Heike Claus

Publications of Heike Claus

• Ion Torrent PGM sequencing for genomic typing of Neisseria meningitidis for rapid determination of multiple layers of typing information.

  Authors: Ulrich Vogel, Rafael Szczepanowski, Heike Claus, Sebastian Jünemann, Karola Prior, Dag Harmsen

  Journal of clinical microbiology. 03/2012;

  Neisseria meningitidis causes invasive meningococcal disease in infants, toddlers and adolescents worldwide. DNA sequence based typing has become the standard for molecular epidemiology of theNeisseria meningitidis causes invasive meningococcal disease in infants, toddlers and adolescents worldwide. DNA sequence based typing has become the standard for molecular epidemiology of the organism including multilocus sequence typing, analysis of genetic determinants of antibiotic resistance, and sequence typing of vaccine antigens. However, PCR of multiple targets and consecutive Sanger sequencing provides logistic constraints to reference laboratories. Taking advantage of the recent development of benchtop next generation sequencers (NGS) and of BIGSdb, a database accommodating and analyzing genome sequence data, we therefore explored the feasibility and accuracy of Ion Torrent Personal Genome Machine™ (PGM™) sequencing for genomic typing of meningococci. Three strains from a previous meningococcus B community outbreak were selected to compare conventional typing results with data generated by semiconductor chip based sequencing. In addition, sequencing of the meningococcal type strain MC58 provided information about the general performance of the technology. The PGM™ technology generated sequence information for almost all target genes addressed. The results were 100% concordant with conventional typing results with no further editing necessary. In addition, the amount of typing information, i.e. nucleotides and target genes analyzed, could be substantially increased by the combined use of genome sequencing and BIGSdb compared to conventional methods. In a near future, affordable and fast benchtop-NGS machines like the PGM™ might enable reference laboratories to switch to genomic typing on a routine basis. This will reduce workload and rapidly provide information for laboratory surveillance, outbreak investigation, assessment of vaccine preventability and antibiotic resistance gene monitoring.

• Capsule null locus meningococci: typing of antigens used in an investigational multicomponent meningococcus serogroup B vaccine.

  Authors: Heike Claus, Markus S Jördens, Pavla Kriz, Martin Musilek, Hanna Jarva, Marie-Christin Pawlik, Seppo Meri, Ulrich Vogel

  Vaccine. 11/2011; 30(2):155-60.

  The investigational multicomponent meningococcus serogroup B vaccine (4CMenB) targets the antigenetically variable population of serogroup B meningococci. Forty-one strains of capsule null locusThe investigational multicomponent meningococcus serogroup B vaccine (4CMenB) targets the antigenetically variable population of serogroup B meningococci. Forty-one strains of capsule null locus (cnl) meningococci, which are frequent among healthy carriers, were selected from nine sequence types (ST), which belong to four clonal complexes (cc), and three countries. They were antigen sequence typed and analyzed for antigen expression to predict whether these strains harbor the genes and express the four vaccine antigens of 4CMenB as measured by the meningococcal antigen typing system (MATS). The PorA variant used in the vaccine was not found. The nadA gene was absent in all but one strain, which did not express the antigen in vitro. Only strains of clonal complex ST-198 harbored a factor H binding protein (FHBP) allele of the cross-reactive variant 1 family which is included in the vaccine. All these strains expressed the antigen. Five variants of the Neisserial heparin binding antigen (NHBA) gene were identified. Expression of NHBA was observed in all strains with highest levels in ST-198 cc and ST-845. The data suggest a potential impact of 4CMenB immunization at least on cnl meningococci of the ST-198 cc and ST-845.

• Sequence analysis of serotype-specific synthesis regions II of Haemophilus influenzae serotypes c and d: evidence for common ancestry of capsule synthesis in Pasteurellaceae and Neisseria meningitidis.

  Authors: Thiên-Trí Lâm, Heike Claus, Matthias Frosch, Ulrich Vogel

  Research in microbiology. 06/2011; 162(5):483-7.

