title: A simple method to elute cell-free HIV from dried blood spots improves their usefulness for monitoring therapy.
abstract: BACKGROUND
  Dried blood spots (DBS) improve access to HIV viral load (VL) testing, but yield increased VL measurements compared to the plasma reference method because of cell-associated viral nucleic acid. In clinical settings, DBS methods may falsely categorize many patients as failing therapy.
  
  
  OBJECTIVE
  Description of a simple method, free virus elution (FVE), to preferentially elute plasma-associated virus from DBS samples with phosphate-buffered saline, and an initial HIV VL performance comparison with standard DBS elution methods.
  
  
  METHODS
  The mechanism of action of FVE was studied with model DBS samples containing purified virus or washed HIV-containing cells, and with a DNA-specific HIV PCR. Using clinical samples, VL results from the new FVE method were compared to results from a dried fluid spot procedure (DFSP) protocol, which uses a guanidinium-based elution method, using plasma VL as the reference method.
  
  
  RESULTS
  Model system experiments suggest that the method efficiently separates virus from cell-associated HIV, with a wide tolerance for incubation time and temperature. In 196 clinical samples, FVE reduced VL over-quantification from DBS, and improved DBS clinical concordance with plasma from 67% to 95%.
  
  
  CONCLUSIONS
  A simple elution in PBS significantly reduced the over-quantification of HIV VL in DBS. Additional studies are needed to validate the method in fingerstick-collected specimens and to further understand the compartmentalization of HIV DNA and RNA in DBS specimens.
authors.affiliation: Roche Molecular Systems, Pleasanton, CA, USA.
authors.forename: Xiaoning
authors.initials: X
authors.lastname: Wu
authors.affiliation: Roche Molecular Systems, Pleasanton, CA, USA.
authors.forename: Megan
authors.initials: M
authors.lastname: Crask
authors.affiliation: Roche Molecular Systems, Pleasanton, CA, USA.
authors.forename: Hector
authors.initials: H
authors.lastname: Ramirez
authors.affiliation: Roche Molecular Systems, Pleasanton, CA, USA.
authors.forename: Trevor
authors.initials: T
authors.lastname: Landas
authors.affiliation: Roche Molecular Systems, Pleasanton, CA, USA.
authors.forename: Tri D
authors.initials: TD
authors.lastname: Do
authors.affiliation: Roche Molecular Systems, Pleasanton, CA, USA.
authors.forename: Christiane
authors.initials: C
authors.lastname: Honisch
authors.affiliation: Roche Molecular Systems, Pleasanton, CA, USA.
authors.forename: Stephen
authors.initials: S
authors.lastname: Will
authors.affiliation: Roche Molecular Systems, Pleasanton, CA, USA. Electronic address: paul.baum@roche.com.
authors.forename: Paul D
authors.initials: PD
authors.lastname: Baum
mesh_terms: D000328:Adult; D059788:Dried Blood Spot Testing; D015658:HIV Infections / Q000188:drug therapy / Q000821:virology; D015497:HIV-1 / Q000235:genetics / Q000302:isolation & purification*; D006801:Humans; D008875:Middle Aged; D012367:RNA, Viral / Q000235:genetics; D013048:Specimen Handling / Q000379:methods; D019562:Viral Load
chemical_list: D012367:RNA, Viral
keywords: DBS; Dried blood spots; HIV; Viral load