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At least 1,135 records · Page 63Linked to original sources
PubMed2005

Immunization with Neisseria meningitidis outer membrane vesicles prevents bacteremia in neonatal mice.

Although vaccines based on outer membrane vesicles (OMV) of Neisseria meningitidis have been developed and administered to children, little is known about the magnitude and quality of the immune response in animal models of early life immunization. We investigated the immunogenicity of meningococcal OMV, and the influence of route and immunization schedule, in neonatal mice. The administration of two intraperitoneal doses of OMV, given at 7 and 14 days after birth, induced a significant antibody response and was highly effective in conferring protection against bacteremia in 21-day-old mice challenged with meningococci. Intranasal immunization was less effective and did not generate a protective immune response. The antibodies elicited by intraperitoneal immunization were cross-reactive with several meningococcal strains and a memory response was demonstrated when mice immunized as neonates were given a booster immunization at 6 weeks of age.

Administration, Intranasal↗
PubMed2005

Sequence constancies and variations in genes encoding three new meningococcal vaccine candidate antigens.

By the strategy "reverse vaccinology" a number of new antigens have been identified in Neisseria meningitidis, which are potential candidates for a highly needed broad-spectrum meningococcal vaccine. In the present study we examined the prevalence, sequence constancies and variations of the genes encoding three of these new antigens designated, genome-derived neisserial antigen (GNA) 1870, GNA1946 and GNA2132. All three genes were present in all N. meningitidis isolates tested. Concerning gna1870, three major variants of the gene sequences and deduced amino acid sequences were identified and 56% of the deduced amino acids were conserved in all isolates. In gna1946, 98% of the deduced amino acids were conserved and in gna2132, 54% of the deduced amino acids were conserved. Based on gene prevalence and conservation, all three antigens are promising candidates for an effective meningococcal vaccine against all N. meningitidis irrespective of serogroup.

Antigens, Bacterial↗
PubMed2006

Response of steroid-treated former preterm infants to a single dose of meningococcal C conjugate vaccine.

Attenuated antibody responses have been reported in preterm infants who received neonatal dexamethasone treatment. The duration of immunosuppression may extend into later infancy. This study assessed the immune response of former preterm infants to a single meningococcal serogroup C conjugate (MCC) immunisation given after infancy. A cohort of 49 toddlers born at less than 33 weeks' gestation were given an initial dose of MCC vaccine at a median age of 13 months; 11 had received dexamethasone in the neonatal period. Sera obtained 4 weeks post immunisation were analysed for serum bactericidal antibody (SBA) and serogroup C-specific IgG antibody concentrations. Immune responses were compared with those of an historical cohort of 70 term toddlers given a single dose of the same vaccine at age 13 months. An SBA titre of > or =8 was taken to indicate a protective response. Following a single MCC dose, the SBA geometric mean titre (GMT) for former preterm infants was 249 (95% C.I. 111, 558), not significantly different from that of the historical term cohort whose SBA GMT was 141 (95% C.I. 89, 224) (p=0.06). A significantly lower proportion of former preterm infants achieved a protective SBA titre of > or =8 compared with term infants, 37/48 (77%) versus 64/70 (91%), (p=0.03). For steroid-treated and non steroid-treated subgroups, SBA GMTs were 1237 (95% C.I. 250, 6132) and 154 (62, 385), respectively, and numbers achieving an SBA titre of > or =8 were 10/11 (91%) and 27/37 (73%), (p=0.42). Most children born at <33 weeks' gestation mount a protective immune response to a single MCC vaccine dose given at age 13 months, but fewer former preterm infants attain a protective SBA titre of 8 compared with term infants. Previous neonatal dexamethasone treatment does not appear to attenuate immune response after infancy.

Antibodies, Bacterial↗
PubMed2006

Relative efficacy of different immunization schedules for the prevention of serogroup C meningococcal disease: a model-based evaluation.

Different immunization strategies have been implemented for the control of serogroup C meningococcal disease (CMD) in Canada and in other developed countries. Results from effectiveness studies of conjugate vaccines in the UK and Spain indicate waning immunity over time. To estimate the life-time protection conferred by different immunization schedules, a simulation model was constructed based on the current epidemiologic situation in Canada. Results showed that the efficacy of any immunization schedule was highly influenced by the rate at which immunity waned and that the benefit of a booster dose increased with increasing rates of waning immunity. Schedules including several doses in early infancy provided little additional benefit over programs starting with 1 dose at the age of 12 months. One-dose programs provided low levels of protection, unless the vaccine was administered at the age of 12 months, and a waning immunity rate of 1% per year or less was assumed. The most effective schedule was 5 doses given at age 2 months, 4 months, 1 year, 12 years, and 18 years, but was only marginally better than 2 doses provided at 12 months and 12 years of age. Existing routine immunization schedules may not be optimal and should be designed to achieve the highest level of protection using the lowest number of doses.

