Carrimycin exhibited broad spectrum inhibitory activities against coronaviruses replication through down-regulating...

Area of Science:

• Virology
• Molecular Biology
• Drug Discovery

Background:

• Carrimycin previously demonstrated pan-coronavirus inhibitory activity, targeting post-entry replication.
• The drug interferes with viral protein translation and nascent viral RNA synthesis.

Purpose of the Study:

• To investigate carrimycin's efficacy against emerging SARS-CoV-2 variants.
• To elucidate the specific host factors and mechanisms involved in carrimycin's antiviral action.

Main Methods:

• Dose-dependent inhibition assays of viral RNA and protein levels in Vero E6 cells.
• Investigation of carrimycin's effect on SARS-CoV-2 double membrane vesicle (DMV) formation.
• Analysis of the role of host transmembrane protein 41B (TMEM41B) in viral replication and carrimycin's mechanism.
• Biochemical assays to determine carrimycin's direct binding to TMEM41B and its effect on TMEM41B ubiquitination and degradation.

Main Results:

• Carrimycin dose-dependently inhibited viral RNA and protein levels in SARS-CoV-2 infected cells.
• Carrimycin disrupted the formation of SARS-CoV-2 DMVs, a process dependent on TMEM41B.
• TMEM41B overexpression enhanced viral replication, while its knockdown reduced it, confirming its role as a host factor.
• Carrimycin directly binds to TMEM41B, inducing its K48-linked ubiquitination and subsequent degradation, thereby inhibiting viral replication.

Conclusions:

• Carrimycin exhibits potent antiviral activity against SARS-CoV-2 variants by targeting the host factor TMEM41B.
• The drug's mechanism involves the degradation of TMEM41B, disrupting viral replication processes.
• These findings deepen the understanding of carrimycin's antiviral mechanisms and highlight the significance of host factors in viral pathogenesis and therapeutic strategies.