Enterotoxigenic Escherichia coli (ETEC) and Shigella are the most common bacterial diarrheal pathogens among young children of low-middle income regions. Enteric pathogens must overcome formidable host defenses, including the protective barrier formed by intestinal mucus. ETEC produce a virulence protein called EatA, a member of the Serine Protease Autotransporter of the Enterobacteriae (SPATE) family, where the secreted passenger domain (EatAp) specifically degrades MUC2, the major mucus secreted by goblet cells of the human intestine. Notably, some Shigella spp., as well as other diarrheagenic E. coli pathovars, secrete homologues of EatA known as SepA, and Pic. Here, we demonstrate that EatA, SepA, and Pic are functionally redundant MUC2 mucinases and that recombinant monoclonal antibodies (mAbs) derived from plasmablasts of ETEC-infected humans can inhibit MUC2 degradation by all three proteases. We present cryo-EM structures of EatA and the related SPATE proteins, SepA, and Pic, complexed to fragment antigen-binding portions of these mAbs to demonstrate that those targeting a core β-helix epitope shared by all three SPATE molecules broadly neutralize the capacity to degrade MUC2. These mAbs effectively prevent MUC2 degradation by each SPATE as well as mucus penetration by ETEC, Shigella flexneri, and Pic-producing enteroaggregative E. coli (EAEC). We anticipate that these studies could facilitate rational design of vaccines that broadly protect against major enteric pathogens by targeting a shared virulence feature.

Campylobacter jejuni tops the list of bacteria responsible for gastroenteritis in humans. Knowledge of capsular polysaccharide (CPS) fine structure allows for the design of chemical conjugation strategies and identification of gene clusters for bioconjugations. CPSs are the basis for a multivalent C. jejuni glycoconjugate vaccine that has as key serological markers variably linked O-methyl-phosphoramidate (MeOPN) moieties and heptoses of rare configurations. Previously, the activation strategy for C. jejuni CPSs whose backbones contained no vicinal diols (serotypes HS:4, HS:10, HS:15, HS:23/36 and HS:53) was based on oxidation of the non-reducing end sugar with periodate, followed by conjugation to protein via reductive amination. Here, we describe the approach taken to functionalize C. jejuni CPSs with inner regions susceptible to periodate centered on TEMPO/bleach-mediated oxidation of primary hydroxyls to carboxyls followed by carbodiimide-directed conjugation. This work describes the syntheses and immunogenicities of such C. jejuni CPS-conjugates, specifically those of serotypes HS:1, HS:2 and HS:3. The stoichiometric TEMPO/bleach-oxidation of CPSs showed preference for specific primary hydroxyl groups, such as C7 of 6-deoxy-heptoses, and furnished conjugates that induced strong IgG responses against the native C. jejuni CPSs. It is postulated that the enhanced immunogenicity of the described conjugates is due to the preservation of CPS structures and the zwitterionic character of CPSs, afforded by the native MeOPN units and unreacted carboxyls.

In 2018/2019, two large Guillain–Barré Syndrome (GBS) outbreaks took place in Peru. Here, we report a comprehensive analysis of biological samples from GBS patients from the 2019 outbreak. We applied metagenomic, microbiologic, and serological analyses to different biological samples collected from GBS patients. Further phenotypic and genomic characterization was conducted on Campylobacter jejuni isolates from GBS samples. Microbiologic and metagenomic analyses revealed several patients with multiple co-infections, yet no common infectious agents were found other than C. jejuni. Four C. jejuni isolates were isolated from rectal swabs. Twenty-one patients had detectable IgG serum antibodies related to C. jejuni, of whom seven had IgM antibodies. Genomic analyses showed that these four strains were clonal (ST2993) and contained the class A lipooligosaccharide biosynthesis locus. These results further support the idea that that C. jejuni is the etiological agent that triggered the GBS outbreak in Peru in 2019 and that the strains are not restricted to Peru, hence could be regarded as a broad public health concern. Furthermore, though we cannot delineate the role played by co-infections in GBS development, results obtained herein highlight metagenomic analysis as a potential new tool for depicting a yet unknown area of research in GBS.