  Sequencing of yet unknown Haemophilus influenzae serotype c (Hic) and d (Hid) capsule synthesis regions II revealed four (ccs1-4) and five (dcs1-5) open reading frames, respectively. The inferredSequencing of yet unknown Haemophilus influenzae serotype c (Hic) and d (Hid) capsule synthesis regions II revealed four (ccs1-4) and five (dcs1-5) open reading frames, respectively. The inferred gene functions were in line with capsular polysaccharide structures. One or more proteins encoded by the Hic capsule synthesis region II showed similarity to Actinobacillus pleuropneumoniae serotype 1 and Actinobacillus suis K1 enzymes. Orthologues to the complete operon were observed in Actinobacillus minor strain 202, where even the gene order was conserved. Furthermore, Ccs4 was related to the capsule O-acetyltransferase of Neisseria meningitidis serogroup W-135. For the Hid locus, similarities to Hie, Mannheimia haemolytica A1 and N. meningitidis serogroup A were identified and the succession of genes was similar in the different species. The resemblance of genes and gene organization found for Hic and Hid with other species suggested horizontal gene transfer during capsule evolution across the bacterial classes.

• Virulence evolution of the human pathogen Neisseria meningitidis by recombination in the core and accessory genome.

  Authors: Biju Joseph, Roland F Schwarz, Burkhard Linke, Jochen Blom, Anke Becker, Heike Claus, Alexander Goesmann, Matthias Frosch, Tobias Müller, Ulrich Vogel, Christoph Schoen

  PloS one. 01/2011; 6(4):e18441.

  Neisseria meningitidis is a naturally transformable, facultative pathogen colonizing the human nasopharynx. Here, we analyze on a genome-wide level the impact of recombination on gene-complementNeisseria meningitidis is a naturally transformable, facultative pathogen colonizing the human nasopharynx. Here, we analyze on a genome-wide level the impact of recombination on gene-complement diversity and virulence evolution in N. meningitidis. We combined comparative genome hybridization using microarrays (mCGH) and multilocus sequence typing (MLST) of 29 meningococcal isolates with computational comparison of a subset of seven meningococcal genome sequences. We found that lateral gene transfer of minimal mobile elements as well as prophages are major forces shaping meningococcal population structure. Extensive gene content comparison revealed novel associations of virulence with genetic elements besides the recently discovered meningococcal disease associated (MDA) island. In particular, we identified an association of virulence with a recently described canonical genomic island termed IHT-E and a differential distribution of genes encoding RTX toxin- and two-partner secretion systems among hyperinvasive and non-hyperinvasive lineages. By computationally screening also the core genome for signs of recombination, we provided evidence that about 40% of the meningococcal core genes are affected by recombination primarily within metabolic genes as well as genes involved in DNA replication and repair. By comparison with the results of previous mCGH studies, our data indicated that genetic structuring as revealed by mCGH is stable over time and highly similar for isolates from different geographic origins. Recombination comprising lateral transfer of entire genes as well as homologous intragenic recombination has a profound impact on meningococcal population structure and genome composition. Our data support the hypothesis that meningococcal virulence is polygenic in nature and that differences in metabolism might contribute to virulence.

• Comparative proteomic analysis of biofilm and planktonic cells of Neisseria meningitidis.

  Authors: Tessa van Alen, Heike Claus, René P Zahedi, Janos Groh, Heinrich Blazyca, Martin Lappann, Albert Sickmann, Ulrich Vogel

  Proteomics. 12/2010; 10(24):4512-21.

  Neisseria meningitidis is a commensal of the human nasopharynx occasionally causing invasive disease. In vitro biofilms have been employed to model meningococcal carriage. A proteomic analysis ofNeisseria meningitidis is a commensal of the human nasopharynx occasionally causing invasive disease. In vitro biofilms have been employed to model meningococcal carriage. A proteomic analysis of meningococcal biofilms was conducted and metabolic changes related to oxygen and nutrient limitation and upregulation of proteins involved in ROS defense were observed. The upregulated MntC which protects against ROS was shown to be required for meningococcal biofilm formation, but not for planktonic growth. ROS-induced proteomic changes might train the biofilm to cope with immune effectors.

