Lipooligosaccharide Locus Research Articles

Zoonotic Transmission of Campylobacter jejuni to Caretakers From Sick Pen Calves Carrying a Mixed Population of Strains With and Without Guillain Barré Syndrome-Associated Lipooligosaccharide Loci.

Campylobacter jejuni causes foodborne gastroenteritis and may trigger acute autoimmune sequelae including Guillain Barré Syndrome. Onset of neuromuscular paralysis is associated with exposure to C. jejuni lipooligosaccharide (LOS) classes A, B, C, D, and E that mimic and evoke antibodies against gangliosides on myelin and axons of peripheral nerves. Family members managing a Michigan dairy operation reported recurring C. jejuni gastroenteritis. Because dairy cattle are known to shed C. jejuni, we hypothesized that calves in the sick pen were the source of human infections. Fecal samples obtained from twenty-five calves, one dog, and one asymptomatic family member were cultured for Campylobacter. C. jejuni isolates were obtained from thirteen calves and the family member: C. coli from two calves, and C. hyointestinalis from two calves. Some calves had diarrhea; most were clinically normal. Typing of lipooligosaccharide biosynthetic loci showed that eight calf C. jejuni isolates fell into classes A, B, and C. Two calf isolates and the human isolate possessed LOS class E, associated mainly with enteric disease and rarely with Guillain Barré Syndrome. Multi-locus sequence typing, porA and flaA typing, and whole genome comparisons of the thirteen C. jejuni isolates indicated that the three LOS class E strains that included the human isolate were closely related, indicating zoonotic transmission. Whole-genome comparisons revealed that isolates differed in virulence gene content, particularly in loci encoding biosynthesis of surface structures. Family members experienced diarrheal illness repeatedly over 2 years, yet none experienced GBS despite exposure to calves carrying invasive C. jejuni with LOS known to elicit antiganglioside autoantibodies.

Molecular and in silico typing of the lipooligosaccharide biosynthesis gene cluster in Campylobacter jejuni and Campylobacter coli.

The extensive genetic variation in the lipooligosaccharide (LOS) core biosynthesis gene cluster has led to the development of a classification system; with 8 classes (I-VIII) for Campylobacter coli (C. coli) LOS region and with 23 classes (A-W) or four groups (1–4) for Campylobacter jejuni (C. jejuni) LOS region. PCR based LOS locus type identification for C. jejuni clinical isolates from a UK hospital as well as in silico LOS locus analysis for C. jejuni and C. coli genome sequences from GenBank was carried out to determine the frequencies of various LOS genotypes in C. jejuni and C. coli. Analysis of LOS gene content in 60 clinical C. jejuni isolates and 703 C. jejuni genome sequences revealed that class B (Group 1) was the most abundant LOS class in C. jejuni. The hierarchy of C. jejuni LOS group prevalence (group 1 > group 2 > group 3 > group 4) as well as the hierarchy of the frequency of C. jejuni LOS classes present within the group 1 (B > C > A > R > M > V), group 2 (H/P > O > E > W), group 3 (F > K > S) and group 4 (G > L) was identified. In silico analysis of LOS gene content in 564 C. coli genome sequences showed class III as the most abundant LOS locus type in C. coli. In silico analysis of LOS gene content also identified three novel LOS types of C. jejuni and previously unknown LOS biosynthesis genes in C. coli LOS locus types I, II, III, V and VIII. This study provides C. jejuni and C. coli LOS loci class frequencies in a smaller collection of C. jejuni clinical isolates as well as within the larger, worldwide database of C. jejuni and C. coli.

Antimicrobial resistance and interspecies gene transfer in Campylobacter coli and Campylobacter jejuni isolated from food animals, poultry processing, and retail meat in North Carolina, 2018-2019.

