Hepatitis C virus: molecular biology and genetic variability

HCV transmission in high-risk communities in Bulgaria

Background

The rate of HIV infection in Bulgaria is low. However, the rate of HCV-HIV-coinfection and HCV infection is high, especially among high-risk communities. The molecular epidemiology of those infections has not been studied before.

Methods

Consensus Sanger sequences of HVR1 and NS5B from 125 cases of HIV/HCV coinfections, collected during 2010–2014 in 15 different Bulgarian cities, were used for preliminary phylogenetic evaluation. Next-generation sequencing (NGS) data of the hypervariable region 1 (HVR1) analyzed via the Global Hepatitis Outbreak and Surveillance Technology (GHOST) were used to evaluate genetic heterogeneity and possible transmission linkages. Links between pairs that were below and above the established genetic distance threshold, indicative of transmission, were further examined by generating k-step networks.

Results

Preliminary genetic analyses showed predominance of HCV genotype 1a (54%), followed by 1b (20.8%), 2a (1.4%), 3a (22.3%) and 4a (1.4%), indicating ongoing transmission of many HCV strains of different genotypes. NGS of HVR1 from 72 cases showed significant genetic heterogeneity of intra-host HCV populations, with 5 cases being infected with 2 different genotypes or subtypes and 6 cases being infected with 2 strains of same subtype. GHOST revealed 8 transmission clusters involving 30 cases (41.7%), indicating a high rate of transmission.

Four transmission clusters were found in Sofia, three in Plovdiv, and one in Peshtera. The main risk factor for the clusters was injection drug use. Close genetic proximity among HCV strains from the 3 Sofia clusters, and between HCV strains from Peshtera and one of the two Plovdiv clusters confirms a long and extensive transmission history of these strains in Bulgaria.

Conclusions

Identification of several HCV genotypes and many HCV strains suggests a frequent introduction of HCV to the studied high-risk communities. GHOST detected a broad transmission network, which sustains circulation of several HCV strains since their early introduction in the 3 cities. This is the first report on the molecular epidemiology of HIV/HCV coinfections in Bulgaria.

Frequency of Interferon-Resistance Conferring Substitutions in Amino Acid Positions 70 and 91 of Core Protein of the Russian HCV 1b Isolates Analyzed in the T-Cell Epitopic Context

Amino acid substitutions R70Q/H and L91M in HCV subtype 1b core protein can affect the response to interferon and are associated with the development of hepatocellular carcinoma. We found that the rate of R70Q/H in HCV 1b from Russia was 31.2%, similar to that in HCV strains from Asia (34.0%), higher than that in the European (18.0%, p = 0.0010), but lower than that in the US HCV 1b strains (62.8%, p < 0.0001). Substitution L91M was found in 80.4% of the Russian HCV 1b isolates, higher than in Asian isolates (43.8%, p < 0.0001). Thus, a significant proportion of Russian HCV 1b isolates carry the unfavorable R70Q/H and/or L91M substitution. In silico analysis of the epitopic structure of the regions of substitutions revealed that both harbor clusters of T-cell epitopes. Peptides encompassing these regions were predicted to bind to a panel of HLA class I molecules, with substitutions impairing peptide recognition by HLA I molecules of the alleles prevalent in Russia. This indicates that HCV 1b with R70Q/H and L91M substitutions may have evolved as the immune escape variants. Impairment of T-cell recognition may play a part in the negative effect of these substitutions on the response to IFN treatment.

Hepatitis C Virus universal screening versus risk based selective screening during pregnancy

OBJECTIVES

We sought to compare the value of HCV universal screening versus risk-based selective screening in pregnant women.

STUDY DESIGN

In a prospective observational study (Jan 2012 - March 2012), pregnant women, in a high risk inner city clinic, who were at "low risk" for HCV infection were tested for HCV antibodies (universal screening) and their medical records were compared to the medical records of pregnant women who were at "high risk" (risk based selective screening as assessed by their obstetricians' screening questionnaire).

RESULTS

During the study period, 419 women delivered at our institution with 8.8% (37/419) at high risk for HCV. In 95% (183/193) of available and consenting low risk women, HCV antibody testing was done. The prevalence of HCV was 3.18% (7/220; 95% CI: 1.36-6.50) in all tested women versus 0.95% (4/419; 95% CI: 0.31-2.59) in risk-based selectively tested women. Overall the screening questionnaire had a sensitivity of 0.85 (0.42-0.99) and a specificity of 0.52 (0.45-0.58) in all women who had HCV antibody testing and questionnaire screening.

