Campylobacter: Molecular and Cellular Biology Chapter Abstracts
Chapter 1
Campylobacter Infection - Clinical Context
Vincent B. Young and Linda S. Mansfield
Abstract
Campylobacter jejuni can cause a spectrum of diseases including gastroenteritis, proctitis, septicaemia, meningitis,
abortion, and autoimmune diseases such as Reiter's arthritis and
Guillain-Barré syndrome (GBS). The most common clinical
syndrome seen in humans infected with C. jejuni is gastroenteritis. In most individuals, C. jejuni-associated gastroenteritis is self-limiting, resolving within a week unless
underlying illness is present such as human immunodeficiency virus
(HIV) infection. Such individuals are also more prone to develop
invasive/systemic disease. Campylobacter spp. are rarely isolated from healthy individuals in developed countries, but
commonly isolated from nonsymptomatic individuals in developing
countries. Campylobacter jejuni has been linked to GBS, a debilitating inflammatory polyneuritis characterized by fever, pain
and weakness that progresses to paralysis, and may results in
long-term disability. Also, reactive arthritis can follow diarrheic
episodes of Campylobacter or asymptomatic exposure to the organism and is attributed to autoimmune response in joints.
Campylobacter jejuni is a known cause of disease in animals. Natural infections with C. jejuni resulting in enteritis have been reported in juvenile macaques, weaning age ferrets, dogs, cats
and swine. Additionally, chickens, rodents, ferrets, dogs, primates,
rabbits, and pigs have been inoculated experimentally by various
routes with C. jejuni to mimic the various syndromes of infection in humans. Recently, concern has been focused on the role
that both normal and diseased animals play in zoonotic transmission
of campylobacters to humans.
Chapter 2
Taxonomy, Phylogeny, and Methods for the Identification of Campylobacter Species
Stephen L. W. On
Abstract
The taxonomy of the genus Campylobacter has changed dramatically since its inception in 1963 by Sebald and Véron,
at which time the genus contained just two taxa, C. fetus and 'C. bubulus'. At present, Campylobacter contains 16 species, six subspecies and several validly named biovars, most of
which are of substantial clinical and economic importance. Moreover,
a variety of taxa previously described as Campylobacter species have been reclassified into other genera. This chapter
reviews the historical development of Campylobacter taxonomy, outlines the phylogeny within and between Campylobacter and related bacteria, summarizes the characteristics and taxonomic
problems of each species and provides an overview of current methods
applied to identify members of this important group of bacteria.
Chapter 3
Population Genetics of Campylobacter jejuni
Kate E. Dingle and Martin C.J. Maiden
Abstract
Population genetic studies have an important role to play in
the investigation of bacterial pathogens and have proved particularly
informative in exploring the epidemiology of Campylobacter jejuni. Improvements in the technology available for
high-throughput nucleotide sequence determination, together with
substantial reductions in its cost and the development of novel
analysis techniques, have facilitated multilocus investigations of
large isolate collections. The data generated by techniques such as
multilocus sequence typing (MLST) are highly accurate and readily
comparable among laboratories. Several MLST studies of C. jejuni have confirmed the genetic diversity of this bacterium and
shown that whilst there is extensive evidence for recombination in
populations of this organism, certain groups of related genotypes,
called clonal complexes, persist over time and during geographical
spread. Most human disease is caused by a relatively limited subset
of these clonal complexes and certain genotypes appear to be
associated with particular animal host species. Single phenotypic or
genotypic characteristics, such as serotype or the flaA gene type, are inconsistent indicators of clonal complex, explaining why
it can be difficult to interpret these data epidemiologically.
Together with MLST data, the clonal complex model provides the
prospect of a single unified typing procedure for C. jejuni.
Chapter 4
Campylobacter jejuni Strain Variation
Collette Fitzgerald, Andrew D. Sails and Patricia I. Fields
Abstract
The diversity within Campylobacter jejuni is well established and has been detected at both the phenotypic and
genotypic level. The application of higher resolution molecular
subtyping methods has resulted in increasing questions regarding the
(in)stability of the Campylobacter genome and the implications of this for molecular epidemiological investigations. Current
evidence suggests that genomic rearrangements play a role in strain
diversity. But stable clones of C. jejuni have also been reported. The aim of this chapter is to review current experimental
data on C. jejuni strain variation based on phenotypic and genotypic methods.
