The primary role of the MAVS signalosome seems to be in inducing apoptosis of the cell after detection of viral nucleic acids (viral RNA) and apoptosis (followed by subsequent autophagy) is a crucial aspect in the antiviral response.

Introduction to the function of the MAVS Signalosome

The 9b accessory protein has two main functions in protein degradation in the mitochondria of the host cell: 
- leads to elongation of the mitochondria by targeting the DRP1 protein
- targets MAVS signalosome (leads to apoptosis)

Ohio State University, Columbus

While the main function of mitochondria is in providing energy for the cell, it also harbors important roles in factors such as cell death (apoptosis) and in the innate antiviral response.

Introduction to the Function of Mitochondria (in regards to Antiviral Response)

Shi, C. S., Qi, H. Y., Boularan, C., Huang, N. N., Abu-Asab, M., Shelhamer, J. H., & Kehrl, J. H. (2014). SARS-coronavirus open reading frame-9b suppresses innate immunity by targeting mitochondria and the MAVS/TRAF3/TRAF6 signalosome. The Journal of Immunology, 193(6), 3080-3089. https://doi.org/10.4049/jimmunol.1303196

SARS-coronavirus open reading frame-9b suppresses innate immunity by targeting mitochondria and the MAVS/TRAF3/TRAF6 signalosome

Relationship between ORF9b Acessory Protein and the Mitochondria of Host cells

The 9b accessory protein facilitates the elongation of the mitochondria by initiating a sequence of events that begin with attaching a small molecule known as ubiquitin (a process known as ubiquitination) to the DRP1 protein (dynamin-like protein) and this essentially tags the DRP1 protein for degradation in the proteasome (protease complex responsible for protein degradation). The elongation of the mitochondria is a factor that may lead to the suppression and potential evasion of the innate response triggered by the host.

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