Enterotoxigenic Escherichia coli (ETEC) cause hundreds of millions of cases of infectious diarrhea annually, predominantly in children from low-middle income regions. Notably, in children, as well as volunteers challenged with ETEC, diarrheal severity is significantly increased in blood group A (bgA) individuals. EtpA, is a secreted glycoprotein adhesin that functions as a blood group A lectin to promote critical interactions between ETEC and blood group A glycans on intestinal epithelia for effective bacterial adhesion and toxin delivery. EtpA is highly immunogenic resulting in robust antibody responses following natural infection and experimental challenge of volunteers with ETEC. To understand how EtpA directs ETEC-blood group A interactions and stimulates adaptive immunity, we mutated EtpA, mapped its glycosylation by mass-spectrometry (MS), isolated polyclonal (pAbs) and monoclonal antibodies (mAbs) from vaccinated mice and ETEC-infected volunteers, and determined structures of antibody-EtpA complexes by cryo-electron microscopy. Both bgA and mAbs that inhibited EtpA-bgA interactions and ETEC adhesion, bound to the C-terminal repeat domain highlighting this region as crucial for ETEC pathogen-host interaction. MS analysis uncovered extensive and heterogeneous N-linked glycosylation of EtpA and cryo-EM structures revealed that mAbs directly engage these unique glycan containing epitopes. Finally, electron microscopy-based polyclonal epitope mapping revealed antibodies targeting numerous distinct epitopes on N and C-terminal domains, suggesting that EtpA vaccination generates responses against neutralizing and decoy regions of the molecule. Collectively, we anticipate that these data will inform our general understanding of pathogen-host glycan interactions and adaptive immunity relevant to rational vaccine subunit design.

ABSTRACTCytolethal distending toxins (CDTs) are released by Gram-negative pathogens into the extracellular medium as free toxin or associated with extracellular vesicles (EVs), commonly known as outer membrane vesicles (OMVs). CDT production by the gastrointestinal pathogen Campylobacter jejuni has been implicated in colorectal tumorigenesis. Despite CDT being a major virulence factor for C. jejuni, little is known about the EV-associated form of this toxin. To address this point, C. jejuni mutants lacking each of the three CDT subunits (A, B, and C) were generated. C. jejuni cdtA, cdtB, and cdtC bacteria released EVs in similar numbers and sizes to wild-type bacteria, ranging from 5 to 530 nm (mean ± SEM = 118 ±6.9 nm). As the CdtAC subunits mediate toxin binding to host cells, we performed “surface shearing” experiments, in which EVs were treated with proteinase K and incubated with host cells. These experiments indicated that CDT subunits are internal to EVs and that surface proteins are probably not involved in EV-host cell interactions. Furthermore, glycan array studies demonstrated that EVs bind complex host cell glycans and share receptor binding specificities with C. jejuni bacteria for fucosyl GM1 ganglioside, P1 blood group antigen, sialyl, and sulfated Lewisx. Finally, we show that EVs from C. jejuni WT but not mutant bacteria induce cell cycle arrest in epithelial cells. In conclusion, we propose that EVs are an important mechanism for CDT release by C. jejuni and are likely to play a significant role in toxin delivery to host cells.IMPORTANCECampylobacter jejuni is the leading cause of foodborne gastroenteritis in humans worldwide and a significant cause of childhood mortality due to diarrheal disease in developing countries. A major factor by which C. jejuni causes disease is a toxin, called cytolethal distending toxin (CDT). The biology of this toxin, however, is poorly understood. In this study, we report that C. jejuni CDT is protected within membrane blebs, known as extracellular vesicles (EVs), released by the bacterium. We showed that proteins on the surfaces of EVs are not required for EV uptake by host cells. Furthermore, we identified several sugar receptors that may be required for EV binding to host cells. By studying the EV-associated form of C. jejuni CDT, we will gain a greater understanding of how C. jejuni intoxicates host cells and how EV-associated CDT may be used in various therapeutic applications, including as anti-tumor therapies.