The Center for Disease Control and Prevention identifies antimicrobial resistant (AMR) Campylobacter as a serious threat to U.S. public health due to high community burden, increased transmissibility, and limited treatability. The National Antimicrobial Resistance Monitoring System (NARMS) plays an important role in surveillance of AMR bacterial pathogens in humans, food animals and retail meats. This study investigated C. coli and C. jejuni from live food animals, poultry carcasses at production, and retail meat in North Carolina between January 2018-December 2019. Whole genome sequencing and bioinformatics were used for phenotypic and genotypic characterization to compare AMR profiles, virulence factors associated with Guillain-Barré Syndrome (GBS) (neuABC and cst-II or cst-III), and phylogenic linkage between 541 Campylobacter isolates (C. coli n = 343, C. jejuni n = 198). Overall, 90.4% (489/541) Campylobacter isolates tested positive for AMR genes, while 43% (233/541) carried resistance genes for three or more antibiotic classes and were classified molecularly multidrug resistant. AMR gene frequencies were highest against tetracyclines (64.3%), beta-lactams (63.6%), aminoglycosides (38.6%), macrolides (34.8%), quinolones (24.4%), lincosamides (13.5%), and streptothricins (5%). A total of 57.6% (114/198) C. jejuni carried GBS virulence factors, while three C. coli carried the C. jejuni-like lipooligosaccharide locus, neuABC and cst-II. Further evidence of C. coli and C. jejuni interspecies genomic exchange was observed in identical multilocus sequence typing, shared sequence type (ST) 7818 clonal complex 828, and identical species-indicator genes mapA, ceuE, and hipO. There was a significant increase in novel STs from 2018 to 2019 (2 in 2018 and 21 in 2019, p<0.002), illustrating variable Campylobacter genomes within food animal production. Introgression between C. coli and C. jejuni may aid pathogen adaption, lead to higher AMR and increase Campylobacter persistence in food processing. Future studies should further characterize interspecies gene transfer and evolutionary trends in food animal production to track evolving risks to public health.

Rapid Replacement of Acinetobacter baumannii Strains Accompanied by Changes in Lipooligosaccharide Loci and Resistance Gene Repertoire.

The population structure of health care-associated pathogens reflects patterns of diversification, selection, and dispersal over time. Empirical data detailing the long-term population dynamics of nosocomial pathogens provide information about how pathogens adapt in the face of exposure to diverse antimicrobial agents and other host and environmental pressures and can inform infection control priorities. Extensive sequencing of clinical isolates from one hospital spanning a decade and a second hospital in the Cleveland, OH, metropolitan area over a 3-year time period provided high-resolution genomic analysis of the Acinetobacter baumannii metapopulation. Genomic analysis demonstrated an almost complete replacement of the predominant strain groups with a new, genetically distinct strain group during the study period. The new group, termed clade F, differs from other global clone 2 (GC2) strains of A. baumannii in several ways, including its antibiotic resistance and lipooligosaccharide biosynthesis genes. Clade F strains are part of a large phylogenetic group with broad geographic representation. Phylogenetic analysis of single-nucleotide variants in core genome regions showed that although the Cleveland strains are phylogenetically distinct from those isolated from other locations, extensive intermixing of strains from the two hospital systems was apparent, suggesting either substantial exchange of strains or a shared, but geographically restricted, external pool from which infectious isolates were drawn. These findings document the rapid evolution of A. baumannii strains in two hospitals, with replacement of the predominant clade by a new clade with altered lipooligosaccharide loci and resistance gene repertoires.IMPORTANCE Multidrug-resistant (MDR) A. baumannii is a difficult-to-treat health care-associated pathogen. Knowing the resistance genes present in isolates causing infection aids in empirical treatment selection. Furthermore, knowledge of the genetic background can assist in tracking patterns of transmission to limit the spread of infections in hospitals. The appearance of a new genetic background in A. baumannii strains with a different set of resistance genes and cell surface structures suggests that strong selective pressures exist, even in highly MDR pathogens. Because the new strains have levels of antimicrobial resistance similar to those of the strains that were displaced, we hypothesize that other features, including host colonization and infection, may confer additional selective advantages and contribute to their increased prevalence.

Surface-Related Features and Virulence Among Acinetobacter baumannii Clinical Isolates Belonging to International Clones I and II.

