2015-10-24-世界卫生组织-WHO_BS_2015.2262_Collaborative_Study_to_Evaluate_the_Proposed_5th_WHO_IS_for_Hepatitis_C_Virus_HCV_RNA_for_Nucleic_Acid_Amplification_Technique_NAT_-Based_Assays_56页_720kb

报告摘要

WHO Collaborative Study on Revised Hepatitis C Virus (HCV) RNA International Standard

Background

Previous WHO HCV NAT IS (4th version, NIBSC code 06/102) established in 2011, with stability issues at ambient temperatures.
Fourth IS used antibody-positive material, affecting stability; third and fourth IS (antibody-negative) showed better stability.
Goal: Establish a new, stable HCV RNA International Standard with clear potency assignment for NAT-based assays.

Pilot Study Findings

A stability pilot study comparing lyophilized antibody-positive/negative formulations did not detect HCV antibody's stabilizing effect.
Lyophilization caused a small but consistent loss of titers, reduced in later formulations.
Concluded use of window-period donation (antibody-negative) suitable to align with blood donation needs.

Main Collaborative Study

Study objective: Evaluate candidate 5th WHO HCV IS (NIBSC code 14/150) for replacement of the fourth.
Material: ~1980 vials of lyophilized antibody-negative genotype 1a HCV RNA.
Study design: 17 laboratories across 11 countries tested pooled and diluted samples over 3-6 months.
Assays included commercial real-time PCR (quantitative) and qualitative assays.

Key Results

Inter-laboratory variability: Generally low (standard deviations <0.50 log IU/mL).
Intra-laboratory precision: Low variability in quantitative assays.
Relative potency: Mean potency of ~5.0 log IU/mL, when reconstituted in 1.1mL. Highest variability in qualitative assays.
Accelerated stability testing: Confirmed good stability at recommended temperatures but allowable small losses at higher temps; no impact on transport conditions observed.

Limitations & Discrepancies

Outliers in qualitative assays possibly due to analytical variations, not standardized end-point detection.
Suggest requirements for secondary reference materials linked calibration.

Conclusion

Proposal to assign relative potency of 5.0 log IU/mL (NIBSC code 14/150) for the new 5th HCV RNA NAT International Standard.


Note: The summary focuses on critical information presented in the report, using conventional and standardized terms used in the referenced methodologies where appropriate.

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