2003-12-19-世界卫生组织-Consultation_on_the_characterization_of_BCG_strains_14页_117kb

报告摘要

Summary of BCG Vaccine Meeting Analysis

Purpose

The meeting aimed to review and update WHO requirements for BCG vaccines, assess molecular and genetic variations among sub-strains, and plan future research and quality control improvements.

Key Discussions

Molecular Characterization: BCG sub-strains exhibit genetic decay, deletions, and variations in antigens like ESAT-6, MPB64, and CFP-10, leading to differences in attenuation and protective efficacy. This decay occurs faster than in wild-type Mycobacterium bovis.
Efficacy and Safety: Clinical trials and epidemiological studies show wide variation in protection rates (e.g., 47-87% against tubercular meningitis) and reactogenicity (e.g., higher rates with Pasteur and Danish sub-strains). Factors include sub-strain differences, cultural conditions, and environmental influences.
Current Issues: WHO standards for BCG vaccines are outdated, and characterization methods need improvement. Questions about meta-analysis of vaccine efficacy remain due to insufficient data from confirmed strains.

Findings

There is overwhelming evidence for genetic and phenotypic variations in BCG sub-strains, affecting vaccine performance.
Current WHO requirements, established in the 1980s, do not align with recent scientific advances and need revision.
variations in clinical outcomes are confounded by methodological factors, making sub-strain effects hard to isolate.

Recommendations

Review and update WHO Requirements for BCG vaccines, including sub-strain nomenclature and standardization.
Investigate the role of genomics and proteomics in vaccine production and control.
Gather data on current BCG manufacturers and sub-strains used.
Conduct collaborative studies on methodology and feasibility of molecular characterization.
Establish a BCG Working Group to coordinate follow-up activities by early 2005.
Develop and test specific assays for sub-strain identification and production monitoring, with funding secured by WHO.

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