title: Comparative effectiveness of dried plasma HIV-1 viral load testing in Brazil using ViveST for sample collection.
abstract: BACKGROUND
  Utilization of dried plasma for HIV-1 viral load testing would significantly decrease sample shipping costs.
  
  
  OBJECTIVE
  To describe the precision and reproducibility of ViveST(®) (ST) as a transportation method for shipping specimens for HIV-1 viral load (VL) testing.
  
  
  METHODS
  Thirty clinical plasma samples were used to generate replicate samples with HIV VL values of 4 log(10), 3 log(10) and 2 log(10) copies/mL for reproducibility testing and an additional 299 samples with HIV VL <50 copies/mL (99); 1.7 log(10) to 3.99 log(10) (100); and 4 log(10) to 5.99 log(10)/mL (100) were used to compare ViveST to frozen plasma samples using the VERSANT(®) HIV-1 RNA 3.0 Assay. Results were compared using Student t-test, Pearson correlation and Bland-Altman analyses.
  
  
  RESULTS
  Mean intra-assay variance among frozen and dried plasma triplicates was 0.15 log(10) and 0.09 log(10) copies/mL respectively (n=10, P=NS). Compared to frozen plasma, there was a mean reduction of 0.3 log(10), 0.27 log(10), and 0.35 log(10) copies/mL at the 4 log(10), 3 log(10), and 2 log(10) copy/mL samples respectively (n=30, all comparisons, P<0.01). Overall correlation between 299 frozen and ViveST samples was r=0.97, where 12 of 99 undetectable frozen VL were positive with ST, and 12 of 200 frozen detectable VL were undetectable with ViveST (mean VL 2.1, 1.9 log(10) copies/mL respectively).
  
  
  CONCLUSIONS
  HIV-1 viral load results using ViveST were reproducible, correlated well with frozen plasma, though yielding minimally lower values. Our data suggest that dried plasma for HIV-1 VL testing using ViveST has promise for use in HIV clinical practice.
authors.affiliation: Retrovirology Laboratory, Federal University of Sao Paulo, Brazil.
authors.forename: Michelle
authors.initials: M
authors.lastname: Zanoni
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Cortes
authors.forename: Ricardo S
authors.initials: RS
authors.lastname: Diaz
authors.forename: M Cecilia
authors.initials: MC
authors.lastname: Sucupira
authors.forename: Denise
authors.initials: D
authors.lastname: Ferreira
authors.forename: Lilian A
authors.initials: LA
authors.lastname: Inocencio
authors.forename: Cintia
authors.initials: C
authors.lastname: Vilhena
authors.forename: Clive
authors.initials: C
authors.lastname: Loveday
authors.forename: R M
authors.initials: RM
authors.lastname: Lloyd
authors.forename: M
authors.initials: M
authors.lastname: Holodniy
mesh_terms: D001938:Brazil; D003890:Desiccation; D015658:HIV Infections / Q000175:diagnosis* / Q000821:virology*; D015497:HIV-1 / Q000302:isolation & purification*; D006801:Humans; D010949:Plasma / Q000821:virology*; D015203:Reproducibility of Results; D013048:Specimen Handling / Q000379:methods*; D019562:Viral Load / Q000379:methods*