Recombinant flagellins with deletions in domains D1, D2, and D3: characterization as novel immunoadjuvants

BIEDMA ME; CAYET D; TABAREAU J; ROSSI AH; IVIčAK-KOCJAN K; MORENO G; ERREA A; SOULARD D; PARISI G; JERALA R; BERGUER P; RUMBO M; SIRARD JC

VACCINE

ELSEVIER SCI LTD

Lugar: Amsterdam; Año: 2019 vol. 37 p. 652 - 663

0264-410X

Bacterialflagellin activates the innate immune system and ultimately theadaptive immune system through a Toll-like receptor 5(TLR5)-dependent signaling mechanism. Given that TLR5 is widelydistributed in epithelia, flagellin is currently being developed as amucosal adjuvant. Flagellin FliC has four domains: the conserved D0and D1 domains and the hypervariable D2 and D3 domains. The deletionof D3 and partial deletion of D2 in the recombinant FliC∆174-400strongly impairs flagellin?s intrinsic antigenicity but does notaffect the TLR5-dependent immunostimulation activity,i.e., the capacity to promote innate responses and adaptive responsesto co-administered antigens. Here, we describe the development ofnovel recombinant flagellins with various deletions encompassing allof D2 and D3, and part of D1. Most of the recombinant moleculesconserved an -helicalsecondary structure that was as resistant to heat denaturation as thenative protein. Whereas the recombinant flagellins? ability totrigger TLR5 varied markedly invitro,most gave equivalent invivo TLR5-dependentinnate immune responses following intranasal administration of 2 gof flagellin to mice. Concordantly, therecombinant flagellinswere also valuable respiratory adjuvants for eliciting antibodyresponses to the foreign antigen ovalbumin, although their intrinsicantigenicity was decreased compared to the native flagellin and notincreased compared to FliC∆174-400.Our results show that the additional deletions of D2 and the distalpart of D1 of FliC∆174-400does not impact on antigenicity and does not significantly modify theimmunostimulatory adjuvant activity. Altogether, this study generateda novel set of recombinant flagellin that constitutes a portfolio ofTLR5-dependent candidate adjuvants for vaccination.p { margin-bottom: 0.25cm; direction: ltr; line-height: 115%; text-align: left; }p.western { font-family: "Cambria", serif; font-size: 12pt; }p.cjk { font-family: "MS Mincho"; font-size: 12pt; }p.ctl { font-size: 12pt; }a:link { color: rgb(0, 0, 255); }a.ctl:link { font-family: "Times New Roman"; }