Acinetobacter baumannii currently represents one of the most important nosocomial infection agent due to its multidrug-resistance and a propensity for the epidemic spread. The A. baumannii strains belonging to the international clonal lineages I (IC I) and II (IC II) are associated with the hospital outbreaks and a high virulence. However, the intra and inter lineage-specific features of strains belonging to these most worldwide spread A. baumannii clones are not thoroughly explored. In this study we have investigated a set of cell surface-related features of A. baumannii IC I (n = 20) and IC II (n = 16) lineage strains, representing 30 distinct pulsed-field gel electrophoresis types in the collection of clinical isolates obtained in Lithuanian tertiary care hospitals. We show that A. baumannii IC II strains are non-motile, do not form pellicle and display distinct capsular polysaccharide profile compared with the IC I strains. Moreover, in contrast to the overall highly hydrophobic IC I strains, IC II strains showed a greater variation in cell surface hydrophobicity. Within the IC II lineage, hydrophilic strains demonstrated reduced ability to form biofilm and adhere to the abiotic surfaces, also possessed twofold thicker cell wall and exhibited higher resistance to desiccation. Furthermore, these strains showed increased adherence to the lung epithelial cells and were more virulent in nematode and mouse infection model compared with the hydrophobic IC II strains. According to the polymerase chain reaction-based locus-typing, the reduction in hydrophobicity of IC II strains was not capsule or lipooligosaccharide locus type-dependent. Hence, this study shows that the most widespread A. baumannii clonal lineages I and II markedly differ in the series of cell surface-related phenotypes including the considerable phenotypic diversification of IC II strains at the intra-lineage level. These findings suggest that the genotypically related A. baumannii strains might evolve the features which could provide an advantage at the specific conditions outside or within the host.

Orthogonal typing methods identify genetic diversity among Belgian Campylobacter jejuni strains isolated over a decade from poultry and cases of sporadic human illness

Campylobacter jejuni is a zoonotic pathogen commonly associated with human gastroenteritis. Retail poultry meat is a major food-related transmission source of C. jejuni to humans. The present study investigated the genetic diversity, clonal relationship, and strain risk-analysis of 403 representative C. jejuni isolates from chicken broilers (n = 204) and sporadic cases of human diarrhea (n = 199) over a decade (2006–2015) in Belgium, using multilocus sequence typing (MLST), PCR binary typing (P-BIT), and identification of lipooligosaccharide (LOS) biosynthesis locus classes. A total of 123 distinct sequence types (STs), clustered in 28 clonal complexes (CCs) were assigned, including ten novel sequence types that were not previously documented in the international database. Sequence types ST-48, ST-21, ST-50, ST-45, ST-464, ST-2274, ST-572, ST-19, ST-257 and ST-42 were the most prevalent. Clonal complex 21 was the main clonal complex in isolates from humans and chickens. Among observed STs, a total of 35 STs that represent 72.2% (291/403) of the isolates were identified in both chicken and human isolates confirming considerable epidemiological relatedness; these 35 STs also clustered together in the most prevalent CCs. A majority of the isolates harbored sialylated LOS loci associated with potential neuropathic outcomes in humans. Although the concordance between MLST and P-BIT, determined by the adjusted Rand and Wallace coefficients, showed low congruence between both typing methods. The discriminatory power of P-BIT and MLST was similar, with Simpson's diversity indexes of 0.978 and 0.975, respectively. Furthermore, P-BIT could provide additional epidemiological information that would provide further insights regarding the potential association to human health from each strain. In addition, certain clones could be linked to specific clinical symptoms. Indeed, LOS class E was associated with less severe infections. Moreover, ST-572 was significantly associated with clinical infections occurring after travelling abroad. Ultimately, the data generated from this study will help to better understand the molecular epidemiology of C. jejuni infection.

Capsular genotype and lipooligosaccharide locus class distribution in Campylobacter jejuni from young children with diarrhea and asymptomatic carriers in Bangladesh.