Chapter 5
Advances in Campylobacter jejuni Comparative Genomics through Whole Genome DNA Microarrays
Nick Dorrell, Olivia L. Champion and Brendan W. Wren
Abstract
DNA microarray technology is revolutionizing the study of
bacteria at both the genomic and transcriptional levels. Whole genome
comparisons from microarray analysis between bacterial strains and
species have expanded our understanding of the genetic diversity and
evolution within bacterial populations. Campylobacter jejuni strain diversity combined with variable host responses results in
a complex spectrum of disease outcomes, ranging from asymptomatic
colonization to severe inflammatory diarrhoea. A major reason for
continued comparative genomics studies is the absence of an animal
model that reflects C. jejuni-associated disease. Precise strain comparisons from well-characterized strains of diverse origins
will allow correlates of pathogenesis to be determined and the
subsequent identification of potential virulence determinants. Also
an understanding of genetic differences between C. jejuni strains from different ecological niches should allow the
identification of host-specific epidemiological markers and the
development of rational approaches to reduce this problematic
pathogen from the food chain. Here an overview of the different
microarray technologies is presented followed by the different types
of C. jejuni microarrays in use today. Published C. jejuni microarray data are discussed along with examples of the
different comparative genomic studies for other bacteria that have
utilized microarray technology and future developments are proposed.
Chapter 6
Prevalence of Campylobacter in the Food and Water supply: Incidence, Outbreaks, Isolation and Detection
William G. Miller and Robert E. Mandrell
Abstract
Campylobacter is the primary cause of bacterial diarrhoeal illness in the developed world, with an estimated 2-3
million Campylobacter-related illnesses occurring in the United States per year. Although thermophilic Campylobacter species are considered food-borne pathogens, most illnesses
caused by Campylobacter occur sporadically. Campylobacter species rarely cause food- or water-borne outbreaks, but in rare
cases serious neuropathy and paralytic illness has occurred in
association with a sporadic Campylobacter infection.
Chapter 7
Methods for Epidemiological Analysis of Campylobacter jejuni
John D. Klena and Michael E. Konkel
Abstract
Identification of Campylobacter spp. to the species level is necessary for unraveling aspects of ecology, prevalence and
potential dissemination of the bacteria through the environment.
Species identification may be achieved by determining expressed
characteristics (phenotypes), heritable traits (genotypes) or a
combination of both. In order to gain further insight into an
isolate's transmission, survival in the environment and virulence
potential, methods must be employed that can discriminate dissimilar
from similar isolates. Molecular methods capable of enhanced
resolution are most effective at determining the differences between
isolates. In addition to discriminatory capability, methods should be
portable; that is, they should be able to be shared with and
reproduced by other laboratories to maximize data exchange. From a
practical aspect, the methods should also be relatively inexpensive
to set up and maintain, and technically simple. Finally, the methods
should have the potential to generate a result in real time. In this
review, we discuss three methods, amplified fragment length
polymorphism (AFLP), multilocus sequence typing (MLST) and whole
genome microarray, used to discriminate between isolates of C. jejuni and highlight the application of these methodologies. Our
intent is to evaluate the use of each technique as it applies to
answering questions regarding the epidemiology and phylogeny of C. jejuni.
Chapter 8
Plasmids of Campylobacter jejuni 81-176
Joseph C. Larsen and Patricia Guerry
Abstract
The significant phenotypic variation that exists among
different C. jejuni strains in virulence in animal models, in vitro invasiveness, as well as clinical severity of illness leads one to rationalize that genetic elements must contribute to
this variation. The major genotypic differences that exist between C. jejuni 81-176, a particularly virulent strain of C. jejuni, and other C. jejuni strains is the presence of two plasmids in 81-176. One of these plasmids, pVir, has been shown
contribute to both in vitro epithelial cell invasion and the ability to cause disease in the ferret diarrhoea model. This chapter
presents a general description of the pVir plasmid and discusses the
potential contribution of pVir to the pathogenesis of C. jejuni 81-176.