CONCLUSIONS

Using a screening questionnaire to identify women at risk for HCV infection during pregnancy under-estimates the real prevalence of HCV. A universal screening should be considered in high risk cities.

Molecular epidemiological analysis of three hepatitis C virus outbreaks in Jammu and Kashmir State, India

Outbreaks of hepatitis C virus (HCV) infection are associated with unsafe injection practices, intravenous drug abuse and other exposure to blood and body fluids. We report here three outbreaks of HCV infection from Jammu and Kashmir (J&K) State, India, which occurred over a period of 3 years and in which molecular epidemiological investigations identified a presumptive common source of infection, most likely a single healthcare venue. Representative blood samples collected from cases of hepatitis C were sent to the National Centre for Disease Control (NCDC) for molecular characterization. These samples were positive by HCV ELISA. Subsequently, specimens were also tested for the presence of HCV RNA by RT-PCR. Sequencing was carried out for all positive samples. A total of 812 cases were laboratory confirmed by HCV ELISA; a total of 115 samples were sent to the NCDC for RT-PCR, and 77 were positive. Subtype 3a of HCV was found in all samples from Anantnag (February 2013); and for subtype 3b, in all samples from Srinagar (May 2015). Subtypes 3a and 3g were identified from two samples from the Kulgam outbreak (July 2014). A detailed epidemiological investigation should be conducted whenever a cluster of HCV cases is revealed, as this potentially allows for the identification of larger outbreaks. Epidemiological investigations of outbreaks should be further supported by inclusion of molecular tests. Efforts to limit therapeutic injections to only those cases having strong medical/surgical indications and to restrict the use of non-sterile needles are essential to prevent transmission of HCV.

Sustained viral load reduction in treatment-naive HCV genotype 1 infected patients after therapeutic peptide vaccination

BACKGROUND

Novel antivirals augment treatment efficacy in chronic HCV infection, to overcome limitations on safety profile alternative approaches are warranted. The effect of a therapeutic peptide vaccine on HCV viral load was investigated in treatment-naïve genotype 1 HCV patients.

METHODS

Fifty patients received 8 intradermal IC41 vaccinations biweekly with topical application of the TLR7 agonist imiquimod (Group A). In Group B, 21 patients received a condensed schedule of 16 subcutaneous vaccinations weekly without imiquimod.

RESULTS

At Week 16 Group A (n=44) showed a statistically significant (p=0.0013) HCV viral load decline of 0.21 log. 24 weeks after the last vaccination the viral load decreased by 0.47 log (p<0.0001) in 34 subjects. This effect was more pronounced in 17 patients with high baseline HCV (>2×10(6)IU/ml) with a 0.61 log decline, which was statistically significant (p<0.02) starting two weeks after the third vaccination. No apparent effect on HCV viral load was observed in Group B (n=21). In Group A eight patients (24%) showed a viral load response defined as a decline of >0.8 log. Overall, about 30-55% of patients showed T cell responses during the vaccination series and up to six months in both groups. No significant correlations between the HCV viral load decrease and T cell immune response were detected.

CONCLUSIONS

This is the first report on a significant antiviral effect of a peptide vaccine in HCV infected patients. Response kinetics with increased HCV RNA decline 24 weeks after the last IC41 vaccination is encouraging.

Impact of HCV genetic differences on pathobiology of disease

Multiple HCV genotypes have been isolated worldwide. Genotype seems to be involved in the main pathological aspects of HCV infection. Insulin resistance, steatosis and progression toward cirrhosis, fibrosis and hepatocellular carcinoma establish and develop following genotype-specific mechanisms. Moreover genotype influences pharmacological treatment in term of dose and duration. Pathways involved in cell proliferation, apoptosis, lipid metabolism, insulin and interferon signaling are impaired to a different extent among genotypes, leading to distinct pathological settings. Genotype 1 is associated with a more aggressive disease with increased insulin resistance, worst response to therapy, higher risk of cirrhosis and hepatocellular carcinoma development, while genotype 3 is associated with increased steatosis and fibrosis. The identification and characterization of HCV types and subtypes provides insight into the different outcome of HCV infection and responsiveness to therapy. In the present article, we focused on the pathogenicity of HCV genotypes and their effect on disease progression and treatment.