Campylobacter jejuni-related diarrheal diseases is one of the major health issues among young children (0-59months old) in low-income countries. Monitoring of the capsular (capsule polysaccharide, CPS) types of virulent C. jejuni strains in regions where the disease is endemic is of great importance for the development of a customized capsule-based multivalent vaccine. Therefore, we aimed to determine the prevalence of CPS genotypes among C. jejuni strains isolated from young children with enteritis (n = 152) and asymptomatic carriers matched by age, sex, and residence defined as the control group (n = 215) in Bangladesh. CPS genotyping was performed using a newly established multiplex polymerase chain reaction (PCR) method and lipooligosaccharide (LOS) locus classes (A-E) were characterized using PCR as well. We identified 24 different CPS genotypes among the 367 isolates. Four prevalent capsular types, HS5/31 complex (n = 27, 18%), HS3 (n = 26, 17%), HS4A (n = 10, 7%), and HS8/17 (n = 10, 7%) covered almost 50% of the strains from enteritis patients and 43% of the isolates from controls. In combination, the CPS genotype and LOS class was not discriminative between cases and controls. Dominant capsular types previously identified in C. jejuni strains isolated from patients with Guillain-Barré syndrome in Bangladesh were rarely detected in strains isolated from the young children. A similar distribution was evident among enteritis- and control-related strains when comparison was done between CPS types and LOS classes. This is the first systematic study presenting the distribution of CPS genotypes of C. jejuni strains isolated in Bangladesh from children with diarrhea and controls, with capsular genotypes HS5/31 complex, HS3, HS4A, and HS8/17 being prevalent in both. In conclusion, systematic studies are required to develop a multivalent capsule-based vaccine for children in low-income countries.

Lipooligosaccharide locus classes and putative virulence genes among chicken and human Campylobacter jejuni isolates.

Background Campylobacter cause morbidity and considerable economic loss due to hospitalization and post infectious sequelae such as reactive arthritis, Guillain Barré- and Miller Fischer syndromes. Such sequelae have been linked to C. jejuni harboring sialic acid structures in their lipooligosaccharide (LOS) layer of the cell wall. Poultry is an important source of human Campylobacter infections but little is known about the prevalence of sialylated C. jejuni isolates and the extent of transmission of such isolates to humans.ResultsGenotypes of C. jejuni isolates from enteritis patients were compared with those of broiler chicken with pulsed-field gel electrophoresis (PFGE), to study the patterns of LOS biosynthesis genes and other virulence associated genes and to what extent these occur among Campylobacter genotypes found both in humans and chickens. Chicken and human isolates generally had similar distributions of the putative virulence genes and LOS locus classes studied. However, there were significant differences regarding LOS locus class of PFGE types that were overlapping between chicken and human isolates and those that were distinct to each source.ConclusionsThe study highlights the prevalence of virulence associated genes among Campylobacter isolates from humans and chickens and suggests possible patterns of transmission between the two species.

Prevalence and characterization of Campylobacter jejuni from chicken meat sold in French retail outlets

Campylobacter was detected in 76% of broiler meat products collected in retail outlets during a monitoring plan carried out in France throughout 2009. Campylobacter jejuni was the most prevalent species (64.7% of products being contaminated). The 175 C. jejuni isolates collected were characterized. MLST typing results confirmed substantial genetic diversity as the 175 C. jejuni isolates generated 76 sequence types (STs). The ST-21, ST-45 and ST-464 complexes predominated accounting for 43% of all isolates.A class-specific PCR to screen the sialylated lipooligosaccharide (LOS) locus classes A, B and C showed that 50.3% of the C. jejuni isolates harbored sialylated LOS.The antimicrobial resistance profiles established using a subset of 97 isolates showed that resistance to tetracycline was the most common (53.6%), followed with ciprofloxacin and nalidixic acid (32.9%, and 32.0% respectively). All the tested isolates were susceptible to erythromycin, chloramphenicol and gentamicin.Clear associations were demonstrated between certain clonal complexes and LOS locus classes and between certain clonal complexes and antimicrobial resistance.This work paints a representative picture of C. jejuni isolated from poultry products circulating in France, providing data on STs, LOS locus classes and antibiotic resistance profiles in isolates recovered from products directly available to the consumer.

