Frequency distribution of HCV resistance-associated variants in infected patients treated with direct-acting antivirals

The Genotypes/Subtypes and Antiviral Drug Resistance of the Hepatitis C Virus from Patients in a Tertiary Care Hospital in Nepal

While direct-acting antivirals (DAAs) are available for the treatment of chronic Hepatitis C virus (HCV) patients in Nepal, knowledge of the circulating genotypes/subtypes and drug target gene mutations of HCV is currently unavailable. Here, we describe HCV genotypes/subtypes and identify antiviral target gene mutations in patients at a tertiary care hospital using genome data. A cross-sectional study was conducted from December 2019 to February 2024, where PCR followed by whole genome sequencing was performed to identify HCV genotypes/subtypes and drug target gene mutations. Among all the patients who tested positive for anti-HCV, 70.6% (149/211) were HCV RNA positive, while 68.2% (30/44) were genotype/subtype 3a, followed by 1a (18.2%, 8/44) and others (13.6%, 6/44), including new subtypes 3g and 3i from Nepal. Subtype 3a was also the dominant subtype (≥70%) among intravenous drug users and sexual routes of transmission. We found 70.5% of the samples with resistant mutations in the NS3/4A region, 22.7% in NS5A, and 45.5% in NS5B. Resistant mutations against sofosbuvir, pibrentasvir, velpatasvir, daclatasvir, and dasabuvir were found at 25%, 18%, 16%, 16%, and 2%, respectively, mostly on subtype 3a. The predominant HCV genotype/subtype in our patient group was 3a, and resistance mutations against direct-acting antivirals were found in most untreated patients.

Catalytic hairpin assembly triggering amplified DNAzyme-feedback for sensitive detection of hepatitis C virus genotype 1b

Developing a simple, reliable, and sensitive hepatitis C virus (HCV) genetic sensing platform is of great significance for diagnosing diseases and selecting appropriate antiviral treatments. Herein, a tandem nucleic acid amplification strategy for sensitive detection of HCV genotype 1b (HCV-1b) was developed by stringing the catalytic hairpin assembly (CHA) and the triggered DNAzyme amplifier. The hairpin reactants were initiated by the target to produce lots of triggering double-stranded DNA sequences which can efficiently activate the subsequent blocked DNAzyme. Thereby, the continuous cleavage of substrate was realized, resulting in the fluorescence signal amplification. The DNA-based isothermal CHA-DNAzyme (CDz) sensing platform was successfully applied for sensitive detection of HCV-1b with the limit of detection (84 pM) and showed good selectivity. Moreover, the practical detection of target DNA in the complex biologic matrix indicated that the developing strategy had good potential for early HCV infection diagnosis.

Single-molecule-binding studies of antivirals targeting the hepatitis C virus core protein

IMPORTANCE

The hepatitis C virus is associated with nearly 300,000 deaths annually. At the core of the virus is an RNA-protein complex called the nucleocapsid, which consists of the viral genome and many copies of the core protein. Because the assembly of the nucleocapsid is a critical step in viral replication, a considerable amount of effort has been devoted to identifying antiviral therapeutics that can bind to the core protein and disrupt assembly. Although several candidates have been identified, little is known about how they interact with the core protein or how those interactions alter the structure and thus the function of this viral protein. Our work biochemically characterizes several of these binding interactions, highlighting both similarities and differences as well as strengths and weaknesses. These insights bolster the notion that this viral protein is a viable target for novel therapeutics and will help to guide future developments of these candidate antivirals.

Hepatitis C Retreatment With First-Line Direct Acting Antiviral Drugs

BACKGROUND AND AIMS

Sofosbuvir (S), daclatasvir (D), ledipasvir, or velpatasvir (V) containing first-line hepatitis C virus (HCV) treatment regimens fail to cure viremia in 5-10%. We report our experience of HCV retreatment using these first-line drugs, in a setting where second-line anti-HCV drugs are not available.

METHODS

Adults, who had relapsed after first complete course of a sofosbuvir-containing first-line, pegylated interferon free, anti-HCV treatment regimen with or without ribavirin (Riba) were included. Retreatment regimen, tailored to the failed anti-HCV regimen, was based on principle of using first-line drugs for 24 weeks with ribavirin and swapping between pangenotypic and genotype-specific regimens. Retreatment outcome was categorized as successful (achieved undetectable HCV RNA at the end of treatment [ETR] and sustained viral response at week 12 [SVR12]), non-responder (failed to achieve ETR), or relapse (achieved ETR but not achieved SVR12).

RESULTS

Twelve patients (9 male; 7 cirrhosis; all genotype 3) who had relapsed to prior anti-HCV treatment (4 SD12, 4 SD24, 1 SDRiba12, 1 SDRiba24, 2 SV12) were included. Following retreatment (2 SDRiba24, 10 SVRiba24), all achieved ETR but only 9 (75%) achieved SVR12. Two among three, in whom retreatment failed, achieved SVR12 following another course of sofosbuvir/velpatasvir/ribavirin for 24 weeks. Overall, 11/12 (92%) patients achieved SVR12 following retreatment with the first-line anti-HCV drugs.

CONCLUSION

HCV retreatment could be a treatment option if second-line anti-HCV drugs are not available. Successful retreatment could be achieved, in a large proportion, with the use of first-line drugs for 24 weeks with ribavirin and swapping of pangenotypic/genotype-specific regimens (NCT03483987).