The LC-MS-based secretome analysis of S. suis WUSS351 provided direct evidence for the T7SS-dependent secretion of LXG effectors. Although LXG1-CT3, LXG5-CT2 and LXG5-CT1 were not directly detected in the secretomes—potentially due to low abundance or technical limitations—their corresponding DUF4176 chaperones exhibited higher expression levels in the WT secretome compared to the ∆T7SS mutant. This observation implies a coordinated upregulation of effector-chaperone pairs when the T7SS is functional.