Experiments were conducted using OMVs, <sup>PPAD-OE</sup>OMVs, and <sup>ΔPPAD</sup>OMVs to identify the special virulence factors in OMVs.<h4>Results</h4>This study revealed that serum levels of SDC1 and HS were significantly higher in patients with stage III-IV periodontitis (P < 0.05). Here, SDC1 is linked to periodontitis.