Editing Helicobacter pylori (section)

===Flagellum===
The first virulence factor of ''Helicobacter pylori'' that enables colonization is its [[flagellum]].<ref name="Duan">{{cite journal |vauthors=Duan Q, Zhou M, Zhu L, Zhu G |title=Flagella and bacterial pathogenicity |journal=J Basic Microbiol |volume=53 |issue=1 |pages=1–8 |date=January 2013 |pmid=22359233 |doi=10.1002/jobm.201100335 |s2cid=22002199 |url=}}</ref> ''H. pylori'' has from two to seven flagella at [[Lophotrichous|the same polar location]] which gives it a high motility. The flagellar filaments are about 3&nbsp;μm long, and composed of two copolymerized [[flagellin]]s, FlaA and FlaB, coded by the genes ''flaA'', and ''flaB''.<ref name="Kao"/><ref name="Yamaoka2" /> The minor flagellin FlaB is located in the proximal region and the major flagellin FlaA makes up the rest of the flagellum.<ref name="IJMS" /> The flagella are sheathed in a continuation of the bacterial outer membrane which gives protection against the gastric acidity. The sheath is also the location of the origin of the outer membrane vesicles that gives protection to the bacterium from bacteriophages.<ref name="IJMS" />

Flagella motility is provided by the [[proton motive force]] provided by urease-driven hydrolysis allowing [[chemotaxis|chemotactic movements]] towards the less acidic [[pH#pH of various body fluids|pH]] gradient in the mucosa.<ref name="Baj" /> The mucus layer is about 300 [[Micrometre|μm]] thick, and the helical shape of ''H. pylori'' aided by its flagella helps it to burrow through  this layer where it colonises a narrow region of about 25 μm closest to the epithelial cell layer, where the pH is near to neutral. They further colonise the [[gastric pits]] and live in the [[gastric glands]].<ref name="Martínez"/><ref name="IJMS">{{cite journal |vauthors=Nedeljković M, Sastre DE, Sundberg EJ |title=Bacterial Flagellar Filament: A Supramolecular Multifunctional Nanostructure |journal=Int J Mol Sci |volume=22 |issue=14 |date=July 2021 |page=7521 |pmid=34299141 |pmc=8306008 |doi=10.3390/ijms22147521 |doi-access=free |url=}}</ref><ref name="Elbehiry">{{cite journal |vauthors=Elbehiry A, Marzouk E, Aldubaib M, Abalkhail A, Anagreyyah S, Anajirih N, Almuzaini AM, Rawway M, Alfadhel A, Draz A, Abu-Okail A |title=Helicobacter pylori Infection: Current Status and Future Prospects on Diagnostic, Therapeutic and Control Challenges |journal=Antibiotics |volume=12 |issue=2 |date=January 2023 |page=191 |pmid=36830102 |pmc=9952126 |doi=10.3390/antibiotics12020191 |doi-access=free |url=}}</ref> Occasionally the bacteria are found inside the epithelial cells themselves.<ref name="pmid12738380">{{cite journal | vauthors = Petersen AM, Krogfelt KA | title = Helicobacter pylori: an invading microorganism? A review | journal = FEMS Immunology and Medical Microbiology | volume = 36 | issue = 3 | pages = 117–26 | date = May 2003 | pmid = 12738380 | doi = 10.1016/S0928-8244(03)00020-8 | type = Review | doi-access = free }}</ref> The use of [[quorum sensing]] by the bacteria enables the formation of a biofilm which furthers persistent colonisation. In the layers of the biofilm, ''H. pylori'' can escape from the actions of antibiotics, and also be protected from host-immune responses.<ref name=Ali>{{cite journal |vauthors=Ali A, AlHussaini KI |title=Helicobacter pylori: A Contemporary Perspective on Pathogenesis, Diagnosis and Treatment Strategies |journal=Microorganisms |volume=12 |issue=1 |date=January 2024 |page=222 |pmid=38276207 |pmc=10818838 |doi=10.3390/microorganisms12010222 |doi-access=free |url=}}</ref><ref name=Zafer>{{cite journal |vauthors=Zafer MM, Mohamed GA, Ibrahim SR, Ghosh S, Bornman C, Elfaky MA |title=Biofilm-mediated infections by multidrug-resistant microbes: a comprehensive exploration and forward perspectives |journal=Arch Microbiol |volume=206 |issue=3 |pages=101 |date=February 2024 |pmid=38353831 |pmc=10867068 |doi=10.1007/s00203-023-03826-z |bibcode=2024ArMic.206..101Z |url=}}</ref> In the biofilm, ''H. pylori'' can change the flagella to become adhesive structures.<ref name="Sun">{{cite journal |vauthors=Sun Q, Yuan C, Zhou S, Lu J, Zeng M, Cai X, Song H |title=Helicobacter pylori infection: a dynamic process from diagnosis to treatment |journal=Front Cell Infect Microbiol |volume=13 |issue= |pages=1257817 |date=2023 |pmid=37928189 |pmc=10621068 |doi=10.3389/fcimb.2023.1257817 |doi-access=free |url=}}</ref>