2015-10-24-世界卫生组织-WHO_BS_2015.2259_Collaborative_Study_to_establish_the_1st_WHO_IS_for_JCV_DNA_for_nucleic_acid_amplification_technique_NAT_-based_assays_52页_3mb

Summary of WHO Collaborative Study to Establish First International Standard for JCV DNA

Objective:
The study aimed to establish the first World Health Organization (WHO) International Standard for JC Virus (JCV) DNA using a collaborative approach to standardize nucleic acid amplification techniques (NAT) for clinical diagnostics and research.

Key Findings:

• A freeze-dried whole virus JCV 1A strain preparation (NIBSC code 14/114) showed excellent stability under various storage conditions (-20°C to 45°C) based on accelerated thermal degradation studies.
• The candidate standard demonstrated good homogeneity and potency, with an average viral copy number of 6.95 log10 copies/mL (7.0 log10 IU/mL assigned for standardization).
• Inter-laboratory variability was high in quantitative and qualitative assays, but relative potency harmonization improved agreement when the candidate was used as a reference.
• The preparation was formulated in a universal buffer for compatibility with clinical matrices (e.g., urine, CSF, plasma).

Recommendations:

• The candidate standard (NIBSC code 14/114) is proposed as the first WHO International Standard for JCV DNA with an assigned potency of 7.0 log10 IU/mL.
• This standard will be used for calibrating secondary reference materials in NAT assays for JCV detection.

Conclusion:
The study supports the establishment of this standard to improve comparability and reliability in JCV diagnostics, particularly in detecting Progressive Multifocal Leukoencephalopathy (PML).