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Updated: Jan 5, 2026
Use of Viral Entry Assays and Molecular Docking Analysis for the Identification of Antiviral Candidates against Coxsackievirus A16
Published on: July 15, 2019
U18666A inhibits classical swine fever virus replication through interference with intracellular cholesterol
Xiao-Dong Liang1, Yun-Na Zhang1, Chun-Chun Liu1
1MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.
Abstract:
The level of cholesterol in host cells has been demonstrated to affect viral infection. Our previous studies showed that cholesterol-rich membrane rafts mediated the entry of classical swine fever virus (CSFV) into PK-15 or 3D4/21 cells, but the role of cholesterol post entry was still not clear. In this study, we found that CSFV replication before fusion was affected when the cholesterol trafficking in infected cells was disrupted using a cholesterol transport inhibitor, U18666A. Our data showed that U18666A affected both the fusion and replication steps in the life cycle of the virus, but not its binding and entry steps. The subsequent experiments confirmed that niemann-pick C1 (NPC1), a lysosomal membrane protein that helps cholesterol to leave the lysosome, was affected by U18666A, which led to the accumulation of cholesterol in lysosomes and inhibition of CSFV replication. Imipramine, a cationic hydrophobic amine similar to U18666A, also inhibited CSFV replication via similar mechanism. Surprisingly, the antiviral effect of U18666A was restored by the histone deacetylase inhibitor (HDACi), Vorinostat, which suggested that HDACi reverted the dysfunction of NPC1, and intra-cellular cholesterol accumulation disappeared and CSFV replicability resumed. Together, these data indicated that CSFV transformed from early endosome and late endosome into lysosome after endocytosis for further replication and that U18666A was a potential drug candidate for anti-pestivirus treatment.
Insights
Disrupting cholesterol transport with U18666A inhibits classical swine fever virus (CSFV) replication by affecting fusion and lysosomal function. Histone deacetylase inhibitors like Vorinostat can restore viral replication by correcting NPC1 dysfunction.
Area of Science:
- Virology
- Cell Biology
- Biochemistry
Background:
- Host cell cholesterol levels influence viral infections.
- Cholesterol-rich membrane rafts are crucial for classical swine fever virus (CSFV) entry.
- The role of cholesterol post-entry in CSFV infection was previously unclear.
Purpose of the Study:
- To investigate the role of cholesterol trafficking in CSFV replication after viral entry.
- To identify host factors and pathways targeted by cholesterol-modulating drugs for antiviral therapy.
Main Methods:
- Utilized the cholesterol transport inhibitor U18666A to disrupt cellular cholesterol trafficking in infected cells.
- Examined the effects of U18666A on CSFV binding, entry, fusion, and replication.
- Investigated the role of Niemann-Pick C1 (NPC1) protein in U18666A-mediated antiviral effects.
- Assessed the impact of imipramine and histone deacetylase inhibitors (HDACi), specifically Vorinostat, on CSFV replication and cholesterol accumulation.
Main Results:
- U18666A inhibited CSFV replication by affecting fusion and post-entry steps, not binding or entry.
- U18666A disrupted Niemann-Pick C1 (NPC1) function, leading to cholesterol accumulation in lysosomes and reduced CSFV replication.
- Imipramine exhibited similar antiviral effects via a comparable mechanism.
- Vorinostat reversed the antiviral effects of U18666A by restoring NPC1 function and reducing intracellular cholesterol accumulation, thereby resuming CSFV replication.
- CSFV was shown to traffic from early and late endosomes to lysosomes for replication.
Conclusions:
- Disruption of cholesterol trafficking, particularly NPC1 function, is a critical factor in inhibiting CSFV replication.
- U18666A demonstrates potential as an antiviral agent against pestiviruses by targeting host cholesterol metabolism.
- HDAC inhibitors like Vorinostat can counteract the antiviral effects of cholesterol transport inhibitors, highlighting a complex interplay between host pathways and viral replication.
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