Chapter 9
Mechanisms of Antimicrobial Resistance in Campylobacter
Diane E. Taylor and Dobryan M. Tracz
Abstract
The modes of action of antibiotics and the mechanisms of
resistance described in Campylobacter species are discussed in the context of antibiotic resistance in general, with primary
emphasis on Campylobacter jejuni. We also review the frequency of resistance in C. jejuni, which appears to be increasing for some antibiotics, particularly tetracycline. In contrast, the
frequency of erythromycin resistance in C. jejunivz, the drug of choice for treatment of serious Campylobacter infections, remains low, often < 1%.
Chapter 10
Multidrug Efflux Systems in Campylobacter
Jun Lin, Masato Akiba and Qijing Zhang
Abstract
Campylobacter jejuni has become increasingly resistant to antimicrobial agents. As a general resistance mechanism, bacterial
antimicrobial efflux machinery plays an essential role in the
intrinsic and acquired resistance to various antibiotics. Based on
the genome sequence of NCTC 11168, Campylobacter contains 13 putative multidrug efflux systems, most of which have not been
functionally characterized. To date, CmeABC is the only defined
antibiotic efflux system in Campylobacter, which functions as an
energy-dependent efflux pump contributing to Campylobacter resistance to antimicrobial agents and adaptation in animal
hosts. As exemplified by CmeABC, the expression and function of the
efflux systems in Campylobacter may be modulated by transcriptional regulation and possible post-translational
modification. It is likely that these efflux systems function
together to meet the normal physiological needs of Campylobacter and facilitate Campylobacter adaptation to different environmental conditions including antibiotic treatments. Better
understanding of the antibiotic efflux machinery in Campylobacter will assist the development of strategies to control the
occurrence and spread of antibiotic-resistant Campylobacter.
Chapter 11
Genetic Bases for the Variation in the Lipooligosaccharide Outer Core of Campylobacter jejuni and Possible Association of Glycosyltransferase Genes with Post-infectious Neuropathies
Michel Gilbert, Peggy C.R. Godschalk, Craig T. Parker, Hubert Ph. Endtz and Warren W. Wakarchuk
Abstract
The lipooligosaccharide (LOS) of Campylobacter jejuni displays considerable variation in the structure of its outer
core. Microarray and PCR probing studies have shown that there is
extensive variation in the gene content of the locus responsible for
the biosynthesis of the LOS. DNA sequencing of this locus from
multiple strains has demonstrated four other mechanisms that C. jejuni uses to vary its LOS outer core: (a) phase variation
because of homopolymeric tracts, (b) gene inactivation by the
deletion or insertion of a single base (without phase variation), (c)
single mutation leading to the inactivation of a glycosyltransferase
and (d) single or multiple mutations leading to glycosyltransferases
with different acceptor specificities. These four mechanisms have
resulted in 'allelic' glycosyltransferases with potential to
phase-vary their expression or modulate their specificity. Alleles
representing each of these four mechanisms have been found for some
of the outer core glycosyltransferases. Although the various types of
alleles have presumably appeared through vertical evolution there is
also evidence that horizontal exchange has further contributed to LOS
outer core variation. The genetic bases for the variation of LOS
outer cores in C. jejuni provide a good example of various adaptive evolution strategies used by a mucosal pathogen to modulate
the structure of a cell-surface carbohydrate in order to better
survive in a host. The role of LOS and ganglioside mimicry in the
pathogenesis of the Guillain-Barré and Miller Fisher syndromes
will also be discussed. Specific LOS biosynthesis genes appear to be
associated with these immune-mediated neuropathies.
Chapter 12
The Polysaccharide Capsule of Campylobacter jejuni
A.V. Karlyshev, O.L. Champion, G.W.P. Joshua and B.W. Wren
Abstract
The discovery of the Campylobacter jejuni capsular polysaccharide (CPS) is one of the most important recent advances in
the study of the biology of this pathogen. The CPS consists of
repeating oligosaccharide units attached to a phospholipid, and it is
not chemically linked to lipooligosaccharide (LOS). In addition, it
is CPS and not LOS that is associated with Penner serotypes. The CPS
structures seem to be relatively stable for particular C. jejuni strains maintained in laboratory conditions, although some
variant structures may be detected. However, among different C. jejuni strains the CPS structures are highly variable and a
number of genetic mechanisms responsible for such variation have been
uncovered. CPS is an important virulence factor and may also be
essential for increased survival of C. jejuni in the environment.
