Fifty-eight million people worldwide are chronically infected with hepatitis C virus (HCV) and are at risk of developing cirrhosis and hepatocellular carcinoma (HCC). Direct-acting antivirals are highly effective; however, they are burdened by high costs and the unchanged risk of HCC and reinfection, making prophylactic countermeasures an urgent medical need. HCV high genetic diversity is one of the main obstacles to vaccine development. The protective role of the humoral response directed against the HCV E2 glycoprotein is well established, and broadly neutralizing antibodies play a crucial role in effective viral clearance.

This review explores the HCV targets and the different vaccination approaches, encompassing different expression systems, antigen selection strategies, and delivery methods, focusing on those aimed at eliciting a broad and effective humoral response. Our search criteria included the keywords 'HCV,' 'Hepatitis C,' and 'vaccine' using publicly available databases. Following the screening, 54 papers were selected.

The investigation of novel vaccine platforms beyond traditional approaches is necessary. While progress has been made in this direction, continued investigations on the HCV virology, immunology, and vaccinology are essential to surmount associated obstacles, heling in the development of an HCV vaccine that can benefit the global public health.

Bandavirus dabieense (DBV) causes severe fever with thrombocytopenia syndrome, which has a mortality rate of 6.18% of 27%. DBV has been classified into five to six genotypes using phylogenetic analyses. However, the absence of clear standards poses challenges in identifying new genotypes. We performed evolutionary and homology analyses using the sequences from GenBank and analysed nucleotide differences between the different genotypes. Nucleotide differences within the same genotype were mostly below 3%, whereas those between different genotypes ranged from 3 to 7%. Consequently, we established and validated a specific genotyping criterion for DBV using phylogenetic tree analysis with a 3% cut-off value and identified 8, 11, and 11 genotypes in the S, M, and L segments, respectively. Furthermore, we compared our method with the previous genotyping methods to elucidate the convenience and advantages of using a 3% cut-off value. Importantly, we also identified new genotypes and fragment reassortments in DBV using our new genotyping criterion. Additionally, we established two simplified genotyping methods for the rapid typing of DBV in clinical settings and demonstrated the existence of geographical and clinical variations among the different genotypes. Our findings provide a more reliable foundation for clinical typing of DBV.

Hepatitis C virus (HCV) vaccines are urgently needed to achieve WHO's goal for the elimination of viral hepatitis by 2030. The lack of suitable animal models for evaluating vaccine efficacy has greatly hindered the development of HCV vaccines. By using the rat model chronically infected with rodent hepacivirus from Rattus norvegicus (RHV-rn1), a hepacivirus homologously close to HCV as a surrogate model of HCV infection, we assessed the protective effectiveness of the RHV-rn1 vaccine Sad23L-RHVns.

Sad23L-RHVns vaccine was constructed with the nonstructural proteins (NS) 3-5B genes of RHV-rn1. SD rats were immunised with Sad23L-RHVns by prime or prime-boost regimen via intramuscular injection, then challenged 4 weeks post vaccination by RHV-rn1. A part of the rats were rechallenged with a variant 15 weeks post the first challenge of RHV-rn1.

The specific T-cell responses to NS3-5B antigens were induced by prime immunisation, which were significantly enhanced by boost vaccination. The inoculated rats and controls were challenged by wild-type RHV-rn1, of all the primed and control rats having persistently high levels of viremia, whereas 7 of 9 (77.8%) boosted rats cleared RHV-rn1 infection. Interestingly, the resolver acquired immune protection against re-challenging with variant and showed significantly higher T-cell responses than the nonresolver in 25 weeks post rechallenge.

Sad23L-RHVns with prime-boost regimen protected 77.8% of rats against wild-type RHV-rn1 infection, and resolvers showed high levels and maintenance of T cell immunity against the variant. Our findings that maintenance of effective T cell immunity is required for RHV-rn1 resolution may provide insight to develop the HCV vaccine in humans.

Hepatitis C virus (HCV) resistance-associated substitutions (RASs) have a significant impact on the treatment of HCV with direct-acting antivirals (DAAs). However, limited research has been conducted, and no standardized methods for detecting RASs in mainland China.

To develop and apply a novel method for detecting HCV RASs in HCV RNA-positive patients in Linzhou, China.

In total, 103 HCV RNA-positive serum specimens and epidemiological questionnaires were collected. A PCR method for detecting HCV RASs encompassing the NS3 to NS5B region was developed.

Demographic analysis revealed a predominance of females (66/103, 64.1 %), with an average age of 70 years. Genotype 1b (GT1b) (17/103, 16.5 %) and GT2a (86/103, 83.5 %) were identified. The prevalence of RASs was higher (17/17, 100 %) in GT1b than in GT2a (7/86, 8 %). In GT1b, a higher frequency of RASs was observed in the NS5B region (17/17, 100 %) than in the NS3 (14/17, 82 %) and NS5A (10/17, 59 %) regions. C316N was the most prevalent, followed by S122G (71 %) and R30Q (35 %).

We introduced an innovative approach for the detection of HCV RASs and provided a wealth of information on HCV RASs in Linzhou, China. The findings support the cautious selection of treatment regimens, potentially improving patient outcomes.

Identification and characterization of antibody epitope targets on the hepatitis C virus (HCV) envelope proteins remain crucial for developing an effective vaccine. Building on prior research defining E1/E2 antibody epitope clustering, we screened a phage display library derived from a chronic HCV patient against detergent-extracted full-length E1/E2 from both the patient's acute-phase isolate (H77, genotype 1a) and a heterologous isolate (S52, genotype 3a). This approach yielded a panel of VH1-69 derived antibody fragments (Fabs) with similar characteristics. Interestingly, all members of the panel exhibited blocking activity against both antigenic region 2 and 3 (AR2 and AR3) in competition ELISAs, which contrasts with the behavior of most previously identified AR3-targeting antibodies. The VH1-69 derived binders had a high affinity for soluble E2 in both Fab and IgG formats, with dissociation constants in the low picomolar range. These Fab binders were broadly neutralizing against a panel of HCV cell culture viruses of genotype 1-6 with higher potency than the well-characterized reference Fab, AR3A. However, in the IgG format the antibodies had similar potency. These findings expand our understanding of potential targets for vaccine development by characterizing a panel of antibodies targeting an AR3 epitope also involving or occluding the back layer of E2. The broad neutralization and high affinity of these antibodies suggest a benefit to targeting both the back layer and the front layer of E2 in HCV vaccine designs to expand the repertoire of broadly neutralizing antibodies, thereby offering promise for the development of more effective preventive measures against this pervasive human pathogen.

