Skip to main content


  • Poster presentation
  • Open Access

Development of a Simple and Affordable S/LS Assay to Distinguish Recent and Established HIV Infection

  • 1Email author,
  • 2,
  • 3,
  • 3,
  • 2 and
  • 3
Retrovirology20052 (Suppl 1) :P41

  • Published:


  • Infectious Disease
  • Gelatin
  • Testing Sample
  • Positive Reaction
  • Great Sensitivity


Sensitive/less-sensitive (S/LS) serologic assays that differentiate recent from established HIV infection may not be suitable for use in resource-limited and financially challenged countries. A more simple and affordable method is needed to address these limitations. Methods: The Serodia HIV-1/HIV-2 particle agglutination assay (PA) was modified to act as a S/LS assay. Antigen-coated gelatin particles were diluted 1:68, and sera were diluted at intervals from 1:10 to 1:80,000; HIV antibody status was confirmed at the 1:10 dilution. 37 clade B seroconversion panels from Trinidad and BBI (n = 309) were tested at each sample dilution to calibrate the PA assay; the last positive reaction (>1+) was considered the endpoint dilution (ED). The greatest sensitivity for correctly classifying recent and established infection samples was determined by ROC analyses. A subset of these panels (n = 181) was also tested by the Vironostika S/LS (DV) as a reference for comparison.


At a dilution of 1:40,000 and a days post SC cutoff of 190 days the PA test gave 97% sensitivity for classifying both recent and established infection samples, as compared with 82% and 53% on a subset tested by the DV; this resulted in a poor concordance of 60% and 73%.


A low cost, simple to perform PA test was modified as a S/LS test and exhibited excellence in distinguishing recent and established HIV infection. The PA S/LS performed more accurately than the reference DV S/LS when testing samples with known times of seroconversion.


Authors’ Affiliations

China Scholarship Council, Yunnan CDC, Kunming, China
Institute of Human Virology, Baltimore, MD, US
University of MD School of Medicine, Baltimore, MD, US


© The Author(s) 2005