Meningococcal vaccines for the United Kingdom
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M A Herbert1, P T Heath, R T Mayon-White
1Oxford Vaccine Group, John Radcliffe Hospital.
Insights
New meningococcal vaccines are urgently needed for infants in the UK, particularly for serogroups B and C. Research explores outer membrane proteins (OMP) and conjugate polysaccharides to overcome challenges in infant immunization.
Area of Science:
- * Vaccinology and Immunology
- * Microbial Pathogenesis
- * Public Health
Background:
- * Urgent need for new meningococcal vaccines in the UK, primarily targeting serogroups B and C.
- * Infants are most affected by Neisseria meningitidis but respond poorly to vaccines.
- * Existing serogroup B vaccines face challenges due to poor infant immunogenicity of capsular polysaccharides.
Purpose of the Study:
- * To explore alternative antigens for infant meningococcal vaccines.
- * To evaluate the efficacy of outer membrane proteins (OMP) and conjugate polysaccharides.
- * To address the immunological challenges in vaccinating infants against meningococcal disease.
Main Methods:
- * Review of existing and developing meningococcal vaccine strategies.
- * Consideration of outer membrane proteins (OMP), iron regulating proteins, and lipopolysaccharide as alternative antigens.
- * Analysis of phase 2 and phase 3 trial data for OMP-based vaccines in various countries.
- * Evaluation of conjugate vaccines for serogroup C and AC polysaccharides.
Main Results:
- * OMP-based vaccines have undergone several phase 3 trials globally.
- * Phase 2 trials have compared different OMP vaccines.
- * Conjugate vaccines show immunogenicity in infants but may have waning antibody titres.
- * A phase 2 trial of a hexavalent class 1 OMP vaccine is ongoing in infants.
Conclusions:
- * Developing effective meningococcal vaccines for infants remains a significant challenge.
- * Alternative antigens like OMP show promise but require further investigation.
- * Conjugate vaccines offer improved infant immunogenicity for serogroup C but antibody persistence is a concern.
Abstract:
New meningococcal vaccines are needed in the United Kingdom with some urgency. Almost all Neisseria meningitidis disease in this country is caused by serogroups B and C. Infants have the highest attack rates, but also make the poorest immunological responses to potential vaccines. The development of vaccines that protect infants is a significant challenge. A capsule-based serogroup B vaccine is unlikely to be successful in infants because the capsule is poorly immunogenic and the polysaccharide molecule mimics a human epitope. Without completely discounting capsule as an immunogen, alternate antigens are being considered for immunisation: outer membrane proteins (OMP), iron regulating proteins, and lipopolysaccharide. Vaccines based on OMP have been used in several phase 3 trials in South Africa, Cuba, Brazil, Norway, and Chile, in which two doses of vaccine were given. The Cuban and Norwegian vaccines have been compared in phase 2 trials in Iceland and Chile. Potential limitations are epitope heterogeneity and the theoretical ability of N. meningitidis to adapt even to hosts who have received polyvalent vaccines. A phase 2 trial of a hexavalent class 1 OMP vaccine is under way in Gloucester, with 100 babies receiving injections at 2, 3, and 4 months. Serogroup C vaccines have been developed from capsular polysaccharide but, unconjugated, these vaccines do not protect those under 2 years of age. Conjugate vaccines with C and AC polysaccharides are immunogenic in infants, but antibody titres may wane quickly.(ABSTRACT TRUNCATED AT 250 WORDS)