Evaluation of Candidate Standard XX (97/650)

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Evaluation of Candidate Standard XX (97/650)

• Clare Davis
• Division of Retrovirology
• National Institute for Biological Standards and
  Control
• (NIBSC)
• UK

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1st International Standard for HIV-1 RNA (NIBSC
code 97/656)

• Established as International Standard in 1999
  (Holmes et al, 2001).
• Assigned a concentration of 100,000 IU per
  vial/ml.
• Based on HIV-1 PCR positive, antibody negative
  plasmapheresis donation.
• Virus diluted 1312.5 in base matrix
  (defibrinated plasma).
• 2400 vials freeze-dried. Held at -200C.
• Preparation showed good stability and correlation
  amongst assays.
• Discussions at SoGAT Jul 2003 (PEI) raised
• Low Stocks ( 650).
• Presence of HBV DNA problematical for multiplex
  assays.

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--- bDNA --- Monitor --Nuclisens --- Abbott ---
in-house
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Re-evaluation of Candidate XX

• Non-syncitium inducing HIV-1 genotype B field
  isolate field isolate (donated by Dr. P.
  Simmonds).
• Supplied as a low passage virus.
• Further propagated on human PBMCs, supernatant
  stored in LN2.
• Virus diluted 1250 in pooled human plasma.
• 2200 vials of material freeze-dried.

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Study Details

• Study purpose-
• Calibrate XX against HIV-1 RNA International
  Standard.
• Confirm stability of XX
• Determine values in current assays
• 9 Laboratories participating.
• International Standard and Candidate XX randomly
  coded.
• Participants asked to test samples in 3
  independent assays.
• Initially 10 fold dilution
• Then 2 subsequent assays half log dilutions
  around the end point.
• NIBSC to analyse data.

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Preliminary analysis of data so
far..Quantitative
Lab Number Assay Used Sample A (copies/ml Log 10) Sample B (copies/ml Log 10)
7 COBAS Taq Man 5.50 5.07
22 Amplicor 5.55 4.96
58 bDNA V3 5.21 4.69
73 COBAS Amplicor 5.84 5.26
Overall Mean 5.52 4.99
Values obtained in previous study 5.31
4.73
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Qualitative
Lab Number Assay Used Sample A (log 10 detectable units/ml) Sample B (log 10 detectable units/ml)
70 In house 4.69 4.69
71 In house 5.36 4.11
72 In house 5.15 5.29
Overall Mean 5.06 4.70
Values obtained in previous study 4.70
4.22
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Conclusion

• Preliminary analysis of data shows good
  correlation with previous study.
• Hope to submit report to ECBS Aug 04.
• Please return any outstanding data to us by end
  Jun 04.