Isolation of scFvs that inhibit the NS3 protease of hepatitis C virus by a combination of phage display and a bacterial genetic screen

The need for inhibitors for enzymes linked with microbial infection, specifically the NS3 protease of hepatitis C virus (HCV), inspired us to develop a unique, rapid and easy color-based method described herein. The NS3 serine protease of HCV has a role in processing viral polyprotein and it has been implicated in interactions with various cell constituents, resulting in phenotypic changes including malignant transformation. NS3 is currently regarded a prime target for antiviral drugs.We established a genetic screen that is based on coexpression of NS3, a beta-galactosidase reporter that is cleavable by NS3, and potential inhibitors within the same bacterial cell. A single-chain antibody (scFv) library was prepared from spleens of NS3-immunized mice and the screen was used to isolate a panel of protease-inhibiting scFvs. Candidate scFvs were validated for inhibitory activity using an o-nitrophenyl-beta-galactoside (ONPG) hydrolysis assay.The methods can be used more generally to isolate protease-inhibiting cytoplasmic intrabodies able to inhibit proteases or other activities that can be linked with the phenotype of Escherichia coli.

Molecular mechanism of a thumb domain hepatitis C virus nonnucleoside RNA-dependent RNA polymerase inhibitor

A new pyranoindole class of small-molecule inhibitors was studied to understand viral resistance and elucidate the mechanism of inhibition in hepatitis C virus (HCV) replication. HCV replicon variants less susceptible to inhibition by the pyranoindoles were selected in Huh-7 hepatoma cells. Variant replicons contained clusters of mutations in the NS5B polymerase gene corresponding to the drug-binding pocket on the surface of the thumb domain identified by X-ray crystallography. An additional cluster of mutations present in part of a unique beta-hairpin loop was also identified. The mutations were characterized by using recombinant replicon variants engineered with the corresponding amino acid substitutions. A single mutation (L419M or M423V), located at the pyranoindole-binding site, resulted in an 8- to 10-fold more resistant replicon, while a combination mutant (T19P, M71V, A338V, M423V, A442T) showed a 17-fold increase in drug resistance. The results of a competition experiment with purified NS5B enzyme with GTP showed that the inhibitory activity of the pyranoindole inhibitor was not affected by GTP at concentrations up to 250 microM. Following de novo initiation, the presence of a pyranoindole inhibitor resulted in the accumulation of a five-nucleotide oligomer, with a concomitant decrease in higher-molecular-weight products. The results of these studies have confirmed that pyranoindoles target the NS5B polymerase through interactions at the thumb domain. This inhibition is independent of GTP concentrations and is likely mediated by an allosteric blockade introduced by the inhibitor during the transition to RNA elongation after the formation of an initiation complex.

Immunogenicity and safety of a novel therapeutic hepatitis C virus (HCV) peptide vaccine: A randomized, placebo controlled trial for dose optimization in 128 healthy subjects

As interferon/ribavirin-based standard therapy is curative in only about half of HCV patients, there remains an important need for alternatives including vaccines. The novel peptide vaccine IC41 consists of five synthetic peptides harboring HCV T cell epitopes and poly-L-arginine as synthetic adjuvant. In this randomized, placebo-controlled trial, 128 HLA-A2 positive healthy volunteers received four s.c. vaccinations of seven different doses IC41, HCV peptides alone, poly-l-arginine alone or saline solution, every 4 weeks. IC41 was safe and well tolerated. Mild to moderate local reactions were transient. Immunogenicity was assessed using T cell epitope specific [3H]-thymidine proliferation, IFN-gamma ELIspot and HLA-tetramer assays. IC41 induced responses in all dose groups. Higher responder rates were recorded in higher dose groups and increasing number of vaccinations were associated with higher responder rates and more robust responses. Poly-L-arginine was required for the aimed-for Th1/Tc1-type immunity (IFN-gamma secreting T cells).

HCV NS3 serine protease-neutralizing single-chain antibodies isolated by a novel genetic screen

