Construction of a Vibrio anguillarum flagellin B mutant and analysis of its immuno-stimulation effects on Macrobrachium rosenbergii

Gao, Qiang; Yi, Shaokui; Luo, Jinping; Xing, Qianqian; Lv, Jiali; Wang, Panhuang; Wang, Cuihua; Li, Yang

doi:10.1016/j.ijbiomac.2021.01.146

Cited by 2 publications

(1 citation statement)

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“…Construction of the flaB deletion mutant strain was performed as described in our previous study ( 21 ). Briefly, the upstream homologous arm fragment (593 bp) and the downstream homologous arm fragment (545 bp) of flaB were amplified, and the fusion fragment (1138 bp) was obtained by overlapping PCR using the two fragments as templates.…”

Section: Methodsmentioning

confidence: 99%

The Role of Flagellin B in Vibrio anguillarum-Induced Intestinal Immunity and Functional Domain Identification

Gao

et al. 2021

Front. Immunol.

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Vibrio anguillarum, an opportunistic pathogen of aquatic animals, moves using a filament comprised of polymerised flagellin proteins. Flagellins are essential virulence factors for V. anguillarum infection. Herein, we investigated the effects of flagellins (flaA, flaB, flaC, flaD and flaE) on cell apoptosis, TLR5 expression, and production of IL-8 and TNF-α. FlaB exhibited the strongest immunostimulation effects. To explore the functions of flaB in infection, we constructed a flaB deletion mutant using a two-step recombination method, and in vitro experiments showed a significant decrease in the expression of TLR5 and inflammatory cytokines compared with wild-type cells. However in the in vivo study, expression of inflammatory cytokines and intestinal mucosal structure showed no significant differences between groups. Additionally, flaB induced a significant increase in TLR5 expression based on microscopy analysis of fluorescently labelled TLR5, indicating interactions between the two proteins, which was confirmed by native PAGE and yeast two-hybrid assay. Molecular simulation of interactions between flaB and TLR5 was performed to identify the residues involved in binding, revealing two binding sites. Then, based on molecular dynamics simulations, we carried out thirteen site-directed mutations occurring at the amino acid sites of Q57, N83, N87, R91, D94, E122, D152, N312, R313, N320, L97, H316, I324 in binding regions of flaB protein by TLR5, respectively. Surface plasmon resonance (SPR) was employed to compare the affinities of flaB mutants for TLR5, and D152, D94, I324, N87, R313, N320 and H316 were found to mediate interactions between flaB and TLR5. Our comprehensive and systematic analysis of V. anguillarum flagellins establishes the groundwork for future design of flagellin-based vaccines.

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Section: Methodsmentioning

confidence: 99%