Structural basis for human Cav1.2 inhibition by multiple drugs and the neurotoxin calciseptine.

Cav1.2 channels play crucial roles in various neuronal and physiological processes. Here, we present cryo-EM structures of human Cav1.2, both in its apo form and in complex with several drugs, as well as the peptide neurotoxin calciseptine. Most structures, apo or bound to calciseptine, amlodipine, or a combination of amiodarone and sofosbuvir, exhibit a consistent inactivated conformation with a sealed gate, three up voltage-sensing domains (VSDs), and a down VSDII. Calciseptine sits on the shoulder of the pore domain, away from the permeation path. In contrast, when pinaverium bromide, an antispasmodic drug, is inserted into a cavity reminiscent of the IFM-binding site in Nav channels, a series of structural changes occur, including upward movement of VSDII coupled with dilation of the selectivity filter and its surrounding segments in repeat III. Meanwhile, S4-5III merges with S5III to become a single helix, resulting in a widened but still non-conductive intracellular gate.

Structural basis for the severe adverse interaction of sofosbuvir and amiodarone on L-type Cav channels.

Drug-drug interaction of the antiviral sofosbuvir and the antiarrhythmics amiodarone has been reported to cause fatal heartbeat slowing. Sofosbuvir and its analog, MNI-1, were reported to potentiate the inhibition of cardiomyocyte calcium handling by amiodarone, which functions as a multi-channel antagonist, and implicate its inhibitory effect on L-type Cav channels, but the molecular mechanism has remained unclear. Here we present systematic cryo-EM structural analysis of Cav1.1 and Cav1.3 treated with amiodarone or sofosbuvir alone, or sofosbuvir/MNI-1 combined with amiodarone. Whereas amiodarone alone occupies the dihydropyridine binding site, sofosbuvir is not found in the channel when applied on its own. In the presence of amiodarone, sofosbuvir/MNI-1 is anchored in the central cavity of the pore domain through specific interaction with amiodarone and directly obstructs the ion permeation path. Our study reveals the molecular basis for the physical, pharmacodynamic interaction of two drugs on the scaffold of Cav channels.

Population pharmacokinetics of ravidasvir in adults with chronic hepatitis C virus infection and impact of antiretroviral treatment.

Ravidasvir (RDV) is a novel NS5A inhibitor that exhibits potent pan-genotypic inhibition of hepatitis C virus (HCV) replication. Sofosbuvir (SOF) plus RDV was demonstrated to be efficacious and safe in adults with active HCV infection, including those living with HIV (LWHIV), in the STORM-C-1 trial. We assessed the population pharmacokinetics (PK) of RDV in a sub-study nested within STORM-C-1 conducted in Thailand and Malaysia. SOF (400 mg) plus RDV (200 mg) was administered orally once daily for 12 weeks to adults with chronic HCV infection, but without cirrhosis and for 24 weeks to those with compensated cirrhosis. Intensive and sparse PK samples were collected at 4, 8, and 12 weeks after treatment initiation. Population PK parameters of RDV and the impact of covariates were evaluated using nonlinear mixed-effects modeling. Five hundred ninety-four participants were included, 235 (40%) had compensated cirrhosis, and 189 (32%) were LWHIV. RDV plasma concentrations were best described by a two-compartment model with first-order elimination. Oral clearance (CL/F) and volume of distribution (Vd/F) parameters were allometrically scaled on fat-free mass. Concomitant antiretroviral treatment (ART) increased RDV CL/F by 30%-60%, with efavirenz-based ART having the largest impact. Females had 16% lower RDV CL/F than males, and higher albumin levels reduced RDV central volume of distribution. While several covariates impact RDV CL/F and Vd/F, the effect on RDV exposures was not clinically relevant based on the efficacy data reported in this diverse Asian adult population. There were no meaningful drug-drug interactions in adults LWHIV on ART.

A novel test and treat program for hepatitis C virus infection utilizing HCV core antigen testing, among police and general population, Islamabad, Pakistan, 2022.

