Whole-genome sequence of the transformable Neisseria meningitidis serogroup A strain WUE2594.
ABSTRACT: Serogroup A meningococci are a leading cause of bacterial meningitis in children and young adults worldwide. However, the genetic basis of serogroup A strains' virulence and their epidemiological properties remain poorly understood. Therefore, we sequenced the complete genome of the transformable Neisseria meningitidis serogroup A strain WUE2594.
Project description:Neisseria meningitidis is a major cause of bacterial meningitis and septicemia worldwide. Seven new serogroup C meningococci were isolated from two provinces of China in January, 2006. Their PorA VR types were P1.20, 9. Multilocus sequence typing results indicated that they all belonged to ST-7. It is a new serogroup C N. meningitidis sequence type clone identified in China. Here we also present the results of a genomic comparison of these isolates with other 15 N. meningitidis serogroup A and B isolates, which belonged to ST-7, based on comparative genomic hybridization analysis. The data described here would be helpful to monitor the spread of this new serogroup C meningococci sequence type clone in China and worldwide. Keywords: comparative genomic hybridization To compare the genome compositions of these menC ST-7 isolates with those of menC ST-4821 isolates, menA ST-7 isolates and menB ST-7 isolates, we performed comparative genomic hybridization (CGH) analysis among 17 N. meningitidis isolates (including two newly identified menC ST-7 isolates) using an updated version of the whole-genome microarray of N. meningitidis serogroup C isolate 053442 .
Project description:Neisseria meningitidis is an obligate human pathogen. While it is a frequent commensal of the upper respiratory tract, in some individuals the bacterium spreads to the bloodstream, causing meningitis and/or sepsis, which are serious conditions with high morbidity and mortality. Here we report the availability of the genome sequence of the widely used serogroup B laboratory strain H44/76.
Project description:Neisseria meningitidis is a human-specific pathogen known for its capability to cause sepsis and meningitis. Here we report the availability of 2 draft genome sequences obtained from patients infected during the same epidemic outbreak. Both bacterial isolates belong to serogroup C, but their genome sequences show local and remarkable differences compared with each other or with the reference genome of strain FAM18.
Project description:Neisseria meningitidis causes meningococcal disease, often resulting in fulminant meningitis, sepsis, and death. Vaccination programs have been developed to prevent infection of this pathogen, but serogroup replacement is a problem. Capsular switching has been an important survival mechanism for N. meningitidis, allowing the organism to evolve in the present vaccine era. However, related mechanisms have not been completely elucidated. Genetic analysis of capsular switching between diverse serogroups would help further our understanding of this pathogen. In this study, we analyzed the genetic characteristics of the sequence type 7 (ST-7) serogroup X strain that was predicted to arise from ST-7 serogroup A at the genomic level. By comparing the genomic structures and sequences, ST-7 serogroup X was closest to ST-7 serogroup A, whereas eight probable recombination regions, including the capsular gene locus, were identified. This indicated that serogroup X originated from serogroup A by recombination leading to capsular switching. The recombination involved approximately 8,540 bp from the end of the ctrC gene to the middle of the galE gene. There were more recombination regions and strain-specific single-nucleotide polymorphisms in serogroup X than in serogroup A genomes. However, no specific gene was found for each serogroup except those in the capsule gene locus.
Project description:Sepsis and meningitis caused by Neisseria meningitidis serogroup B (NMGB) are serious diseases in infants and young adults, but no effective vaccine is available. The capsular polysaccharide (PS) of NMGB has poor immunogenicity and a structural similarity to polysialic acid (PSA) on neuronal tissue that may elicit autoantibodies. Using HmenB3, a protective and nonautoreactive monoclonal antibody (MAb) to NMGB capsular PS, we produced an anti-idiotypic MAb, Naid60, which mimics the capsular PS of NMGB. We produced an anti-anti-idiotypic MAb, MoB34, by using the immunogenic site on Naid60 responsible for inducing the anti-NMGB PS antibody response. MoB34 elicited the complement-mediated killing of representative strains of serogroup B meningococci. MoB34 did not bind to CHP-134, a neuroblastoma cell line expressing alpha(2-8) PSA, or to mouse brain cryosections at a high concentration. Naid60-keyhole limpet hemocyanin immunization inhibited the growth of live NMGB in intraperitoneally challenged mice; in contrast, three of five control mice developed bacteremia. Thus, Naid60 has an immunogenic site that elicits antibodies with bactericidal activity against NMGB and no autoimmunity to PSA. We suggest that the immunogenic region of Naid60 is a candidate for the development of a new vaccine against NMGB.
Project description:We have developed a novel Neisseria meningitidis serogroup-specific loop-mediated isothermal amplification (LAMP) assay for six of the most common meningococcal serogroups (A, B, C, W, X, and Y). The assay was evaluated using a set of 31 meningococcal LAMP assay positive cerebrospinal fluid (CSF) specimens from 1574 children with suspected meningitis identified in prospective surveillance between 1998 and 2002 in Vietnam, China, and Korea. Primer specificity was validated using 15 N. meningitidis strains (including serogroups A, B, C, E, W, X, Y, and Z) and 19 non-N. meningitidis species. The N. meningitidis serogroup LAMP detected down to ten copies and 100 colony-forming units per reaction. Twenty-nine CSF had N. meningitidis serogroup identified by LAMP compared with two CSF in which N. meningitidis serogroup was identified by culture and multi-locus sequence typing. This is the first report of a serogroup-specific identification assay for N. meningitidis using the LAMP method. Our results suggest that this assay will be a rapid, sensitive, and uniquely serogroup-specific assay with potential for application in clinical laboratories and public health surveillance systems.
