The nonstructural protein 1 of respiratory syncytial virus hijacks host mitophagy as a novel mitophagy receptor to evade the type I IFN response in HEp-2 cells

Mitochondria are good targets for viruses to manipulate their hosts. However, it remains obscure whether respiratory syncytial virus (RSV) target mitochondria to suppress the type I interferon (IFN) responses. Here, we show that nonstructural protein 1 (NS1) protein of RSV interacts with Tu translation elongation factor mitochondrial (TUFM), which can lead to its localization in mitochondria and finally induce TUFM-dependent Mitophagy and inhibition of IFNβ. Mechanically, NS1-mediated TUFM-dependent Mitophagy does not depend on the PINK1-PARKIN pathway and classic Mitophagy receptors. Importantly, NS1 may act as a new receptor protein to bridge mitochondria and autophagosomes by interacting with TUFM and LC3B. The LIR motif of NS1 protein is essential for its interaction with LC3B and is of great importance for its Mitophagy induction and IFNβ suppression. Finally, NS1-induced TUFM-dependent Mitophagy was essential for its attenuated IFNβ response using autophagy-deficient cells and mice. Our study provides a novel Mitophagy receptor molecular and a new Antiviral option by suppressing Antiviral innate immune via targeting TUFM-dependent Mitophagy. IMPORTANCE It is a worthy concern for us to understand virus-host interactions which affect progression and prognosis of disease. We demonstrated that the non-structural protein 1 of respiratory syncytial virus (RSV NS1) may act as a novel Mitophagy receptor to induce Mitophagy by binding LC3B and mitochondrial protein TUFM, and finally dampen interferon (IFN) responses induced by RIG1 and RSV Infection. TUFM is beneficial for RSV replication in vivo and vitro. It is new and interesting that RSV NS1 may function as a Mitophagy receptor to interact with LC3B. The LIR motif of NS1 protein is essential for its interaction with LC3B. We further confirm that RSV NS1 inhibited IFNβ response and promoted RSV replication in autophagy-dependent mechanisms in vivo and vitro. Our study contributes to understanding virus-host interaction, enriching our insights into RSV pathogenic mechanism and exploiting new Antiviral treatments targeting TUFM.

IFNβ; RSV NS1 protein; TUFM; mitophagy; viral replication.