Background: Capsid assembly modulators (CAMs) have emerged as a promising class of antiviral agents. We studied the effects of twenty-one newly designed and synthesized CAMs including heteroaryldihydropyrimidine compounds (HAPs), their analogs and standard compounds on hepatitis B virus (HBV) capsid assembly. Methods: Cytoplasmic expression of the HBV core (HBc) gene driven by the exogenously delivered recombinant alphavirus RNA replicon was used for high level production of the full-length HBc protein in mammalian cells. HBV capsid assembly was assessed by native agarose gel immunoblot analysis, electron microscopy and inhibition of virion secretion in HepG2.2.15 HBV producing cell line. Induced fit docking simulation was applied for modelling the structural relationships of the synthesized compounds and HBc. Results: The most efficient were the HAP class compounds—dihydropyrimidine 5-carboxylic acid n-alkoxyalkyl esters, which induced the formation of incorrectly assembled capsid products and their accumulation within the cells. HBc product accumulation in the cells was not detected with the reference HAP compound Bay 41-4109, suggesting different modes of action. A significant antiviral effect and substantially reduced toxicity were revealed for two of the synthesized compounds. Conclusions: Two new HAP compounds revealed a significant antiviral effect and a favorable toxicity profile that allows these compounds to be considered promising leads and drug candidates for the treatment of HBV infection. The established alphavirus based HBc expression approach allows for the specific selection of capsid assembly modulators directly in the natural cell environment.
An estimated 240 million persons worldwide are chronically infected with hepatitis B virus (HBV). Chronic hepatitis B (CHB) in up to 40% of cases progresses to liver cirrhosis, hepatic decompensation, and hepatocellular carcinoma, a leading cause of cancer-related morbidity and mortality worldwide [1]. We are focused on original antiviral strategy intended to suppress the self-assembly process of HBV core (HBc) protein as one of the promising ways to cure CHB without induction of drug resistance. Targeting the capsid protein of HBV and thus interrupting normal capsid formation have been an attractive approach to block the replication of HBV.Heteroaryldihydropyrimidines (HAPs) were shown to bind the HBV core proteins and misdirect the assembly of the capsid in vitro. We carried out structural optimizations based on HAPs analogue Bay 41-4109 and structure-activity relationship studies [2].Newly synthesized HAPs 1 and 2 were evaluated for their ability to disrupt the capsid assembly in cell culture, and promising candidates were selected for further evaluation of antiviral activity and discovery of mechanisms of compound action.
Acknowledgments:The author gratefully acknowledges Gunārs and Renāte Duburi for provided scholarship.
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