D-alanylation of Teichoic Acids in Bacilli impedes the immune sensing of peptidoglycan in Drosophila

Modification of cell wall components is a prominent mean for pathogens to hinder host immune defenses. Here, using the model, we aimed at characterizing the role of D-alanine esterification of teichoic acids (TAs) in the resistance of to host defenses . We show that, by preventing cationic antimicrobial effectors-mediated bacterial lysis, this cell wall modification also limits the release of peptidoglycan immunostimulatory fragments thus impeding their sensing and the subsequent induction of the IMD- NF-κB pathway. Interestingly, we show that this strategy is also adopted by , a commensal, to fine-tune its immunomodulatory potential in the gut. Markedly, we show that the D-alanylation of TAs is essential for the resistance of to gut lysozyme. Altogether our data shed light on the mechanism underlying the persistence and the low immunostimulatory potential of in the gut.