Pneumococcal Vaccines
Streptococcus pneumoniae Vaccine
Vaccines against Streptococcus pneumoniae
from James C. Paton writing in Vaccine Design: Innovative Approaches and Novel Strategies
Existing vaccines against Streptococcus pneumoniae are targeted at the capsular polysaccharide (PS) of which there are 91 distinct serotypes. Polyvalent purified PS vaccines are immunogenic in healthy adults, but not in high risk groups such as young children and the elderly. Development of PS-protein conjugate vaccines has overcome the poor immunogenicity of PS in children, but the protection imparted is strictly serotype-specific, and the number of included serotypes is even more restricted than in the PS vaccine formulations. Widespread introduction of conjugate vaccines in developed countries has dramatically reduced the incidence of invasive pneumococcal disease due to serotypes included in the vaccine. However, these benefits are being eroded by increases in the incidence of disease caused by non-vaccine serotypes. Conjugate vaccines are also expensive, limiting their use in developing countries, where the burden of pneumococcal disease is greatest. Clearly, there is an urgent need to develop alternative pneumococcal vaccines that are (i) inexpensive, (ii) immunogenic in young children, and (iii) provide protection against all pneumococci regardless of serotype. Of particular importance are vaccines comprising pneumococcal proteins that contribute to virulence and are common to all serotypes.
Further reading: Vaccine Design: Innovative Approaches and Novel Strategies | Bacterial Polysaccharides: Current Innovations and Future Trends
from James C. Paton writing in Vaccine Design: Innovative Approaches and Novel Strategies
Existing vaccines against Streptococcus pneumoniae are targeted at the capsular polysaccharide (PS) of which there are 91 distinct serotypes. Polyvalent purified PS vaccines are immunogenic in healthy adults, but not in high risk groups such as young children and the elderly. Development of PS-protein conjugate vaccines has overcome the poor immunogenicity of PS in children, but the protection imparted is strictly serotype-specific, and the number of included serotypes is even more restricted than in the PS vaccine formulations. Widespread introduction of conjugate vaccines in developed countries has dramatically reduced the incidence of invasive pneumococcal disease due to serotypes included in the vaccine. However, these benefits are being eroded by increases in the incidence of disease caused by non-vaccine serotypes. Conjugate vaccines are also expensive, limiting their use in developing countries, where the burden of pneumococcal disease is greatest. Clearly, there is an urgent need to develop alternative pneumococcal vaccines that are (i) inexpensive, (ii) immunogenic in young children, and (iii) provide protection against all pneumococci regardless of serotype. Of particular importance are vaccines comprising pneumococcal proteins that contribute to virulence and are common to all serotypes.
Further reading: Vaccine Design: Innovative Approaches and Novel Strategies | Bacterial Polysaccharides: Current Innovations and Future Trends
Protective Capacity of Antibodies
Category: Vaccines | Immunology
New Analytical Approaches for Measuring Protective Capacity of Antibodies
from Moon H. Nahm and Carl E. Frasch writing in Vaccine Design: Innovative Approaches and Novel Strategies
Antibodies to the pneumococcal polysaccharide capsule protect the host by opsonizing pneumococci for host phagocytes, while antibodies to the meningococcal polysaccharide capsule protect by directly killing meningococci in the presence of complement. In vitro measurement of serum bactericidal antibody (SBA) against the meningococcus has been used for a long time as a measure of protective immunity. Technical developments of pneumococcal opsonophagocytosis assays (OPA) in the past decade permit measurements of opsonic capacity of sera from persons immunized with pneumococcal vaccines. Experience with OPAs shows that opsonic capacities of antisera are better than their antibody levels in predicting vaccine efficacy. Thus, measurements of opsonic capacity could be a surrogate of clinical studies of pneumococcal vaccines. By being the surrogate for clinical studies, the assays for protective function of antibodies would reduce the need for large clinical trials and facilitate vaccine developments and improvements.
Further reading: Vaccine Design: Innovative Approaches and Novel Strategies
from Moon H. Nahm and Carl E. Frasch writing in Vaccine Design: Innovative Approaches and Novel Strategies
Antibodies to the pneumococcal polysaccharide capsule protect the host by opsonizing pneumococci for host phagocytes, while antibodies to the meningococcal polysaccharide capsule protect by directly killing meningococci in the presence of complement. In vitro measurement of serum bactericidal antibody (SBA) against the meningococcus has been used for a long time as a measure of protective immunity. Technical developments of pneumococcal opsonophagocytosis assays (OPA) in the past decade permit measurements of opsonic capacity of sera from persons immunized with pneumococcal vaccines. Experience with OPAs shows that opsonic capacities of antisera are better than their antibody levels in predicting vaccine efficacy. Thus, measurements of opsonic capacity could be a surrogate of clinical studies of pneumococcal vaccines. By being the surrogate for clinical studies, the assays for protective function of antibodies would reduce the need for large clinical trials and facilitate vaccine developments and improvements.
Further reading: Vaccine Design: Innovative Approaches and Novel Strategies