• New diagnostic PCR for Haemophilus influenzae serotype e based on the cap locus of strain ATCC 8142.

  Authors: Thiên-Trí Lâm, Johannes Elias, Matthias Frosch, Ulrich Vogel, Heike Claus

  International journal of medical microbiology : IJMM. 10/2010; 301(2):176-9.

  A new PCR protocol for molecular typing of Haemophilus influenzae serotype e (Hie) was developed. To this end, the sequence of the cap region II of Hie strain ATCC8142 was identified, which was >99%A new PCR protocol for molecular typing of Haemophilus influenzae serotype e (Hie) was developed. To this end, the sequence of the cap region II of Hie strain ATCC8142 was identified, which was >99% identical to the recently published sequence of Hie isolate 274. The PCR using primer pair TTL63/TTL64 amplifies an internal 592-bp fragment of ecs4, an e-specific capsule synthesis gene, in 40 of 40 Hie strains. Of all non-Hie strains, there were no false positives. False-negative results of the PCR proposed by Falla et al. (1994) are explained by single nucleotide insertions in the primer sequences.

• Comparative genome biology of a serogroup B carriage and disease strain supports a polygenic nature of meningococcal virulence.

  Authors: Biju Joseph, Susanne Schneiker-Bekel, Anja Schramm-Glück, Jochen Blom, Heike Claus, Burkhard Linke, Roland F Schwarz, Anke Becker, Alexander Goesmann, Matthias Frosch, Christoph Schoen

  Journal of bacteriology. 10/2010; 192(20):5363-77.

  Neisseria meningitidis serogroup B strains are responsible for most meningococcal cases in the industrialized countries, and strains belonging to the clonal complex ST-41/44 are among the mostNeisseria meningitidis serogroup B strains are responsible for most meningococcal cases in the industrialized countries, and strains belonging to the clonal complex ST-41/44 are among the most prevalent serogroup B strains in carriage and disease. Here, we report the first genome and transcriptome comparison of a serogroup B carriage strain from the clonal complex ST-41/44 to the serogroup B disease strain MC58 from the clonal complex ST-32. Both genomes are highly colinear, with only three major genome rearrangements that are associated with the integration of mobile genetic elements. They further differ in about 10% of their gene content, with the highest variability in gene presence as well as gene sequence found for proteins involved in host cell interactions, including Opc, NadA, TonB-dependent receptors, RTX toxin, and two-partner secretion system proteins. Whereas housekeeping genes coding for metabolic functions were highly conserved, there were considerable differences in their expression pattern upon adhesion to human nasopharyngeal cells between both strains, including differences in energy metabolism and stress response. In line with these genomic and transcriptomic differences, both strains also showed marked differences in their in vitro infectivity and in serum resistance. Taken together, these data support the concept of a polygenic nature of meningococcal virulence comprising differences in the repertoire of adhesins as well as in the regulation of metabolic genes and suggest a prominent role for immune selection and genetic drift in shaping the meningococcal genome.

• Molecular discrimination between Neisseria meningitidis serogroups W-135 and Y based on the nucleotide recognition domain sequence of the capsule polymerases.

  Authors: Heike Claus, Wataru Matsunaga, Ulrich Vogel

  Journal of clinical microbiology. 09/2010; 48(9):3459-60.

• Multicenter study for defining the breakpoint for rifampin resistance in Neisseria meningitidis by rpoB sequencing.

  Authors: Muhamed-Kheir Taha, Sara Thulin Hedberg, Marek Szatanik, Eva Hong, Corinne Ruckly, Raquel Abad, Sophie Bertrand, Francoise Carion, Heike Claus, Alejandra Corso [......] Per Olcén, Marina Pana, Anna Skoczynska, Cecilia Sorhouet Pereira, Paola Stefanelli, Georgina Tzanakaki, Magnus Unemo, Julio A Vázquez, Ulrich Vogel, Izabela Wasko

  Antimicrobial agents and chemotherapy. 09/2010; 54(9):3651-8.

