title: HIV-1 variability and viral load technique could lead to false positive HIV-1 detection and to erroneous viral quantification in infected specimens.
abstract: OBJECTIVE
  Viral load (VL) testing is used for early HIV diagnosis in infants (EID) and for detecting early therapeutic failure events, but can be affected by HIV genetic variability. Dried blood samples (DBS) increase VL access and EID in remote settings and when low blood volume is available.
  
  
  METHODS
  This study compares VL values using Siemens VERSANT HIV-1 RNA 1.0 kPCR assay (kPCR) and Roche CAP/CTM Quantitative test v2.0 (CAP/CTM v2.0) in 176 DBS carrying different HIV-1 variants collected from 69 Equatoguinean mothers and their infants with known HIV-1 status (71 infected, 105 uninfected).
  
  
  RESULTS
  CAP/CTM v2.0 provided false positive VLs in 11 (10.5%) cases. VL differences above 0.5 log10 were observed in 42/49 (87.5%) DBS, and were above 1 log10 in 18 cases. CAP/CTM v2.0 quantified all the 41 specimens with previously inferred HIV-1 variant by phylogenetic analysis (68.3% recombinants) whereas kPCR only identified 90.2% of them, and was unable to detect 14.3% of 21 CRF02_AG viruses. CAP/CTM v2.0 showed higher sensitivity than kPCR (95.8% vs. 70.1%), quantifying a higher rate of viruses in infected DBS from subjects under antiretroviral exposure at sampling time compared to kPCR (94.7% vs. 96.2%, p-value<0.001). kPCR showed maximum specificity (100%) whereas for CAP/CTM v2.0 was 89.5%.
  
  
  CONCLUSIONS
  VL assays should increase their sensitivity and specificity to avoid overestimated HIV-1 quantifications, which could be interpreted as virological failure events, or false negative diagnostic results due to genetic variability. We recommend using the same VL technique for each patient during antiretroviral therapy monitoring.
authors.affiliation: HIV-1 Molecular Epidemiology Laboratory, Microbiology and Parasitology Department Hospital Universitario Ramón y Cajal, IRYCIS and CIBERESP, Madrid, Spain.
authors.forename: Patricia
authors.initials: P
authors.lastname: Alvarez
authors.affiliation: HIV-1 Molecular Epidemiology Laboratory, Microbiology and Parasitology Department Hospital Universitario Ramón y Cajal, IRYCIS and CIBERESP, Madrid, Spain.
authors.forename: Leticia
authors.initials: L
authors.lastname: Martín
authors.affiliation: Hospital Universitario de Getafe, Madrid, Spain.
authors.forename: Luis
authors.initials: L
authors.lastname: Prieto
authors.affiliation: Hospital Provincial de Bata, Ministerio de Sanidad y Bienestar Social, Equatorial Guinea.
authors.forename: Jacinta
authors.initials: J
authors.lastname: Obiang
authors.affiliation: Centro Nacional de Medicina Tropical, Instituto de Salud Carlos III-Madrid, RICET, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Vargas
authors.affiliation: Centro Nacional de Medicina Tropical, Instituto de Salud Carlos III-Madrid, RICET, Spain.
authors.forename: Pedro
authors.initials: P
authors.lastname: Avedillo
authors.affiliation: Hospital Universitario Doce de Octubre, Madrid, Spain.
authors.forename: Pablo
authors.initials: P
authors.lastname: Rojo
authors.affiliation: HIV-1 Molecular Epidemiology Laboratory, Microbiology and Parasitology Department Hospital Universitario Ramón y Cajal, IRYCIS and CIBERESP, Madrid, Spain.
authors.forename: Carolina
authors.initials: C
authors.lastname: Fernández McPhee
authors.affiliation: Centro Nacional de Medicina Tropical, Instituto de Salud Carlos III-Madrid, RICET, Spain.
authors.forename: Agustín
authors.initials: A
authors.lastname: Benito
authors.affiliation: Hospital Universitario Clínico San Carlos, Madrid, Spain.
authors.forename: José Tomás
authors.initials: JT
authors.lastname: Ramos
authors.affiliation: HIV-1 Molecular Epidemiology Laboratory, Microbiology and Parasitology Department Hospital Universitario Ramón y Cajal, IRYCIS and CIBERESP, Madrid, Spain. Electronic address: africa.holguin@salud.madrid.org.
authors.forename: África
authors.initials: Á
authors.lastname: Holguín
mesh_terms: D000328:Adult; D003951:Diagnostic Errors; D059788:Dried Blood Spot Testing; D005189:False Positive Reactions; D005260:Female; D015658:HIV Infections / Q000175:diagnosis* / Q000821:virology; D015497:HIV-1 / Q000235:genetics / Q000302:isolation & purification* / Q000502:physiology*; D006801:Humans; D007223:Infant; D009035:Mothers; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012367:RNA, Viral / Q000235:genetics; D011933:Reagent Kits, Diagnostic; D012680:Sensitivity and Specificity; D013048:Specimen Handling; D019562:Viral Load / Q000379:methods*; D055815:Young Adult
chemical_list: D012367:RNA, Viral; D011933:Reagent Kits, Diagnostic
keywords: CAP/CTM; DBS; HIV-1 diagnosis; Treatment failure; Viral load; kPCR