Hepatitis C virus core antigen (HCVcAg) testing can simplify and decrease costs of HCV infection confirmation compared to molecular testing (nucleic acid testing). We piloted HCVcAg testing for the confirmation of active infection. The study was conducted during June through December 2022 among the police and the general population of Islamabad, Pakistan age 18 years and older. Initial screening for HCV antibody was conducted using a rapid diagnostic test (RDT) for all consenting participants. Those who tested positive had venous blood samples tested for HCVcAg, platelets and aspartate aminotransferase (AST). Persons with HCVcAg values ≥3 fmol/L were defined as viremic, and they were offered treatment with direct acting antiviral (DAA) medications, sofosbuvir and daclatasvir. Aspartate aminotransferase to platelet ratio index (APRI) was calculated for each HCV infected person, and those with an APRI score <1.5 received treatment for 12 weeks, while those with APRI ≥ to 1.5 received 24 weeks of treatment. A total of 15,628 persons were screened for anti-HCV using RDT and 643 (4.1%) tested positive. HCVcAg values of ≥3 fmol/L was found in 399/643 (62.1%), and all were offered and accepted treatment. Of those treated, 273/399 (68.4%) returned for a follow-up SVR and HCVcAg was not detected in 261/273, a 95.6% cure rate. The pilot study demonstrated the effectiveness of reaching and treating an urban population using RDT for screening and HCVcAg for confirmation of infection and test of cure.

Health-related quality of life in patients aged 6-18 years with chronic hepatitis C treated with sofosbuvir/velpatasvir.

BACKGROUND & AIMS: The aim of this study was to assess the effect of treatment with sofosbuvir/velpatasvir (SOF/VEL) on the health-related quality of life (HRQL) of children with chronic hepatitis C. METHODS: In the non-commercial, non-randomized, open-label PANDAA-PED study, 50 children aged 6-18 years with chronic hepatitis C were treated with a fixed dose of SOF/VEL. All patients achieved sustained virologic response 12 weeks after the end of treatment (SVR12). Evaluation of HRQL was performed twice: at baseline (before the treatment) and during the SVR12 analysis using the KIDSCREEN-27 questionnaires, which included 5 dimensions of HRQL, for child self-reporting and parent proxy reporting. The normal range for the population was set to T values of 50 ± 10 points. Child-parent agreement was analysed using the intra-class correlation coefficient (ICC) and Bland-Altman test. RESULTS: Mean T values were within the normal range for all dimensions, both before and after treatment. There was a significant improvement in physical well-being based on the children's self-assessment (from 48.53 to 51.21, p = .03). In addition, a trend towards better scores in the 'social support & peers' part of the parent proxy evaluation (from 45.98 to 48.66, p = .06) was noticed. After the treatment, the proportion of children self-assessing their physical well-being as below normal significantly decreased from 17% to 5% (p = .007). HRQL scores were not associated with patients' sex, but in most cases, younger age correlated with better HRQL. Evaluation of the ICC for child self-reports versus parent proxy reports revealed poor to moderate agreement for most single measures. Bland-Altman analysis showed that in all dimensions, both before and after treatment, the limits of agreement (LoAs) exceeded ±5 points (half of the SD and considered a maximum allowed difference). CONCLUSIONS: A significant proportion of children with chronic hepatitis C have decreased HRQL in all dimensions, but effective treatment with SOF/VEL leads to an improvement in some areas of well-being. As the effect of HCV on HRQL is more pronounced in older patients, treatment of younger children should be indicated to prevent them from experiencing decreased HRQL due to ongoing HCV infection in the future.

Comparative efficacy and safety of Sofosbuvir/Velpatasvir and Danoprevir for the treatment of chronic hepatitis C: the real-world data in China.

