Procleix

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Procleix WNV Assay A TMA-based Assay for
Screening Blood Donations for West Nile Virus RNA
SoGATJuly 3, 2003

• Jeff Linnen, Ph.D.
• Research and Development
• Gen-Probe Incorporated,
• San Diego, CA USA

Procleix is a registered trademark of Chiron
Corporation
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Procleix WNV Assay

• Based on Transcription Mediated Amplification
  (TMA)
• Uses same instrument platform as Gen-Probes
  licensed NAT blood screening assay
• Procleix Semi-automated System currently used
  withProcleix HIV-1/HCV Assay

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Specificity of the Procleix WNV Assay

• 1,680 normal blood donations were tested at
  Gen-Probe
• 99.8 initial specificity 100 resolved
  specificity
• over 40,000 archived samples from 2002 high risk
  populations have been tested by American Red
  Cross (S. Stramer)
• No cross reactivity to other blood borne viruses
• Testing included HTLV, HIV-1/-2, HCV, HBV, HGV,
  Rubella, HAV, CMV, EBV, HCV, Parvo B19
• Assay designed to specifically detect West Nile
  virus
• No cross reactivity to other flaviviruses
  Dengue (1-4), Yellow Fever Virus, and St. Louis
  Encephalitis virus weak cross reactivity to
  Murray Valley Encephalitis virus
• Detects Kunjin virus (Australian subtype of West
  Nile virus)

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Analytical Sensitivity
Based on data from Procleix WNV Assay kit lot
manufactured at 2 million test scale
virus quantified by BBI TaqMan Assay (BBI
Diagnostics, West Bridgewater, MA).
Probit Analysis (results from BBI
panels) Lineage 1 95 detection at 4 to 14
copies/mL Lineage 2 95 detection at 4 to 8
copies/mL
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Samples from CDC WNV Transfusion Transmission
Case Investigations (2002)

• Positive Results from testing 383 blinded
  samples sent to Gen-Probe from the American Red
  Cross
• All donations implicated in transfusion
  transmission were detected at 116 dilution with
  TMA

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Nationwide WNV Blood Screeningin the United
States, 2003

• Testing using the Procleix WNV Assay started on
  June 19
• Implemented nationwide on July 1
• Test development which normally takes 2 to 3
  years was condensed into less than 9 months.
• Procleix WNV Assay is being used to test over 80
  of the US blood supply
• Most donations are being tested in pools of 16
  (some sites are testing individual donations)
• reactive pools will be resolved to individual
  donation
• Testing will reduce the risk of WNV transfusion
  transmission
• will provide real time surveillance of human WNV
  activity in North America

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Acknowledgements

• Gen-Probe WNV Assay Development Team
• (Front to back, left to right) Mike Shih, Josh
  Cary, Geoffrey Dennis, Janice Cline, Martha
  Alden, Wen Wu, Mackenzie Lewis, Michelle Cass,
  Amy Broulik, Jeff Linnen, Stephanie Miller

• National Heart, Lung, and Blood Institute
  (NHLBI) for partial funding
• Susan Stramer, American Red Cross
• Chiron Corporation