Chapter 13
Protein Glycosylation in Campylobacter
Christine M. Szymanski, Scarlett Goon, Brenda Allan and Patricia Guerry
Abstract
Glycoproteins are ubiquitous in eukaryotes where it is estimated
that more than half of all proteins are glycosylated (Apweiler et al., 1999). The significance of co-translational modification of
proteins with sugars is well known. Both N- and O-linked sugar modifications influence multiple biological processes and changes in their biosynthetic pathways have been
implicated in several diseases. It is now known that bacteria also
glycosylate their proteins. Many O-linked systems have been described including flagellar modification with pseudaminic acid
derivatives in Campylobacter and Helicobacter organisms. Recently, the first report of an N-linked bacterial protein glycosylation pathway has been described in
Campylobacter jejuni. An overview of the literature describing these two protein glycosylation pathways in campylobacters will be
presented. Further studies describing the commonality and
significance of bacterial protein glycosylation will also be
discussed.
Chapter 14
Metabolism, Electron Transport and Bioenergetics of Campylobacter jejuni: Implications for Understanding Life in the Gut and Survival in the Environment
David J. Kelly
Abstract
Understanding the ability of Campylobacter jejuni to survive in the food chain and the environment, but to be a commensal
in the avian gut and a pathogen in humans, will require a detailed
knowledge of its metabolism and electron transport. This chapter
focuses on aspects of carbon, nitrogen and electron flow which are
relevant to developing such knowledge. It appears that C. jejuni is unable to use hexose sugars as carbon sources because
of the absence of the key glycolytic enzyme 6-phosphofructokinase,
yet the presence of a typical catabolic pyruvate kinase suggests some
catabolic role for the lower part of the Embden-Meyerhof pathway, in
addition to a major function in gluconeogenesis. The major carbon and
nitrogen sources likely to be used by C. jejuni in vivo are amino acids, and it possesses several enzymes for the amino
acid deamination. Serine catabolism is especially significant. A
major prediction from the genome sequence is an unexpected complexity
in the electron transport chains of C. jejuni, with a wide variety of electron donors and alternative electron acceptors to
oxygen capable of being utilized. This underlines a hitherto
unappreciated metabolic versatility in this bacterium, which may
contribute to its ability to occupy diverse niches. Nevertheless, C. jejuni appears to be unable to grow under strictly anaerobic
conditions, due to the use of an oxygen-dependent ribonucleotide
reductase for DNA synthesis.
Chapter 15
Iron Transport and Regulation
Karl G. Wooldridge and Arnoud H.M. van Vliet
Abstract
Given the small size of the genome of Campylobacter jejuni, a surprisingly large number of its genes are implicated
in iron scavenging, metabolism, storage and regulation. This is
likely to reflect the central role of iron in the host-pathogen
relationship. C. jejuni is known to utilize haem iron and ferric siderophores, both of which are likely to be available during
intestinal colonization and infection. Genomic data suggest that
there are additionaliron uptake pathways in C. jejuni: these include a ferrous iron transporter and receptors for additional,
uncharacterized iron sources. Furthermore, there is genetic
heterogeneity among C. jejuni isolates: some pathways are common to all isolates, while other pathways are restricted to a
subset of strains. Two iron-responsive regulatory circuits in C. jejuni are responsible for regulation of iron homeostasis, and
for protection against oxidative stress, respectively.
Chapter 16
Campylobacter jejuni Stress Responses During Survival in the Food Chain and Colonization
Simon F. Park
Abstract
Campylobacter jejuni is probably the most ubiquitous bacterial pathogen in the food chain and is the leading cause of
bacterial food borne diarrhoeal disease throughout the world. It can
be isolated from a wide variety of environments including farms,
surface waters, foods and the intestinal tracts of various animals.