  Identification of clinical isolates of Neisseria meningitidis that are resistant to rifampin is important to avoid prophylaxis failure in contacts of patients, but it is hindered by the absence of aIdentification of clinical isolates of Neisseria meningitidis that are resistant to rifampin is important to avoid prophylaxis failure in contacts of patients, but it is hindered by the absence of a breakpoint for resistance, despite many efforts toward standardization. We examined a large number (n = 392) of clinical meningococcal isolates, spanning 25 years (1984 to 2009), that were collected in 11 European countries, Argentina, and the Central African Republic. The collection comprises all clinical isolates with MICs of > or = 0.25 mg/liter (n = 161) received by the national reference laboratories for meningococci in the participating countries. Representative isolates displaying rifampin MICs of < 0.25 mg/liter were also examined (n = 231). Typing of isolates was performed, and a 660-bp DNA fragment of the rpoB gene was sequenced. Sequences differing by at least one nucleotide were defined as unique rpoB alleles. The geometric mean of the MICs was calculated for isolates displaying the same allele. The clinical isolates displaying rifampin MICs of > 1 mg/liter possessed rpoB alleles with nonsynonymous mutations at four critical amino acid residues, D542, H552, S548, and S557, that were absent in the alleles found in all isolates with MICs of < or = 1 mg/liter. Rifampin-susceptible isolates could be defined as those with MICs of < or = 1 mg/liter. The rpoB allele sequence and isolate data have been incorporated into the PubMLST Neisseria database (http://pubmlst.org/neisseria/). The rifampin-resistant isolates belonged to diverse genetic lineages and were associated with lower levels of bacteremia and inflammatory cytokines in mice. This biological cost may explain the lack of clonal expansion of these isolates.

• Vaccine development against Neisseria meningitidis.

  Authors: Ulrich Vogel, Heike Claus

  Microbial biotechnology. 05/2010; 4(1):20-31.

  Meningococcal disease is communicable by close contact or droplet aerosols. Striking features are high case fatality rates and peak incidences of invasive disease in infants, toddlers andMeningococcal disease is communicable by close contact or droplet aerosols. Striking features are high case fatality rates and peak incidences of invasive disease in infants, toddlers and adolescents. Vaccine development is hampered by bacterial immune evasion strategies including molecular mimicry.As for Haemophilus influenzae and Streptococcus pneumoniae, no vaccine has therefore been developed that targets all serogroups of Neisseria meningitidis. Polysaccharide vaccines available both in protein conjugated and non-conjugated form, have been introduced against capsular serogroups A, C,W-135 and Y, but are ineffective against serogroup B meningococci, which cause a significant burden of disease in many parts of the world. Detoxified outer membrane vesicles are used since decades to elicit protection against epidemic serogroup B disease. Genome mining and biochemical approaches have provided astounding progress recently in the identification of immunogenic, yet reasonably conserved outer membrane proteins. As subcapsular proteins nevertheless are unlikely to immunize against all serogroup B variants, thorough investigation by surrogate assays and molecular epidemiology approaches are needed prior to introduction and post-licensure of protein vaccines. Research currently addresses the analysis of life vaccines, meningococcus B polysaccharide modifications and mimotopes, as well as the use of N. lactamica outer membrane vesicles.

• First survey of metallo-beta-lactamases in clinical isolates of Pseudomonas aeruginosa in a German university hospital.

  Authors: Giuseppe Valenza, Biju Joseph, Johannes Elias, Heike Claus, Anett Oesterlein, Kathrin Engelhardt, Doris Turnwald, Matthias Frosch, Marianne Abele-Horn, Christoph Schoen

  Antimicrobial agents and chemotherapy. 05/2010; 54(8):3493-7.

