title: Use of dried clinical samples for storing and detecting influenza RNA.
abstract: BACKGROUND
  Most clinical samples collected for diagnostic influenza testing and monitoring require refrigerated or frozen storage or shipment, which imparts logistic and cost burdens. The ability to store and ship dried clinical specimens under ambient conditions for influenza testing would significantly reduce costs and protect samples from improper storage or equipment failure, especially in remote or resource-limited areas.
  
  
  OBJECTIVE
  To evaluate the collection and storage of dried clinical samples on a transport matrix (ViveST™, ST) for influenza RNA testing by real-time reverse-transcription PCR (RT-PCR).
  
  
  METHODS
  Viral transport medium from swab or sputum samples was applied to ST, dried, and stored under ambient conditions from 2 days to 6 months. Additional aliquots of samples were frozen. Testing of frozen and ST-stored samples was performed using the WHO/CDC real-time influenza A (H1N1) RT-PCR protocol and compared to the Luminex xTAG RVP assay.
  
  
  RESULTS
  ST-stored samples yielded slightly higher threshold cycle values (median 2·54 cycles) compared to frozen samples tested in parallel. This difference was consistent regardless of viral input. There was no significant difference in signal recovery between samples stored for 1 week versus samples stored for 3 weeks, or from three samples stored for 6 months. Qualitatively, clinical specimens stored on ST were 100% concordant (36/36) with frozen samples for detecting the presence of influenza A RNA.
  
  
  CONCLUSIONS
  ST-processed dried specimens produced similar rates of seasonal or novel 2009 HIN1 influenza RNA detection compared to conventional sample processing and thus presents a viable alternative to refrigerated or frozen samples.
authors.affiliation: VA Palo Alto Health Care System, Palo Alto, CA, USA. mark.winters@stanford.edu
authors.forename: Mark
authors.initials: M
authors.lastname: Winters
authors.forename: Robert
authors.initials: R
authors.lastname: Lloyd
authors.forename: Azra
authors.initials: A
authors.lastname: Shahidi
authors.forename: Sheldon
authors.initials: S
authors.lastname: Brown
authors.forename: Mark
authors.initials: M
authors.lastname: Holodniy
mesh_terms: D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000235:genetics / Q000302:isolation & purification; D009980:Influenza A virus / Q000235:genetics / Q000302:isolation & purification*; D007251:Influenza, Human / Q000175:diagnosis / Q000821:virology*; D012367:RNA, Viral / Q000235:genetics*; D060888:Real-Time Polymerase Chain Reaction; D013048:Specimen Handling / Q000295:instrumentation / Q000379:methods*
chemical_list: D012367:RNA, Viral