Deletion of Glaesserella parasuis nanA promotes apoptosis by inhibiting PINK1/Parkin pathway.

Glaesserella parasuis (G. parasuis) is the primary pathogen responsible for Glasser's disease in large-scale pig farms. It causes annual mortality rates of 10-20% in weaned piglets due to meningitis, serositis, and sudden death syndrome. The rapid spread of multidrug-resistant strains has reduced the cure rate of macrolide antibiotics and other drugs, resulting in significant economic losses in the livestock industry. Based on a previously established Tildipirosin-resistant G. parasuis strain (Wang et al., 2025), this study confirmed that nanA is a virulence gene. To investigate its function, we constructed a ΔnanA deletion mutant. The results demonstrated that nanA deletion markedly reduced G. parasuis adhesion to PK-15 cells, cellular toxicity, and minimum inhibitory concentration (MIC), suggesting that this gene plays a crucial role in bacterial pathogenicity and resistance. Further studies revealed that G. parasuis infection induced mitophagy in PK-15 cells, a process that was significantly inhibited by the ΔnanA mutant. By knocking down the Pink1 gene, we confirmed that the ΔnanA mutant strain attenuated G. parasuis-induced mitophagy via the PINK1/Parkin signaling pathway, a mechanism validated in mouse models. Furthermore, qPCR and flow cytometry results indicated that nanA deletion exacerbated G. parasuis-induced apoptosis. In summary, this study demonstrates that G. parasuis enhances its virulence by inducing mitophagy, whereas nanA deletion promotes apoptosis by inhibiting autophagy. These findings elucidate a key aspect of G. parasuis pathogenesis and highlight the central role of NanA in this process.