Hepatitis C virus (HCV) infection is a major world-wide health problem causing chronic hepatitis, liver cirrhosis and primary liver cancer. The high frequency of treatment failure points to the need for more specific, less toxic and more active antiviral therapies for HCV. The HCV NS3 is currently regarded as a prime target for anti-viral drugs, thus specific inhibitors of its activity are of utmost importance. Here, we report the development of a novel bacterial genetic screen for inhibitors of NS3 catalysis and its application for the isolation of single-chain antibody-inhibitors. Our screen is based on the concerted co-expression of a reporter gene, of recombinant NS3 protease and of fusion-stabilized single-chain antibodies (scFvs) in Escherichia coli. The reporter system had been constructed by inserting a short peptide corresponding to the NS5A/B cleavage site of NS3 into a permissive site of the enzyme beta-galactosidase. The resulting engineered lacZ gene, coding for an NS3-cleavable beta-galactosidase, is carried on a low copy plasmid that also carried the NS3 protease-coding sequence. The resultant beta-galactosidase enzyme is active, conferring a Lac+ phenotype (blue colonies on indicator 5-bromo-4-chloro-3-indolyl beta-D-galactoside (X-gal) plates), while induction of NS3 expression results in loss of beta-galactosidase activity (transparent colonies on X-gal plates). The identification of inhibitors, as shown here by isolating NS3-inhibiting single-chain antibodies, expressed from a compatible high copy number plasmid, is based on the appearance of blue colonies (NS3 inhibited) on the background of colorless colonies (NS3 active). Our source of inhibitory scFvs was an scFv library that we prepared from spleens of NS3-immunized mice and subjected to limited affinity selection. Once isolated, the inhibitors were validated as genuine and specific NS3 binders by an enzyme-linked immunosorbent assay and as bone fide NS3 serine protease inhibitors by an in vitro catalysis assay. We further show that upon expression as cytoplasmic intracellular antibodies (intrabodies) in NS3-expressing mammalian cells, three of the scFvs inhibit NS3-mediated cell proliferation. Although applied here for the isolation of antibody-based inhibitors, our genetic screen should be applicable for the identification of candidate inhibitors from other sources.

Mitogen-induced upregulation of hepatitis C virus expression in human lymphoid cells

Considering growing evidence indicating that hepatitis C virus (HCV) replicates in lymphoid cells, establishment of a reliable and sensitive method for detection of HCV in these cells may provide means for monitoring the infection and the efficacy of sterilizing antiviral therapy. In this study, conditions for ex vivo augmentation and detection of the HCV genome in peripheral blood mononuclear cells (PBMCs) from patients with chronic hepatitis C (CHC) or after a sustained virological response (SVR) to antiviral treatment were assessed. Following stimulation with combinations of mitogens and/or cytokines, PBMCs and, in certain cases, affinity-purified T and B cells were examined for HCV positive- and negative-strand RNA by using RT-PCR followed by nucleic acid hybridization, while the presence of viral NS3 protein was determined by flow cytometry. HCV RNA augmentation was assessed by quantification of Southern and dot-blot hybridization signals. The results showed that treatment of peripheral lymphoid cells with mitogens stimulating T- and B-cell proliferation and with cytokines supporting their growth significantly increased HCV RNA detection in patients with both CHC and SVR. This enhancement was up to 100-fold for the HCV genome and fivefold for the NS3 protein compared with untreated cells. In conclusion, HCV RNA can be readily detected in circulating lymphoid cells in progressing hepatitis C and following SVR after ex vivo cell stimulation. As such, this method offers a new investigative tool to study HCV lymphotropism and to monitor virus presence during the course of HCV infection.

Infectious agents and cancer: criteria for a causal relation

Infectious agents, mainly viruses, are among the few known causes of cancer and contribute to a variety of malignancies worldwide. The agents and cancers considered here are human papillomaviruses (cervical carcinoma); human polyomaviruses (mesotheliomas, brain tumors); Epstein-Barr virus (B-cell lymphoproliferative diseases and nasopharyngeal carcinoma); Kaposi's Sarcoma Herpesvirus (Kaposi's Sarcoma and primary effusion lymphomas); hepatitis B and hepatitis C viruses (hepatocellular carcinoma); Human T-cell Leukemia Virus-1 (T-cell leukemias); and helicobacter pylori (gastric carcinoma), which account for up to 20% of malignancies around the globe. The criteria most often used in determining causality are consistency of the association, either epidemiologic or on the molecular level, and oncogenicity of the agent in animal models or cell cultures. However use of these generally applied criteria in deciding on causality is selective, and the criteria may be weighted differently. Whereas for most of the tumor viruses the viral genome persists in an integrated or episomal form with a subset of viral genes expressed in the tumor cells, some agents (HBV, HCV, helicobacter) are not inherently oncogenic, but infection leads to transformation of cells by indirect means. For some malignancies the viral agent appears to serve as a cofactor (Burkitt's lymphoma-EBV; mesothelioma - SV(40)). For others the association is inconsistent (Hodgkin's Disease, gastric carcinomas, breast cancer-EBV) and may either define subsets of these malignancies, or the virus may act to modify phenotype of an established tumor, contributing to tumor progression rather than causing the tumor. In these cases and for the human polyomaviruses the association with malignancy is less consistent or still emerging. In contrast despite the potent oncogenic properties of some strains of human adenovirus in tissue culture and animals the virus has not been linked with any human cancers. Finally it is likely that more agents, most likely viruses, both known and unidentified, have yet to be implicated in human cancer. In the meantime study of tumorigenic infectious agents will continue to illuminate molecular oncogenic processes.

