Conjugate vaccines and polysaccharide response
http://www.100md.com
《加拿大医疗协会学报》
Purified polysaccharide vaccines work by activation of B cells in a T-independent manner, producing predominantly IgM and little memory B cells.1 Protein-polysaccharide conjugate vaccines (such as Prevnar/PCV7 which uses 7 prevalent polysaccharides to bind to non-toxic variant of diphtheria toxin, CRM197) allow the protein to present antigen on B cells and CD40/CD40L interaction, while T cells allow antibody class switching from IgM to IgG producing memory cells and longer response. Conjugated vaccines usually use polyribosylribitol phosphate (PRP) conjugated with protein carriers and conjugate vaccines for Haemophilus influenzae and Neisseria meningitidis (using outer membrane proteins, OMP) have already been developed.2
However, conjugate vaccines may not work in high-risk categories like HIV-positive children3 and asplenics,2 and the PPV23 vaccine failure comorbid elderly4needs to be identified and followed up. IgG subclass measurement for evaluation of vaccine response is vital; anti-IgG1 pneumococcal antibodies in children (both with normal and abnormal immunity) and anti-IgG2 antibodies in adults are the best discriminatory laboratory measure.5 The future seems certain for conjugate vaccines, and PPV23 may end up being a test to see polysaccharide response in an individual.
REFERENCES
Kellner JD, Church DL, MacDonald J, et al. Progress in the prevention of pneumococcal infection. CMAJ 2005;173(10):1149-51.
Prevention and control of meningococcal disease. Recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Recomm Rep 2005;54(RR-7):1-21. Available: www.cdc.gov/mmwr/preview/mmwrhtml/rr5407a1.htm (accessed 2 Mar 2006).
Spoulou VI, Tsoumas DL, Papaevangelou VG, et al. Immunogenicity and immunological memory induced by a 7-valent pneumococcal CRM197 conjugate vaccine in symptomatic HIV-1 infected children. Vaccine 2005;23(46-47):5289-93.
Lexau CA, Lynfield R, Danila R, et al; Active Bacterial Core Surveillance Team. Changing epidemiology of invasive pneumococcal disease among older adults in the era of pediatric pneumococcal conjugate vaccine. JAMA 2005;294(16):2043-51.
Sikkema DJ, Ziembiec NA, Jones TR, et al. Assignment of weight-based immunoglobulin G1 (IgG1) and IgG2 units in antipneumococcal reference serum lot 89-S(F) for pneumococcal polysaccharide serotypes 1, 4, 5, 7F, 9V, and 18C. Clin Diagn Lab Immunol 2005;12(1):218-23.(Sujoy Khan)
However, conjugate vaccines may not work in high-risk categories like HIV-positive children3 and asplenics,2 and the PPV23 vaccine failure comorbid elderly4needs to be identified and followed up. IgG subclass measurement for evaluation of vaccine response is vital; anti-IgG1 pneumococcal antibodies in children (both with normal and abnormal immunity) and anti-IgG2 antibodies in adults are the best discriminatory laboratory measure.5 The future seems certain for conjugate vaccines, and PPV23 may end up being a test to see polysaccharide response in an individual.
REFERENCES
Kellner JD, Church DL, MacDonald J, et al. Progress in the prevention of pneumococcal infection. CMAJ 2005;173(10):1149-51.
Prevention and control of meningococcal disease. Recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Recomm Rep 2005;54(RR-7):1-21. Available: www.cdc.gov/mmwr/preview/mmwrhtml/rr5407a1.htm (accessed 2 Mar 2006).
Spoulou VI, Tsoumas DL, Papaevangelou VG, et al. Immunogenicity and immunological memory induced by a 7-valent pneumococcal CRM197 conjugate vaccine in symptomatic HIV-1 infected children. Vaccine 2005;23(46-47):5289-93.
Lexau CA, Lynfield R, Danila R, et al; Active Bacterial Core Surveillance Team. Changing epidemiology of invasive pneumococcal disease among older adults in the era of pediatric pneumococcal conjugate vaccine. JAMA 2005;294(16):2043-51.
Sikkema DJ, Ziembiec NA, Jones TR, et al. Assignment of weight-based immunoglobulin G1 (IgG1) and IgG2 units in antipneumococcal reference serum lot 89-S(F) for pneumococcal polysaccharide serotypes 1, 4, 5, 7F, 9V, and 18C. Clin Diagn Lab Immunol 2005;12(1):218-23.(Sujoy Khan)