The global public health nonprofit organization PATH hosted the third Vaccines Against Shigella and Enterotoxigenic Escherichia coli (VASE) Conference in Washington, DC, from November 29 to December 1, 2022. This international gathering focused on cutting-edge research related to the development of vaccines against neglected diarrheal pathogens including Shigella, enterotoxigenic Escherichia coli (ETEC), Campylobacter, and non-typhoidal Salmonella. In addition to the conference's plenary content, the agenda featured ten breakout workshops on topics of importance to the enteric vaccine field. This unique aspect of VASE Conferences allows focused groups of attendees to engage in in-depth discussions on subjects of interest to the enteric vaccine development community. In 2022, the workshops covered a range of topics. Two focused on the public health value of enteric vaccines, with one examining how to translate evidence into policy and the other on the value proposition of potential combination vaccines against bacterial enteric pathogens. Two more workshops explored new tools for the development and evaluation of vaccines, with the first on integrating antigen/antibody technologies for mucosal vaccine and immunoprophylactic development, and the second on adjuvants specifically for Shigella vaccines for children in low- and middle-income countries. Another pair of workshops covered the status of vaccines against two emerging enteric pathogens, Campylobacter and invasive non-typhoidal Salmonella. The remaining four workshops examined the assessment of vaccine impact on acute and long-term morbidity. These included discussions on the nature and severity of intestinal inflammation; cellular immunity and immunological memory in ETEC and Shigella infections; clinical and microbiologic endpoints for Shigella vaccine efficacy studies in children; and intricacies of protective immunity to enteric pathogens. This article provides a brief summary of the presentations and discussions at each workshop in order to share these sessions with the broader enteric vaccine field.

A key aspect to vaccine efficacy is formulation stability. Biochemical evaluations provide information on optimal compositions or thermal stability but are routinely validated by ex vivo analysis and not efficacy in animal models. Here we assessed formulations identified to improve or reduce stability of the mucosal adjuvant dmLT being investigated in polio and enterotoxigenic E. coli (ETEC) clinical vaccines. We observed biochemical changes to dmLT protein with formulation or thermal stress, including aggregation or subunit dissociation or alternatively resistance against these changes with specific buffer compositions. However, upon injection or mucosal vaccination with ETEC fimbriae adhesin proteins or inactivated polio virus, experimental findings indicated immunization route and co-administered antigen impacted vaccine immunogenicity more so than dmLT formulation stability (or instability). These results indicate the importance of both biochemical and vaccine-derived immunity assessment in formulation optimization. In addition, these studies have implications for use of dmLT in clinical settings and for delivery in resource poor settings.

We set out to develop and characterize a small animal model of Campylobacter jejuni(CJ) infection that recapitulates human campylobacteriosis. Adult C57BL/6J mice are rendered susceptible to colonization and disease by pre-treatment with a zinc deficient diet and a broad-spectrum antibiotic cocktail. We have established this model with four strains with diverse capsular serotypes and flagellar groups, two key virulence factors for CJ pathogenesis. We measured colonization, weight loss, diarrhea, fecal inflammatory markers, and cytokine production by mesenteric lymphocytes and splenocytes. Diarrhea containing visible mucous and/or blood and degree of weight loss vary in severity depending on the strain and dose. Interestingly, we identified an inverse relationship between inoculum dose and levels of fecal inflammatory markers, with lower inoculum doses inducing significantly higher inflammation. We also observed production of IFNγ and IL-17 at day 9 post infection and despite no decrease in CJ colonization, IFNγ and IL-17 levels decreased by day 21 with a subsequent increase in IL-10 production. We also observed higher levels of IFNγ and IL-17 in mice challenged with strain CG8486 relative to those challenged with strain 81–176 pointing to potential strain differences. These differences observed were more striking in mesenteric lymphocytes versus splenocytes, indicating that local cellular responses differed from systemic responses. We have developed a model of inflammatory diarrhea in adult mice that exhibits hallmarks of CJ infection and further identified significant shifts in cytokine expression associated with the duration of infection, bacterial strain utilized, and therapeutic treatment. Research reported in this presentation is supported by Navy work unit number: 6000.RAD1.DA3.A0308 and CARB-X. CARB-X’s funding for this project is sponsored by the Cooperative Agreement Number IDSEP160030 from ASPR/BARDA and by awards from Wellcome Trust, the UK Global Antimicrobial Resistance Innovation Fund (GAMRIF) funded by the UK Government Department of Health and Social Care (DHSC) and the Bill & Melinda Gates Foundation. The content is solely the responsibility of the authors and does not necessarily represent the official views of CARB-X or any of its funders. Disclaimers: The views expressed in this work are those of the authors and do not necessarily reflect the official policy or position of the Department of the Navy, Department of Defense, nor the U.S. Government. F. Poly is an employee of the U.S. Government. This work was prepared as part of official duties. Title 17 U.S.C. §105 provides that ‘Copyright protection under this title is not available for any work of the United States Government.’ Title 17 U.S.C. §101 defines a U.S. Government work as a work prepared by a military service member or employee of the U.S. Government as part of that person’s official duties.The animal study protocol was reviewed and approved by the Naval Medical Research Center IACUC in compliance with all applicable Federal regulations governing the protection of animals in research.

