LDHA-lactate axis modulates mitophagy inhibiting CSFV replication.

Lactate dehydrogenase A (LDHA) plays a crucial role in regulating lactate synthesis in various biological processes. Lactate, a byproduct of glycometabolism, has been recognized as a unique molecule with implications in both metabolism and immunity. Classical swine fever (CSF), caused by the classical swine fever virus (CSFV), is a highly contagious and severe infectious disease that primarily affects pigs. Prior research has shown that CSFV infection disrupts the normal glycolytic process, leading to an accumulation of lactate within the host. Nevertheless, it remains unclear whether there is mutual regulation between the CSFV and LDHA-lactate axis. Here, we have found that CSFV infection increases LDHA expression in vivo and in vitro, which may be attributed to attenuated ISGylation of LDHA. Furthermore, CSFV infection induces L-lactate production via LDHA dependence in vitro. The cellular biology research on LDHA has revealed that LDHA not only localizes to the mitochondria but also inhibits PINK1-Parkin-mediated mitophagy. Through various experimental techniques such as western blot to detect mitophagy marker proteins, laser confocal microscopy to observe the flow of mitophagy, and transmission electron microscopy to assess changes in the number of mitochondria enclosed within autophagosome-like vesicles, it has been discovered that the addition of exogenous lactate can inhibit PINK1-Parkin-mediated mitophagy. Importantly, we have observed that lactate activates the JAK1-STAT1-ISG15 network and suppresses CSFV replication by antagonizing CCCP-induced mitophagy. These results represent the first report on the mechanisms through which the LDHA-lactate axis regulates mitophagy, the JAK-STAT pathway, and CSFV replication. This study provides novel insights into the roles of the LDHA-lactate axis in glycometabolism and viral replication.

Importance: This research unveils how CSFV interacts with cellular metabolism through LDHA. By revealing LDHA's dual role and how lactate influences cellular processes during CSFV infection, this study uncovers new pathways for viral replication. These findings not only deepen our understanding of viral-host interactions but also open doors for innovative antiviral strategies centered around manipulating cellular metabolism.