BACKGROUND: Sofosbuvir/Velpatasvir (Epclusa, ECS) is the first pan-genotype direct-acting antiviral agent (DAA) for hepatitis C virus (HCV) infection, and Danoprevir (DNV) is the first DAA developed by a Chinese local enterprise, which is suitable for combined use with other drugs to treat genotype 1b chronic hepatitis C. However, previous reports have never compared the real-world data of ECS and DNV. PATIENTS AND METHODS: 178 chronic hepatitis C patients were retrospectively recruited, and 94cases were accepted with Sofosbuvir/Velpatasvir ± Ribavirin (ECS group), and others (n = 84 treated with DNV combination therapy (DNV group). The HCV genotype, virological response, adverse effects and some laboratory biochemical indexes were contrasted between above two groups in the real world study. RESULTS: DNV group had significantly lower level of alpha-fetoprotein (AFP), lower rates of decompensated cirrhosis ( P < 0.05). ECS group possessed more 6a (31.91% vs.13.10%) while DNV group was provided with more 1b (48.81% vs. 22.34%) patients. Significantly poor liver function was detected in ECS group at 4-week treatment (ALT and AST) and 12-week follow-up (AST) (all P < 0.05). The SVR12 undetectable rates of both groups were 100%, and no serious event was observed during the treatment and follow-up in both groups. CONCLUSION: In this retrospective real-world study, the efficacy of DNV combined therapy is similar to Sofosbuvir/Velpatasvir ± Ribavirin for chronic HCV infection, and the safety is comparable. DNV based therapy is a promising regimen for chronic hepatitis C.

Serum MicroRNA profiles in chronic hepatitis C Egyptian patients before and after combined sofosbuvir and daclatasvir treatment.

BACKGROUND: MicroRNAs (miR) are small sequence of nucleotides that can affect multiple genes involved in the hepatitis C virus (HCV) life cycle and disease development. The purpose of the present study was to investigate the clinical significance of serum microRNA profiles in a cohort of Egyptian patients with chronic HCV infection before and after combined sofosbuvir and daclatasvir treatment, as well as to gain a better understanding of the exact interaction mechanism in HCV transcriptional activity via differentially expressed miRNAs. For 12 weeks, 50 patients were eligible for and received sofosbuvir (400 mg daily) and daclatasvir (60 mg daily) treatment. Each patient's blood was obtained twice: once before therapy began and again three months afterwards. RESULTS: The current study found that serum levels of circulating miR-122, miR-221, miR-23a, miR-125, miR-217, miR-224, and miR-181a were high in HCV pre-treatment patients, but after 12 weeks of direct-acting antiviral (DAAs) treatment, there was a statistically significant reduction in expression levels of miR-122, miR-221, miR-23a, miR-125, miR-217, and miR-224 (p < 0.001). There is no statistical significance for miR-181a. CONCLUSION: The key differentially expressed microRNAs before and after the direct-acting antiviral (DAA) regimen were connected to the dynamics of chronic HCV infection, suggesting their potential as predictive biomarkers for HCV clearance after sofosbuvir and daclatasvir therapy.

Cardiac effects of direct anti-viral treatment in type II diabetic patients with hepatitis C infection.

BACKGROUND: The link between diabetes mellitus and chronic hepatitis C infection remains well established. It is estimated that up to one third of chronic hepatitis C patients have type II diabetes mellitus. Hepatitis C virus infection is one of the main global health burdens. Sofosbuvir and Daclatasvir are used as effective antiviral inhibitors of hepatitis C virus. The cardiovascular effects of those drugs are not well studied. We used electrocardiography and echocardiography with global longitudinal strain assessment by speckle tracking to detect their effect on cardiac function. METHODS AND RESULTS: One hundred diabetic patients with hepatitis C infection were included in the study. Abdominal ultrasound and laboratory work up were carried out for all participants. Left ventricular systolic and diastolic function were assessed by 2D-echocardiography and global longitudinal strain, before and 3 months after treatment. Results showed significant decrease in global longitudinal strain 3 months after therapy (-21 ± 4 vs. -18 ± 7; P < 0.001) but other echocardiographic findings showed no significant changes. CONCLUSIONS: Sofosbuvir and Daclatasvir were associated with early left ventricular systolic dysfunction as assessed by global longitudinal strain in diabetic patients. More deterioration in left ventricular systolic function was detected among those with Child-Pough class B. Further long-term follow-up may be required.