The molecular basis of HCV-mediated immune dysregulation

Chronic hepatitis C virus (HCV) infection, which occurs in over 85% of patients and causes mild to severe liver disease, is a growing burden to health systems worldwide. The propensity of HCV to establish persistent infection suggests that the virus, which is non-cytopathic, has evolved one or more mechanisms aimed at evading host immunity. In addition to the appearance of quasispecies, which may arise under selective pressure during B and T cell responses, HCV gene products interact with host proteins in order to subvert immune surveillance. Gaining insight into these interactions may provide the basis for novel therapies aimed at preventing chronic HCV infection.

Correlation between histologic staging, hepatitis C virus genotypes and clinical features in HCV chronic hepatitis: evidence of a new pattern

Genome heterogeneity may be related to the wide variability of clinical and pathological features in hepatitis C virus (HCV)-related chronic liver disease. This paper addresses the possible association between HCV subtypes and clinical and histological features of chronically infected patients. Sixty-eight consecutive liver biopsies of chronic hepatitis constituted the basis of the study. HCV genotyping was performed on frozen tissue. Grading of necroinflammatory activity and staging of fibrosis were histologically assessed. Serologic HCV-RNA and liver function were assessed at the same time. All information was compared with clinical data including age, sex, HCV serology, and probable data and route of infection. Two cases were excluded as inadequate tissue was available. Five cases were negative to HCV-RNA in both serum and tissue. In 61 cases HCV RNA was present at the same time in serum and liver tissue. Forty-four patients were men (72%) and 17 (28%) were women. Two peaks of age were observed: 1 in the 4th decade of life, the 2nd in the 7th. The 2 groups had different HCV genotypes. Patients with genotypes 1b (mean age 50.7 years), 2c (mean age 61.3 years), and a subgroup of coinfections (mean age 60 years) were older than patients with genotypes 1a (mean age 35.5 years), 3 (mean age 36 years), and a subgroup of coinfections (mean age 33 years). Patients with genotypes 1b, 2, or 2c and a subgroup of coinfections more frequently had a history of blood transfusion and or surgical intervention dating up to 49 years previously. Patients with HCV 1a, 3, and a subgroup of coinfections frequently admitted a period of intravenous drug abuse. Patients with advanced liver disease, i.e., severe fibrosis and cirrhosis, showed the same 2 peaks of incidence: in the 4th and 7th decades of life, the first group mainly comprising patients with HCV types 1a and 3, the second, patients with HCV types 1b and 2c. Both these groups shared a clinical history of a long-standing infection. Two profiles of patients emerged. The largest group was composed of elderly patients, infected by HCV genotypes 1b or 2c, with a history of blood transfusion and/or surgery, presenting an advanced stage of liver disease (namely, severe fibrosis or cirrhosis). The second group was composed of younger patients, mainly in the 4th decade of life, infected by HCV types 3 or 1a, often presenting with chronic hepatitis in the stage of severe fibrosis or cirrhosis. The latter could be the profile of HCV infection in the near future.

Dynamic changes of HVR1 quasispecies in chronic hepatitis C after IFN therapy

AIM: To evaluate the correlation between the complexity of HCV HVR1 quasi-species and their response to IFN therapy in patients with chronic hepatitis C.

METHODS: Twenty patients with chronic hepatitis C received IFN therapy (3 mu/d, three times/week for 24 wk). Serum quasispecies complexity of HVR1 was analyzed by polymerase chain reaction mediated singl-strand conformation polymorphism (SSCP) before and 3 mo, 6 mo post-therapy, respectively.

RESULTS: Of 20 patients, 7 had low level of complexity (SSCP bands ≤ 3), 13 had high level of complexity (SSCP bands > 3). The rate of HCV RNA negative in low level complexity group was higher than that in high level complexity group. Patients with low level of complexity prior to therapy had good responsive to IFN; Serum HCV RNA in some patients did not convert to negative after IFN therapy, however, the number of SSCP bands decreased gradually.

CONCLUSION: HCV HVR1 quasi-species complexity is a predictive factor in response to IFN therapy, a statistically significant correlation between high level of complexity of HCV HVR1 quasi-species and lacking of response to IFN therapy in patients with chronic hepatitis C was found.