In particular, C. jejuni is widely distributed in the intestinal tract of poultry. The organism is able to survive exposure
to a multitude of inimical conditions whilst in the food chain, and
also during infection, and its ability to tolerate these is
fundamental to the continuation of the contamination cycle. The
following discussion will focus on the stress responses elicited by
this pathogen, and how these correlate with its ability to survive in
the food chain and to tolerate the non-immune defence mechanisms
encountered in the human host.
Chapter 17
Motility
Aparna Jagannathan and Charles Penn
Abstract
A key feature of many pathogenic bacteria is motility by
means of flagella. Motility and flagellar synthesis have been
implicated by several classical studies in intestinal colonization
and virulence, and C. jejuni also depends on flagellar motility for its pathogenicity. With the involvement of more than 40
flagellar structural and regulatory genes, the flagellar system
includes a type III secretion system necessary for flagellar
assembly. It differs significantly however from the E. coli/Salmonella paradigm of regulation of flagellar gene expression. The regulation of expression of these genes is probably
influenced primarily by cell cycle events, but in addition flagellar
expression appears to be linked to flagellin glycosylation and to be
potentially phase-variable. The association of these phenomena with
virulence modulation in C. jejuni is under-investigated.
Chapter 18
Campylobacter Chemotaxis
Victoria Korolik and Julian Ketley
Abstract
Bacterial motility is subject to sensory control to introduce
bias in swimming direction towards beneficial environments and away
from unfavourable conditions. Chemotactic motility is central to the
intestinal lifestyle of C. jejuni and a prerequisite for pathogenesis in human disease. The genome sequence of C. jejuni NCTC 11168 reveals the presence of orthologues of cheA,
cheW, cheV, cheY, cheR and cheB that are involved in chemotaxis and aerotaxis in E. coli and other bacteria. C. jejuni also appears to encode 10 chemoreceptor and two aerotaxis (Aer) orthologues. Based on the
genome content of chemotaxis components and their domain organization
in C. jejuni it is possible to provide a basic model for how campylobacters detect and respond to chemotactic signals. The
chemotaxis signal transduction pathway may even have input into the
expression of other virulence determinants in campylobacters. A
thorough understanding of the chemotaxis system in campylobacters
will be important in addressing the problem of the intestinal
colonization of poultry and livestock animals and the initiation of
disease in man.
Chapter 19
Invasion
Lan Hu and Dennis J. Kopecko
Abstract
Campylobacter is the leading cause of food-borne bacterial enteritis worldwide. The results of intestinal biopsies of
patients, infected primates and other experimentally infected model
animals, together with experimental infection of cultured human
intestinal epithelial cells have clearly demonstrated that C. jejuni invade the intestine. Further, these collective data
emphasize the importance of bacterial invasiveness as a virulence
factor for Campylobacter pathogenesis. Following passage through the stomach, Campylobacter adhere to and invade colonic epithelial cells, trigger signal transduction events that
induce host cytoskeletal rearrangements and bacterial uptake, induce
interleukin 8 production, and cause colitis. The molecular components
of the invasion process (es) are just beginning to be characterized.
Chapter 20
Cytolethal Distending Toxin
Carol L. Pickett and Robert B. Lee
Abstract
Many toxic activities have been reported to be produced by
Campylobacter jejuni, but current work is centred on an exotoxin that is a member of the cytolethal distending toxin (CDT)
family of toxins. CDT is encoded by three adjacent genes, termed
cdtA, cdtB, and cdtC. The CDT holotoxin consists of one copy of each gene product. CDT is capable of causing
eucaryotic cells of different lineages to become irreversibly blocked
in the G1 or G2 phase of the cell cycle, and
recent work has shown that the CdtB subunit carries a DNase activity
that is responsible for bringing about cell cycle arrest. Current
research includes studies of the role of the CdtA and CdtC subunits
in receptor binding, as well as on CDT uptake, trafficking,
secretion, and its role in disease production.
