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Background. In the absence of an efficacious broadly protective vaccine, serogroup B Neisseria meningitidis (MenB) is the leading cause of bacterial meningitis and septicemia in many industrialized countries. An investigational recombinant vaccine that contains 3 central proteins; Neisserial adhesin A (NadA), factor H binding protein (fHBP) and Neisserial heparin binding antigen (NHBA) has been developed. These antigens have been formulated with and without outer membrane vesicles (rMenB+OMV and rMenB, respectively) from the New Zealand epidemic strain (B:4:P1.7–2,4). In this trial, we assessed the immunogenicity of these formulations in infants, who are at greatest risk of contracting MenB disease. Methods. A total of 147 infants from the United Kingdom were enrolled and randomly assigned to receive rMenB or rMenB+OMV at 2, 4, 6, and 12 months of age or a single dose at 12 months of age. Serum samples taken before and after vaccination were assayed in a standardized serum bactericidal antibody assay against 7 MenB strains. Local and systemic reactogenicity were recorded for 7 days after each vaccination. Analysis was according to protocol. Results. After 3 doses, both vaccines were immunogenic against strains expressing homologous or related NadA and fHBP. rMenB+OMV demonstrated greater immunogenicity than did rMenB and was immunogenic against strains expressing homologous PorA. Both vaccines elicited anamnestic responses after the fourth dose. For both vaccines, responses were lower against strains expressing heterologous fHBP variants and after a single dose at 12 months. Conclusions. The rMenB+OMV vaccine has the potential to protect infants from MenB disease, although the breadth of protection afforded to heterologous antigens requires additional investigation.

This phase 1 clinical trial assessed the safety and immunogenicity of a native outer membrane vesicle (NOMV) vaccine prepared from a lpxL2(−) synX(−) mutant of strain 44/76 with opcA expression stabilized. Thirty-four volunteers were assigned to one of the three dose groups (25 mcg, 25 mcg with aluminum hydroxide adjuvant, and 50 mcg) to receive three intramuscular injections at 0, 6 and 24 weeks. Specific local and systemic adverse events (AEs) were solicited by diary and at visits on days 1, 2, 7 and 14 after each vaccination and at the end of the study at 30 weeks. Blood chemistries, complete blood count, and coagulation studies were measured on each vaccination day and again two days later. Blood for antibody measurements and bactericidal assays were drawn 0, 14, and 42 days after each vaccination. The proportion of volunteers who developed a fourfold or greater increase in serum bactericidal activity (SBA) to the wild-type parent of the vaccine strain with high opcA expression at 6 weeks after the third dose was 12/26 (0.46, 95% confidence interval 0.27–0.65). Antibody levels to OpcA were significantly higher in vaccine responders than in non-responders ( p = 0.008), and there was a trend for higher antibody levels to the lipooligosaccharide (LOS) ( p = 0.059). Bactericidal depletion assays on sera from volunteers with high-titer responses also indicate a major contribution of anti-OpcA and anti-LOS antibodies to the bactericidal response.These results suggest that genetically modified NOMV vaccines can induce protection against group B meningococcus.

A novel multicomponent vaccine against meningococcal capsular group B (MenB) disease contains four major components: factor-H-binding protein, neisserial heparin binding antigen, neisserial adhesin A, and outer-membrane vesicles derived from the strain NZ98/254. Because the public health effect of the vaccine, 4CMenB (Novartis Vaccines and Diagnostics, Siena, Italy), is unclear, we assessed the predicted strain coverage in Europe. We assessed invasive MenB strains isolated mainly in the most recent full epidemiological year in England and Wales, France, Germany, Italy, and Norway. Meningococcal antigen typing system (MATS) results were linked to multilocus sequence typing and antigen sequence data. To investigate whether generalisation of coverage applied to the rest of Europe, we also assessed isolates from the Czech Republic and Spain. 1052 strains collected from July, 2007, to June, 2008, were assessed from England and Wales, France, Germany, Italy, and Norway. All MenB strains contained at least one gene encoding a major antigen in the vaccine. MATS predicted that 78% of all MenB strains would be killed by postvaccination sera (95% CI 63–90, range of point estimates 73–87% in individual country panels). Half of all strains and 64% of covered strains could be targeted by bactericidal antibodies against more than one vaccine antigen. Results for the 108 isolates from the Czech Republic and 300 from Spain were consistent with those for the other countries. MATS analysis showed that a multicomponent vaccine could protect against a substantial proportion of invasive MenB strains isolated in Europe. Monitoring of antigen expression, however, will be needed in the future. Novartis Vaccines and Diagnostics.