A novel high throughput screening assay for HCV NS3 serine protease inhibitors

Hepatitis C virus (HCV) infection is a major worldwide health problem, causing chronic hepatitis, liver cirrhosis and primary liver cancer (Hepatocellular carcinoma). HCV encodes a precursor polyprotein that is enzymatically cleaved to release the individual viral proteins. The viral non-structural proteins are cleaved by the HCV NS3 serine protease. NS3 is regarded currently as a potential target for anti-viral drugs thus specific inhibitors of its enzymatic activity should be of importance. A prime requisite for detailed biochemical studies of the protease and its potential inhibitors is the availability of a rapid reliable in vitro assay of enzyme activity. A novel assay for measurement of HCV NS3 serine protease activity was developed for screening of HCV NS3 serine protease potential inhibitors. Recombinant NS3 serine protease was isolated and purified, and a fluorometric assay for NS3 proteolytic activity was developed. As an NS3 substrate we engineered a recombinant fusion protein where a green fluorescent protein is linked to a cellulose-binding domain via the NS5A/B site that is cleavable by NS3. Cleavage of this substrate by NS3 results in emission of fluorescent light that is easily detected and quantitated by fluorometry. Using our system we identified NS3 serine protease inhibitors from extracts obtained from natural Indian Siddha medicinal plants. Our unique fluorometric assay is very sensitive and has a high throughput capacity making it suitable for screening of potential NS3 serine protease inhibitors.

Ultrastructural visualization of hepatitis C virus components in human and primate liver biopsies

BACKGROUND/AIMS

Molecular and structural studies of hepatitis C virus (HCV) replication and infection have been performed on cultured cells and on serum of infected patients. No conclusive studies were conducted yet on human liver biopsies. This paper describes the ultrastructural findings of hepatitis C virus components in liver biopsies.

METHODS

Liver specimens from acutely and chronically HCV-infected chimpanzees (five each) and 29 chronic hepatitis C patients were studied. Diagnosis of HCV infection was based on clinical, serological, light microscopic and immunohistochemical data and on HCV RNA polymerase chain reaction.

RESULTS

In HCV-infected chimpanzees, tubular aggregates were observed in the cytoplasm of a significant number of hepatocytes and proven by immuno-electron microscopy to contain HCV-E2 viral envelope material. Identical tubular aggregates were seen in hepatocytes of chronic HCV-infected patients, although in smaller quantity and less frequently. A few single enveloped virus-like particles of 50-60 nm in diameter were seen for the first time in the hyaloplasm of hepatocytes of HCV-infected chimpanzees and patients.

CONCLUSIONS

For the first time, HCV envelope material was ultrastructurally identified in hepatocytes of HCV-infected chimpanzees and patients. Virus-like particles, although strongly suggestive for HCV, failed final confirmation at least by routinely used methods.

Hepatitis G virus genotypes in a tertiary care centre in southern India

BACKGROUND

The association of GBV-C/HGV in patients at high risk of parenteral infection and those with chronic liver disease in southern India is unknown.

OBJECTIVES

To study the occurrence of GBV-C/HGV in three patient groups attending a tertiary care centre in Vellore and identify the prevailing genotype(s).

STUDY DESIGN

Two hundred and twenty-seven individuals were studied using an RT-PCR assay with primers specific for the 5'NCR and the NS5a-coding regions. Ten randomly selected samples were sequenced in the 5'NCR region of the GBV-C/HGV genome.

RESULTS

GBV-C/HGV RNA was detected in 37/70 (52.9%) of renal transplant recipients, 18/70 (25.7%) of patients with haematological disorders and in 9/87 (10.3%) patients with chronic liver disease. Nine of the ten sequences could be assigned to genotype 2a while the remaining sequence could not be assigned.

CONCLUSIONS

In this centre, GBV-C/HGV is widely prevalent in patients with high parenteral risk and in those with chronic liver disease. The predominantly circulating genotype among study patients is genotype 2a.

Detection of neutralizing antibodies to hepatitis C virus using a biliary cell infection model

The identification and characterization of neutralizing anti-hepatitis C virus (HCV) antibodies may have a major impact on understanding HCV pathogenesis. However, to date, their detection has only been based on the inhibition of either the E2 envelope protein or HCV virions binding to different target cells. The permissiveness of primary biliary cells for HCV infection has been demonstrated previously. In the present report, infection of biliary cells was demonstrated further by combining PCR and immunohistochemical detection of the HCV core protein. This study demonstrates, using both serum and purified IgG, the presence of neutralizing anti-HCV antibodies in the serum of patients showing long-term response to antiviral therapy. Overall, the usefulness of the primary biliary cell infection model to investigate anti-HCV neutralization is shown.

Immunopathogenesis of hepatitis C virus in the immunosuppressed host

The prevalence of chronic hepatitis C virus (HCV) infection among various groups of immunosuppressed patients is high. These groups include patients co-infected with human immunodeficiency virus (HIV), recipients of organ transplants, and those with hypogammaglobulinemia. The liver disease in the immunosuppressed host is typically severe with an unusually rapid progression to cirrhosis. This is somewhat paradoxical, as the classical model for HCV-induced liver disease assumes that cell-mediated immune responses induce liver injury. It is likely that a combination of viral-related factors and host-related factors plays a role in this accelerated natural history of HCV. Data are accumulating in immunocompromised hosts that address the immunopathogenesis of liver injury, although there are still fundamental gaps in our understanding of this process. In this review, we will focus on our current understanding of the mechanisms of liver injury and how it relates to the accelerated liver disease progression in immunocompromised hosts.

An altered cellular response to interferon and up-regulation of interleukin-8 induced by the hepatitis C viral protein NS5A uncovered by microarray analysis

There is evidence for an inhibition of interferon-alpha antiviral activity by the hepatitis C viral protein, NS5A. To identify the mechanisms through which NS5A blocks interferon activity, we compared the gene expression profile of interferon-treated Huh7 cells, stably expressing NS5A with control, using microarrays. Following interferon treatment, 50 genes were up-regulated by at least twofold in control clones, whereas induction of 9 of the 50 genes was significantly reduced in NS5A-expressing clones. The strongest effect of NS5A on interferon response was observed for the OAS-p69 gene. Remarkably, Huh7 cells expressing NS5A showed an up-regulation of interleukin-8. Up-regulation of interleukin-8 was also observed upon transient expression of NS5A mutants isolated from patients responsive or resistant to interferon therapy. Addition of interleukin-8 to Huh7 cells inhibited the antiviral activity of interferon and, similarly to NS5A, reduced the induction by interferon-alpha of selective genes including OAS-p69. Our findings provide a mechanism for NS5A-mediated interferon resistance.

The cost-effectiveness of hepatitis A vaccination in patients with chronic hepatitis C viral infection in the United States

OBJECTIVE

Hepatitis A vaccination is recommended for patients with chronic hepatitis C. Our aim was to analyze the cost-effectiveness of hepatitis A vaccination in these patients. The specific strategies evaluated were: no vaccination, targeted vaccination, and universal vaccination.

METHODS

Clinical estimates were based on published data. Costs estimates were based on published data and institutional Medicare reimbursement rates. Health-related quality-of-life weights were derived from published data and expert estimates. The target population consisted of patients 45 yr of age with chronic hepatitis C followed every 6 months until death. We adopted a societal perspective.

RESULTS

Compared with no vaccination, targeted vaccination was associated with an incremental cost-effectiveness ratio of $51,000 per quality-adjusted life-year. The incremental cost-effectiveness ratio of universal vaccination compared with targeted vaccination was $3,900,000 per quality-adjusted life-year. The results were particularly sensitive to the incidence of hepatitis A, probability of fulminant hepatic failure, and costs of hepatitis A antibody screening and vaccination.

CONCLUSIONS

Targeted vaccination for hepatitis A in patients with chronic hepatitis C may be a cost-effective strategy to decrease the morbidity and mortality associated with hepatitis A superinfection. Universal vaccination is not a cost-effective alternative to targeted vaccination in this target population.

Perspectives: towards a peptide-based vaccine against hepatitis C virus

Hepatitis C virus (HCV) is a widespread infectious disease in humans with the negative implication of becoming chronic in most persons. Patients infected with HCV are at risk of liver cirrhosis or hepatocellular carcinoma at later stages. In contrast to hepatitis A and hepatitis B, there is no immunization yet available, neither prophylactic nor therapeutic. Thus, there is an urgent need to develop a safe, protective vaccine against this fatal disease. Developing countries are even more at risk for HCV. There are currently a number of scientific approaches aimed towards solving this problem. Taking both risks and costs of immunization into consideration, a peptide-based vaccine may be a reasonable prophylactic protection. Also, it might be of therapeutic use in already infected patients by increasing a specific CTL response against HCV. In our lab, we are focusing on immunopotentiating reconstituted influenza virosomes (IRIVs) as carriers for immunogenic HLA-A2-restricted core epitopes to induce peptide-specific cytotoxic T lymphocytes (CTLs). The IRIVs are similar to liposomes, but in addition contain influenza-derived hemagglutinin and neuraminidase on their outer surface which makes them fusogenic, thus, permitting antigen delivery to host cells. So far, virosomes have been successfully used for vaccine development and as a result a virosomal vaccine against both influenza virus (Inflexal) BERNA) and hepatitis A virus (HAV) (Epaxal) BERNA) already exist on the market. This paper focuses on the importance of development of a successful vaccine against HCV and, more specifically, we discuss the use, advantages and disadvantages of a peptide-based vaccine. A brief report of our latest findings will be included.