Chapter 21
Interactions of Campylobacter jejuni with Non-professional Phagocytic Cells
Brian H. Raphael, Marshall R. Monteville, John D. Klena, Lynn A. Joens and Michael E. Konkel
Abstract
Campylobacteriosis is a multifactorial process involving the
organism's translocation of the intestinal epithelium, followed by
adherence to host cells, secretion of virulence proteins, and
epithelial cell invasion. In vitro evidence suggests that C. jejuni migrates across polarized epithelial cells, adheres to
the basolateral surface of host cells, and invades preferentially at
sites of extracellular matrix-host cell contact. Adherence of C. jejuni to host cells is mediated by a number of constitutively
synthesized factors including PEB1A, JlpA, and the fibronectin
binding protein, CadF. Adhesins play a major role in colonization
in vivo as supported by the inability of a cadF mutant to colonize the ceca of experimentally inoculated newly hatched Leghorn
chickens. Maximal invasion of epithelial cells requires the secretion
of the Cia (Campylobacter invasion antigens) proteins. Mutations in ciaB reduce the organism's invasiveness and prevent the secretion of the other Cia
proteins. Genetic evidence indicates that the Cia proteins are
secreted via the flagellar export system and that the minimum
secretion-competent structure requires a basal body, hook, and at
least one of the filament proteins, FlaA or FlaB. Uptake of C. jejuni by epithelial cells requires both microfilaments and
microtubules and induces the phosphorylation of paxillin, a focal
adhesion molecule. Intracellular calcium also plays a role in C. jejuni uptake either by its involvement with microfilament
rearrangement or its effects on cell signalling systems. Finally, C. jejuni are able to survive intracellularly for extended time
periods (> 96 hours), however, the cellular compartment in which the
organism resides has not yet been elucidated.
Chapter 22
Campylobacter jejuni Interactions with Professional Phagocytes
Lynn Joens
Abstract
Campylobacter jejuni interacts with inflammatory cells during the course of infection. In experimental Campylobacter enteritis, large numbers of infiltrating leucocytes are observed
in the lamina propria. In vitro, C. jejuni taken up by macrophages survive for extended periods of time (>72 h). At least
one bacterial product, catalase (KatA), is required for optimal
intra-macrophage survival of C. jejuni. However, variation in intracellular survival between environmental and clinical isolates
of C. jejuni suggests the presence of additional bacterial survival enhancing factors. While the majority of C. jejuni phagocytosed by J774A.1 macrophages appear to co-localize with
markers of the normal endocytic pathway which becomes acidified, a
subpopulation may exist in a modified endosome. However, it is
unclear which of these populations survive for extended periods.
Finally, bacterial induced macrophage killing appears to occur by a
process involving both apoptosis and necrosis, with the latter
occurring in a bacterial dose-dependent manner.
Chapter 23
Campylobacter spp. and the Ability to Elicit Intestinal Inflammatory Responses
Paul Everest
Abstract
Campylobacters, particularly C. jejuni and coli, cause acute gastrointestinal infection which presents clinically as diarrhoea and intestinal epithelial damage. It has been
proposed that primary infection for patients in both developed and
developing countries is inflammation of the host intestinal tissues
and these inflammatory events may be modified by subsequent exposure
and maturing immunity. The organism can initiate these inflammatory
signals by interaction (adhesion and invasion) with host cells and
activate signalling pathways that lead to inflammatory cytokine
production and recruitment of phagocytes, particularly neutrophils,
into infected tissue. The molecular basis of this host/bacterial
interaction is beginning to be understood which should facilitate the
investigation of the role that inflammation plays in instigating the
clinical symptoms of Campylobacter-induced diarrhoeal disease.
Chapter 24
Campylobacter jejuni Interaction with Enterocytes - Using Host Gene Expression Analysis to Unravel Potential Disease Mechanisms
Amanda MacCallum, Pawel Herzyk, Catriona Young, Julian Ketley and Paul Everest
Abstract
Abstract
Campylobacter jejuni is a common food-borne pathogen causing diarrhoeal disease worldwide. Little is known of the mechanisms
responsible for the clinical symptoms associated with infection.
Focusing on data derived using microarray technology and comparisons
with published literature, possible events involved in the
interaction of C. jejuni with host cells are highlighted. The identification of host cell responses to C. jejuni can be used to develop testable models and highlight novel areas for future
research.
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