Mitochondrial OXPHOS restricts SARS-CoV-2 replication.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) rewires host metabolism to optimize virus production. Although glycolysis is necessary for virus production, the importance of mitochondrial oxidative phosphorylation (OXPHOS) is unknown. The mitochondrial DNA (mtDNA) codes for 13 critical OXPHOS polypeptides plus the 22 transfer RNAs (tRNAs) and 2 ribosomal RNAs (rRNAs) for mitochondrial protein synthesis. We found an ∼5- to 100-fold greater SARS-CoV-2 virus production in infected human ACE2-expressing A549 lung cells when OXPHOS was inhibited by mtDNA depletion (ρ0 cells), inhibition of mitochondrial translation with chloramphenicol (CAP), or chemical inhibition of OXPHOS complexes. OXPHOS inhibition led to a marked increase in the size and distribution of viral replication centers and accelerated the production and release of infectious particles, occurring ∼2 hours earlier than in parental A549-ACE2 (wild type) cells. Subsequently, we found that increased glycolytic capacity was required for enhanced viral replication whereas differences in innate immune pathway activation were not. Reintroduction of mtDNA from a well-defined maternal lineage into the ρ0 cells reinstated OXPHOS, impaired SARS-CoV-2 replication, and reversed associated viral and glycolytic correlates. Thus, metabolic balance regulates SARS-CoV-2 replication, with OXPHOS exerting an antiviral effect.