Direct-Acting Antiviral Therapy for Patients with Chronic Hepatitis C Infection and Decompensated Cirrhosis.

Patients with chronic hepatitis C virus (HCV) infection and decompensated cirrhosis are an important population for antiviral therapy yet under-represented in clinical trials. HCV direct-acting antiviral (DAA) therapies, unlike interferon-containing regimens, can be safely utilized in decompensated patients. Per guidelines from the American Association for the Study of Liver Diseases (AASLD), therapy of choice in HCV and decompensated cirrhosis is sofosbuvir, an HCV polymerase inhibitor, combined with a replication complex inhibitor (NS5A inhibitor) with or without ribavirin. Combination therapy with a HCV protease inhibitor and an NS5A inhibitor is effective in this population but is specifically not recommended in AASLD guidelines due to safety concerns. Important risk factors for further decompensation during DAA therapy are serum albumin < 3.5 g/dL, MELD (Model for End-Stage Liver Disease) score > 14, or HCV genotype 3 infection. Although sustained virologic response (SVR) is achieved less often in patients with decompensated vs compensated cirrhosis, in clinical studies response rates are > 80%. Both Child-Turcotte-Pugh Class at baseline and viral genotype can affect these response rates. Achieving SVR lowers risk of mortality, but to a lesser extent than in individuals with compensated cirrhosis. Likewise, treating patients for HCV infection along with successful treatment for hepatocellular carcinoma improves risks of both liver-related and overall mortality. In fewer than one third of cases, treating transplant-eligible, HCV-infected patients pre-transplant enables their delisting from transplant wait lists.

A new fluorescence probe for sofosbuvir analysis in dosage form and spiked human plasma.

A simple, rapid, and low-cost technique was developed to allow reliable analysis of the anti-hepatitis C drug sofosbuvir in bulk, tablet form, and spiked human plasma. This method depends on the ability of sofosbuvir to quench the fluorescence of the newly synthesized 2-amino-3-cyano-4,6-dimethylpyridine (reagent 3). Elemental analysis and spectral data were used to validate the structure of the synthesized reagent. The newly synthesized reagent exhibited a satisfactory level of fluorescence emission at 365 nm after excitation at 247 nm. All experimental variables that might affect the quenching process were analyzed and optimized. Linearity, range, accuracy, precision, limit of detection (LOD), and limit of quantitation (LOQ) were all validated in accordance with the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICH) guidelines. The concentration range was shown to be linear between 0.1 and 1.5 µg/mL. The technique was effectively utilized for sofosbuvir analysis in both its tablet dosage form and spiked human plasma, with mean percentage recoveries of 100.13 ± 0.35 and 94.26 ± 1.69, respectively.

Morphometric, biochemical and histopathological effects of sofosbuvir (sovaldi) on testes of adult male albino rats.

Sofosbuvir treatment regimens for chronic HCV infection have recently been linked to extra hepatic side effects. This study aimed to show how sofosbuvir affected the adult male albino rat testis. Forty adult male albino rats were used. The rats were equally split into two main groups (I and II), then each group subdivided into two subgroups (A and B). Each rat in group I (control) received 0.5 ml of distilled water every day for four weeks. Each rat in group II (sofosbuvir-treated) received 0.5 ml of distilled water containing 7.2 mg of sofosbuvir every day for four weeks. After four weeks (subgroups IA and IIA) and eight weeks (subgroups IB and IIB) of treatment, the rats were sacrificed. Histological, biochemical, and morphometric studies on the testes were conducted. The data were analyzed. Examination of testes of sovaldi treated group revealed histopathological changes. Biochemical and morphometric analysis showed reduced levels of reduced glutathione and seminiferous tubule epithelial height respectively. Following a 4-week drug withdrawal period, the testes only partially recovered. We concluded that sofosbuvir induced deteriorating changes in the adult male albino rats' testes. These changes were proved by histological and biochemical studies. These changes were incompletely reversible after cession of treatment. Researches investigating the effect of adding drugs that have antioxidant properties during sofosbuvir therapy are recommended.

Sofosbuvir Suppresses the Genome Replication of DENV1 in Human Hepatic Huh7 Cells.

Dengue virus (DENV) causes dengue fever and dengue hemorrhagic fever, and DENV infection kills 20,000 people annually worldwide. Therefore, the development of anti-DENV drugs is urgently needed. Sofosbuvir (SOF) is an effective drug for HCV-related diseases, and its triphosphorylated metabolite inhibits viral RNA synthesis by the RNA-dependent RNA polymerase (RdRp) of HCV. (2'R)-2'-Deoxy-2'-fluoro-2'-methyluridine (FMeU) is the dephosphorylated metabolite produced from SOF. The effects of SOF and FMeU on DENV1 replication were analyzed using two DENV1 replicon-based methods that we previously established. First, a replicon-harboring cell assay showed that DENV1 replicon replication in human hepatic Huh7 cells was decreased by SOF but not by FMeU. Second, a transient replicon assay showed that DENV1 replicon replication in Huh7 cells was decreased by SOF; however, in hamster kidney BHK-21 cells, it was not suppressed by SOF. Additionally, the replicon replication in Huh7 and BHK-21 cells was not affected by FMeU. Moreover, we assessed the effects of SOF on infectious DENV1 production. SOF suppressed infectious DENV1 production in Huh7 cells but not in monkey kidney Vero cells. To examine the substrate recognition of the HCV and DENV1 RdRps, the complex conformation of SOF-containing DENV1 RdRp or HCV RdRp was predicted using AlphaFold 2. These results indicate that SOF may be used as a treatment for DENV1 infection.

Evaluation of the clinical and economic value of sofosbuvir/velpatasvir (SOF/VEL) in patients with chronic hepatitis C in Spain during the last 5 years.

OBJECTIVE: Direct-acting antivirals for the treatment of hepatitis C virus (HCV) represented a paradigm shift. In 2017, sofosbuvir/velpatasvir (SOF/VEL-Epclusa®) was approved, which showed a high cure rate in all patient, contributing to HCV elimination. The analysis aimed to quantify the clinical and economic value of SOF/VEL in HCV chronic patients since its approval in Spain. METHODS: An economic evaluation was elaborated adapting a Markov model that simulated the lifetime disease progression in of all HCV chronic patients treated with SOF/VEL (30,488 patients) since its launch (5-years), compared to previous therapies. Patients entered the model and were distributed between the fibrosis states (F0-to-F4) in treated and untreated. All patients (100%) were treated with SOF/VEL regardless of their fibrosis, and 49% with previous therapies in ≥F2. The average sustained viral response (SVR) rates 98.9% SOF/VEL versus 61.0% previous therapies. All parameters for the analysis were obtained from real-life data and literature. Only direct healthcare costs associated with disease management were included. The SOF/VEL value was measured as the number of hepatic complications avoided and their associated cost, and hepatic mortality compared to previous therapies. National Health System perspective and a 3% discount rate was applied. RESULTS: SOF/VEL decreased the number of liver complications, avoiding 92% decompensated cirrhosis, 80% hepatocellular carcinomas, and 87% liver transplants, as well as 85% liver-related mortality. Their cost associated was reduced, amounting to savings of 197M€. CONCLUSION: SOF/VEL adds relevant value to the HCV treatment, reducing the clinical and economic disease burden and contributing to HCV elimination in Spain.

Prognosis Following Sustained Virologic Response in Korean Chronic Hepatitis C Patients Treated with Sofosbuvir-Based Treatment: Data from a Multicenter Prospective Observational Study up to 7 Years.

Background and Objectives: Chronic hepatitis C (CHC) can be cured with direct-acting antiviral (DAA) therapy. In Korea, sofosbuvir (SOF) and ledipasvir (LDV)/SOF were launched in 2016. Patients who achieve a sustained virologic response (SVR) following DAA treatment are predicted to have a favorable prognosis. Nevertheless, little is known regarding the prognosis of Korean CHC patients who receive SOF-based treatment and achieve SVR. Therefore, the purpose of this study was to look into the long-term outcomes for these patients. Materials and Methods: This was a prospective, multicenter observational study. CHC patients were enrolled who, following SOF or LDV/SOF treatment, had achieved SVR. The last day for follow-up was December 2023. The primary endpoint was HCC occurrence, which was checked at least once per year. Results: A total of 516 patients were included in this analysis, with a median follow-up duration of 39.0 months. Among them, 231 were male patients (44.8%), with a median age of 62.0 years. Genotypes were 1 (90, 17.4%), 2 (423, 82.0%), and 3 (3, 0.6%). The combination of SOF plus ribavirin was the most common treatment (394, 76.4%). In total, 160 patients were cirrhotic (31.0%), and the mean Child-Pugh score was 5.1. Within a maximum of 7 years, 21 patients (4.1%) developed HCC. Patients with HCC were older (69 vs. 61 years, p = 0.013) and had a higher cirrhosis incidence (81.0 vs. 28.9%, p < 0.001), higher AFP (6.0 vs. 3.3, p = 0.003) and higher APRI (0.8 vs. 0.5, p = 0.005). Age over 65 (p = 0.016) and cirrhosis (p = 0.005) were found to be significant risk factors for HCC by Cox regression analysis. Conclusions: Patients who achieved SVR with SOF-based treatment had a relatively favorable prognosis. However, the risk of HCC was not eliminated, especially in older and cirrhotic patients. Therefore, routine follow-up, surveillance, and early treatment are required.

Efficacy, safety, and quality of life profile of Genotype-3 Chronic Hepatitis-C Pakistani patients receiving ledipasvir plus sofosbuvir treatment.

Objective: This study aimed to assess the overall treatment response of Genotype-3 Chronic HCV Pakistani Patients with or without cirrhosis to Ledipasvir plus Sofosbuvir combination. Method: In this observational study, HCV Genotype-3 patients were enrolled from Liver Center, DHQ Hospital, Faisalabad and divided into two groups, i.e., non-cirrhotic and compensated cirrhotic patients. The study spanned for a period of 24 months (November 2019 - November 2021) from the first enrollment to the last follow up. Non-cirrhotic patients received Ledipasvir/Sofosbuvir (LDV/SOF) 90/400mg for 12 weeks and cirrhotic patients received LDV/SOF with Ribavirin (RBV) for 12 weeks and without RBV for 24 weeks. The treatment efficacy in terms of sustained virological response (SVR12) was monitored 12 weeks post-treatment. The safety profile, and health-related quality of life (HRQoL) were monitored from baseline to follow-up visits. Results: Two hundred and ninety out of 309 (93.85%) non-cirrhotic and 31 out of 33 (93.94%) compensated cirrhotic patients achieved SVR-12. The safety profile of the non-cirrhotic and compensated cirrhotic patients was comparable throughout the study duration. Fatigue was the most commonly reported adverse event (AE) in non-cirrhotic and compensated cirrhotic patients, followed by headache, nausea, and fever. The HRQoL improved from baseline to follow-up visits among patients of both groups. Conclusion: It is concluded that LDV and SOF combination regimen is safe and effective for treating Genotype-3 HCV patients without cirrhosis/compensated cirrhosis, and also improves the patient's HRQoL.

The pre-conception maternal exposure to Sofosbuvir affects the mitochondrial biogenesis in prenatal fetal tissues: Experimental study on rats.