Lipooligosaccharide locus class of Campylobacter jejuni: sialylation is not needed for invasive infection

Campylobacter jejuni is a highly diverse enteropathogen that is commonly detected worldwide. It can sometimes cause bacteraemia, but the bacterial characteristics facilitating bloodstream infection are not known. A total of 73 C. jejuni isolates, consecutively collected from blood-borne infections during a 10-year period all over Finland and for which detailed clinical information of the patients were available, were included. We screened the isolates by PCR for the lipooligosaccharide (LOS) locus class and for the presence of the putative virulence genes ceuE, ciaB, fucP, and virB11. The isolates were also tested for γ-glutamyl transpeptidase production. The results were analysed with respect to the clinical characteristics of the patients, and the multilocus sequence types (MLSTs) and serum resistance of the isolates. LOS locus classes A, B, and C, which carry genes for sialylation of LOS, were detected in only 23% of the isolates. These isolates were not more resistant to human serum than those with the genes of non-sialylated LOS locus classes, but were significantly more prevalent among patients with underlying diseases (p 0.02). The fucose permease gene fucP was quite uncommon, but was associated with the isolates with the potential to sialylate LOS (p <0.0001). LOS locus classes and some of the putative virulence factors were associated with MLST clonal complexes. Although some of the bacterial characteristics studied here have been suggested to be important for the invasiveness of C. jejuni, they did not explain why the clinical isolates in the present study were able to cause bacteraemia.

Comparative genomics of unintrogressed Campylobacter coli clades 2 and 3

BackgroundCampylobacter jejuni and C. coli share a multitude of risk factors associated with human gastrointestinal disease, yet their phylogeny differs significantly. C. jejuni is scattered into several lineages, with no apparent linkage, whereas C. coli clusters into three distinct phylogenetic groups (clades) of which clade 1 has shown extensive genome-wide introgression with C. jejuni, yet the other two clades (2 and 3) have less than 2% of C. jejuni ancestry. We characterized a C. coli strain (76339) with four novel multilocus sequence type alleles (ST-5088) and having the capability to express gamma-glutamyltranspeptidase (GGT); an accessory feature in C. jejuni. Our aim was to further characterize unintrogressed C. coli clades 2 and 3, using comparative genomics and with additional genome sequences available, to investigate the impact of horizontal gene transfer in shaping the accessory and core gene pools in unintrogressed C. coli.ResultsHere, we present the first fully closed C. coli clade 3 genome (76339). The phylogenomic analysis of strain 76339, revealed that it belonged to clade 3 of unintrogressed C. coli. A more extensive respiratory metabolism among unintrogressed C. coli strains was found compared to introgressed C. coli (clade 1). We also identified other genes, such as serine proteases and an active sialyltransferase in the lipooligosaccharide locus, not present in C. coli clade 1 and we further propose a unique scenario for the evolution of Campylobacter ggt.ConclusionsWe propose new insights into the evolution of the accessory genome of C. coli clade 3 and C. jejuni. Also, in silico analysis of the gene content revealed that C. coli clades 2 and 3 have genes associated with infection, suggesting they are a potent human pathogen, and may currently be underreported in human infections due to niche separation.

Characterization of clinical Campylobacter jejuni isolates with special emphasis on lipooligosaccharide locus class, putative virulence factors and host response

Recent studies have indicated a role of the lipooligosaccharide (LOS) of Campylobacter jejuni in the severe neurological Guillain Barré syndrome, as well as in development of more severe symptoms of acute enteritis. We evaluated the role of the LOS locus class in C. jejuni infection among 163 enteritis patients. The prevalence of LOS locus classes differed according to the origin of the isolates. Furthermore, LOS locus classes A and B were significantly associated with susceptibility or resistance to ciprofloxacin and doxycycline. However, our results do not corroborate earlier findings that isolates with potential to sialylate LOS might be associated with more severe symptoms of enteritis. Instead, in an infection model, such isolates gave weaker epithelial IL-8 responses than nonsialylated isolates. Absence of the iron transport protein encoded by the gene ceuE as well as the putative fucose permease gene cj0486 was associated with increased in vitro IL-8 secretion.