Campylobacter jejuni is a major cause of bacterial diarrhea worldwide and associated with numerous sequela, including Guillain-Barré Syndrome, inflammatory bowel disease, reactive arthritis, and irritable bowel syndrome. C. jejuni is unusual for an intestinal pathogen in its ability to coat its surface with a polysaccharide capsule (CPS). The genes responsible for the biosynthesis of the phase variable CPS is located in the hypervariable region of C. jejuni genome which has been used to develop multiplex PCR to classify CPS types based on the Penner serotypes. However, there still are non-typable CPS C. jejuni by the current multiplex PCR scheme. The application of the next generation sequencing and whole genome analysis software were used for the identification of novel capsule biosynthesis of C. jejuni isolates. Unique PCR primers were designed to identify these new capsule biosynthesis loci. The designed primers sets were combined in a new multiplex mix called epsilon. The unique sequences provide an additional information of the biosynthesis loci responsible for some of the common CPS sugars/residues such as heptose, deoxtyheptose and MeOPN among C. jejuni in this new group of CPS multiplex assay. This new primer complements the current C. jejuni multiplex capsule typing system and will help in identifying previously untypeable capsule locus of C. jejuni isolates.

Infectious diarrhea is a World Health Organization public health priority area due to the lack of effective vaccines and an accelerating global antimicrobial resistance crisis. New strategies are urgently needed such as immunoprophylactic for prevention of diarrheal diseases. Hyperimmune bovine colostrum (HBC) is an established and effective prophylactic for infectious diarrhea. The commercial HBC product, Travelan® (Immuron Ltd, Australia) targets multiple strains of enterotoxigenic Escherichia coli (ETEC) is highly effective in preventing diarrhea in human clinical studies. Although Travelan® targets ETEC, preliminary studies suggested cross-reactivity with other Gram-negative enteric pathogens including Shigella and Salmonella species. For this study we selected an invasive diarrheal/dysentery-causing enteric pathogen, Shigella, to evaluate the effectiveness of Travelan®, both in vitro and in vivo. Here we demonstrate broad cross-reactivity of Travelan® with all four Shigella spp. (S. flexneri, S. sonnei, S. dysenteriae and S. boydii) and important virulence factor Shigella antigens. Naïve juvenile rhesus macaques (NJRM) were randomized, 8 dosed with Travelan® and 4 with a placebo intragastrically twice daily over 6 days. All NJRM were challenged with S. flexneri 2a strain 2457T on the 4th day of treatment and monitored for diarrheal symptoms. All placebo-treated NJRM displayed acute dysentery symptoms within 24-36 hours of challenge. Two Travelan®-treated NJRM displayed dysentery symptoms and six animals remained healthy and symptom-free post challenge; resulting in 75% efficacy of prevention of shigellosis (p = 0.014). These results strongly indicate that Travelan® is functionally cross-reactive and an effective prophylactic for shigellosis. This has positive implications for the prophylactic use of Travelan® for protection against both ETEC and Shigella spp. diarrheal infections. Future refinement and expansion of pathogens recognized by HBC including Travelan® could revolutionize current management of gastrointestinal infections and outbreaks in travelers' including military, peacekeepers, humanitarian workers and in populations living in endemic regions of the world.