Hepatitis C virus (HCV) infection remains a global health concern. This study analyzed 95,864 plasma samples from Saudi patients between 2011 and 2022 to examine HCV seroconversion, viral load, and genotype distribution. Serological screening was performed using the ARCHITECT anti-HCV assay, and HCV RNA levels were quantified with real-time RT-PCR. Of the 970 HCV-positive cases, 47.9 % experienced spontaneous recovery, while 52.1 % had persistent infection. The annual seropositivity rate declined significantly from 2.05 % in 2011 to 0.34 % in 2022. Genotyping of 107 persistently infected samples showed genotypes 4 (49.5 %) and 1a (17.8 %) as the most common, with other genotypes appearing less frequently. Additionally, 13 (12.1 %) samples had untypable genotypes. This study highlights the decrease in HCV infection rates, the high rate of spontaneous recovery, and the predominance of genotypes 4 and 1a. Ongoing surveillance and genotyping, including untypable cases, are essential for effective HCV management in Saudi Arabia.

Hepatitis C virus (HCV) infects approximately 58 million individuals worldwide, often progressing to chronic liver disease, cirrhosis, and hepatocellular carcinoma. The viral envelope glycoproteins E1 and E2 are critical for HCV entry and serve as primary targets for neutralizing antibodies. Recent advancements in cryo-electron tomography have provided high-resolution structures (3.5 Å) of the E1E2 heterodimer, revealing interactions between the E1 and E2 ectodomains, as well as neutralizing antibody complexes (e.g., AR4A, AT1209, IGH505). This structural information facilitates the design of a synthetic peptide vaccine targeting conserved E1 and E2 regions. We suggest developing a vaccine tailored to the HLA-A*24:02 allele, the most prevalent in the Indian population. Epitope candidates will be screened using immunoinformatics tools, incorporating epitopes derived from epitope mapping with 7t6x protein structure modeling. Molecular docking studies will identify high-affinity interactions with human MHC-Class I alleles, using tools such as AutoDock and HADDOCK. GROMACS molecular dynamics simulations will assess peptide-HLA binding stability and dynamics. Among ten screened epitopes, KWEYVVLLF and QWQVLPCSF emerged as the most promising based on their toxicity profiles, conservation, and docking scores with HLA-A*24:02 (- 9.3 kcal/mol for KWEYVVLLF and - 225.34 kcal/mol for QWQVLPCSF). Molecular dynamics simulations indicated that the KWEY segment of KWEYVVLLF underwent structural changes, while the VVLLF region maintained stable binding to Chain A, suggesting immunogenic potential. These epitopes represent strong candidates for T-cell-based vaccines, and the reverse vaccinology approach, supported by computational tools, offers a population-specific strategy for HCV vaccine development, advancing precision immunotherapy.

Occult HCV infection (OCI) is defined by the presence of HCV RNA in hepatocytes and/or peripheral blood mononuclear cells (PBMCs) without detectable HCV RNA or anti-HCV antibodies in plasma. OCI is underrecognized and may contribute to HCV transmission. This study estimated OCI prevalence and associated risk factors in adults from Mexico City. Methods: A retrospective cross-sectional study was conducted, analyzing 507 general population volunteers. Demographic data and potential risk factors were collected via questionnaire. Anti-HCV detection was performed using two techniques: immunochromatographic rapid test and chemiluminescent microparticle immunoassay (CMIA). Nested PCR was employed to detect HCV RNA in plasma and PBMCs. Positive samples were genotyped through sequencing and phylogenetic analysis of the Core/E1 region. Results: Of 507 participants, four were anti-HCV positive. HCV RNA was found in PBMCs of 27 individuals, while plasma samples tested negative, indicating a 5.3% OCI prevalence. OCI was significantly associated with blood donation (p = 0.015), drug use (p = 0.019), particularly cocaine (p = 0.001), and endoscopy (p = 0.043). Genotypes 1b, 1a, 2b, 3a, and 2j were detected in OCI cases. Conclusions: OCI prevalence in Mexico City's general population is notable, with significant links to blood donation, cocaine use, and endoscopy. Enhanced diagnostic strategies are crucial to detect OCI and mitigate HCV transmission.

The study aimed to investigate hepatitis C virus (HCV) specific markers in chronically infected children. The main objective was to explore the patterns of marker variability.

HCV RNA, core antigen, anti-HCV IgM, and antibodies to individual viral proteins were detected using commercially available assays or experimental ELISA. RNA genotyping and recombination were performed by sequencing.

HCV RNA and core antigen were detected in serum samples of all children (N.=100). Anti-HCV IgM, anti-NS4AB IgG, and anti-NS5A IgG were revealed less often than antibodies to core and NS3 proteins. To elucidate the cause of this finding, all subjects were divided into 4 groups differing in hepatitis duration. It was anti-NS4AB only whose detection depended on the infection duration. A trend was established that the longer the hepatitis duration, the more frequently anti-HCV IgM was observed. No significant impact of HCV RNA load and NS4A/NS4B amino acid substitutions on anti-NS4AB IgG detection was found. The increase HCV genotype 3 was observed among children infected after 2000. The earliest case of infection caused by HCV intergenotype recombinant RF1_2k/1b was identified in a child vertically infected in 1997.

HCV genotypes and subtypes were found to be variable virus specific markers in children infected in 1997-2015. Over the period, there has been a trend to change the dominant HCV subtype and appearance of recombinant RF1_2k/1b in children. Among humoral markers, anti-NS4AB revealing is depended on chronic hepatitis C duration, while for anti-HCV IgM, only a trend was established. The detection of anti-NS4AB can be helpful in assessing the duration of chronic hepatitis C.

Chronic hepatitis C virus (HCV) infection poses a major health risk worldwide, with patients susceptible to liver cirrhosis and hepatocellular carcinoma. This study focuses on the development of effective therapeutic strategies for HCV infection through the investigation of immunogenic properties of a DNA construct based on the NS3/4A gene of HCV genotype (g)3a. Gene expression of the mutagenized (mut) NS3/4A target genes was assessed through reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and Western blot analysis. Additionally, bioinformatics tools were employed to evaluate the impact of the mut-NS3/4A-based DNA vaccine. Analysis revealed increased mut-NS3/4A mRNA levels and target protein abundance compared with the native sequence. Elevated mut-NS3/NS4A levels could result from increased RNA stability and proper protein folding. Physicochemical analyses of the protein demonstrated favorable attributes such as thermostability and solubility. Three-dimensional mut-NS3/4A protein modeling confirmed its high stability and agreement with known protein structures. Additionally, potential immunogenic regions of both T and B cell epitopes were discovered based on peptide binding to major histocompatibility complex molecules of Asian origin. Importantly, these epitopes exhibited nonallergenic and nontoxic characteristics. These findings highlight the potential of the NS3/4A-based DNA construct as a promising candidate for an HCVg3a vaccine tailored for the Asian population, providing valuable insights for future immunotherapeutic approaches.