Lipooligosaccharide locus classes are associated with certain Campylobacter jejuni multilocus sequence types

The lipooligosaccharide (LOS) locus class was determined using polymerase chain reaction (PCR) in 335 Finnish Campylobacter jejuni strains isolated from humans, poultry and bovines with known multilocus sequence types. The results revealed an association between clonal complexes/sequence types (STs) and LOS locus classes. Based on these results, we further predicted the LOS locus classes distribution among the STs of 209 additional C. jejuni strains from Finnish human domestically acquired infections. Non-sialylated LOS locus classes were associated with STs that comprised ≈55% of patient strains. Sialylated LOS locus classes A and B were associated with STs infrequently isolated, whereas class C was correlated with the ST-21 complex, found in ≈14% of human strains. A combination of the LOS locus class and multilocus sequence type may provide new information on the epidemiology and association of C. jejuni strains with certain disease outcomes.

Characteristics of Lipo-Oligosaccharide Loci of Campylobacter jejuni Isolates Associated with Guillain-Barré Syndrome from Hebei, China

Ganglioside mimicry by C.jejuni lipo-oligosaccharides (LOS) could induce the production of autoantibodies against gangliosides and the development of Guillain-Barré syndrome (GBS). The LOS biosynthesis region exhibits significant variation with different strains. Using PCR amplifications of genes from published LOS loci and sequencing the LOS biosynthesis loci, the eight GBS-associated C. jejuni strains from HeBei could be classified into four classes. The expression of sialylated LOS structures (class A) or non-sialylated LOS structures(class F, H and P) in the C. jejuni LOS is considered to be two different factors for the induction of GBS.

Binary genomotyping using lipooligosaccharide biosynthesis genes distinguishes betweenCampylobacter jejuniisolates within poultry-associated multilocus sequence types

Campylobacter jejuni is a leading cause of human bacterial gastroenteritis throughout the industrialized world. We investigated whether or not differences in gene complement at the lipooligosaccharide (LOS) biosynthesis locus can identify epidemiologically useful binary genomotypes in 87 C. jejuni isolates from poultry-associated multilocus sequence types (STs) collected during the course of a sentinel surveillance study. Using a PCR-based approach, we correlated assignment of both isolate LOS locus class and binary genomotype with ST. We found that isolates within STs 45, 190, 354 and 474 displayed mosaicism in gene complement at the intra-ST level. For example, based upon their binary genomotypes, we assigned individual ST-45 isolates from human clinical cases as probably originating from either a poultry or wild-bird source. However, intra-ST mosaicism in gene complement was observed alongside broader patterns of congruence in LOS locus class and gene complement that distinguished between isolates from different STs.

Sialylation of Campylobacter jejuni lipo-oligosaccharides is associated with severe gastro-enteritis and reactive arthritis

We used various genotyping methods to identify bacterial genetic markers for development of arthritic symptoms following Campylobacter enteritis. We genotyped a collection of population derived Campylobacter strains, with detailed information on clinical characteristics, including arthritic symptoms. Besides using whole genome screening methods, we focused on the lipo-oligosaccharide (LOS) gene locus in which marker genes for developing post- Campylobacter neurological disease are present. Patients with arthritic symptoms were more frequently infected with Campylobacter jejuni strains with a class A LOS locus. We also found that patients who were infected with a C. jejuni strain containing sialic acid-positive LOS (class A, B or C) more frequently had bloody diarrhoea and a longer duration of symptoms. Furthermore, the IgM antibody response against Campylobacter was stronger in patients with a sialic acid containing LOS. Ganglioside auto-antibodies were observed in a small number of patients following infection with a class C strain. We conclude that sialylation of C. jejuni LOS is not only a risk factor for development of post-infectious symptoms, but is also associated with increased severity of enteric disease.

Correlation between genotypic diversity, lipooligosaccharide gene locus class variation, and caco-2 cell invasion potential of Campylobacter jejuni isolates from chicken meat and humans: contribution to virulotyping.