  A total of 489 clinical isolates of Pseudomonas aeruginosa was investigated for metallo-beta-lactamase (MBL) production. Molecular analysis detected a blaVIM-1 gene in the chromosome of one isolateA total of 489 clinical isolates of Pseudomonas aeruginosa was investigated for metallo-beta-lactamase (MBL) production. Molecular analysis detected a blaVIM-1 gene in the chromosome of one isolate and a blaVIM-2 gene carried on the plasmid in seven isolates. Moreover, we showed that an initial screening by combined susceptibility testing of imipenem and ceftazidime followed by a confirmatory EDTA combination disk test represents a valid alternative to the molecular investigation of MBL genes, making MBL detection possible in routine diagnostic laboratories.

• A dual role of extracellular DNA during biofilm formation of Neisseria meningitidis.

  Authors: Martin Lappann, Heike Claus, Tessa van Alen, Morten Harmsen, Johannes Elias, Søren Molin, Ulrich Vogel

  Molecular microbiology. 02/2010; 75(6):1355-71.

  Major pathogenic clonal complexes (cc) of Neisseria meningitidis differ substantially in their point prevalence among healthy carriers. We show that frequently carried pathogenic cc (e.g. sequenceMajor pathogenic clonal complexes (cc) of Neisseria meningitidis differ substantially in their point prevalence among healthy carriers. We show that frequently carried pathogenic cc (e.g. sequence type ST-41/44 cc and ST-32 cc) depend on extracellular DNA (eDNA) to initiate in vitro biofilm formation, whereas biofilm formation of cc with low point prevalence (ST-8 cc and ST-11 cc) was eDNA-independent. For initial biofilm formation, a ST-32 cc type strain, but not a ST-11 type strain, utilized eDNA. The release of eDNA was mediated by lytic transglycosylase and cytoplasmic N-acetylmuramyl-L-alanine amidase genes. In late biofilms, outer membrane phospholipase A-dependent autolysis, which was observed in most cc, but not in ST-8 and ST-11 strains, was required for shear force resistance of microcolonies. Taken together, N. meningitidis evolved two different biofilm formation strategies, an eDNA-dependent one yielding shear force resistant microcolonies, and an eDNA-independent one. Based on the experimental findings and previous epidemiological observations, we hypothesize that most meningococcal cc display a settler phenotype, which is eDNA-dependent and results in a stable interaction with the host. On the contrary, spreaders (ST-11 and ST-8 cc) are unable to use eDNA for biofilm formation and might compensate for poor colonization properties by high transmission rates.

• O-acetyltransferase gene neuO is segregated according to phylogenetic background and contributes to environmental desiccation resistance in Escherichia coli K1.

  Authors: Ines L Mordhorst, Heike Claus, Christa Ewers, Martin Lappann, Christoph Schoen, Johannes Elias, Julia Batzilla, Ulrich Dobrindt, Lothar H Wieler, Anne K Bergfeld, Martina Mühlenhoff, Ulrich Vogel

  Environmental microbiology. 09/2009;

  Escherichia coli K1 causes disease in humans and birds. Its polysialic acid capsule can be O-acetylated via phase-variable expression of the acetyltransferase NeuO encoded by prophage CUS-3. The roleEscherichia coli K1 causes disease in humans and birds. Its polysialic acid capsule can be O-acetylated via phase-variable expression of the acetyltransferase NeuO encoded by prophage CUS-3. The role of capsule O-acetylation in ecological adaptation or pathogenic invasion of E. coli K1 is largely unclear. A population genetics approach was performed to study the distribution of neuO among E. coli K1 isolates from human and avian sources. Multilocus sequence typing revealed 39 different sequence types (STs) among 183 E. coli K1 strains. The proportion of the ST95 complex (STC95) was 44%. NeuO was found in 98% of the STC95 strains, but only in 24% of other STs. Grouping of STs and prophage genotypes revealed a segregation of prophage types according to STs, suggesting coevolution of CUS-3 and the E. coli K1 host. Within the STC95, which is known to harbour both human and avian pathogenic isolates, CUS-3 genotypes were shared irrespective of the host species. Functional analysis of a variety of strain pairs revealed that NeuO-mediated K1 capsule O-acetylation enhanced desiccation resistance. In contrast, NeuO expression led to a reduced biofilm formation in biofilm positive E. coli K1 isolates. These findings suggest a delicate ecological balance of neuO'on'/'off' switching.

• Streptococcus merionis sp. nov., isolated from Mongolian jirds (Meriones unguiculatus).

  Authors: Dennis Tappe, Rüdiger Pukall, Peter Schumann, Sabine Gronow, Markus Spiliotis, Heike Claus, Klaus Brehm, Ulrich Vogel

  International journal of systematic and evolutionary microbiology. 05/2009; 59(Pt 4):766-70.

  Gram-positive, catalase-negative, chain-forming, coccus-shaped organisms were isolated both from intraperitoneally grown vesicles of the fox tapeworm Echinococcus multilocularis and the oropharyngesGram-positive, catalase-negative, chain-forming, coccus-shaped organisms were isolated both from intraperitoneally grown vesicles of the fox tapeworm Echinococcus multilocularis and the oropharynges of laboratory-kept Mongolian jirds (Meriones unguiculatus). The strains displayed no haemolytic activity on Columbia sheep blood agar, pyrrolidonyl arylamidase activity was negative and the organisms reacted weakly with Lancefield group D antiserum. On the basis of phenotypic characteristics, the strains were tentatively identified as members of the genus Streptococcus. Comparative 16S rRNA gene sequencing studies confirmed their assignment to the genus Streptococcus and revealed that Streptococcus hyointestinalis DSM 20770(T) was their closest phylogenetic neighbour (96.5 % sequence similarity). The levels of 16S rRNA gene sequence similarity between the isolates and representatives of species of the genus Streptococcus were only 95.7-96.2 %. On the basis of the phenotypic and molecular data presented, the isolates from Mongolian jirds represent a novel species of the genus Streptococcus, for which the name Streptococcus merionis sp. nov. is proposed. The type strain is WUE3771(T) (=DSM 19192(T)=CCUG 54871(T)).

• Laboratory diagnostics of Neisseria meningitidis from the viewpoint of the German Reference Laboratory for Meningococci

  Authors: Ulrich Vogel, Johannes Elias, Heike Claus, Matthias Frosch

  LaboratoriumsMedizin. 01/2009; 33(5):245-253.

• The polysialic acid specific O-acetyltransferase OatC from Neisseria meningitidis serogroup C evolved apart from other bacterial sialate:O-acetyltransferases.

  Authors: Anne K Bergfeld, Heike Claus, Nina K Lorenzen, Fabian Spielmann, Ulrich Vogel, Martina Mühlenhoff

  The Journal of biological chemistry. 12/2008;

  Neisseria meningitidis serogroup C is a major cause of bacterial meningitis and septicaemia. This human pathogen is protected by a capsule composed of alpha2,9-linked polysialic acid which representsNeisseria meningitidis serogroup C is a major cause of bacterial meningitis and septicaemia. This human pathogen is protected by a capsule composed of alpha2,9-linked polysialic acid which represents an important virulence factor. In the majority of strains, the capsular polysaccharide is modified by O-acetylation at position C-7 or C-8 of the sialic acid residues. The gene encoding the capsule modifying O-acetyltransferase is part of the capsule gene complex and shares no sequence similarities with other proteins. Here we describe the purification and biochemical characterization of recombinant OatC. The enzyme was found as a homodimer, with the first 34 amino acids forming an efficient oligomerization domain that worked even in a different protein context. Using acetyl-CoA as donor substrate, OatC transferred acetyl-groups exclusively onto polysialic acid joined by alpha2,9-linkages and did not act on free or CMP-activated sialic acid. Motif scanning revealed a nucleophile elbow motif (GXS(286)XGG), which is a hallmark of alpha/beta-hydrolase fold enzymes. In a comprehensive site-directed mutagenesis study, we identified a catalytic triad composed of Ser-286, Asp-376, and His 399. Consistent with a double-displacement mechanism common to alpha/beta-hydrolase fold enzymes, a covalent acetyl-enzyme intermediate was found. Together with secondary structure prediction highlighting an alpha/beta-hydrolase fold topology, our data provide strong evidence that OatC belongs to the alpha/beta-hydrolase fold family. This clearly distinguishes OatC from all other bacterial sialate:O-acetyltransferases known so far, since these are members of the hexapeptide repeat family, a class of acyltransferases that adopt a left-handed beta-helix fold and assemble into catalytic trimers.