Invasive meningococcal disease (IMD) caused by Neisseria meningitidis can result in life-threatening meningitis and septicaemia. There are twelve serogroups of N. meningitidis, but most cases of IMD are caused by serogroups A, B, C, W, X and Y. In Europe, serogroup B (MenB) accounts for 51 % of documented cases as recently reported by the European Centre for Disease Prevention and Control (ECDC). As a major cause of IMD, genomic surveillance of circulating MenB strains and assessment of the potential impact of vaccination programs could help inform public health policy. In this study, a collection of 493 strains was analysed, collected in Belgium by the National Reference Centre between 2016 and 2022. Slide agglutination was used for serogroup determination and whole genome sequencing (WGS) was used to further characterize these strains. The observed serogroups were: MenB (n = 281), MenY (n = 95), MenW (n = 83), MenC (n = 30), non-groupable isolates (n = 2), MenE (n = 1) and MenX (n = 1). A higher prevalence of MenY and MenW was observed in older adults. MenB isolates were grouped into 110 sequence types (STs), 89 of which belonged to 16 clonal complexes (CCs). Coverage of the MenB-FHbp vaccine (Trumenba, bivalent rLP2086; Pfizer Inc., New York, NY, USA ipv Philadelphia) was predicted using the Meningococcal Deduced Vaccine Antigen Reactivity (MenDeVAR) index. Of the 281 MenB strains collected between 2016 and 2022, 89.1 % (lower limit – upper limit: 78.6–100.0 %) were predicted by MenDeVAR to be covered by the vaccine. This study highlights the benefits of a pathogen surveillance program and the need for experimental characterization of continuously evolving antigenic variants. •MenB was the leading cause of IMD in individuals under 65 years of age in Belgium from 2016 to 2022.•Increased prevalence of MenY and MenW observed in older adults.•High diversity of MenB isolates circulating in Belgium, with 110 STs detected, including 32 novel STs.•MenDeVAR predicts a coverage of 89.1 % for the MenB-FHbp vaccine (range: 78.6 % - 100.0 %).

Neisseria meningitidis is a major cause of endemic cases and epidemics of meningitis and devastating septicemia. Although effective vaccines exist for several serogroups of pathogenic N. meningitidis, conventional vaccinology approaches have failed to provide a universal solution for serogroup B (MenB) which consequently remains an important burden of disease worldwide. The advent of whole-genome sequencing changed the approach to vaccine development, enabling the identification of potential vaccine candidates starting directly with the genomic information, with a process named reverse vaccinology. The application of reverse vaccinology to MenB allowed the identification of new protein antigens able to induce bactericidal antibodies. Three highly immunogenic antigens (fHbp, NadA and NHBA) were combined with outer membrane vesicles and formulated for human use in a multicomponent vaccine, named 4CMenB. This is the first MenB vaccine based on recombinant proteins able to elicit a robust bactericidal immune response in adults, adolescents and infants against a broad range of serogroup B isolates. This review describes the successful story of the development of the 4CMenB vaccine, with particular emphasis on the functional, immunological and structural characterization of the protein antigens included in the vaccine.

In Italy, Invasive Meningococcal Disease (IMD) due to Neisseria meningitidis serogroup B (MenB) showed the highest incidence rates in infants under one year of age. This study describes the main characteristics of MenB responsible for invasive diseases circulating in Italy from 2010 to 2021. Data collected within the framework of National Surveillance System (NSS) for IMD were analysed. Serogroup confirmed IMD cases were included in the study. For unspecified meningococcal serogroup, a multinomial model was used to impute the serogroup. Antimicrobial susceptibility and genotyping by Sanger or whole genome sequencing were performed on viable meningococci. Core genome MLST (cgMLST) was evaluated using a gene-by-gene approach, and MenDeVAR analyses were used to assess potential coverage by MenB vaccines. A total of 1845 IMD cases were reported to the NSS, of which 704 were laboratory confirmed as MenB and another 232 were statistically attributed to this serogroup. The highest incidence rate for IMD due to MenB was observed in infants <1 year, followed by children aged 1-4 years. MenB isolates were susceptible to antimicrobials except for 4 isolates, of which 2 resistant to penicillin G, 1 to rifampicin and 1 to ciprofloxacin. High genetic variability was observed, with clonal complex (cc) cc41/44 being replaced by the cc162 since 2015. MenDeVAR analyses highlighted a high proportion of genomes classified as \"insufficient data,\" especially among recent isolates. Despite the low incidence of IMD in Italy, MenB increased in specific age groups during the study period. Continuous genomic surveillance, including MenDeVAR monitoring, remains essential to detect changes in circulating MenB and predict vaccine coverage.