Hepatitis C virus (HCV) has high genetic diversity and is classified into 8 genotypes and >90 subtypes, with some endemic to specific world regions. This could compromise direct-acting antiviral efficacy and global HCV elimination.

We characterized HCV subtypes "rare" in the United Kingdom (non-1a/1b/2b/3a/4d) by means of whole-genome sequencing via a national surveillance program. Genetic analyses to determine the genotype of samples with unresolved genotypes were undertaken by comparison with International Committee on Taxonomy of Viruses HCV reference sequences.

Two HCV variants were characterized as being closely related to the recently identified genotype (GT) 8, with >85% pairwise genetic distance similarity to GT8 sequences and within the typical intersubtype genetic distance range. The individuals infected by the variants were UK residents originally from Pakistan and India. In contrast, a third variant was only confidently identified to be more similar to GT6 compared with other genotypes across 6% of the genome and was isolated from a UK resident originally from Guyana. All 3 were cured with pangenotypic direct-acting antivirals (sofosbuvir-velpatasvir or glecaprevir-pibrentasvir) despite the presence of resistance polymorphisms in NS3 (80K/168E), NS5A (28V/30S/62L/92S/93S) and NS5B (159F).

This study expands our knowledge of HCV diversity by identifying 2 new GT8 subtypes and potentially a new genotype.

Existing data on the prevalence of hepatitis C virus (HCV) genotypes and subtypes in Rwanda need to be strengthened. The aim of this study was to identify HCV genotypes and subtypes among HCV-infected patients, as well as their geographical distribution in Rwanda, and to identify the social and economic factors that could influence HCV epidemiology which would make it possible to target national preventive and management actions for infected patients.

This study included 560 patients with confirmed chronic HCV infection. Patients were recruited from various health facilities in the four provinces of Rwanda as well as in the City of Kigali and had never received treatment with direct-acting antiviral (DAAs). HCV viral loads were measured using Cobas® AmpliPrep/Cobas® TaqMan® HCV Quantitative Test, version 2.0. HCV genotyping was performed using an in-house sequencing protocol targeting the NS5B central region. Genotypic HCV prevalence was correlated with patient geographic location, sociodemographic, behavioral, lifestyle, and clinical factors.

HCV genotype 4 was detected in 99.3% of the patients, while genotype 3 was identified in 0.7%. A total of eight (8) HCV subtypes were detected, with 4k being the predominant subtype nationwide (49.5%), followed by subtypes 4r (21.2%), 4q (16.2%), 4v (7.9%), 4b (2.0%), 4l (1.8%), 4c and 3h represent 0.7% each. Our findings reveal subtype distribution variations among provinces. Subtype 4k was prevalent across regions, particularly in Kigali (64.0%) and the Eastern Province (61.6%). Subtype 4q was more common in the northern province (40.7%), 4r in the southern (43.9%) and western provinces (37.1%), and 4v in the eastern province (17.8%). Farmers exhibit a distinct infection profile compared to other occupations, showing a lower prevalence of subtype 4k but a higher prevalence of subtype 4r.

Our study revealed that HCV infection is unevenly distributed in Rwanda, dominated by HCV genotype 4, with considerable heterogeneity in the repartition of the different subtypes. We found potential associations between rural/urban lifestyles and HCV subtype profiles. Determined HCV distribution and diversity can serve as basis not only for HCV infection awareness and prevention campaigns, but also success and guidance for personalized treatment.

The hepatitis C virus (HCV) infection, a global health concern, can lead to chronic liver disease. The HCV core antigen (HCVcAg), a viral protein essential for replication, offers a cost-effective alternative to HCV RNA testing, particularly in resource-limited settings. This review explores the significance of HCVcAg, a key protein in the hepatitis C virus, examining its structure, function, and role in the viral life cycle. It also evaluates its clinical use in diagnosis and treatment monitoring, comparing its performance to the standard HCV RNA assay using data from PubMed and Google Scholar. HCVcAg assays show high pooled sensitivity (93.5%) and pooled specificity (99.2%) compared to HCV RNA assays, correlating closely (r = 0.87) with HCV RNA levels. Hence, HCVcAg testing offers a cost-effective way to diagnose active HCV infections and monitor treatment, especially in resource-limited settings, but its sensitivity can vary and standardization is needed. HCVcAg also predicts liver disease progression and assesses liver damage risk, aiding patient management. It helps to identify patients at risk for fibrosis or carcinoma, making it vital in hepatitis C care. HCVcAg testing can expand access to HCV care, simplify management, and contribute to global elimination strategies, especially in low- and middle-income countries.

Background and Objectives: The relationship between circulating retinol-binding protein 4 (RBP4) levels and hepatitis C virus (HCV) infection remains unclear. This study aims to systematically assess RBP4 expression in patients with HCV and its correlation with disease severity. Materials and Methods: We searched the Embase, PubMed, and Cochrane databases for relevant studies up to 1 January 2024. This study was registered on PROSPERO (CRD42023489051). Results: Our analysis included eight studies with 2612 participants (1152 controls and 1282 patients with HCV). Overall, RBP4 levels did not significantly differ between patients with HCV and controls (SMD: -0.36; 95% CI: -0.94, 0.23; p = 0.23). However, in a subgroup of Asian subjects, patients with HCV showed significantly lower RBP4 levels (SMD: -0.40; 95% CI: -0.49, -0.31; p = 0.10). Additionally, a negative correlation between RBP4 levels and disease severity was observed across all studied populations. Conclusions: RBP4 levels may vary due to HCV genotype, ethnicity, and environmental factors. In the context of HCV infection, RBP4 levels appear to reflect the severity of disease progression. Our findings indicate that RBP4 could serve as a biomarker for HCV disease progression. Further research is needed to elucidate the complex mechanisms of RBP4 in HCV infection.

