D015658:HIV Infections / Q000175:diagnosis* / Q000821:virology; D006679:HIV Seropositivity / Q000175:diagnosis; D015497:HIV-1 / Q000302:isolation & purification*; D006801:Humans; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity