Neisseria genomics: current status and future perspectives

Pangenome graphs in infectious disease: a comprehensive genetic variation analysis of Neisseria meningitidis leveraging Oxford Nanopore long reads

Whole genome sequencing has revolutionized infectious disease surveillance for tracking and monitoring the spread and evolution of pathogens. However, using a linear reference genome for genomic analyses may introduce biases, especially when studies are conducted on highly variable bacterial genomes of the same species. Pangenome graphs provide an efficient model for representing and analyzing multiple genomes and their variants as a graph structure that includes all types of variations. In this study, we present a practical bioinformatics pipeline that employs the PanGenome Graph Builder and the Variation Graph toolkit to build pangenomes from assembled genomes, align whole genome sequencing data and call variants against a graph reference. The pangenome graph enables the identification of structural variants, rearrangements, and small variants (e.g., single nucleotide polymorphisms and insertions/deletions) simultaneously. We demonstrate that using a pangenome graph, instead of a single linear reference genome, improves mapping rates and variant calling for both simulated and real datasets of the pathogen Neisseria meningitidis. Overall, pangenome graphs offer a promising approach for comparative genomics and comprehensive genetic variation analysis in infectious disease. Moreover, this innovative pipeline, leveraging pangenome graphs, can bridge variant analysis, genome assembly, population genetics, and evolutionary biology, expanding the reach of genomic understanding and applications.

Neisseria lisongii sp. nov. and Neisseria yangbaofengii sp. nov., isolated from the respiratory tracts of marmots

Four Gram-stain-negative, oxidase-positive, non-motile, cocci-shaped bacteria strains (ZJ106T, ZJ104, ZJ785T and ZJ930) were isolated from marmot respiratory tracts. Phylogenetic analyses based on 16S rRNA genes, 53 ribosomal protein sequences and 441 core genes supported that all four strains belonged to the genus Neisseria with close relatives Neisseria weixii 10022T and Neisseria iguanae ATCC 51483T. Average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values were below the species-level thresholds (95-96 % for ANI, and 70 % for dDDH). The major fatty acids of all four strains were C16 : 1  ω7c /C16 : 1  ω6c, C16 : 0 and C18 : 1  ω9c. Major polar lipids were composed of diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol. MK-8 was the major menaquinone. Based on Virulence Factor Database analysis, the four strains were found to contain NspA and PorB H-factor binding proteins that promote evasion of host immunity. Strains ZJ106T and ZJ104 contained structures similar to the capsule synthesis manipulator of Neisseria meningitidis. Based on phenotypic and phylogenetic evidence, we propose that strains ZJ106T and ZJ785T represent two novel species of the genus Neisseria, respectively, with the names Neisseria lisongii sp. nov. and Neisseria yangbaofengii sp. nov. The type strains are ZJ106T (=GDMCC 1.3111T=JCM 35323T) and ZJ785T (=GDMCC 1.1998T=KCTC 82336T).

Whole Genome Analyses Accurately Identify Neisseria spp. and Limit Taxonomic Ambiguity

Genome sequencing facilitates the study of bacterial taxonomy and allows the re-evaluation of the taxonomic relationships between species. Here, we aimed to analyze the draft genomes of four commensal Neisseria clinical isolates from the semen of infertile Lebanese men. To determine the phylogenetic relationships among these strains and other Neisseria spp. and to confirm their identity at the genomic level, we compared the genomes of these four isolates with the complete genome sequences of Neisseria gonorrhoeae and Neisseria meningitidis and the draft genomes of Neisseria flavescens, Neisseria perflava, Neisseria mucosa, and Neisseria macacae that are available in the NCBI Genbank database. Our findings revealed that the WGS analysis accurately identified and corroborated the matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) species identities of the Neisseria isolates. The combination of three well-established genome-based taxonomic tools (in silico DNA-DNA Hybridization, Ortho Average Nucleotide identity, and pangenomic studies) proved to be relatively the best identification approach. Notably, we also discovered that some Neisseria strains that are deposited in databases contain many taxonomical errors. The latter is very important and must be addressed to prevent misdiagnosis and missing emerging etiologies. We also highlight the need for robust cut-offs to delineate the species using genomic tools.

Assessment of Antibiotic Resistance and Efflux Pump Gene Expression in Neisseria Gonorrhoeae Isolates from South Africa by Quantitative Real-Time PCR and Regression Analysis

Introduction

Treatment of gonorrhoea infection is limited by the increasing prevalence of multidrug-resistant strains. Cost-effective molecular diagnostic tests can guide effective antimicrobial stewardship. The aim of this study was to correlate mRNA expression levels in Neisseria gonorrhoeae antibiotic target genes and efflux pump genes to antibiotic resistance in our population.

Methods

This study investigated the expression profile of antibiotic resistance-associated genes (penA, ponA, pilQ, mtrR, mtrA, mtrF, gyrA, parC, parE, rpsJ, 16S rRNA, and 23S rRNA) and efflux pump genes (macAB, norM, and mtrCDE), by quantitative real-time PCR, in clinical isolates from KwaZulu-Natal, South Africa. Whole-genome sequencing was used to determine the presence or absence of mutations.

Results

N. gonorrhoeae isolates, from female and male patients presenting for care at clinics in KwaZulu-Natal, South Africa, were analysed. As determined by binomial regression and ROC analysis, the most significant (p ≤ 0.05) markers for resistance prediction in this population, and their cutoff values, were determined to be mtrC (p = 0.024; cutoff <0.089), gyrA (p = 0.027; cutoff <0.0518), parE (p = 0.036; cutoff <0.0033), rpsJ (p = 0.047; cutoff <0.0012), and 23S rRNA (p = 0.042; cutoff >7.754).

Conclusion

Antimicrobial stewardship includes exploring options to conserve currently available drugs for gonorrhoea treatment. There is the potential to predict an isolate as either susceptible or nonsusceptible based on the mRNA expression level of specific candidate markers, to inform patient management. This real-time qPCR approach, with few targets, can be further investigated for use as a potentially cost-effective diagnostic tool to detect resistance.

Genomic sequence of the non-pathogen Neisseria sp. strain MA1-1 with antibiotic resistance and virulence factors isolated from a head and neck cancer patient

Recent research has claimed virulence factors or antimicrobial resistance in commensal or non-pathogenic Neisseria spp. This study aimed to isolate and analyze commensal microorganisms related to the genus Neisseria from the oral cavity of a patient with head and neck cancer. We successfully isolated strain MA1-1 and identified its functional gene contents. Although strain MA1-1 was related to Neisseria flava based on 16S rRNA gene sequence similarity, genomic relatedness analysis revealed that strain MA1-1 was closely related to Neisseria mucosa, reported as a commensal Neisseria species. The strain MA1-1 genome harbored genes for microaerobic respiration and the complete core metabolic pathway with few transporters for nutrients. A number of genes have been associated with virulence factors and resistance to various antibiotics. In addition, the comparative genomic analysis showed that most genes identified in the strain MA1-1 were shared with other Neisseria spp. including two well-known pathogens, Neisseria gonorrhoeae and Neisseria meningitidis. This indicates that the gene content of intra-members of the genus Neisseria has been evolutionarily conserved and is stable, with no gene recombination with other microbes in the host. Finally, this study provides more fundamental interpretations for the complete gene sequence of commensal Neisseria spp. and will contribute to advancing public health knowledge.

Bioinformatics tools used for whole-genome sequencing analysis of Neisseria gonorrhoeae: a literature review

Whole-genome sequencing (WGS) data are well established for the investigation of gonococcal transmission, antimicrobial resistance prediction, population structure determination and population dynamics. A variety of bioinformatics tools, repositories, services and platforms have been applied to manage and analyze Neisseria gonorrhoeae WGS datasets. This review provides an overview of the various bioinformatics approaches and resources used in 105 published studies (as of 30 April 2021). The challenges in the analysis of N. gonorrhoeae WGS datasets, as well as future bioinformatics requirements, are also discussed.

Virulence genes and previously unexplored gene clusters in four commensal Neisseria spp. isolated from the human throat expand the neisserial gene repertoire

Commensal non-pathogenic Neisseria spp. live within the human host alongside the pathogenic Neisseria meningitidis and Neisseria gonorrhoeae and due to natural competence, horizontal gene transfer within the genus is possible and has been observed. Four distinct Neisseria spp. isolates taken from the throats of two human volunteers have been assessed here using a combination of microbiological and bioinformatics techniques. Three of the isolates have been identified as Neisseria subflava biovar perflava and one as Neisseria cinerea. Specific gene clusters have been identified within these commensal isolate genome sequences that are believed to encode a Type VI Secretion System, a newly identified CRISPR system, a Type IV Secretion System unlike that in other Neisseria spp., a hemin transporter, and a haem acquisition and utilization system. This investigation is the first to investigate these systems in either the non-pathogenic or pathogenic Neisseria spp. In addition, the N. subflava biovar perflava possess previously unreported capsule loci and sequences have been identified in all four isolates that are similar to genes seen within the pathogens that are associated with virulence. These data from the four commensal isolates provide further evidence for a Neisseria spp. gene pool and highlight the presence of systems within the commensals with functions still to be explored.

Genotypic characterization and genome comparison reveal insights into potential vaccine coverage and genealogy of Neisseria meningitidis in military camps in Vietnam

Background

Neisseria meningitidis remains the main cause of sporadic meningitis and sepsis in military camps in Vietnam. Yet, very limited molecular data of their genotypic and epidemiological characteristics are available from Vietnam, and particularly the military environment. Whole genome sequencing (WGS) has proven useful for meningococcal disease surveillance and guiding preventative vaccination programs. Previously, we characterized key genetic and epidemiological features of an invasive N. meningitidis B isolate from a military unit in Vietnam. Here, we extend these findings by sequencing two additional invasive N. meningitidis B isolated from cerebrospinal fluid (CSF) of two meningitis cases at another military unit and compared their genomic sequences and features. We also report the sequence types and antigenic profiles of 25 historical and more recently emerged N. meningitidis isolates from these units and other units in proximity.

Methods

Strains were sequenced using the Illumina HiSeq platform, de novo assembled and annotated. Genomes were compared within and between military units, as well as against the global N. meningitidis collection and other isolates from the Southeast Asia region using PubMLST. Variations at the nucleotide level were determined, and phylogenetic relationships were estimated. Antigenic genotypes and vaccine coverage were analyzed using gMATS and PubMLST. Susceptibility of isolates against commonly used antibiotic agents was examined using E-test.

Results

Genome comparison revealed a high level of similarity among isolates both within and between units. All isolates showed resistance to chloramphenicol and carried identical catP gene with other Southeast Asian isolates, suggesting a common lineage. Their antigenic genotypes predicted no coverage by either Bexsero^®or Trumenba^®, and nucleotide variation analysis revealed diverse new, unassigned alleles at multiple virulence loci of all strains. Groups of singleton and unique novel sequence types extending beyond individual camps were found from epidemiological data of 25 other isolates. Our results add to the sparse published molecular data of N. meningitidis in the military units in Vietnam, highlight their diversity, distinct genetic features and antibiotic resistance pattern, and emphasize the need for further studies on the molecular characteristics of N. meningitidis in Vietnam.

The global meningitis genome partnership

Genomic surveillance of bacterial meningitis pathogens is essential for effective disease control globally, enabling identification of emerging and expanding strains and consequent public health interventions. While there has been a rise in the use of whole genome sequencing, this has been driven predominately by a subset of countries with adequate capacity and resources. Global capacity to participate in surveillance needs to be expanded, particularly in low and middle-income countries with high disease burdens. In light of this, the WHO-led collaboration, Defeating Meningitis by 2030 Global Roadmap, has called for the establishment of a Global Meningitis Genome Partnership that links resources for: N. meningitidis (Nm), S. pneumoniae (Sp), H. influenzae (Hi) and S. agalactiae (Sa) to improve worldwide co-ordination of strain identification and tracking. Existing platforms containing relevant genomes include: PubMLST: Nm (31,622), Sp (15,132), Hi (1935), Sa (9026); The Wellcome Sanger Institute: Nm (13,711), Sp (> 24,000), Sa (6200), Hi (1738); and BMGAP: Nm (8785), Hi (2030). A steering group is being established to coordinate the initiative and encourage high-quality data curation. Next steps include: developing guidelines on open-access sharing of genomic data; defining a core set of metadata; and facilitating development of user-friendly interfaces that represent publicly available data.

Meningococcal core and accessory phasomes vary by clonal complex

Neisseria meningitidis is a Gram-negative human commensal pathogen, with extensive phenotypic plasticity afforded by phase-variable (PV) gene expression. Phase variation is a stochastic switch in gene expression from an ON to an OFF state, mediated by localized hypermutation of simple sequence repeats (SSRs). Circulating N. meningitidis clones vary in propensity to cause disease, with some clonal complexes (ccs) classified as hypervirulent and others as carriage-associated. We examined the PV gene repertoires, or phasome, of these lineages in order to determine whether phase variation contributes to disease propensity. We analysed 3328 genomes representative of nine circulating meningococcal ccs with PhasomeIt, a tool that identifies PV genes by the presence of SSRs and homologous gene clusters. The presence, absence and functions of all identified PV gene clusters were confirmed by annotation or blast searches within the Neisseria PubMLST database. While no significant differences were detected in the number of PV genes or the core, conserved phasome content between hypervirulent and carriage lineages, individual ccs exhibited major variations in PV gene numbers. Phylogenetic clusters produced by phasome or core genome analyses were similar, indicating co-evolution of PV genes with the core genome. While conservation of PV clusters is high, with 76 % present in all meningococcal isolates, maintenance of an SSR is variable, ranging from conserved in all isolates to present only in a single cc, indicating differing evolutionary trajectories for each lineage. Diverse functional groups of PV genes were present across the meningococcal lineages; however, the majority directly or indirectly influence bacterial surface antigens and could impact on future vaccine development. Finally, we observe that meningococci have open pan phasomes, indicating ongoing evolution of PV gene content and a significant potential for adaptive changes in this clinically relevant genus.

Immunoinformatics and Vaccine Development: An Overview

The use of vaccines have resulted in a remarkable improvement in global health. It has saved several lives, reduced treatment costs and raised the quality of animal and human lives. Current traditional vaccines came empirically with either vague or completely no knowledge of how they modulate our immune system. Even at the face of potential vaccine design advance, immune-related concerns (as seen with specific vulnerable populations, cases of emerging/re-emerging infectious disease, pathogens with complex lifecycle and antigenic variability, need for personalized vaccinations, and concerns for vaccines' immunological safety -specifically vaccine likelihood to trigger non-antigen-specific responses that may cause autoimmunity and vaccine allergy) are being raised. And these concerns have driven immunologists toward research for a better approach to vaccine design that will consider these challenges. Currently, immunoinformatics has paved the way for a better understanding of some infectious disease pathogenesis, diagnosis, immune system response and computational vaccinology. The importance of this immunoinformatics in the study of infectious diseases is diverse in terms of computational approaches used, but is united by common qualities related to host–pathogen relationship. Bioinformatics methods are also used to assign functions to uncharacterized genes which can be targeted as a candidate in vaccine design and can be a better approach toward the inclusion of women that are pregnant into vaccine trials and programs. The essence of this review is to give insight into the need to focus on novel computational, experimental and computation-driven experimental approaches for studying of host–pathogen interactions and thus making a case for its use in vaccine development.

Genetic diversity of Neisseria gonorrhoeae multi-antigen sequence types in Russia and Europe

OBJECTIVES

The goal of this work was to assess the genetic diversity of Neisseria gonorrhoeae isolates in Russia and Europe and to compare the distribution of the N. gonorrhoeae multi-antigen sequencing types (NG-MAST) of Russian isolates with that of isolates from European countries.

METHODS

NG-MAST typing was performed for 804 N. gonorrhoeae isolates collected in Russia in 2013-2018. For isolates from European countries, data from the https://pathogen.watch/collection/eurogasp2013 database were used.

RESULTS

Among the isolates from Russia, 296 NG-MAST types were found. A maximum likelihood phylogenetic tree was constructed. Phylogenetic analysis revealed seven major genogroups uniting the most frequent Russian sequence types: G807, G1993, G9476, G14942, G1152, G9486, and G12531.

CONCLUSIONS

The NG-MAST type distribution in Russia differed from that in European countries. Most of the Russian isolates had sequence types that were not found in Europe. Only 33% of the Russian isolates belonged to genogroups established for European countries, and the widespread European genogroup G1407 was represented by only nine isolates. Analysis of the Russian isolates belonging to phylogenetically close European genogroups indicated similarities in drug resistance, although no epidemically dangerous drug-resistant clones were found among the Russian isolates.

Detailed Evaluation of Data Analysis Tools for Subtyping of Bacterial Isolates Based on Whole Genome Sequencing: Neisseria meningitidis as a Proof of Concept

Whole genome sequencing is increasingly recognized as the most informative approach for characterization of bacterial isolates. Success of the routine use of this technology in public health laboratories depends on the availability of well-characterized and verified data analysis methods. However, multiple subtyping workflows are now often being used for a single organism, and differences between them are not always well described. Moreover, methodologies for comparison of subtyping workflows, and assessment of their performance are only beginning to emerge. Current work focuses on the detailed comparison of WGS-based subtyping workflows and evaluation of their suitability for the organism and the research context in question. We evaluated the performance of pipelines used for subtyping of Neisseria meningitidis, including the currently widely applied cgMLST approach and different SNP-based methods. In addition, the impact of the use of different tools for detection and filtering of recombinant regions and of different reference genomes were tested. Our benchmarking analysis included both assessment of technical performance of the pipelines and functional comparison of the generated genetic distance matrices and phylogenetic trees. It was carried out using replicate sequencing datasets of high- and low-coverage, consisting mainly of isolates belonging to the clonal complex 269. We demonstrated that cgMLST and some of the SNP-based subtyping workflows showed very good performance characteristics and highly similar genetic distance matrices and phylogenetic trees with isolates belonging to the same clonal complex. However, only two of the tested workflows demonstrated reproducible results for a group of more closely related isolates. Additionally, results of the SNP-based subtyping workflows were to some level dependent on the reference genome used. Interestingly, the use of recombination-filtering software generally reduced the similarity between the gene-by-gene and SNP-based methodologies for subtyping of N. meningitidis. Our study, where N. meningitidis was taken as an example, clearly highlights the need for more benchmarking comparative studies to eventually contribute to a justified use of a specific WGS data analysis workflow within an international public health laboratory context.

Whole-genome sequencing and characterization of an antibiotic resistant Neisseria meningitidis B isolate from a military unit in Vietnam

Background

Invasive meningococcal disease (IMD) persists in military units in Vietnam despite the availability of antibiotics and vaccines. A hindrance to reducing the incidence of IMD in Vietnam is a lack of molecular data from isolates of the causative agent, Neisseria meningitidis from this country. Here, we characterized key genetic and epidemiological features of an invasive N. meningitidis isolate from a military unit in Vietnam using whole-genome sequencing.

Methods

Neisseria meningitidis was isolated from a conscript admitted for meningitis and tested against seven antibiotics. DNA from the isolate was extracted and sequenced using the Illumina HiSeq platform. Denovo assembly and scaffolding were performed to construct a draft genome assembly, from which genes were predicted and functionally annotated. Genome analysis included epidemiological characterization, genomic composition and identification of antibiotic resistance genes.

Results

Susceptibility testing of the isolate showed high levels of resistance to chloramphenicol and diminished susceptibility to ampicillin and rifampicin. A draft genome of ~ 2.1 Mb was assembled, containing 2451 protein coding sequences, 49 tRNAs and 3 rRNAs. Fifteen coding sequences sharing ≥ 84% identity with known antibiotic resistance genes were identified. Genome analysis revealed abundant repetitive DNAs and two prophages. Epidemiological typing revealed newly described sequence type, antigenic finetype and Bexsero^® Antigen Sequence Typing (BAST). The BAST profile showed no coverage by either Bexsero^® or Trumenba^®.

Conclusions

Our results present the first genome assembly of an invasive N. meningitidis isolate from a military unit in Vietnam. This study illustrates the usefulness of whole genome sequencing (WGS) analysis for epidemiological and antibiotic resistance studies and surveillance of IMD in Vietnam.

Gen2Epi: an automated whole-genome sequencing pipeline for linking full genomes to antimicrobial susceptibility and molecular epidemiological data in Neisseria gonorrhoeae

BACKGROUND

Recent adva1nces in whole genome sequencing (WGS) based technologies have facilitated multi-step applications for predicting antimicrobial resistance (AMR) and investigating the molecular epidemiology of Neisseria gonorrhoeae. However, generating full scaffolds of N. gonorrhoeae genomes from short reads, and the assignment of molecular epidemiological information (NG-MLST, NG-MAST, and NG-STAR) to multiple assembled samples, is challenging due to required manual tasks such as annotating antimicrobial resistance determinants with standard nomenclature for a large number of genomes.

RESULTS

We present Gen2Epi, a pipeline that assembles short reads into full scaffolds and automatically assigns molecular epidemiological and AMR information to the assembled genomes. Gen2Epi is a command-line tool integrating third-party software and tailored specifically for N. gonorrhoeae. For its evaluation, the Gen2Epi pipeline successfully assembled the WGS short reads from 1484 N. gonorrhoeae samples into full-length genomes for both chromosomes and plasmids and was able to assign in silico molecular determinant information to each dataset automatically. The assemblies were generated using raw as well as trimmed short reads. The median genome coverage of full-length scaffolds and "N" statistics (N50, NG50, and NGA50) were higher than, or comparable to, previously published results and the scaffolding process improved the quality of the draft genome assemblies. Molecular antimicrobial resistant (AMR) determinants identified by Gen2Epi reproduced information for the 1484 samples as previously reported, including NG-MLST, NG-MAST, and NG-STAR molecular sequence types.

CONCLUSIONS

Gen2Epi can be used to assemble short reads into full-length genomes and assign accurate molecular marker and AMR information automatically from NG-STAR, NG-MAST, and NG-MLST. Gen2Epi is publicly available under "CC BY-NC 2.0 CA" Creative Commons licensing as a VirtualBox image containing the constituent software components running on the LINUX operating system (CentOS 7). The image and associated documentation are available via anonymous FTP at ftp://www.cs.usask.ca/pub/combi or ftp://ftp.cs.usask.ca/pub/combi.

Microevolution of Neisseria lactamica during nasopharyngeal colonisation induced by controlled human infection

Neisseria lactamica is a harmless coloniser of the infant respiratory tract, and has a mutually-excluding relationship with the pathogen Neisseria meningitidis. Here we report controlled human infection with genomically-defined N. lactamica and subsequent bacterial microevolution during 26 weeks of colonisation. We find that most mutations that occur during nasopharyngeal carriage are transient indels within repetitive tracts of putative phase-variable loci associated with host-microbe interactions (pgl and lgt) and iron acquisition (fetA promotor and hpuA). Recurrent polymorphisms occurred in genes associated with energy metabolism (nuoN, rssA) and the CRISPR-associated cas1. A gene encoding a large hypothetical protein was often mutated in 27% of the subjects. In volunteers who were naturally co-colonised with meningococci, recombination altered allelic identity in N. lactamica to resemble meningococcal alleles, including loci associated with metabolism, outer membrane proteins and immune response activators. Our results suggest that phase variable genes are often mutated during carriage-associated microevolution.

The CRISPR/Cas system in Neisseria meningitidis affects bacterial adhesion to human nasopharyngeal epithelial cells

Neisseria meningitidis, a commensal β-proteobacterium of the human nasopharynx, constitutes a worldwide leading cause of sepsis and epidemic meningitis. A recent genome-wide association study suggested an association of its type II-C CRISPR/Cas system with carriage and thus less invasive lineages. Here, we show that knock-out strains lacking the Cas9 protein are impaired in the adhesion to human nasopharyngeal cells which constitutes a central step in the pathogenesis of invasive meningococcal disease. Transcriptome sequencing data further suggest that meningococcal Cas9 does not affect the expression of surface adhesins but rather exerts its effect on cell adhesion in an indirect manner. Consequently, we speculate that the meningococcal CRISPR/Cas system exerts novel functions beyond its established role in defence against foreign DNA.

Vaccine prevention of meningococcal disease in Africa: Major advances, remaining challenges

Africa historically has had the highest incidence of meningococcal disease with high endemic rates and periodic epidemics. The meningitis belt, a region of sub-Saharan Africa extending from Senegal to Ethiopia, has experienced large, devastating epidemics. However, dramatic shifts in the epidemiology of meningococcal disease have occurred recently. For instance, meningococcal capsular group A (NmA) epidemics in the meningitis belt have essentially been eliminated by use of conjugate vaccine. However, NmW epidemics have emerged and spread across the continent since 2000; NmX epidemics have occurred sporadically, and NmC recently emerged in Nigeria and Niger. Outside the meningitis belt, NmB predominates in North Africa, while NmW followed by NmB predominate in South Africa. Improved surveillance is necessary to address the challenges of this changing epidemiologic picture. A low-cost, multivalent conjugate vaccine covering NmA and the emergent and prevalent meningococcal capsular groups C, W, and X in the meningitis belt is a pressing need.

Comparative proteomics analysis of Neisseria gonorrhoeae strains in response to extended-spectrum cephalosporins

Neisseria gonorrhoeae strains displaying reduced susceptibility and resistance to extended-spectrum cephalosporins (ESCs) are major public health concerns. Although resistance mechanisms of ESCs have extensively been studied, the proteome-wide investigation on the biological response to the antibiotic stress is still limited. Herein, a proteomics approach based on two-dimensional gel electrophoresis and MALDI-TOF/TOF-MS analysis was applied to investigate the global protein expression under ESC stresses of ESC-susceptible and ESC-reduced susceptible N. gonorrhoeae strains. Upon exposure to ceftriaxone, 14 and 21 proteins of ESC-susceptible and ESC-reduced susceptible strains, respectively, were shown to be differentially expressed. In the meanwhile, differential expressions of 13 and 17 proteins were detected under cefixime stress for ESC-susceptible and ESC-reduced susceptible strains, respectively. ESC antibiotics have been proven to trigger the expression of several proteins implicated in a variety of biological functions including transport system, energy metabolism, stress response and pathogenic virulence factors. Interestingly, macrophage infectivity potentiators (Ng-MIP) showed increased expression for ESC-reduced susceptible strain under ESC stress. The altered expression of Ng-MIP was found to be a unique response to ESC stresses. Our finding proposes a broad view on proteomic changes in N. gonorrhoeae in response to ESC antibiotics that provides further insights into the gonococcal antimicrobial resistance and physiological adaptation mechanism.