HCV infection continues to be a major global health burden despite effective antiviral treatments. The urgent need for a protective vaccine is hindered by the scarcity of suitable HCV-permissive animal models tractable in vaccination and challenge studies. Currently, only antibody neutralization studies in infectious cell culture systems or studies of protection by passive immunization of human liver chimeric mice offer the possibility to evaluate the effect of vaccine-induced antibodies. However, differences between culture-permissive and in vivo-permissive viruses make it a challenge to compare analyses between platforms. To address this problem, we aimed at developing genotype-specific virus variants with genetic stability both in vitro and in vivo.

We demonstrated infection of human liver chimeric mice with cell culture-adapted HCV JFH1-based Core-NS2 recombinants of genotype 1-6, with a panel of 10 virus strains used extensively in neutralization and receptor studies. Clonal re-engineering of mouse-selected mutations resulted in virus variants with robust replication both in Huh7.5 cells and human liver chimeric mice, with genetic stability. Furthermore, we showed that, overall, these virus variants have similar in vitro neutralization profiles as their parent strains and demonstrated their use for in vivo neutralization studies.

These mouse-selected HCV recombinants enable the triage of new vaccine-relevant antibodies in vitro and further allow characterization of protection from infection in vivo using identical viruses in human liver chimeric mice. As such, these viruses will serve as important resources in testing novel antibodies and can thus guide strategies to develop an efficient protective vaccine against HCV infection.

Biologically active proteins/regions without stable structure (i.e., intrinsically disordered proteins and regions (IDPs and IDRs)) are commonly found in all proteomes. They have a unique functional repertoire that complements the functionalities of ordered proteins and domains. IDPs/IDRs are multifunctional promiscuous binders capable of folding at interaction with specific binding partners on a template- or context-dependent manner, many of which undergo liquid-liquid phase separation, leading to the formation of membrane-less organelles and biomolecular condensates. Many of them are frequently related to the pathogenesis of various human diseases. All this defines IDPs/IDRs as attractive targets for the development of novel drugs. However, their lack of unique structures, multifunctionality, binding promiscuity, and involvement in unusual modes of action preclude direct use of traditional structure-based drug design approaches for targeting IDPs/IDRs, and make disorder-based drug discovery for these "protein clouds" challenging. Despite all these complexities there is continuing progress in the design of small molecules affecting IDPs/IDRs. This article describes the major structural features of IDPs/IDRs and the peculiarities of the disorder-based functionality. It also discusses the roles of IDPs/IDRs in various pathologies, and shows why the approaches elaborated for finding drugs targeting ordered proteins cannot be directly used for the intrinsic disorder-based drug design, and introduces some novel methodologies suitable for these purposes. Finally, it emphasizes that regardless of their multifunctionality, binding promiscuity, lack of unique structures, and highly dynamic nature, "protein clouds" are principally druggable. Significance Statement Intrinsically disordered proteins and regions are highly abundant in nature, have multiple important biological functions, are commonly involved in the pathogenesis of a multitude of human diseases, and are therefore considered as very attractive drug targets. Although dealing with these unstructured multifunctional protein/regions is a challenging task, multiple innovative approaches have been designed to target them by small molecules.

Direct-acting antivirals (DAAs) show high cure rates in treating chronic hepatitis C virus (HCV). However, the effect of DAAs on patients infected with genotype 2 (GT2) is difficult to determine despite the availability of several DAA regimens.

A systematic search of six databases (PubMed, Embase, Cochrane Library, Web of Science, CNKI, and Clinicaltrial.gov) was conducted through April 20, 2022. We considered the sustained virological response 12 weeks after treatment (SVR12) as the efficacy outcome, and adverse events (AEs) as the safety outcome. By calculating the mean SVR12 and the proportion of AEs among patients, we considered the intervention effect for each DAA regimen. The random effect model was then used in all meta-analyses. This systematic review and meta-analysis aimed to summarize the evidence on efficacy and safety of DAAs in patients infected with HCV GT2. The Bayesian Markov Chain Monte Carlo (MCMC) network metanalysis was used to indirectly compare regimen in GT2 patients.

Among 31 articles included (2,968 participants), consisting of 1,387 treatment-naive patients and 354 patients with cirrhosis. The overall pooled SVR12 rate was 94.62% (95% CI: 92.43-96.52%) among the participants who received all doses of treatment. Meta-analysis results of AEs revealed that fatigue was the most common AE (14.0%, 95% CI: 6.4-21.6%), followed by headache (13.1%, 95% CI: 9.2-17.1%), whereas death and serious adverse events were uncommon.

We compared DAA-based treatments indirectly using meta-analysis and found the combination of Sofosbuvir plus Velpatasvir and Glecaprevir plus Pibrentasvir, each administered over a 12-week period, were identified as the most effective and relatively safe in managing chronic hepatitis C virus genotype 2 (HCV GT2) infection. Both treatments achieved a SVR12 of 100% (95% CI 99-100%).

The World Health Organization has set a target to eliminate viral hepatitis as a public threat by 2030. In pursuit of this goal, Thailand initiated a hepatitis C virus (HCV) microelimination project targeting Phetchabun province, a well-recognized high-burden HCV endemic area. However, the historical transmission dynamics of HCV in Phetchabun, and in Thailand in general, remain unclear. This study investigates the epidemic histories of HCV in Phetchabun, focusing on Subtypes 1b, 3a, and 6f, and their relationship with HCV in other regions of Thailand, using molecular phylogenetic analyses. Our results reveal nationwide the presence of Subtypes 1b and 3a, while Subtype 6f is mainly confined to Phetchabun. The initial spread of Subtype 1b was inferred to coincide with World War II and the period of suboptimal medical and hygienic standards in Thai blood transfusion services, suggesting a correlation between the two. The early expansion of Subtype 3a was, on the other hand, found to correlate with the epidemic of intravenous drug use in Thailand during the time of Vietnam War. The early expansion of Subtype 6f, in contrast, appears to coincide with the period of severe regional political conflict and social and economic instability. All these findings suggest the complex interplay between social determinants of health and HCV transmission. Post the mid-1990s/early 2000s, all subtypes showed significantly reduced population growth rates, aligning with improvements in blood transfusion safety standards, the nationwide "War on Drugs" policy, and enhanced accessibility to public healthcare and HCV treatments. These combined efforts likely have contributed to curbing the spread of HCV in Thailand. Nevertheless, our analyses reveal that the prevalence of HCV in Thailand remains high overall, emphasizing the need for further research and a nationwide approach to more effectively reduce the HCV burden in Thailand.

Despite remarkable progress in the treatment of hepatitis C virus (HCV) infection, it remains a significant global health burden, necessitating the development of an effective prophylactic vaccine. This review paper presents the current landscape of HCV vaccine candidates and approaches, including more traditional, based on inactivated virus, and more modern, such as subunit protein, vectored, based on nucleic acids (DNA and mRNA) and virus-like particles. The concept of the HCV vaccine is first put in the context of viral genetic diversity and adaptive responses to HCV infection, an understanding of which is crucial in guiding the development of an effective vaccine against such a complex virus. Because ethical dimensions are also significant in vaccine research, development, and potential deployment, we also address them in this paper. The road to a safe and effective vaccine to prevent HCV infection remains bumpy due to the genetic variation of HCV and its ability to evade immune responses. The progress in cell-culture systems allowed for the production of an inactivated HCV vaccine candidate, which can induce cross-neutralizing antibodies in vitro, but whether this could prevent infection in humans is unknown. Subunit protein vaccine candidates that entered clinical trials elicited HCV-specific humoral and cellular responses, though it remains to be shown whether they translate into effective prevention of HCV infection or progression of infection to a chronic state. Such responses were also induced by a clinically tested vector-based vaccine candidate, which decreased the viral HCV load but did not prevent chronic HCV infection. These disappointments were not readily predicted from preclinical animal studies. The vaccine platforms employing virus-like particles, DNA, and mRNA provide opportunities for the HCV vaccine, but their potential in this context has yet to be shown. Ensuring the designed vaccine is based on conserved epitope(s) and elicits broadly neutralizing immune responses is also essential. Given failures in developing a prophylactic HCV vaccine, it is crucial to continue supporting national strategies, including funding for screening and treatment programs. However, these actions are likely insufficient to permanently control the HCV burden, encouraging further mobilization of significant resources for HCV vaccine research as a missing element in the elimination of viral hepatitis as a global public health.

Hepatitis C virus (HCV) is an important infectious disease that imposes a significant burden on healthcare systems. Determining the prevalence of HCV genotypes in a area is essential for the successful implementation of HCV elimination programs and allocation of financial resources to direct-acting antiviral direct-acting antivirals (DAA) treatments against prevalent HCV genotypes. Accordingly, we conducted a registry-based cross-sectional cohort study to investigate the prevalence of HCV genotypes and factors associated with cirrhosis, fatty liver, and viral load in Kermanshah Province, Western Iran.

Patients presenting to the Hepatitis Clinic of the Research Center for Infectious Diseases affiliated with Kermanshah University of Medical Sciences between 1999 and 2023 were enrolled in this study. Serum samples were collected to assess HCV genotypes and viral load. Additionally, demographic data and the status of cirrhosis and fatty liver were extracted from the registry system records throughout the study period.

Records of 828 patients with an average age of 40.38 ± 11.72 years (range: 11-80 years) were included in the study that 721 individuals were male, and 107 were female. The prevalence of fatty liver and cirrhosis was 30.3% and 12.9%, respectively. Four genotypes (1, 2, 3, and 4) and four subtypes (1a, 1b, 3a, and 3b) were identified, with subtype 3a (55.7%) being the most prevalent, followed by subtype 1a (34.3%). None of the variables including age, gender, viral load level, and genotypes 1 and 3 were associated with fatty liver or cirrhosis. However, age, gender, and genotype were correlated with the viral load (p ≤ 0.05).

The most common HCV subtypes in Kermanshah were 3a and 1a. Genotypes 2 and 4 were identified in one case each. Further studies on identifying HCV subtypes in different regions of the country are recommended to manage HCV infection and predict the prognosis.

Unlike hepatitis C virus (HCV) genotype (GT) 6, which is widely circulated in Southeast Asia and South China, GT 6 was not reported in Taiwan until 2006. GT 1b and 2a, also known as global HCV subtypes, have been reported as major GTs circulating in Taiwan. Because of improvement in genotyping kits and sequencing techniques for the subtyping of HCV, an increasing number of GT 6 subtypes have been reported, especially subtype 6a among intravenous drug users with human immunodeficiency virus infection after an outbreak since 2003. Thus, HCV GT 6 infection is regarded to be closely associated with injection drug use. However, recently, we found an unexpectedly high GT 6 prevalence in the general population in Tainan, southern Taiwan. Most of these GT 6 samples belonged to a putative novel subtype closely related to 6g and 6w instead of 6a. Phylogenetic analyses indicated that this putative 6g-related novel subtype and 6w could be indigenous in southern Taiwan for centuries. Southern Taiwan could be the origin of HCV subtype 6w. This finding might change the perspective of HCV epidemiology in Taiwan.

Therapy against the Hepatitis C virus (HCV) has significantly improved with the introduction of direct-acting antiviral drugs (DAAs), achieving over 95% sustained virological response (SVR). Despite this, the development of an effective anti-HCV vaccine remains a critical challenge due to the low number of patients treated with DAAs and the occurrence of HCV reinfections in high-risk groups. Current vaccine strategies aim to stimulate either B-cell or T-cell responses. Vaccines based on E1 and E2 proteins can elicit broad cross-neutralizing antibodies against all major HCV genotypes, though with varying efficiencies and without full protection against infection. In humans, the neutralizing antibodies induced by such vaccines mainly target the AR3 region, but their levels are generally insufficient for broad neutralization. Various HCV proteins expressed through different viral vectors have been utilized to elicit T cell immune responses, showing sustained expansion of HCV-specific effector memory T cells and improved proliferation and polyfunctionality of memory T cells over time. However, despite these advancements, the frequency and effectiveness of T-cell responses remain limited.

The high genetic diversity of hepatitis C virus (HCV) has led to the emergence of eight genotypes and a large number of subtypes in limited geographical areas. Currently approved pangenotypic DAA regimens have been designed and developed to be effective against the most common subtypes (1a, 1b, 2a, 2b, 2c, 3a, 4a, 5a and 6a). However, large populations living in Africa and Asia, or who have migrated from these regions to industrialised countries, are infected with 'unusual', non-epidemic HCV subtypes, including some that are inherently resistant to currently available direct-acting antiviral (DAA) drugs due to the presence of natural polymorphisms at resistance-associated substitution positions. In this review article, we describe the origin and subsequent global spread of HCV genotypes and subtypes, the current global distribution of common and unusual HCV subtypes, the polymorphisms naturally present in the genome sequences of unusual HCV subtypes that may confer inherently reduced susceptibility to DAA drugs and the available data on the response of unusual HCV subtypes to first-line HCV therapy and retreatment. We conclude that the problem of unusual HCV subtypes that are inherently resistant to DAAs and its threat to the global efforts to eliminate viral hepatitis are largely underestimated and warrant vigorous action.

The hepatitis C virus (HCV) is responsible for approximately 50 million infections worldwide. Effective drug treatments while available face access barriers, and vaccine development is hampered by viral hypervariability and immune evasion mechanisms. The CD4+ and CD8+ T-cell responses targeting HCV non-structural (NS) proteins have shown a role in the viral clearance. In this paper, we reviewed the studies exploring the relationship between HCV structural and NS proteins and their effects in contributing to the elicitation of an effective T-cell immune response. The use of different vaccine platforms, such as viral vectors and virus-like particles, underscores their versability and efficacy for vaccine development. Diverse HCV antigens demonstrated immunogenicity, eliciting a robust immune response, positioning them as promising vaccine candidates for protein/peptide-, DNA-, or RNA-based vaccines. Moreover, adjuvant selection plays a pivotal role in modulating the immune response. This review emphasizes the importance of HCV proteins and vaccination strategies in vaccine development. In particular, the NS proteins are the main focus, given their pivotal role in T-cell-mediated immunity and their sequence conservation, making them valuable vaccine targets.

The emergence of drug-resistance-inducing mutations in Hepatitis C virus (HCV) coupled with genotypic heterogeneity has made targeting NS3/4A serine protease difficult. In this work, we investigated the mutagenic variations in the binding pocket of Genotype 3 (G3) HCV NS3/4A and evaluated ligands for efficacious inhibition. We report mutations at 14 positions within the ligand-binding residues of HCV NS3/4A, including H57R and S139P within the catalytic triad. We then modelled each mutational variant for pharmacophore-based virtual screening (PBVS) followed by covalent docking towards identifying a potential covalent inhibitor, i.e., cpd-217. The binding stability of cpd-217 was then supported by molecular dynamic simulation followed by MM/GBSA binding free energy calculation. The free energy decomposition analysis indicated that the resistant mutants alter the HCV NS3/4A-ligand interaction, resulting in unbalanced energy distribution within the binding site, leading to drug resistance. Cpd-217 was identified as interacting with all NS3/4A G3 variants with significant covalent docking scores. In conclusion, cpd-217 emerges as a potential inhibitor of HCV NS3/4A G3 variants that warrants further in vitro and in vivo studies. This study provides a theoretical foundation for drug design and development targeting HCV G3 NS3/4A.

Hepatitis C virus (HCV) is a plus-stranded RNA virus that often chronically infects liver hepatocytes and causes liver cirrhosis and cancer. These viruses replicate their genomes employing error-prone replicases. Thereby, they routinely generate a large 'cloud' of RNA genomes (quasispecies) which-by trial and error-comprehensively explore the sequence space available for functional RNA genomes that maintain the ability for efficient replication and immune escape. In this context, it is important to identify which RNA secondary structures in the sequence space of the HCV genome are conserved, likely due to functional requirements. Here, we provide the first genome-wide multiple sequence alignment (MSA) with the prediction of RNA secondary structures throughout all representative full-length HCV genomes. We selected 57 representative genomes by clustering all complete HCV genomes from the BV-BRC database based on k-mer distributions and dimension reduction and adding RefSeq sequences. We include annotations of previously recognized features for easy comparison to other studies. Our results indicate that mainly the core coding region, the C-terminal NS5A region, and the NS5B region contain secondary structure elements that are conserved beyond coding sequence requirements, indicating functionality on the RNA level. In contrast, the genome regions in between contain less highly conserved structures. The results provide a complete description of all conserved RNA secondary structures and make clear that functionally important RNA secondary structures are present in certain HCV genome regions but are largely absent from other regions. Full-genome alignments of all branches of Hepacivirus C are provided in the supplement.

10 million people are chronically infected with the hepatitis C virus (HCV) in sub-Saharan Africa. The assessment of viral genotypes and treatment response in this region is necessary to achieve the WHO target of worldwide elimination of viral hepatitis by 2030. We aimed to investigate the prevalence of HCV genotypes and outcomes of treatment with direct-acting antiviral agents in Benin, a country with a national HCV seroprevalence of 4%.

This prospective cohort study was conducted at two referral hospitals in Benin. Individuals were eligible for inclusion if they were seropositive for HCV and willing to consent to participation in the study; exclusion criteria were an inability to give consent or incarceration. Viraemia was confirmed by PCR. The primary outcomes were to identify HCV genotypes and measure sustained virological response rates 12 weeks after completion of treatment (SVR12) with a 12-week course of sofosbuvir-velpatasvir or sofosbuvir-ledipasvir, with or without ribavirin. We conducted phylogenetic and resistance analyses after the next-generation sequencing of samples with a cycle threshold (Ct) value of 30 or fewer cycles. The in-vitro efficacy of NS5A inhibitors was tested using a subgenomic replicon assay.

Between June 2, 2019, and Dec 30, 2020, 148 individuals were screened for eligibility, of whom 100 were recruited prospectively to the study. Plasma samples from 79 (79%) of the 100 participants were positive for HCV by PCR. At the time of the study, 52 (66%) of 79 patients had completed treatment, with an SVR12 rate of 94% (49 of 52). 57 (72%) of 79 samples had a Ct value of 30 or fewer cycles and were suitable for whole-genome sequencing, from which we characterised 29 (51%) samples as genotype 1 and 28 (49%) as genotype 2. Three new genotype 1 subtypes (1q, 1r, and 1s) and one new genotype 2 subtype (2xa) were identified. The most commonly detected subtype was 2d (12 [21%] of 57 samples), followed by 1s (eight [14%]), 1r (five [9%]), 1b (four [7%]), 1q (three [5%]), 2xa (three [5%]), and 2b (two [3%]). 20 samples (11 genotype 2 and nine genotype 1) were unassigned new singleton lineages. 53 (93%) of 57 sequenced samples had at least two resistance-associated substitutions within the NS5A gene. Subtype 2d was associated with a lower-than-expected SVR12 rate (eight [80%] of ten patients). For one patient, with subtype 2b, treatment was not successful.

This study revealed a high SVR rate in Benin among individuals treated for HCV with sofosbuvir-velpatasvir, including those with highly diverse viral genotypes. Further studies of treatment effectiveness in genotypes 2d and 2b are indicated.

Medical Research Council, Wellcome, Global Challenges Research Fund, Academy of Medical Sciences, and PHARMBIOTRAC.

Background & objectives Hepatitis C virus (HCV) exhibits extensive genetic diversity in infected hosts. There are few published reports of HCV genotype (GT) distribution from the north-east Indian States lying close to the 'Golden Triangle' known for illicit drug trafficking. Real-time knowledge of HCVGT distribution is important for studies on epidemiologic aspects and virus evolution and for the development of new target-specific, direct-acting antiviral drugs. This study aims to examine the distribution of HCVGTs and their subtypes in different risk groups from Assam, north-east India. Methods It is a hospital-based cross-sectional study. Plasma samples reactive for anti-HCV antibody in enzyme-linked immunosorbent assay (ELISA) were subjected to viral load test and genotyping by real-time Reverse Transcription-Polymerase Chain Reaction (RT-PCR) or characterization of non-structural protein NS5B region by nested PCR. Nucleotide sequences were subjected to phylogenetic analysis. Results The most common HCVGT detected was GT-3 (95.89%), followed by GT-1 (3.42%), GT-6xa (0.34%) and GT-8 (0.34%). The mean age of subjects was 30.24 yr, and males outnumbered females. The most commonly associated risk factor was injecting drug use (IDU) (74.31%), followed by tattooing and/or piercing (33.22%), transfusion of blood/blood products (10.27%), and haemodialysis (9.25%). Co-infection with human immunodeficiency virus (HIV) was found in 17.8 per cent, and with Hepatitis B virus (HBV) in 3.42 per cent of the cases. Interpretation & conclusions The detection of HCVGT-8 makes this the first report from Assam and the second from India as per the authors' knowledge. This may indicate strain's endemic nature in India. The increasing trend of HCV infection among young IDUs and HCV-HIV co-infection indicates the need for enhancing surveillance and intensified prevention efforts among young adults.

This study aimed to investigate alterations in the expression of four key cytokines (IL-7, IL-11, IL-15, and IL-27) and assess differential FAM26F expression in response to Hepatitis C virus (HCV) infection. Additionally, it sought to analyze changes in these cytokines after treatment in 244 chronic HCV patients and 28 controls undergoing various treatments, including standard interferon, pegylated interferon, and Direct Acting Antivirals (DAAs). The objective was to compare immune system regulation between treatment groups. The expression levels of FAM26F and the cytokines (IL-7, IL-11, IL-15, and IL-27) were evaluated using Real-time qPCR in PBMCs of treatment groups. Results revealed significant downregulation of IL-7 and IL-27 in infected individuals compared to healthy controls, persisting even after treatment. This suggests the crucial roles of these immune modulators in facilitating the necessary T-cell response for viral clearance. IL-11 expression also remained suppressed post-treatment, supporting viral clearance by restoring the Th1 response. The decrease in IL-11 levels during treatment indicates the restoration of the Th1 response, vital for viral clearance. IL-15, the key cytokine regulating cytotoxic cells (NKT and NK cells), displayed consistent expression across all sample groups, indicating maintained IL-15-induced cytotoxicity in both control and infected individuals. Additionally, FAM26F expression was reduced in the HCV-infected group compared to controls, but higher in HCV-recovered cases, potentially due to reduced infection and enhanced immunity. In conclusion, this research unveils the relationship between FAM26F and HCV infection, highlighting the virus's tendency to suppress cytokine and FAM26F expression. An effective treatment strategy for establishing an ideal host immune response may involve restoring FAM26F and cytokine expression to their normal levels.

Hepatitis C virus (HCV) remains a significant global health challenge. Approximately 50 million people were living with chronic hepatitis C based on the World Health Organization as of 2024, contributing extensively to global morbidity and mortality. The advent and approval of several direct-acting antiviral (DAA) regimens significantly improved HCV treatment, offering potentially high rates of cure for chronic hepatitis C. However, the promising aim of eventual HCV eradication remains challenging. Key challenges include the variability in DAA access across different regions, slightly variable response rates to DAAs across diverse patient populations and HCV genotypes/subtypes, and the emergence of resistance-associated substitutions (RASs), potentially conferring resistance to DAAs. Therefore, periodic reassessment of current HCV knowledge is needed. An up-to-date review on HCV is also necessitated based on the observed shifts in HCV epidemiological trends, continuous development and approval of therapeutic strategies, and changes in public health policies. Thus, the current comprehensive review aimed to integrate the latest knowledge on the epidemiology, pathophysiology, diagnostic approaches, treatment options and preventive strategies for HCV, with a particular focus on the current challenges associated with RASs and ongoing efforts in vaccine development. This review sought to provide healthcare professionals, researchers, and policymakers with the necessary insights to address the HCV burden more effectively. We aimed to highlight the progress made in managing and preventing HCV infection and to highlight the persistent barriers challenging the prevention of HCV infection. The overarching goal was to align with global health objectives towards reducing the burden of chronic hepatitis, aiming for its eventual elimination as a public health threat by 2030.

The discovery of the hepatitis C virus (HCV) and direct-acting antiviral (DAA) drugs is one of the major milestones in the last 3 decades of medicine. These discoveries encouraged the World Health Organization (WHO) to set an ambitious goal to eliminate HCV by 2030, meaning "a 90% reduction in new cases of chronic HCV, a 65% reduction in HCV deaths, and treatment of 80% of eligible people with HCV infections."

This review summarizes the key achievements from the discovery of HCV to the development of effective treatment and global elimination strategies. A better understanding of HCV structure, enzymes, and lifecycle led to the introduction of new drug targets and the discovery of DAA. Massive public health interventions are required, such as screening, access to care, treatment, and post-care follow-up, to make the most of DAA's potential. Screening must be supported by fast, accessible, sensitive, specific HCV diagnostic tests and noninvasive methods to determine the stage of liver disease. Linkage to care and treatment access are critical components of a comprehensive HCV elimination program, and decentralization plays a key role in ensuring their effectiveness.

Effective and simple screening strategies, rapid diagnostic tools, linkage to health care, and accessible treatment are key elements to achieving the WHO's goal. Incorporating treatment as prevention strategies into elimination programs together with preventive education and harm reduction interventions can have a profound and lasting impact on reducing both the incidence and prevalence of HCV. However, WHO's goal can be challenging to implement because of the need for high financial resources and strong political commitment.