Bacteria have developed several strategies for cell colonization and immune evasion. Knowledge of the host and pathogen factors involved in these mechanisms is crucial to build efficacious countermoves. Neisserial adhesin A (NadA) is a meningococcal surface protein included in the anti-meningococcus B vaccine 4CMenB, which mediates adhesion to and invasion of epithelial cells. Although NadA has been shown to bind to other cell types, like myeloid and endothelial cells, it still remains orphan of a defined host receptor. We have identified two strong NadA interactors, Siglec-5 and Siglec-14, which are mainly expressed on myeloid cells. This showcases that NadA is an additional and key player among the Neisseria meningitidis factors targeting immune cells. We thus provide novel insights on the strategies exploited by N. meningitidis during the infection process, which can progress to a severe illness and death.

We report a cluster of serogroup B invasive meningococcal disease identified via genomic surveillance in older adults in England and describe the public health responses. Genomic surveillance is critical for supporting public health investigations and detecting the growing threat of serogroup B Neisseria meningitidis infections in older adults.

This study assessed whether systematically using finetype data in national surveillance of invasive meningococcal disease serogroup B (IMD-B) in the Netherlands could improve cluster detection in order to prevent further cases through public health actions. We analysed 2005–2023 data, including 1,642 IMD-B cases with complete finetype and municipality information (95%; N = 1729). Using a generalized linear model, we calculated expected baselines for each finetype, including temporal trends. Using SaTScan™, we applied Poisson scan-statistics with a 365-day window to identify spatiotemporal clusters, comparing results to epidemiological and core-genome multi-locus sequence typing (cgMLST) data. Of 453 finetypes, 308 (68%) occurred once; diversity was high (Gini-Simpson index 0.96). We identified 42 spatiotemporal clusters across 37 finetypes, comprising 132 cases (8%), with a median cluster size of two (range 2–21) and duration of 45 days (range 6–356). Between zero and five clusters were detected yearly. Among 18 cases with known epidemiological links, 14 (78%) were within detected spatiotemporal clusters. CgMLST data from eight clusters supported some clusters but rejected others. Systematic cluster detection using finetype could reveal missed epidemiological links, potentially enabling public health action. However, its impact in preventing additional IMD-B cases is likely limited due to small cluster sizes, though meaningful given the severity of IMD-B. Simple finetype mapping may provide a resource-efficient alternative to SaTScan™.

Background MenB-FHbp is a licensed meningococcal B vaccine targeting factor H-binding protein. Two phase 3 studies assessed the safety of the vaccine and its immunogenicity against diverse strains of group B meningococcus. Methods We randomly assigned 3596 adolescents (10 to 18 years of age) to receive MenB-FHbp or hepatitis A virus vaccine and saline and assigned 3304 young adults (18 to 25 years of age) to receive MenB-FHbp or saline at baseline, 2 months, and 6 months. Immunogenicity was assessed in serum bactericidal assays that included human complement (hSBAs). We used 14 meningococcal B test strains that expressed vaccine-heterologous factor H-binding proteins representative of meningococcal B epidemiologic diversity; an hSBA titer of at least 1:4 is the accepted correlate of protection. The five primary end points were the proportion of participants who had an increase in their hSBA titer for each of 4 primary strains by a factor of 4 or more and the proportion of those who had an hSBA titer at least as high as the lower limit of quantitation (1:8 or 1:16) for all 4 strains combined after dose 3. We also assessed the hSBA responses to the primary strains after dose 2; hSBA responses to the 10 additional strains after doses 2 and 3 were assessed in a subgroup of participants only. Safety was assessed in participants who received at least one dose. Results In the modified intention-to-treat population, the percentage of adolescents who had an increase in the hSBA titer by a factor of 4 or more against each primary strain ranged from 56.0 to 85.3% after dose 2 and from 78.8 to 90.2% after dose 3; the percentages of young adults ranged from 54.6 to 85.6% and 78.9 to 89.7%, after doses 2 and 3, respectively. Composite responses after doses 2 and 3 in adolescents were 53.7% and 82.7%, respectively, and those in young adults were 63.3% and 84.5%, respectively. Responses to the 4 primary strains were predictive of responses to the 10 additional strains. Most of those who received MenB-FHbp reported mild or moderate pain at the vaccination site. Conclusions MenB-FHbp elicited bactericidal responses against diverse meningococcal B strains after doses 2 and 3 and was associated with more reactions at the injection site than the hepatitis A virus vaccine and saline. (Funded by Pfizer; ClinicalTrials.gov numbers, NCT01830855 and NCT01352845 ).