BACKGROUND: Hepatitis C virus (HCV) infection is a global public health problem and Egypt has the highest HCV prevalence worldwide. Hence, global efforts target to eliminate HCV by 2030. Sofosbuvir is a nucleotide analogue inhibitor of HCV polymerase essential for viral replication. Animal studies prove that Sofosbuvir metabolites cross the placenta and are excreted in the milk of nursing animals. We aimed to investigate the possible effects of preconception maternal exposure to Sofosbuvir on mitochondrial biogenesis in prenatal fetal liver, skeletal muscle, and placental tissues. METHODS: The study was conducted on 20 female albino rats divided into a control group receiving a placebo and an exposed group receiving 4 mg/kg orally/day for 3 months of Sofosbuvir. At the end of the treatment period, pregnancy was induced in both groups by mating with healthy male rats overnight. At gestational day 17, all pregnant female rats were sacrificed. Each fetus was dissected to obtain the fetal liver, skeletal muscle, and placental tissues. RESULTS: The results of our study indicated that the exposure of young female rats to Sofosbuvir affects pregnancy outcomes. Fetal liver and muscle showed lower mitochondrial DNA-copy number (mtDNA-CN) by about 24% and 29% respectively, peroxisome proliferator-activated receptor-gamma coactivator-1 alpha and its downstream targets; nuclear respiratory factor-1 and mitochondrial transcription factor A. While the placental tissues showed different patterns, particularly elevated in mtDNA-CN by about 43%. CONCLUSIONS: The study provides preliminary evidence of the detrimental effects of Sofosbuvir on the pregnancy outcomes of the exposed females and may impair the placental and fetal organs' development. These effects may be mediated through modulating mitochondrial homeostasis and functions.

Sofosbuvir and its tri-phosphate metabolite inhibit the RNA-dependent RNA polymerase activity of non-structural protein 5 from the Kyasanur forest disease virus.

Kyasanur forest disease is a neglected zoonotic disease caused by a single-stranded RNA-based flavivirus, the incidence of which was first recorded in 1957 in the Southern part of India. Kyasanur forest disease virus is transmitted to monkeys and humans through the infected tick bite of Haemophysalis spinigera. Kyasanur forest disease is a febrile illness, which in severe cases, results in neurological complications leading to mortality. The current treatment regimens are symptomatic and supportive, and no targeted therapies are available for this disease. In this study, we evaluated the ability of FDA-approved drugs sofosbuvir (and its active metabolite) and Dasabuvir to inhibit the RNA-dependent RNA polymerase activity of NS5 protein from the Kyasanur forest disease virus. NS5 protein containing the N-terminal methyl transferase domain and C-terminal RNA-dependent RNA polymerase domain was expressed in Escherichia coli, and RNA-dependent RNA polymerase activity was demonstrated with the purified protein. The RNA-dependent RNA polymerase assay conditions were optimized, followed by the determination of apparent Km,ATP to validate the enzyme preparation. Half maximal-inhibitory concentrations against RNA-dependent RNA polymerase activity were determined for Sofosbuvir and its active metabolite. Dasabuvir did not show detectable inhibition with the tested conditions. This is the first demonstration of the inhibition of RNA-dependent RNA polymerase activity of NS5 protein from the Kyasanur forest disease virus with small molecule inhibitors. These initial findings can potentially facilitate the discovery and development of targeted therapies for treating Kyasanur forest disease.

The tolerability of sofosbuvir/velpatasvir for 12 weeks in patients treated in the ASTRAL 1, 2 and 3 studies: A pooled safety analysis.