The supercoiling of bacterial and archaeal flagellar filaments is required for motility. Archaeal flagellar filaments have no homology to their bacterial counterparts and are instead homologs of bacterial type IV pili. How these prokaryotic flagellar filaments, each composed of thousands of copies of identical subunits, can form stable supercoils under torsional stress is a fascinating puzzle for which structural insights have been elusive. Advances in cryoelectron microscopy (cryo-EM) make it now possible to directly visualize the basis for supercoiling, and here, we show the atomic structures of supercoiled bacterial and archaeal flagellar filaments. For the bacterial flagellar filament, we identify 11 distinct protofilament conformations with three broad classes of inter-protomer interface. For the archaeal flagellar filament, 10 protofilaments form a supercoil geometry supported by 10 distinct conformations, with one inter-protomer discontinuity creating a seam inside of the curve. Our results suggest that convergent evolution has yielded stable superhelical geometries that enable microbial locomotion.

Campylobacter jejuni infection is a leading cause of foodborne disease, common to children, adult travelers, and military populations in low- to middle-income countries. In the absence of a licensed vaccine, efforts to evaluate prophylactic agents are underway. The prophylactic efficacy of a twice-daily, 550 mg dose of the antibiotic rifaximin demonstrated no efficacy against campylobacteriosis in a controlled human infection model (CHIM); however, samples from the CHIM study were utilized to assess how the human gut microbiome responds to C. jejuni infection, and if a ‘protective’ microbiota exists in study participants not developing campylobacteriosis. Statistically significant, but minor, differences in study participant beta diversity were identified during the challenge period (p = 0.002, R 2 = 0.042), but no significant differences were otherwise observed. Pre-challenge alpha diversity was elevated in study participants who did not develop campylobacteriosis compared to those who did (p < 0.001), but alpha diversity declined in all study participants from the pre-challenge period to post-discharge. Our work provides insight into gut microbiome shifts observed during a C. jejuni CHIM and following antibiotic treatment. This study utilized a high dose of 1.7 x 10 5 colony-forming units of C. jejuni ; future work could include CHIM studies performed with inocula more closely mimicking natural exposure as well as field studies involving naturally-occurring enteric infections.

Thousands of angstroms long, the flagellar filament serves as the propeller of the bacterial flagellum. In the two-state switching model, protofilaments of the flagella switch between one of two states which allows for changing between different flagellar waveforms, associated with different modes of motility. Many pathogenic bacteria have flagellar-based motility and thus produce thousands of copies of the flagellar filament subunit, the flagellin. A small region of about 10 amino acids in domain D1 in most bacterial flagellins such as those from Salmonella typhimurium and Bacillus subtilis are recognized by toll-like receptor 5 (TLR5) which then activates innate immune response. ε Proteobacteria such as Campylobacter jejuni and H. pylori escape detection by TLR5 due to sequence changes in this 10 AA region of their flagellin sequence. When mutated onto the S. typhimurium flagellin the H. pylori sequence impairs flagellar filament formation, thus motility. The similar C. jejuni sequence is thought to have the same destabilizing interactions. This leads to the question "How do ε Proteobacteria compensate for these destabilizing mutations in their D1 domains?". With a 3.5 Å resolution cryoEM structure of straight C. jejuni G508A flagellar filaments we are able to show a unique and extensive network of interactions between the outer domains of adjacent flagellins which compensates for weakened interactions in D1. These interactions are further stabilized by glycosylation of specific residues with pseudaminic acid. Lastly, recent high-resolution structures of the wild type flagellar filament and flagellar hook have called into question the validity of the two-state switching model for flagella. Using single particle and helical cryoEM reconstruction techniques, as well as cryo-electron tomography and fluorescence light microscopy we investigate the structure of wildtype supercoiled C. jejuni flagellar filaments.

