Swarming motility is a typical synergistic motion, in which bacteria use flagella and Type Ⅳ Pili together to move collectively on semi-solid surfaces. Swarming motility is a hot topic of research in the field of microbiology because of its close relationship with biofilm formation, fruiting bodies formation, pathogen invasion and microbial dispersal and symbiosis. A large number of studies have been conducted on bacterial swarming motility, including changes in the expression of key proteins, changes in chemical communications between bacteria as well as mechanical changes. The expression of flagellin and the level of intracellular c-di-GMP complicatedly regulates the collective behavior of bacteria in colonies, which consequently impacts the swarming motility. The unique physical properties of swarmer cells are conducive to the expansion of the whole colony. Factors such as nutrient and water content in the surrounding growth environment of bacteria also affect the ability of bacteria to swarm to different degrees. It is challenging to construct a universal model of swarming motility based on the molecular mechanisms of swarming in the future.
Bacteria ; Flagellin ; Symbiosis ; Water

Flagellin is a subunit protein of the flagellum, a whip-like appendage that enables bacterial motility. Traditionally, flagellin was viewed as a virulence factor that contributes to the adhesion and invasion of host cells, but now it has emerged as a potent immune activator, shaping both the innate and adaptive arms of immunity during microbial infections. In this review, we summarize our understanding of bacterial flagellin and host immune system interactions and the role flagellin as an adjuvant, anti-tumor and radioprotective agent, and we address important areas of future research interests.
Arm ; Flagella ; Flagellin ; Immune System ; Virulence

No Abstract Available.
Diagnosis* ; Enzyme-Linked Immunosorbent Assay* ; Flagellin* ; Leptospirosis*

The motile marine bacterium, Vibrio vulnificus has a total of six flagellins. Flagellin is a structural component of flagellar filament in various locomotive bacteria and is the ligand of Toll-like receptor 5 (TLR5). TLRs, highly expressed on various types of cells including dendritic cells (DCs), recognize invading microorganisms and finally trigger host immune responses. In this study, we prepared all of six recombinant flagellin proteins and assessed the effect of six flagellins on IL-8 activation through TLR5 recognition. Although showed different activities, five out of the six flagellins stimulated significant IL-8 activation. We also investigated the immunomodulatory roles of Vv-FlaB, the crucial building block of V. vulnificus flagellar filament, on human dendritic cells. Treatment of immature DCs with Vv-FlaB resulted in an increased expression of co-stimulatory molecules and induced strong allo-T cell proliferative activities of the DCs. These results show that the Vv-FlaB may serve an epochal immune adjuvant possessing effective immunomodulatory activities.
Bacteria ; Dendritic Cells* ; Flagellin* ; Flow Cytometry ; Humans* ; Interleukin-8 ; Toll-Like Receptor 5 ; Vibrio vulnificus* ; Vibrio*

No abstract available.
Clone Cells* ; Cloning, Organism* ; DNA* ; Flagellin* ; Helicobacter pylori* ; Helicobacter* ; Sequence Analysis, DNA*

Akabane and bovine ephemeral fever (BEF) viruses cause vector-borne diseases. In this study, inactivated Akabane virus (AKAV)+Bovine ephemeral fever virus (BEFV) vaccines with or without recombinant vibrio flagellin (revibFlaB) protein were expressed in a baculovirus expression system to measure their safety and immunogenicity. Blood was collected from mice, guinea pigs, sows, and cattle that had been inoculated with the vaccine twice. Inactivated AKAV+BEFV vaccine induced high virus neutralizing antibody (VNA) titer against AKAV and BEFV in mice and guinea pigs. VNA titers against AKAV were higher in mice and guinea pigs immunized with the inactivated AKAV+ BEFV vaccine than in animals inoculated with vaccine containing revibFlaB protein. Inactivated AKAV+BEFV vaccine elicited slightly higher VNA titers against AKAV and BEFV than the live AKAV and live BEFV vaccines in mice and guinea pigs. In addition, the inactivated AKAV+BEFV vaccine was safe, and induced high VNA titers, ranging from 1 : 64 to 1 : 512, against both AKAV and BEFV in sows and cattle. Moreover, there were no side effects observed in any treated animals. These results indicate that the inactivated AKAV+BEFV vaccine could be used in cattle with high immunogenicity and good safety.
Animals ; Antibodies, Neutralizing ; Baculoviridae ; Cattle ; Cattle* ; Ephemeral Fever* ; Flagellin ; Guinea Pigs ; Mice ; Vaccines ; Vibrio

The bacterial flagellar structure can be divided into the basal body, the hook and the filament. Three minor components called hook associated proteins (HAP1, HAP2 and HAP3) form a junction between the hook and the filament (HAP1 and HAP3) and a capping structure at the distal end of flagellar filament (HAP2). Vibrio vulnificus is a halophilic pathogenic bacterium that is locomotive by means of a polar flagellum. From a V. vulnificus genome sequencing project, we obtained sequences of V. vulnificus flgK (Vv-flgK), flgL (Vv-flgL), and flaH (Vv-flaH) genes that encode HAP1, HAP3, and HAP2, respectively. To investigate roles of the HAP proteins, deletion mutants of the Vv-flgK, Vv-flgL and Vv-flaH were constructed. Electron microscopic analysis showed that the Vv-flgK or Vv-flgL mutant did not produce an intact polar flagellum while the Vv-flaH mutant produced a fragile flagellar structure. Western blot analysis against a major polar flagellin proposed that the null HAP1 and HAP3 mutations resulted in a failure of normal flagellar assembly since flagellins produced by the mutants were secreted out in the culture supernatants without long flagellar filaments. Motility was completely abolished by a single mutation in HAP1 or HAP3, and the HAP2 mutant showed a decreased motility. Also each of the mutants showed an impaired cytotoxicity and adherence to HeLa cell compared with the isogenic wild type strain. LD(50) increased by 10- and 11-fold in the V. vulnificus HAP3 and HAP2 mutant, respectively. These results suggest that the HAP proteins play important roles in polar flagellation and the virulence of V. vulnificus.
Bacterial Proteins ; Blotting, Western ; Electrons ; Flagella ; Flagellin ; Genome ; HeLa Cells ; Humans ; Proteins ; Sprains and Strains ; Vibrio ; Vibrio vulnificus

