2003-12-31-世界卫生组织-Recommendations_for_the_production_and_control_of_Meningococcal_group_C_conjugate_vaccines,_Annex_2,_TRS_No_924_27页_159kb

WHO Recommendations for Production and Control of Meningococcal Group C Conjugate Vaccines (2004)

1. Overview

• These recommendations (formerly requirements) for meningococcal polysaccharide vaccines were first adopted in 1976 and amended in 1978 and 1981.
• Key advances: Conjugate vaccines (e.g., based on group C polysaccharide linked to tetanus toxoid or CRM197 protein) offer improved immunogenicity in infants and induce T-cell-dependent immunity.
• Limitations: Plain polysaccharide vaccines lack immunogenicity in young infants and do not elicit immunological memory.

2. General Production and Control Principles

• GMP Compliance: Adhere to WHO Good Manufacturing Practices, with specific additions for conjugate vaccines.
• Definition: Meningococcal group C conjugate vaccine is a preparation of group C capsular polysaccharide covalently linked to a carrier protein.
• Regulatory Role: National regulatory authorities should adopt or modify these recommendations, ensuring vaccines maintain at least equivalent safety and efficacy.

3. Part A: Manufacturing Recommendations (A.1–A.8)

3.1. Polysaccharide Control

• Strains: Use N. meningitidis strains capable of producing group C polysaccharide (e.g., C11, C2241).
• Purity Tests: Purity must be verified, including identity (serological tests or NMR), molecular size distribution (e.g., gel filtration via HPSEC), and limits for protein/nucleic acid/ endotoxin contamination.
• O-Acetylation: Monitor O-acetyl content (at least 1.5 mmol/g for acetylated polysaccharide) for consistency.

3.2. Carrier Protein Control

• Protein Purity: Carrier proteins (e.g., CRM197, tetanus toxoid) must be non-toxic and highly pure (e.g., CRM197 >90% purity via HPLC).
• Testing: Include identity (SDS-PAGE, MS), purity, and toxicological (e.g., absence of specific toxicity).

3.3. Conjugate Control (Bulk Purified)

• Conjugation: Method must ensure covalent binding, validated to remove unreacted functional groups; assess markers (e.g., carbohydrate-to-protein ratio, size distribution).
• Tests: Determine polysaccharide content, free polysaccharide levels, and protein content.

3.4. Final Bulk and Lot Release

• Mixing: Combine adjuvants, preservatives (if added), and bulk conjugate to meet safety specifications.
• Sterility: Test for bacterial/mycotic contamination using validated methods.
• Potency: Control tests (e.g., pyrogenicity, pH) must align with clinical trial data and stability studies.

3.5. Stability Testing

• Accelerated vs Real-Time: Conduct thorough stability studies to determine expiry dates.
• Key Factors: Focus on polysaccharide hydrolysis, structural integrity of conjugates, adjuvant binding, and storage conditions (typically 2–8°C).
• Bioavailability: If using aluminium-based adjuvants, monitor antigen desorption over time.

4. Part B: Recommendations for National Regulatory Authorities (B.1–B.3)

• Official Lot Release: A vaccine lot must meet national requirements and Part A recommendations after certified consistency.
• Control Certification: Release certification documents facilitate international vaccine exchange.
• Clinical Assessment:
  • Demand safety/immunogenicity data from clinical trials (including memory induction).
  • Repeated clinical assessments are needed for production changes or new combination vaccines.
• Serological Testing:
  • SBA Test: Serum bactericidal titre ≥1:128 indicates protection, but thresholds below 1:8 are predictive of susceptibility.
  • ELISA: Recommended for structure-based immunity, though correlation with SBA may vary and requires further validation.

Key Considerations

• Preclinical Testing: Animal immunogenicity and potency tests are not routine, if consistency is ensured via physicochemical methods.
• Impact of Combinations: Assess safety and immunogenicity of group C conjugate vaccines when co-formulated with other antigens.