KLK11 and infection: HA (hemagglutinin) and NA (neuraminidase) on the surface of the influenza virus play an important role in viral entry and release [21,22], and TLP (trypsin-like proteases) produced by oral bacteria (e.g., Staphylococcus aureus, Pseudomonas aeruginosa, and pneumococcus) mediate influenza virus HA modification to activate infection [23,24].