title: Ultrasensitive quantitative HIV-1 p24 antigen assay adapted to dried plasma spots to improve treatment monitoring in low-resource settings.
abstract: BACKGROUND
  Our group has previously developed a quantitative and ultrasensitive HIV-1 p24 antigen assay that is inexpensive, easy-to-perform, and can be carried out in low-resource settings. Since antiretroviral therapies are becoming more accessible in resource-constrained countries, methods to assess HIV-1 viraemia are urgently needed to achieve a high standard of care in HIV-1 management.
  
  
  OBJECTIVE
  To adapt our quantitative assay to dried plasma spots (DPS), in order to further simplify this test and make it more accessible to resource-constrained countries.
  
  
  METHODS
  DPS from 47 HIV-seropositive, treated or untreated adult individuals and 30 healthy individuals were examined.
  
  
  RESULTS
  A specificity of 100% was observed when p24 antigen was measured using DPS, and no differences of p24 concentration could be seen between DPS and venous plasma. The correlation between DPS and venous plasma p24 was excellent (R=0.93, CI(95%)=0.88-0.96, p<0.0001). Similarly, p24 antigen concentrations using DPS were well correlated with RNA viral load (R=0.53, CI(95%)=0.27-0.72, p=0.0002).
  
  
  CONCLUSIONS
  This quantitative p24 antigen test has similar sensitivity and specificity using DPS and venous plasma, and has the potential to improve health care delivery to HIV-affected individuals in resource-constrained countries.
authors.affiliation: Swiss National Center for Retroviruses, University of Zürich, Gloriastrasse 30/32, CH-8006 Zürich, Switzerland.
authors.forename: Marlyse C
authors.initials: MC
authors.lastname: Knuchel
authors.forename: Zuzana
authors.initials: Z
authors.lastname: Tomasik
authors.forename: Roberto F
authors.initials: RF
authors.lastname: Speck
authors.forename: Ruedi
authors.initials: R
authors.lastname: Lüthy
authors.forename: Jörg
authors.initials: J
authors.lastname: Schüpbach
mesh_terms: D015492:AIDS Serodiagnosis / Q000191:economics / Q000379:methods*; D000328:Adult; D019380:Anti-HIV Agents / Q000627:therapeutic use; D016022:Case-Control Studies; D002648:Child; D003365:Costs and Cost Analysis; D004797:Enzyme-Linked Immunosorbent Assay; D005069:Evaluation Studies as Topic; D015483:HIV Antibodies / Q000097:blood / Q000737:chemistry; D015488:HIV Antigens / Q000097:blood; D016655:HIV Core Protein p24 / Q000097:blood*; D015658:HIV Infections / Q000097:blood / Q000175:diagnosis* / Q000188:drug therapy / Q000821:virology*; D006679:HIV Seropositivity; D015497:HIV-1 / Q000276:immunology*; D006358:Hot Temperature; D006801:Humans; D011489:Protein Denaturation; D012680:Sensitivity and Specificity; D016896:Treatment Outcome; D019562:Viral Load
chemical_list: D019380:Anti-HIV Agents; D015483:HIV Antibodies; D015488:HIV Antigens; D016655:HIV Core Protein p24