The severe acute respiratory syndrome coronavirus type 1 (SARS-CoV-1) open reading frame-9b protein (ORF-9b or 9b) is an accessory protein that may have a function during virus assembly (Xu K, et al. 2009) and may influence virus-host interplay and pathogenesis (Shi CS et al. 2014; Jiang HW et al. 2020). SARS-CoV-1 9b is highly homologous to SARS-CoV-2 9b (Jiang HW et al. 2020; Gordon DE et al. 2020). Viral 9b of both SARS-CoV-1 and SARS-CoV-2 were found to localize to the membrane of mitochondria to suppress host innate immunity (Shi CS et al. 2014; Jiang HW et al. 2020; Gordon DE et al. 2020). Viral 9b targets the mitochondrial antiviral signaling protein (MAVS) signalosome (Shi CS et al. 2014). 9b was shown to recruit poly(rC) binding protein 2 (PCBP2) and the HECT domain E3 ligase AIP4 (ITCH) to trigger the K48-linked polyubiquitination and subsequent degradation of MAVS via the proteasomal pathway (Shi CS et al. 2014). The structural studies revealed that viral 9b forms a 2-fold symmetric dimer constructed from two adjacent twisted β sheets with an amphipathic surface, and a central hydrophobic cavity that is thought to be involved in membrane attachment (Meier C et al. 2006). Self-interactions of 9b were also shown by co-immunoprecipitation (CoIP) assay in human embryonic kidney (HEK 293T) cells (von Brunn A et al. 2007).