Human melanocytes are not simply pigment-producing cells. It may be part of the inflammatory response, during which the pigmentary system may produce more melanin or suppress melanization. Toll-like receptors (TLRs) have been implicated in both innate host defense against pathogens and inflammatory response. Therefore, it may be possible that activation of TLRs in melanocytes may play a role in the modulation of melanogenesis. In this study, we investigated whether normal human melanocytes expressed TLRs and analyzed pigmentation changes upon TLR stimulation. The expression of TLR1~10 mRNA in cultured human melanocyte was analyzed using RT-PCR, Western blotting and immunocytochemistry. Human melanocytes constitutively express mRNA and protein for TLR2, 3, 4, 5, 7, 9 and 10. Stimulation of TLR1/2 and 4 with Pam3CSK4 and lipopolysaccharide induced pigmentation of melanocytes. Activation of TLR5 and 7 with flagellin and imiquimod treatments reduced pigmentation of melanocytes and zebrafish. In summary, the results provided evidence for TLRs expression in normal human melanocytes. It is speculated that a response of melanocyte to TLR ligands may play a role in the pigmentary change in the skin.
Aminoquinolines ; Blotting, Western ; Flagellin ; Humans ; Immunohistochemistry ; Ligands ; Melanins ; Melanocytes ; Pigmentation ; RNA, Messenger ; Skin ; Toll-Like Receptors ; Zebrafish

PURPOSE: Recombinant subunit vaccines provide safe and targeted protection against microbial infections. However, the protective efficacy of recombinant subunit vaccines tends to be less potent than the whole cell vaccines, especially when they are administered through mucosal routes. We have reported that a bacterial flagellin has strong mucosal adjuvant activity to induce protective immune responses. In this study, we tested whether FlaB could be used as a fusion partner of subunit vaccine for tetanus. MATERIALS AND METHODS: We constructed fusion proteins consisted with tetanus toxin fragment C (TTFC), the nontoxic C-terminal portion of tetanus toxin, and a Toll-like receptor 5 agonist from Vibrio vulnificus (FlaB). Mice were intranasally administered with fusion protein and protective immune responses of the vaccinated mice were analyzed. RESULTS: FlaB-TTFC recombinant protein induced strong tetanus-specific antibody responses in both systemic and mucosal compartments and prolonged the survival of mice after challenge with a supra-lethal dose of tetanus toxin. CONCLUSION: This study establishes FlaB as a successful fusion partner for recombinant subunit tetanus vaccine applicable through mucosal route, and it further endorses our previous observations that FlaB could be a stable adjuvant partner for mucosal vaccines.
Animals ; Antibody Formation ; Flagellin* ; Mice ; Tetanus ; Tetanus Toxin* ; Tetanus Toxoid ; Toll-Like Receptor 5 ; Vaccines ; Vaccines, Subunit ; Vibrio vulnificus

Porcine proliferative enteropathy (PPE) caused by Lawsonia intracellularis (LI) is a global cause for substantial economic losses in the swine industry. Here, we constructed live attenuated Salmonella typhimurium (ST) mutant strains expressing and secreting 4 selected immunogenic LI antigens, namely, optA, optB, Lawsonia flagellin (LfliC), and Lawsonia hemolysin (Lhly); the resultant recombinant strains were designated Sal-optA, Sal-optB, Sal-LfliC, or Sal-Lhly, respectively. Using the BALB/c mouse model, we demonstrate that mice vaccinated once orally, either with a mixture of all 4 recombinant strains or with an individual recombinant strain, show significant (p < 0.05) production of LI-specific systemic immunoglobulin (Ig) G and mucosal IgA responses compared to the Salmonella alone group. Upon restimulation of vaccinated splenocytes with the LI-specific antigens, significant (p < 0.05) and comparable production of interferon-γ responses are found in all vaccinated groups, except the Sal-Lhly group, which shows non-significant levels. Challenge studies were performed in C57BL/6 vaccinated mice. On challenge with the LI (10(6.9) 50% tissue culture infectious dose) 14 days post-vaccination, 20% (1/5) of mice in all vaccinated groups, except Sal-Lhly group, show the presence of the LI-specific genomic DNA (gDNA) in stool samples. In contrast, 40% (2/5) and 60% (3/5) of mice vaccinated with the Sal-Lhly strain and the attenuated Salmonella alone, respectively, were found positive for the LI-specific gDNA. Furthermore, 0% mortality was observed in mice vaccinated against the ST challenge compared to the 30% mortality observed in the unvaccinated control group. In conclusion, we demonstrate that the Salmonella-based LI-vaccines induce LI-specific humoral and cell-mediated immunities, and encompass the potential to offer dual protection against PPE and salmonellosis.
Animals ; DNA ; Flagellin ; Immunity, Cellular ; Immunoglobulin A ; Immunoglobulins ; Lawsonia Bacteria ; Mice ; Mortality ; Salmonella Infections ; Salmonella typhimurium ; Salmonella ; Swine