Msp impairs neutrophil chemotaxis in whole bacteria. In a transwell chemotaxis assay, murine neutrophils were exposed to T. denticola 35405 wild type or MHE (Msp mutant) bacteria for 1 hour to allow chemotaxis toward the bacteria through a membrane. Cells that migrated across the membrane were fixed, stained with crystal violet, and counted. Neutrophils exposed to the wild type and MHE bacterial strains were compared to each other, with more neutrophils migrated toward MHE than the wild type strain. Neutrophils alone and unstimulated with fMLP served as a negative control, while neutrophils stimulated with fMLP as the positive control for neutrophil chemotaxis and were compared to each other. Results were normalized to the control +fMLP. Graphs represents mean ± SEM of 3 independent experiments (*** P < 0.001 and **** P < 0.0001 by unpaired t test).