• Whole-genome comparison of disease and carriage strains provides insights into virulence evolution in Neisseria meningitidis.

  Authors: Christoph Schoen, Jochen Blom, Heike Claus, Anja Schramm-Glück, Petra Brandt, Tobias Müller, Alexander Goesmann, Biju Joseph, Sebastian Konietzny, Oliver Kurzai, Corinna Schmitt, Torben Friedrich, Burkhard Linke, Ulrich Vogel, Matthias Frosch

  Proceedings of the National Academy of Sciences of the United States of America. 04/2008; 105(9):3473-8.

  Neisseria meningitidis is a leading cause of infectious childhood mortality worldwide. Most research efforts have hitherto focused on disease isolates belonging to only a few hypervirulent clonalNeisseria meningitidis is a leading cause of infectious childhood mortality worldwide. Most research efforts have hitherto focused on disease isolates belonging to only a few hypervirulent clonal lineages. However, up to 10% of the healthy human population is temporarily colonized by genetically diverse strains mostly with little or no pathogenic potential. Currently, little is known about the biology of carriage strains and their evolutionary relationship with disease isolates. The expression of a polysaccharide capsule is the only trait that has been convincingly linked to the pathogenic potential of N. meningitidis. To gain insight into the evolution of virulence traits in this species, whole-genome sequences of three meningococcal carriage isolates were obtained. Gene content comparisons with the available genome sequences from three disease isolates indicate that there is no core pathogenome in N. meningitidis. A comparison of the chromosome structure suggests that a filamentous prophage has mediated large chromosomal rearrangements and the translocation of some candidate virulence genes. Interspecific comparison of the available Neisseria genome sequences and dot blot hybridizations further indicate that the insertion sequence IS1655 is restricted only to N. meningitidis; its low sequence diversity is an indicator of an evolutionarily recent population bottleneck. A genome-based phylogenetic reconstruction provides evidence that N. meningitidis has emerged as an unencapsulated human commensal from a common ancestor with Neisseria gonorrhoeae and Neisseria lactamica and consecutively acquired the genes responsible for capsule synthesis via horizontal gene transfer.

• Living in a changing environment: insights into host adaptation in Neisseria meningitidis from comparative genomics.

  Authors: Christoph Schoen, Biju Joseph, Heike Claus, Ulrich Vogel, Matthias Frosch

  International journal of medical microbiology : IJMM. 12/2007; 297(7-8):601-13.

  Neisseria meningitidis (the meningococcus) colonizes the human nasopharynx of about 10% of the human population. However, for reasons that are still mostly unknown meningococci occasionally enter theNeisseria meningitidis (the meningococcus) colonizes the human nasopharynx of about 10% of the human population. However, for reasons that are still mostly unknown meningococci occasionally enter the cerebrospinal fluid leading to often fatal bacterial meningitis especially in children and young adults. The genetic basis for the observed differences in the pathogenic potential of different strains has only partially been unravelled so far. With the advent of whole genome sequencing technologies, complete genome sequences from three pathogenic meningococcal strains have become available and allow for a comprehensive analysis of the genomic and genetic differences occurring within this species. In this review, the general properties of the meningococcal genomes so far sequenced is given with an emphasis on the chromosomal rearrangements that have occurred, and the genomic islands and prophages that have been identified. The concomitant development of microarray technology for comparative genome hybridization studies of a large set of different meningococcal isolates as well as strains from other Neisseria species has extended our understanding of meningococcal population genetics on a genome-wide scale thus bridging the gap between meningococcal epidemiology and genomics. Finally, we briefly discuss the potential impact of meningococcal life style on its genome architecture and how in turn this genomic make-up might lead to a virulent phenotype making N. meningitidis an accidental pathogen. The overall properties of the meningococcal genome are characterized by genomic variability and instability, resulting in increased functional flexibility within this species.