Adolescent↗
PubMed1996

Full 1H NMR assignment and detailed O-acetylation patterns of capsular polysaccharides from Neisseria meningitidis used in vaccine production.

We report essentially complete 1H NMR assignments for the capsular polysaccharides from Neisseria meningitidis serotypes A, C, W-135, and Y. These polysaccharides are components of current polysaccharide vaccines against meningococcal infection and of the polysaccharide-protein conjugate vaccines under development. From these NMR data the pattern of O-acetylation was determined. O-Acetylation of the W-135 polysaccharide is reported for the first time. We also show that, for the Types C and W-135 polysaccharides a migration of O-acetyl groups occurs during storage in solution, and demonstrate that high field 1H NMR represents a simple and sensitive method to define the O-acetylation pattern of individual batches of these polysaccharides.

Acetylation↗
PubMed2001

Efficacy of meningococcal serogroup C conjugate vaccine in teenagers and toddlers in England.

The UK was the first country to use meningococcal serogroup C conjugate (MCC) vaccines, which were licensed on the basis of immunogenicity and safety data but without a formal efficacy study. Increased surveillance during the first 9 months since introduction has shown that short-term efficacy of the MCC vaccine in England was 97% (95% CI 77-99) for teenagers and 92% (65-98) for toddlers. These early results confirm the superiority of MCC over plain C polysaccharide vaccines, which are ineffective in young children.

Adolescent↗
PubMed2002

W135 meningococcal disease in England and Wales associated with Hajj 2000 and 2001.

An outbreak of W135 meningococcal disease was seen in 2000 and 2001 among pilgrims returning from Saudi Arabia and their contacts. The Public Health Laboratory Service set up enhanced surveillance to monitor spread and virulence of the outbreak strain, and to collect data on case characteristics. The number of cases reported from England and Wales in 2001 was similar to the number reported during 2000, despite a change in the recommendation for pilgrims to receive quadrivalent vaccine (against serogroup A, C, W135, and Y) instead of the A/C vaccine recommended in 2000. Both the recommendation and vaccine were not available until January, 2001, and coverage among pilgrims to the Hajj 2001 was low. The case--fatality ratio was high, and sustained transmission of the virulent outbreak strain was seen. Current control policies, both in primary and secondary prevention, might need better implementation.

Disease Outbreaks↗
PubMed2002

Development of vaccines against meningococcal disease.

Neisseria meningitidis is a major cause of bacterial meningitis and sepsis. Polysaccharide-protein conjugate vaccines for prevention of group C disease have been licensed in Europe. Such vaccines for prevention of disease caused by groups A (which is associated with the greatest disease burden worldwide), Y, and W135 are being developed. However, conventional approaches to develop a vaccine for group B strains, which are responsible for most cases in Europe and the USA, have been largely unsuccessful. Capsular polysaccharide-based vaccines can elicit autoantibodies to host polysialic acid, whereas the ability of most non-capsular antigens to elicit broad-based immunity is limited by their antigenic diversity. Many new membrane proteins have been discovered during analyses of genomic sequencing data. These antigens are highly conserved and, in mice, elicit serum bactericidal antibodies, which are the serological hallmark of protective immunity in man. Therefore, there are many promising new vaccine candidates, and improved prospects for development of a broadly protective vaccine for group B disease, and for control of all meningococcal disease.

Algorithms↗
PubMed2003

Effectiveness of meningococcal C conjugate vaccine in teenagers in England.

Meningococcal C conjugate vaccine was introduced into clinical practice in the UK before phase 3 trials had been undertaken. We therefore did a case-control study in teenagers to assess vaccine effectiveness. All cases (n=31) enrolled had laboratory confirmed meningococcal C disease. We also enrolled between one and three controls (n=65) per case, matched by age, sex, and general practitioner. Three patients and 23 controls had been vaccinated. The protective effectiveness of the vaccine, estimated by conditional logistic regression, was 93% (95% CI 39-99), which is similar to screening method estimates. The estimated protective effectiveness varied little when potential confounding risk factors were taken into account. Our findings indicate that the vaccine is highly protective against invasive meningococcal C disease.

Adolescent↗
PubMedDate not supplied

Effectiveness of meningococcal serogroup C conjugate vaccine 4 years after introduction.

The meningococcal serogroup C conjugate (MCC) vaccine programme in England has successfully controlled the incidence of serogroup C disease, as a result of high short-term vaccine effectiveness and substantial herd immunity. However, the long-term effectiveness of the vaccine remains unknown. We assessed surveillance data from the 4 years since introduction of the programme. Vaccine effectiveness remained high in children vaccinated in the catch-up campaign (aged 5 months to 18 years). However, for children vaccinated in the routine infant immunisation programme, the effectiveness of the MCC vaccine fell to low levels after only 1 year. The number of individuals in these cohorts remains low, but alternative routine immunisation schedules should be considered to ensure high levels of protection are sustained.

Adolescent↗