Table 1.
Overview on C. jejuni virulence factors
| Virulence factor | Gene | Functions | Features |
|---|---|---|---|
| I. Adhesins | |||
| CadF (Campylobacter adhesion protein to fibronectin) | cadF | Binding to fibronectin of epithelial cells | Outer membrane protein, adhesion to fibronectin is required for the delivery of Cia proteins into the cyotosol of the host cells |
| FlpA (fibrin-like peptide A) | flpA | Binding to fibronectin of epithelial cells | Outer membrane protein |
| CapA (Campylobacter adhesion protein A) | capA | Impact on the ability to adhere to and penetrate into host cells | Outer membrane, surface-exposed lipoprotein with autotransporter function |
| HtrA (high temperature requirement protein A) | htrA | Cleavage of E-cadherin and occludin; proper adhesion folding | Responsible for growth at elevated temperature, proliferation under high oxygen content, expression of protease activity, adhesion, invasion, and transmigration |
| Peb1, 3, and 4 (periplasmic-binding protein) | peb1,3,4 | Influencing the transport of CadF to the outer membrane as chaperones | |
| JlpA (jejuni lipoprotein) | jlpA | Binding to a heat shock protein (HSP 90a), inflammatory response | Surface-exposed, glycosylated lipoprotein, containing multiple ligand binding sites |
| II. Invasion factors | |||
| Cia (Campylobacter invasion antigens) | cia | Initiate the internalization of Campylobacter via rearrangement of the cytoskeleton and subsequent membrane ruffling | Cia proteins are secreted by the flagellar T3SS and introduced into the cytoplasm |
| Invasion-associated protein | iamA | Invasion | |
| III. Toxins | |||
| CDT (cytolethal distending toxin) | cdtABC | Cytotoxicity, inflammation | CdtB is the active component, while cdtA and cdtC mediate the binding to and internalization into the host cell |
| IV. Iron acquisition factors | |||
| Ferrous uptake | FeoB | Growth under iron restriction | Membrane porin |
| Enterobactin uptake | cfr, ceu | Growth under iron restriction | Siderophore receptor |
| Lactoferrin and transferrin uptake | Ceu, cfpb | Growth under iron restriction | Siderophore receptor |
| Hemin uptake | Chu | Growth under iron restriction | Siderophore receptor |
| Ferric regulation | fur | Iron homeostasis | |
| Ferritin bacterioferritin | cft bfr | Iron storage and protection against oxidative stress | |
| V. Flagellum | |||
| (a) Motility | |||
| Movement through the viscous intestinal mucin layer | |||
| Filament | flaABC | Motility, secretion invasion | The flagellin proteins are O-glycosylated with pseudamic acid, which is essential for polymerization |
| Rod | flgE, flgG, flgL, flgK | Motility | |
| Hook | Anchoring | ||
| Discs (basal, medial, proximal | flgP, PflA, pflB, motAB | Motility | Surrounding the flagellum anchor in the periplasmic space |
| Flagellar motor proteins | motAB, fliM, fliY | Motility | The motor is composed of 17 stators, which are oriented on the disc skeleton to create a greater distance to the central motor axis and the rotor. This results in greater torque and force |
| MS ring | fliF | ||
| C ring | fliG | ||
| (b) Chemotaxis | |||
| Che-kinases | cheABRVWYZ | Transmitting the information to the flagellar motor through phosphorylation | |
| Chemotactic receptors | Tlp, AfcB | Sensoring the exogenous stimuli | Methyl-accepting chemotaxis proteins (also called transducer-like proteins) |
| Energy taxis system | cetAB | Transduction of the energy signal to the chemotactic system | |
| (c) Secretion | |||
| Type III secretion system | flhA, flhB, fliQ, fliP, fliO, fliR | Secretes various proteins such as Cia, Fed and FlaC, IamA | Located in the core of the flagellum |
| Type VI secretion system | tssA-M, virB11 | Adaption to bile acids | Colonization factor |
| VI. Surface structures | |||
| LOS (lipooligosaccharide) | Influence on immunogenicity and invasion ability, mediating cellular interactions | O- or HS-antigen Phase-variable structure resembles to human neural gangliosides | |
| CPS (capsular polysaccharide) | cps kps | Influences colonization, adhesion and invasion, resistance factors and immune response | Phase-variable serotype specificity |
| VII. Others | |||
| Post-transcriptional regulation | csrA | Regulation of virulence factors and metabolism, biofilms | mRNA-binding regulator |
| Quorum sensing | luxS | Regulation of virulence factors, biofilm formation, colonization | AI-2 biosynthesis enzyme (hydrolysis of S-adenosylhomocysteine) |
| Resistance | cme | Multidrug and bile resistance | CME efflux pumps consist of a periplasmic protein (CmeA), inner membrane efflux transporter (CmeC) and outer membrane protein (CmeC) |
| Antimicrobial proteins | virK | Protection | |
| Antioxidant proteins | Sod, katA, ahpC, tpx | Protection against oxidative stress | Survival outside the host |
| Stress resistance | dnaJ | Coding for a heat shock protein | |
| Synthesis of an outer membrane phospholipase | pldA | Related to cell invasion and colonization | |
| Glycosylation | pgl | N-linked glycosylation of other outer membrane proteins | |