Study of biological activity of deletion variants of flagellin, the TLR5 agonist.

MARINA BIEDMA; GRISELDA MORENO; ANDRES HUGO ROSSI; BRUNO BLANCA; JULIEN TABAREAU; DAVID ROMANIN; PAULA M. BERGUER; JEAN CLAUDE SIRARD; MARTIN RUMBO

Mar del Palata

Congreso; LXII Reunión científica anual de la sociedad Argentina de inmunología SAI; 2014

Sociedad Argentina de Inmunología

Activation of Toll-like receptors (TLRs) results in recruitment of immune cells to the site of infection and antigen presenting cells activation and maturation, promoting the generation of a strong adaptive immune response. Consequently, TLR ligands have adjuvant properties and some of them are already used in commercial vaccines. TLR5 has a widespread distribution in mucosal epithelia and its ligand, flagellin, has been proposed as mucosal adjuvant. Flagellin includes four domains, D0, D1, D2 y D3, being D0 and D1 involved in TLR5 activation, whereas D2 and D3 contain the main antigenic sites of the molecule. However, the contribution of D2 and D3 to TLR5 activation has not been fully explored. In the present work, we used 8 different flagellin deletion variants affecting different domains: FliC WT (no deletion), FliC Δ200-369, FLiC Δ61-405, FLiC Δ100-405 6H, FLiC Δ138/160 174-450 6H, FliC Δ174-400, FliC Δ174-400 6H, FliC Δ138-405 6H. Our aim was to analyze the capacity to activate TLR5 of these different variants using a TLR5-responsive reporter cellular system (Caco2-CCL20-luciferase). Furthermore, the structural properties of the different variants were analyzed by circular dichroism (CD). In spite that all variants have intact D0 and D1 domains, we found that the deletions affect differentially the capacity to trigger TLR5. FliC Δ200-369 has the same capacity to activate TLR5 than the wild type variant, whereas other deletions affected significantly this activity (p