To evaluate the safety and tolerability of the fixed-dose, single-tablet regimen sofosbuvir/velpatasvir (SOF/VEL) for the treatment of hepatitis C virus (HCV) infection in three Phase 3 studies in patients with and without compensated cirrhosis. Data from three registrational trials (ASTRAL-1, NCT02201940; ASTRAL-2, NCT02220998; ASTRAL-3, NCT02201953) were pooled by treatment regimen. Researchers assessed treatment-emergent adverse events (TEAEs) and laboratory abnormalities in patients randomized to SOF/VEL or placebo for 12 weeks in ASTRAL-1 and SOF/VEL for 12 weeks in ASTRAL-2 and ASTRAL-3. Overall, 1035 patients were treated with SOF/VEL, and 116 patients received placebo. Rates of any TEAE were generally similar between patients receiving SOF/VEL (79.4%) and those receiving placebo (76.7%). The majority of TEAEs were mild to moderate, with 23 (2.2%) treatment-emergent serious AEs in patients treated with SOF/VEL. Of these treatment-emergent serious AEs, none led to premature study discontinuation, nor were they considered related to treatment. Presence of compensated cirrhosis, greater age and mild renal impairment did not impact incidence or severity of TEAEs with SOF/VEL treatment. The most common TEAEs (incidence ≥10%) were headache, fatigue, nausea and nasopharyngitis in patients receiving SOF/VEL; similar rates were observed in placebo-treated patients. Three deaths (<1%) were reported in patients treated with SOF/VEL, all posttreatment and none assessed as related to study treatment. Similar to that of placebo, SOF/VEL treatment of HCV infection had a safety/tolerability profile that was not affected by baseline factors, such as the presence of compensated cirrhosis, mild renal impairment or advanced age.

Construction and characterization of a new hepatitis C virus genotype 6a subgenomic replicon that is prone to render the sofosbuvir resistance.

Hepatitis C virus (HCV) infection remains a challenge to human public health despite the development of highly effective direct-acting antivirals (DAAs). Sofosbuvir (SOF), a key component in most DAA-based anti-HCV cocktail regimens, is a potent viral RNA polymerase (NS5B) inhibitor with a high barrier to drug resistance. The serine-to-threonine mutation at NS5B 282 (S282T) confers the SOF resistance, but severely impairs viral replication in most HCV genotypes (GTs) and cannot be stably maintained after the termination of the SOF-based therapies. In this study, we first developed a new HCV GT-6a subgenomic replicon PR58D6. Next, we selected SOF-resistant PR58D6 variants by culturing the replicon cells in the presence of SOF. Interestingly, unlike many other HCV replicons which require additional mutations to compensate for the S282T-inducing fitness loss, S282T alone in PR58D6 is genetically stable and confers the SOF resistance without significantly impairing viral replication. Furthermore, we showed that amino acid residue at NS5B 74 (R74) and 556 (D556) which are conserved in GT 6a HCV contribute to efficient replication of PR58D6 containing S282T. Finally, we showed that the G556D mutation in NS5B could rescue the replication deficiency of the S282T in JFH1, a GT-2a replicon. In conclusion, we showed that a novel GT-6a HCV replicon may easily render SOF resistance, which may call for attention to potential drug resistance during DAA therapies of HCV GT-6a patients.

Identification and characterization of Sofosbuvir-resistant mutations of hepatitis C virus genotype 3a replicon.

Hepatitis C virus (HCV) infection is a major cause of chronic liver disease worldwide. Among its 8 genotypes (GT), GT3 has a relatively lower sustained virological response to highly effective direct-acting antiviral agents (DAA). Sofosbuvir (SOF), an anti-NS5B polymerase inhibitor, is a core component of many anti-HCV DAA cocktail regimens, and its resistant mutations are rare in clinics because these mutations usually severely impair the NS5B polymerase activity, including a mutation S282T in NS5B, the most frequently reported SOF-resistant mutation. In this study, we selected SOF-resistant variants of a previously developed GT3 subgenomic replicon (PR87A7). Two mutations were identified in the viral genome of SOF-resistant PR87A7 variants, Q606R in nontargeted NS3 and S282T in targeted N5SB. We demonstrated that Q606R could rescue the replication defect of S282T in PR87A7, and the resulting double mutant confers the SOF resistance. Finally, we showed that NS3-606R could not compensate for the replication defect of S282T in other GTs. In conclusion, we identified a novel GT3-specific combination of two mutations that confers SOF resistance. Our result calls for attention to potential mutations that may arise in nontargeted viral proteins during the SOF-based DAA treatment of chronic HCV.