The Campylobacter jejuni capsule type HS1 complex is one of the most common serotypes identified worldwide, and consists of strains typing as HS1, HS1/44, HS44 and HS1/8. The capsule structure of the HS1 type strain was shown previously to be composed of teichoic-acid like glycerol-galactosyl phosphate repeats [4-)-α-D-Galp-(1–2)-Gro-(1-P-] with non-stoichiometric fructose branches at the C2 and C3 of Gal and non-stoichiometric methyl phosphoramidate (MeOPN) modifications on the C3 of the fructose. Here, we demonstrate that the capsule of an HS1/44 strain is identical to that of the type strain of HS1, and the capsule of HS1/8 is also identical to HS1, except for an additional site of MeOPN modification at C6 of Gal. The DNA sequence of the capsule locus of an HS44 strain included an insertion of 10 genes, and the strain expressed two capsules, one identical to the HS1 type strain, but with no fructose branches, and another composed of heptoses and MeOPN. We also characterize a HS1 capsule biosynthesis gene, HS1.08, as a fructose transferase responsible for the attachment of the β-D-fructofuranoses residues at C2 and C3 of the Gal unit. In summary, the common component of all members of the HS1 complex is the teichoic-acid like backbone that is likely responsible for the observed sero-cross reactivity.

Introduction While Campylobacter jejuni is a leading foodborne bacterial pathogen worldwide, it poses a particular risk to susceptible populations in low- and middle-income countries (LMICs). A capsule-conjugate vaccine approach has been proposed as a potential solution, but little information exists on circulating C. jejuni capsule types in LMICs. The capsule is the major serodeterminant of the Penner typing scheme, which is based on serum recognition of Campylobacter heat-stable antigens. We conducted a systematic review and meta-analysis to estimate the distribution of Penner serotypes associated with C. jejuni enteritis in LMICs. Vaccine coverage assessments for hypothetical regional and global C. jejuni vaccines were also estimated. Methods A systematic review of the literature published from 1980 to 2019 was performed using PubMed, Scopus, and Web of Science databases. Articles were assessed for eligibility and data were abstracted. Pooled C. jejuni serotype prevalence in LMICs was estimated by region and globally using random-effects models. Results A total of 36 studies were included, capturing 4,434 isolates from LMICs. Fifteen serotypes were present in a sufficient number of studies to be included in analyses. Among these, HS4c was the most common serotype globally (12.6%), though leading capsule types varied among regions. HS2, HS3c, HS4c, HS5/31, HS8/17, and HS10 were all among the 10 most common region-specific serotypes. Conclusions The results of this review suggest that an octavalent vaccine could provide up to 66.9% coverage of typable strains worldwide, and 56.8-69.0% regionally. This review also highlights the paucity of available data on capsules in LMICs; more testing is needed to inform vaccine development efforts.

Significance Flagella are used by many pathogenic bacteria not only for motility but also for adhesion to host cells and to other bacteria in biofilm formation. Since thousands of copies of flagellin, the protein that forms the flagellar filament, are exposed on the surface of bacteria, they are a target for immune surveillance by hosts. Some bacteria important to human health, such as Campylobacter jejuni and Helicobacter pylori , have managed to evade the innate immune recognition of their flagellin. We show, with an atomic structure of the Campylobacter jejuni flagellar filament, how mutations that destabilize the filament in one region recognized by vertebrates have been compensated for by new contacts not seen in other flagellar filaments that would stabilize these filaments.

Campylobacter jejuni is a major cause of infectious diarrhea worldwide. Increasing incidence of C. jejuni is attributed to new non-culture based detection methods and antibiotic resistance is unfortunately on the rise, necessitating development of interventions. Therapeutics development like vaccines have been hampered by lack of a small animal model that recapitulates campylobacteriosis symptoms. To better facilitate vaccine efficacy testing, we adapted a recently-published mouse C. jejuni infection model to adult mice fed a zinc-deficient diet and pre-treated with antibiotics prior to oral infection with C. jejuni strain 81–176. Non-vaccinated infected mice develop diarrhea, lose weight and show increased expression of fecal inflammatory markers indicating development of campylobacteriosis. We tested whether an 81–176 C. jejuni capsule conjugate vaccine delivered with a potent liposome adjuvant containing monophosphoryl lipid A and QS-21 known as ALFQ could protect mice against 81–176. Vaccinated mice developed high levels of anti-CPS IgG1 and IgG2b titers and serum bactericidal responses against 81–176. Vaccinated infected mice were protected against development of diarrhea, did not lose weight, and had significantly lower levels of fecal inflammatory marker expression. Importantly, vaccinated infected animals were protected against C. jejuni colonization indicating that parenteral vaccination with a conjugate vaccine plus the ALFQ adjuvant may provide protection against both C. jejuni disease and colonization. These promising results support further development of a multivalent C. jejuni conjugate vaccine platform delivered with potent adjuvant systems for use in human clinical studies.

