Barrier-Independent, Fitness-Associated Differences in Sofosbuvir Efficacy against Hepatitis C Virus

Abstract

f Sofosbuvir displays a high phenotypic barrier to resistance, and it is a component of several combination therapies for hepatitis C virus (HCV) infections. HCV fitness can be a determinant of decreased sensitivity to direct-acting antiviral agents such as telaprevir or daclatasvir, but fitness-dependent decreased drug sensitivity has not been established for drugs with a high phenotypic barrier to resistance. Low-and high-fitness HCV populations and biological clones derived from them were used to infect Huh-7.5 hepatoma cells. Sofosbuvir efficacy was analyzed by measuring virus progeny production during several passages and by selection of possible sofosbuvir resistance mutations determined by sequencing the NS5B-coding region of the resulting populations. Sofosbuvir exhibited reduced efficacy against high-fitness HCV populations, without the acquisition of sofosbuvirspecific resistance mutations. A reduced sofosbuvir efficacy, similar to that observed with the parental populations, was seen for high-fitness individual biological clones. In independently derived high-fitness HCV populations or clones passaged in the presence of sofosbuvir, M289L was selected as the only substitution in the viral polymerase NS5B. In no case was the sofosbuvir-specific resistance substitution S282T observed. High HCV fitness can lead to decreased sensitivity to sofosbuvir, without the acquisition of specific sofosbuvir resistance mutations. Thus, fitness-dependent drug sensitivity can operate with HCV inhibitors that display a high barrier to resistance. This mechanism may underlie treatment failures not associated with selection of sofosbuvirspecific resistance mutations, linked to in vivo fitness of pretreatment viral populations. Hepatitis C virus (HCV) infection affects about 2.3% of the world population, with treatment and patient management costs being an important burden for health systems (1). Treatment efficacy, quantified as the rate of sustained viral response, has improved markedly with the introduction of direct-acting antiviral agents (DAAs) (2). DAAs include inhibitors of the viral protease NS3-4A (telaprevir [TPV], boceprevir, simeprevir, paritaprevir/ritonavir, asunaprevir, etc.), of nonstructural protein NS5A (daclatasvir [DCV], ledipasvir, ombitasvir, etc.), and the polymerase NS5B (nonnucleoside analogues, such as dasabuvir, and one nucleoside analogue, such as sofosbuvir [SOF]). Many DAAs have been licensed for human use, and others are still in preclinical and clinical assessment.A major issue in antiviral treatments is the selection of inhibitor-resistant mutants leading to treatment failure. Selection is influenced by genetic and phenotypic barriers to resistance. The genetic barrier depends on the number and type of mutations needed for the RNA to encode amino acid substitutions needed to confer resistance. The phenotypic barrier is determined by the fitness cost inflicted upon the virus by the mutations associated with resistance. Barriers vary depending on the nature of the antiviral agent, the viral ...

Guanosine inhibits hepatitis C virus replication and increases indel frequencies, associated with altered intracellular nucleotide pools

“…Here, we document inhibition of HCV replication by Gua in single and serial infections of Huh-7.5 cells that led to loss of infectivity without significant toxicity for the host cells. The antiviral action of Gua was also exerted on high fitness HCV, albeit without loss of infectivity after 5 passages in the presence of Gua, in agreement with the drug resistance phenotype displayed by high fitness HCV (Fig 1) [14][15][16][17]. The antiviral effect of Gua was not observed for FMDV in BHK-21 cells or for LCMV and VSV in Huh-7.5 cells (Fig 3).…”

“…Only the decrease in progeny production in the presence of 800 µM reached statistical significance ( Fig 1E). Thus, the results showed increased resistance of HCV p100 to Gua compared to HCV p0 (compare Fig 1A, 1B, and 1E) as was previously observed with several antiviral drugs [16,17].…”

“…The HCV p100 virus [HCV p0 passaged 100 times in Huh-7.5 reporter cells], shows a relative fitness that is 2.2 times higher than that of the HCV p0 parental population [14]. Since viral fitness can influence the response of the virus to antiviral agents [15][16][17], HCV p100 was used to study the response of a high fitness HCV to Gua. For this, HCV p100 was subjected to 5 serial passages in Huh-7.5 reporter cells using an initial m.o.i.…”

Hepatitis C virus early kinetics and resistance‐associated substitution dynamics during antiviral therapy with direct‐acting antivirals

“…RASs were detected in 7 out of 8 non‐SVR patients (88%) either at baseline or at the time of failure but even so, selection of RASs was not observed at very early time points during treatment. Treatment failure despite no evidence of selection of RAS in Patient 1 may be related to high fitness which is a potential drug resistance determinant 32,33 . In contrast, no RASs were observed at higher frequency than the clinically relevant cut‐off (15%) in the control SVR group.…”

Quasispecies dynamics in disease prevention and control

“…8.3]. HCVp45 and HCVp100 displayed significantly increased resistance to all inhibitors tested, as compared with the parental population HCVp0 Gallego et al, 2016) (Fig. 8.8).…”