Significant interest in studying the lipooligosaccharide (LOS) of Campylobacter jejuni has stemmed from its potential role in postinfection paralytic disorders. In this study we present the results of PCR screening of five LOS locus classes (A, B, C, D, and E) for a collection of 116 C. jejuni isolates from chicken meat (n = 76) and sporadic human cases of diarrhea (n = 40). We correlated LOS classes with clonal complexes (CC) assigned by multilocus sequence typing (MLST). Finally, we evaluated the invasion potential of a panel of 52 of these C. jejuni isolates for Caco-2 cells. PCR screening showed that 87.1% (101/116) of isolates could be assigned to LOS class A, B, C, D, or E. Concordance between LOS classes and certain MLST CC was revealed. The majority (85.7% [24/28]) of C. jejuni isolates grouped in CC-21 were shown to express LOS locus class C. The invasion potential of C. jejuni isolates possessing sialylated LOS (n = 29; classes A, B, and C) for Caco-2 cells was significantly higher (P < 0.0001) than that of C. jejuni isolates with nonsialylated LOS (n = 23; classes D and E). There was no significant difference in invasiveness between chicken meat and human isolates. However, C. jejuni isolates assigned to CC-206 (correlated with LOS class B) or CC-21 (correlated with LOS class C) showed statistically significantly higher levels of invasion than isolates from other CC. Correlation between LOS classes and CC was further confirmed by pulsed-field gel electrophoresis. The present study reveals a correlation between genotypic diversity and LOS locus classes of C. jejuni. We showed that simple PCR screening for C. jejuni LOS classes could reliably predict certain MLST CC and add to the interpretation of molecular-typing results. Our study corroborates that sialylation of LOS is advantageous for C. jejuni fitness and virulence in different hosts. The modulation of cell surface carbohydrate structure could enhance the ability of C. jejuni to adapt to or survive in a host.

Can Campylobacter coli induce Guillain-Barré syndrome?

Can Campylobacter coli induce Guillain-Barré syndrome?

Characterization of Lipooligosaccharide-Biosynthetic Loci ofCampylobacter jejuniReveals New Lipooligosaccharide Classes: Evidence of Mosaic Organizations

The lipooligosaccharide (LOS) biosynthesis region is one of the more variable genomic regions between strains of Campylobacter jejuni. Indeed, eight classes of LOS biosynthesis loci have been established previously based on gene content and organization. In this study, we characterize additional classes of LOS biosynthesis loci and analyze various mechanisms that result in changes to LOS structures. To gain further insights into the genomic diversity of C. jejuni LOS biosynthesis region, we sequenced the LOS biosynthesis loci of 15 strains that possessed gene content that was distinct from the eight classes. This analysis identified 11 new classes of LOS loci that exhibited examples of deletions and insertions of genes and cassettes of genes found in other LOS classes or capsular biosynthesis loci leading to mosaic LOS loci. The sequence analysis also revealed both missense mutations leading to "allelic" glycosyltransferases and phase-variable and non-phase-variable gene inactivation by the deletion or insertion of bases. Specifically, we demonstrated that gene inactivation is an important mechanism for altering the LOS structures of strains possessing the same class of LOS biosynthesis locus. Together, these observations suggest that LOS biosynthesis region is a hotspot for genetic exchange and variability, often leading to changes in the LOS produced.

Comparison of lipooligosaccharide biosynthesis genes of Campylobacter jejuni strains with varying abilities to colonize the chicken gut and to invade Caco-2 cells

Campylobacter jejuni strains develop a high variability of lipooligosaccharide (LOS) structures on the cell surface based on variations in the genetic content of the LOS biosynthesis locus. While the importance of these variations for ganglioside mimicry as a critical factor in the triggering of Guillain-Barré syndrome has already been shown, little work has been done on the investigation of LOS structures and their function in the pathogenesis of gastrointestinal disease. In this study, the presence of several LOS genes in 40 C. jejuni strains with different abilities to colonize the chicken gut and to invade Caco-2 cells was investigated by PCR. Two genes, cgtB and wlaN, encoding putative beta-1,3-galactosyltransferases were detected in most strongly invasive strains and rarely in non-invasive strains. A homopolymeric tract within the wlaN gene resulted in an intact gene product only in strongly invasive strains. The specific function of these genes during LOS biosynthesis is still unknown. cgtB and wlaN gene products are suggested to be involved in development of the colonization and invasion ability of C. jejuni. After a classification of the complete LOS loci, an association between a particular LOS class and colonization and invasion ability of the C. jejuni strain could not be detected. Lack of the pglB gene involved in protein glycosylation in one strain could be responsible for the weak colonization and invasion ability of this strain. There is some evidence that different genetic characteristics were responsible for strong or weak colonization and the invasion ability of C. jejuni strains.