We have examined the draft genomes of 189 Campylobacter species isolates from the Global Enteric Multicenter Study, in which Campylobacter species were identified as significant pathogens.

Abstract Background Campylobacter jejuni (C. jejuni) is one of the most common bacteria responsible for human gastroenteritis worldwide. The mode of human transmission is foodborne infections due to consumption of contaminated food, especially poultry. Type 6 secretion systems (T6SS) were described recently as Campylobacter virulence mechanisms. Furthermore, infection sequelae associated with neurological disorders like Guillain–Barré (GBS) and Miller Fisher (MF) syndromes can become serious health problems in some patients after Campylobacter gastroenteritis. Our objective was to determine the distribution of these virulence genes among C. jejuni isolated from stool of human diarrhea. Methods A total of 524 C. jejuni strains from travelers and pediatric cases of acute diarrhea in Thailand were selected for this study. All isolates belonged to one of 20 known capsule types and all were assayed by PCR for T6SS, a hemolysin co-regulated protein (hcp) gene, and GBS-associated genes (cgtA, cgtB, cstII HS19 and cstII HS2 ) which are involved in sialic acid production in the lipooligosaccharide (LOS) cores of C. jejuni. The distribution of these genes are summarized and discussed. Results Of all isolates with these 20 capsule types identified, 328 (62.6%) were positive for hcp, ranging from 29.2 to 100% among 10 capsule types. The GBS-associated LOS genes were detected among 14 capsule type isolates with 24.4% and 23.3% of C. jejuni isolates possessed either cstII HS19 or all three genes (cgtA, cgtB and cstII HS19 ), which were classified as LOS classes A and B whereas 9.2% of C. jejuni isolates possessing cstII HS2 were classified as LOS class C. The C. jejuni isolates of LOS A, B, and C together accounted for 56.9% of the isolates among 14 different capsule types while 31.1% of all C. jejuni isolates did not possess any GBS-associated genes. No significant difference was detected from C. jejuni isolates possessing GBS-associated LOS genes among travelers and children, but changes between those with hcp were significant (p < 0.05). Conclusions Our results suggested a high diversity of hcp and GBS-associated LOS genes among capsule types of C. jejuni isolated from Thailand.

Abstract Campylobacter jejuni is a leading cause of bacterial diarrhoea worldwide. The objective of this study was to examine the association between C. jejuni capsule types and clinical signs and symptoms of diarrhoeal disease in a well-defined birth cohort in Peru. Children were enrolled in the study at birth and followed until 2 years of age as part of the Malnutrition and Enteric Infections birth cohort. Associations between capsule type and clinical outcomes were assessed using the Pearson's χ2 and the Kruskal–Wallis test statistics. A total of 318 C. jejuni samples (30% from symptomatic cases) were included in this analysis. There were 22 different C. jejuni capsule types identified with five accounting for 49.1% of all isolates. The most common capsule types among the total number of isolates were HS4 complex (n = 52, 14.8%), HS5/31 complex (n = 42, 11.9%), HS15 (n = 29, 8.2%), HS2 (n = 26, 7.4%) and HS10 (n = 24, 6.8%). These five capsule types accounted for the majority of C. jejuni infections; however, there was no significant difference in prevalence between symptomatic and asymptomatic infection (all p > 0.05). The majority of isolates (n = 291, 82.7%) were predicted to express a heptose-containing capsule. The predicted presence of methyl phosphoramidate, heptose or deoxyheptose on the capsule was common.