MMP9 and susceptibility to pneumonia measurement: The protease encoded by zmpC cleaves human matrix metalloproteinase 9 and has, in mouse pneumonia models, been correlated to increased virulence in comparison to knockout strains (Oggioni et al., 2003) and inhibit neutrophil influx to the lung by cleavage of P-Selectin Glycoprotein 1 (Surewaard et al., 2013).