• Biochemical characterization of a Neisseria meningitidis polysialyltransferase reveals novel functional motifs in bacterial sialyltransferases.

  Authors: Friedrich Freiberger, Heike Claus, Almut Günzel, Imke Oltmann-Norden, Justine Vionnet, Martina Mühlenhoff, Ulrich Vogel, Willie F Vann, Rita Gerardy-Schahn, Katharina Stummeyer

  Molecular microbiology. 10/2007; 65(5):1258-75.

  The extracellular polysaccharide capsule is an essential virulence factor of Neisseria meningitidis, a leading cause of severe bacterial meningitis and sepsis. Serogroup B strains, the primaryThe extracellular polysaccharide capsule is an essential virulence factor of Neisseria meningitidis, a leading cause of severe bacterial meningitis and sepsis. Serogroup B strains, the primary disease causing isolates in Europe and America, are encapsulated in alpha-2,8 polysialic acid (polySia). The capsular polymer is synthesized from activated sialic acid by action of a membrane-associated polysialyltransferase (NmB-polyST). Here we present a comprehensive characterization of NmB-polyST. Different from earlier studies, we show that membrane association is not essential for enzyme functionality. Recombinant NmB-polyST was expressed, purified and shown to synthesize long polySia chains in a non-processive manner in vitro. Subsequent structure-function analyses of NmB-polyST based on refined sequence alignments allowed the identification of two functional motifs in bacterial sialyltransferases. Both (D/E-D/E-G and HP motif) are highly conserved among different sialyltransferase families with otherwise little or no sequence identity. Their functional importance for enzyme catalysis and CMP-Neu5Ac binding was demonstrated by mutational analysis of NmB-polyST and is emphasized by structural data available for the Pasteurella multocida sialyltransferase PmST1. Together our data are the first description of conserved functional elements in the highly diverse families of bacterial (poly)sialyltransferases and thus provide an advanced basis for understanding structure-function relations and for phylogenetic sorting of these important enzymes.

• Deletion of the meningococcal fetA gene used for antigen sequence typing of invasive and commensal isolates from Germany: frequencies and mechanisms.

  Authors: Heike Claus, Johannes Elias, Christine Meinhardt, Matthias Frosch, Ulrich Vogel

  Journal of clinical microbiology. 10/2007; 45(9):2960-4.

  Antigen sequence typing (ST) of FetA is part of the molecular typing scheme of Neisseria meningitidis. Among invasive meningococcal isolates from 2,201 patients in Germany, we identified 11 strainsAntigen sequence typing (ST) of FetA is part of the molecular typing scheme of Neisseria meningitidis. Among invasive meningococcal isolates from 2,201 patients in Germany, we identified 11 strains lacking the fetA gene because of deletions mediated by repeat arrays flanking the gene, i.e., Correia elements, repeat sequence 13 (RS13), and duplicated RS3. Geographic mapping and multilocus ST of invasive isolates revealed that fetA deletion was a sporadic event without genetic fixation. Among 821 carrier strains, 12 strains lacked fetA, suggesting that fetA is maintained during asymptomatic carriage. Interestingly, most of these isolates belonged to the multilocus ST-35 clonal complex (cc). ST-35 cc strains and the recently published ST-192 strains from Burkina Faso may benefit from loss of fetA, but their infrequent occurrence among invasive isolates currently does not affect fetA antigen ST.