The Acid Ceramidase Is a SARS-CoV-2 Host Factor

Area of Science:

• Virology
• Biochemistry
• Drug Discovery

Background:

• SARS-CoV-2 variants necessitate new therapeutic strategies.
• Fluoxetine was previously shown to inhibit viral entry by targeting acid sphingomyelinase (ASM).
• The role of acid ceramidase in SARS-CoV-2 infection was unexplored.

Purpose of the Study:

• To identify acid ceramidase as a novel target of fluoxetine.
• To investigate the mechanism by which fluoxetine and its derivative AKS466 inhibit SARS-CoV-2 replication.
• To explore the potential of targeting acid ceramidase for COVID-19 treatment.

Main Methods:

• Synthesis of an ASM-independent fluoxetine derivative (AKS466).
• High-resolution SARS-CoV-2-RNA Fluorescence In Situ Hybridization (FISH) and RTqPCR.
• Biochemical assays to assess enzyme activity, lysosomal pH, and cellular localization.
• Treatment with specific inhibitors and exogenous supplementation.

Main Results:

• AKS466 down-regulates SARS-CoV-2 gene expression.
• SARS-CoV-2 infection deacidifies lysosomal pH via ORF3 protein; AKS466 and fluoxetine reverse this.
• AKS466 and fluoxetine inhibit acid ceramidase, elevate endo-lysosomal ceramide, and impede viral replication.
• Specific acid ceramidase inhibitor Ceranib-2 and C6-ceramide supplementation reduce viral replication.

Conclusions:

• Acid ceramidase is a SARS-CoV-2 host factor essential for viral replication.
• Fluoxetine and AKS466 exert antiviral effects by inhibiting acid ceramidase and modulating lysosomal function.
• Targeting acid ceramidase presents a promising therapeutic avenue against SARS-CoV-2.