Abstract
The hepatitis C virus (HCV) life cycle is a tightly regulated process, during which structural and non-structural proteins cooperate. However, the interplay between HCV proteins during genomic RNA replication and progeny virion assembly is not completely understood. Here, we studied the dynamics and intracellular localization of non-structural 5A protein (NS5A), which is a protein involved both in genome replication and encapsidation. An NS5A-eGFP (enhanced green fluorescent protein) tagged version of the strain JFH-1-derived wild-type HCV was compared to the corresponding assembly-deficient viruses Δcore, NS5A basic cluster 352–533 mutant (BCM), and serine cluster 451 + 454 + 457 mutant (SC). These analyses highlighted an increase of NS5A motility when the viral protein core was lacking. Although to a lesser extent, NS5A motility was also increased in the BCM virus, which is characterized by a lack of interaction of NS5A with the viral RNA, impairing HCV genome encapsidation. This observation suggests that the more static NS5A population is mainly involved in viral assembly rather than in RNA replication. Finally, NS4B exhibited a reduced co-localization with NS5A and lipid droplets for both Δcore and SC mutants, which is characterized by the absence of interaction of NS5A with core. This observation strongly suggests that NS5A is involved in targeting NS4B to lipid droplets (LDs). In summary, this work contributes to a better understanding of the interplay between HCV proteins during the viral life cycle.
Highlights
Efficient direct-acting antivirals were recently approved, hepatitis C remains a major health problem, responsible for nearly 400,000 deaths every year [1]
In order to analyze the impact of core on non-structural 5A protein (NS5A) dynamics, we generated a JFH-1derived sub-genomic replicon, where NS5A was tagged with eGFP
The hepatitis C virus (HCV) assembly process represents a complex step of the viral life cycle, which remains incompletely understood
Summary
Efficient direct-acting antivirals were recently approved, hepatitis C remains a major health problem, responsible for nearly 400,000 deaths every year [1]. The causative agent of this disease is the hepatitis C virus (HCV), which is an enveloped positive single-strand RNA virus belonging to the Flaviviridae family. HCV genome is about 9600 nucleotides long. It codes for a single polyprotein precursor [2] that is co- and post-translationally processed by both cellular and viral proteases, to generate 10 proteins [3]. The other ones are non-structural (NS) proteins NS2, NS3, NS4A, NS4B, NS5A, and NS5B, and the viroporin p7 [4]. Five of these NS proteins represent the minimal unit required for HCV RNA replication and
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