The HIV-1 provirus mainly consists of internal coding region flanked by 1 long terminal repeats (LTRs) at each terminus. The LTRs play important roles in HIV-1 reverse transcription, integration, and transcription. However, despite of the significant study advances of the internal coding regions of HIV-1 by using definite reference classification, there are no systematic and phylogenetic classifications for HIV-1 5' LTRs, which hinders our elaboration on 5' LTR and a better understanding of the viral origin, spread and therapy. Here, by analyzing all available resources of 5' LTR sequences in public databases following 4 recognized principles for the reference classification, 83 representatives and 14 consensus sequences were identified as representatives of 2 groups, 6 subtypes, 6 sub-subtypes, and 9 CRFs. To test the reliability of the supplemented classification system, the constructed references were applied to identify the 5' LTR assignment of the 22 clinical isolates in China. The results revealed that 16 out of 22 tested strains showed a consistent subtype classification with the previous LTR-independent classification system. However, 6 strains, for which recombination events within 5' LTR were demonstrated, unexpectedly showed a different subtype classification, leading a significant change of binding sites for important transcription factors including SP1, p53, and NF-κB. The binding change of these transcriptional factors would probably affect the transcriptional activity of 5' LTR. This study supplemented a unified classification system for HIV-1 5' LTRs, which will facilitate HIV-1 characterization and be helpful for both basic and clinical research fields.

Comparison of diagnostic accuracy for commercial hepatitis C virus (HCV) genotyping (Abbott RealTime HCV Genotyping II, Roche Cobas Genotyping) and investigational Abbott HCV Genotype plus RUO assays designed to discriminate genotype (GT)-1a, 1b or 6 in cases of ambiguous GT from the Abbott commercial assay remains limited. 743 HCV-viremic samples were subjected to analysis using Abbott and Roche commercial as well as Abbott HCV Genotype plus RUO assays. Next-generation sequencing (NGS) targeting core region was employed as the reference standard. Diagnostic accuracy was reported as the number of participants (percentages) along with 95% confidence intervals (CIs). Using NGS, 741 samples (99.7%) yielded valid genotyping results. The diagnostic accuracies were 97.6% (95% CI: 96.1%-98.5%) and 95.3% (95% CI: 93.4%-96.6%) using Abbott and Roche commercial assays (p = 0.0174). Abbott commercial assay accurately diagnosed HCV GT-6a and 6w, whereas Roche commercial assay accurately diagnosed HCV GT-6a. Both assays demonstrated low accuracies for HCV GT-6b, 6e, 6g, and 6n. Abbott HCV Genotype plus RUO assay discriminated 13 of the 14 samples (92.9%; 95% CI: 64.2%-99.6%) that yielded ambiguous GT. Both assays were capable of diagnosing mixed HCV infections when the minor genotype comprised >8.4% of the viral load. The diagnostic performance of commercial HCV genotyping assays is commendable. Abbott assay demonstrated superior performance compared to Roche assay in diagnosing HCV GT-6. Abbott HCV Genotype plus RUO assay aids in discriminating ambiguous GT. Both commercial assays are proficient in diagnosing mixed HCV infections at a cut-off viral load of 8.4% in minor genotype.

Equine hepacivirus (EqHV, Flaviviridae, hepacivirus) is a small, enveloped RNA virus generally causing sub-clinical hepatitis with occasional fatalities. EqHV is reported in equids worldwide, but for Italy data are limited. To address this, a survey study was set up to estimate prevalence at a national level and among different production categories (equestrian; competition; work and meat; reproduction) and national macro-regions (North, Central, South, and Islands). Data obtained testing 1801 horse serum samples by Real-Time RT PCR were compared within the categories and regions. The NS3 fragment of the PCR-positive samples was sequenced by Sanger protocol for phylogenetic and mutational analysis. The tertiary structure of the NS3 protein was also assessed. The estimated national prevalence was 4.27% [1.97-6.59, 95% CI] and no statistical differences were detected among production categories and macro-regions. The phylogenesis confirmed the distribution in Italy of the three known EqHV subtypes, also suggesting a possible fourth sub-type that, however, requires further confirmation. Mutational profiles that could also affect the NS3 binding affinity to the viral RNA were detected. The present paper demonstrates that EqHV should be included in diagnostic protocols when investigating causes of hepatitis, and in quality control protocols for blood derived products due to its parental transmission.

Direct acting antivirals (DAAs) have been developed for hepatitis C virus (HCV) therapy, and they are usually effective, however resistance to DAA regimens has also been reported to have a significant impact. Resistance associated substitutions (RASs) in the NS5A region are known to be correlated with failure of DAA therapy. HCV genotypes 3a and 1 are the most prevalent genotypes in Thailand. This study analyzed the type and frequency of RASs associated with DAA failure, focusing on the NS5A region. Serum samples of HCV genotype 3a, 1a, and 1b infection from Thai blood donors were selected. The NS5A region was amplified using reverse transcription-polymerase chain reaction (RT-PCR). A phylogenetic tree was constructed to identify the genotypes of HCV. Nucleotide sequencing and amino acid sequencing were conducted to determine the prevalence of RASs. Construction of the phylogenetic tree indicated that 29 samples were genotype 3a, 11 samples were genotype 1a, and 9 were genotype 1b. Both HCV genotypes 1a and 3a can be categorized into two subclades. Results showed that the NS5A substitutions A30V/K, A62T/V/I/M/P/S/L, and S98G were present in HCV genotype 3a. In HCV genotype 1a, only NS5A RASs H54Y was detected. NS5A amino acid substitutions Q54H and P58L were found in HCV genotype 1b. In conclusion, NS5A RASs at amino acid positions 30, 62, 54, 58, and 98 are present within HCV genotypes 3a and 1. While keeping in mind that additional information was not available on the anonymous blood donors tested in this study, these findings can contribute to understand the NS5A mutation. Further study with known patients under drug treatment is recommended.

Hepatitis C virus (HCV) remains a significant global health challenge, affecting millions of people worldwide, with chronic infection a persistent threat. Despite the advent of direct-acting antivirals (DAAs), challenges in diagnosis and treatment remain, compounded by the lack of an effective vaccine. The HCV genome, characterized by high genetic variability, consists of eight distinct genotypes and over ninety subtypes, underscoring the complex dynamics of the virus within infected individuals. This study delves into the intriguing realm of HCV genetic diversity, specifically exploring the phenomenon of mixed infections and the subsequent detection of recombinant forms within the conserved internal ribosome entry site (IRES) region. Previous studies have identified recombination as a rare event in HCV. However, our findings challenge this notion by providing the first evidence of 1a/3a (and vice versa) inter-genotypic recombination within the conserved IRES region. Utilizing advanced sequencing methods, such as deep sequencing and molecular cloning, our study reveals mixed infections involving genotypes 1a and 3a. This comprehensive approach not only confirmed the presence of mixed infections, but also identified the existence of recombinant forms not previously seen in the IRES region. The recombinant sequences, although present as low-frequency variants, open new avenues for understanding HCV evolution and adaptation.