Project description:Despite the introduction of conjugated polysaccharide vaccines for many of the Neisseria meningitidis serogroups, neisserial infections continue to cause septicaemia and meningitis across the world. This is in part due to the difficulties in developing a, cross-protective vaccine that is effective against all serogroups, including serogroup B meningococci. Although convalescent N. meningitidis patients develop a natural long-lasting cross-protective immunity, the antigens that mediate this response remain unknown. To help define the target of this protective immunity we identified the proteins recognized by IgG in sera from meningococcal patients by a combination of 2D protein gels, western blots and mass spectrometry. Although a number of outer membrane antigens were identified the majority of the antigens were cytoplasmic, with roles in cellular processes and metabolism. When recombinant proteins were expressed and used to raise sera in mice, none of the antigens elicited a positive SBA result, however flow cytometry did demonstrate that some, including the ribosomal protein, RplY were localised to the neisserial cell surface.
Project description:Serogroup A Neisseria meningitidis has repeatedly caused widespread epidemics of meningitis and septicemia throughout the 20th century. Recently, in a limited collection of strains, epidemic serogroup A isolates were found to have elevated mutation rates that was caused by defects in mismatch repair pathways. To ascertain the role of these mutators in the epidemic spread of this serogroup, the prevalence of hypermutability in a collection of 95 serogroup A N. meningitidis invasive isolates was determined. Overall mutability in Neisseriae can be described by measuring both missense mutation rates as well as phase variation frequencies of "contingency loci." Fifty-seven percent of serogroup A isolates possessed elevated mutability, which could be divided into two classes: intermediate and high level. Eleven of 20 high-level mutators, with phase variation rates >100-fold higher than wild-type isolates, were defective in mismatch repair. Ten of the 34 intermediate mutators possessing >10-fold increases in phase variation rates could be partially complemented by a wild-type mutL allele. A high prevalence of mutators in epidemic isolates indicates that hypermutability may play a major role in the transmission of this pathogen. The added diversity derived from increased phase variation rates may allow fixation of mutator alleles more frequently during epidemic spread.
Project description:The lipooligosaccharide (LOS) of immunotype L11 is unique within serogroup A meningococci. In order to resolve its molecular structure, we conducted LOS genotyping by PCR analysis of genes responsible for alpha-chain sugar addition (lgtA, -B, -C, -E, -H, and -F) and inner core substituents (lgtG, lpt-3, and lpt-6). For this study, we selected seven strains belonging to subgroup III, a major clonal complex responsible for meningococcal meningitis epidemics in Africa. In addition, we sequenced the homopolymeric tract regions of three phase-variable genes (lgtA, lgtG, and lot-3) to predict gene functionality. The fine structure of the L11 LOS of each strain was determined using composition and glycosyl linkage analyses, NMR, and mass spectrometry. The masses of the dephosphorylated oligosaccharides were consistent with an oligosaccharide composed of two hexoses, one N-acetyl-hexosamine, two heptoses, and one KDO, as proposed previously. The molar composition of LOS showed two glucose residues to be present, in agreement with lgtH sequence prediction. Despite phosphoethanolaminetransferase genes lpt-3 and lpt-6 being present in all seven Neisseria meningitidis strains, phosphoethanolamine (PEtn) was found at both O-3 and O-6 of HepII among the three ST-5 strains, whereas among the four ST-7 strains, only one PEtn was found and located at O-3 of the HepII. The L11 LOS was found to be O-acetylated, as was indicated by the presence of the lot-3 gene being in-frame in all of the seven N. meningitidis strains. To our knowledge, these studies represent the first full genetic and structural characterization of the L11 LOS of N. meningitidis. These investigations also suggest the presence of further regulatory mechanisms affecting LOS structure microheterogeneity in N. meningitidis related to PEtn decoration of the inner core.
Project description:Neisseria meningitidis is a Gram-negative bacterial pathogen that causes life threatening meningitis and septicemia. Neisseria Heparin Binding Antigen (NHBA) is an outer membrane protein that binds heparin and heparan sulfate and DNA. This protein is one of the four antigens in the meningococcal serogroup B vaccine Bexsero. In the current study, we sought to define the full glycan-binding repertoire of NHBA to better understand its role in meningococcal pathogenesis and vaccine efficacy. Glycan array analysis revealed binding to 28 structures by recombinant NHBA. Surface plasmon resonance was used to confirm the binding phenotype and to determine the affinity of the interactions. These studies revealed that the highest affinity binding of NHBA was with chondroitin sulfate (KD?=?5.2?nM). This affinity is 10-fold higher than observed for heparin. Analysis of binding with well-defined disaccharides of the different chondroitin sulfate types demonstrated that the most preferred ligand has a sulfate at the 2 position of the GlcA/IdoA and 6 position of the GalNAc, which is an equivalent structure to chondroitin sulfate D. Chondroitin sulfate is widely expressed in human tissues, while chondroitin sulfate D is predominantly expressed in the brain and may constitute a new receptor structure for meningococci.