Quality of life in HCV-infection: lack of association with ALT levels

OBJECTIVES

To examine the impact of HCV infection in an Australian clinic population and identify the relationships between morbidity, psychosocial variables and one clinical indicator of HCV activity, alanine aminotransferase (ALT).

METHOD

Ninety-five untreated HCV-infected patients (21-69 years) in infectious and liver diseases clinics who were all positive for HCV-RNA and had no significant comorbidities or coinfections completed a survey containing the Short Form 36 (SF36), as well as the six-item Social Support Questionnaire (SSQ6), demographic items and questions concerning respondents' perceptions of their mode and duration of infection. Nine volunteers from this group participated in semi-structured qualitative interviews aimed at exploring the social impact of HCV status. These data were compared with serum ALT levels. SF36 scores were compared to population norms and according to participant variables.

RESULTS

Mean SF36 scores were significantly lower, across all modalities, than population norms. SF36 scores differed significantly according to age, sex, mode of infection, alcohol and methadone use, and satisfaction with social support. They did not differ significantly according to perceived or actual ALT level or pattern of ALT activity. Worry about ALT was prevalent (>50%) and this was independent of perceived ALT level.

CONCLUSIONS AND IMPLICATIONS

HCV-infection is associated with significantly reduced quality of life and includes the perception of substantial social discrimination. ALT levels are of limited usefulness in ascertainment of a person's sense of wellbeing and quality of life in HCV-infection. Increased support and information for affected individuals and measures aimed at countering social discrimination are important recommendations of the current study.

Distribution of hepatitis C virus infection in liver biopsies from children and adults with chronic hepatitis C

Chronic hepatitis C in children is characterized by milder forms of liver damage than those found in adults. Such a difference has been attributed to a low viral load in children that may lead to poor recognition of infected cells by the immune system. One approach that could be used to confirm this hypothesis may be to examine the number of infected hepatocytes in liver biopsies. Paraffin embedded liver biopsies from 21 children and 15 adults with chronic hepatitis C virus (HCV) infection (with a similar duration of the infection) were hybridized in situ and the percentage of infected hepatocytes was correlated with the histological activity index, alanine aminotransferase levels and HCV viraemia levels. Histological activity index and HCV viraemia levels were statistically higher (P < 0.05 and P < 0.01 respectively) in adults than in children, and the percentage of infected hepatocytes was higher in adults (11.0 +/- 19.7%) than in children (4.6 +/- 3.6%), although it did not reach statistical significance. Also, the percentage of infected hepatocytes correlated with HCV-RNA concentration in serum in both children (r = 0.683, P = 0.001) and adults (r = 0.768, P = 0.001). The results show that liver damage in children with chronic hepatitis C is not related to the extent of infection in the liver. This findings support the hypothesis of that liver injury in chronic HCV infection is mediated by the host immune response.

Nucleotide and amino acid complexity of hepatitis C virus quasispecies in serum and liver

The quasispecies nature of the hepatitis C virus (HCV) is thought to play a central role in maintaining and modulating viral replication. Several studies have tried to unravel, through the parameters that characterize HCV circulating quasispecies, prognostic markers of the disease. In a previous work we demonstrated that the parameters of circulating viral quasispecies do not always reflect those of the intrahepatic virus. Here, we have analyzed paired serum and liver quasispecies from 39 genotype 1b-infected patients with different degrees of liver damage, ranging from minimal changes to cirrhosis. Viral level was quantified by real-time reverse transcription-PCR, and viral heterogeneity was characterized through the cloning and sequencing of 540 HCV variants of a genomic fragment encompassing the E2-NS2 junction. Although in 95% of patients, serum and liver consensus HCV amino acid sequences were identical, quasispecies complexity varied considerably between the viruses isolated from each compartment. Patients with HCV quasispecies in serum more complex (26%) than, less complex (28%) than, or similarly complex (41%) to those in liver were found. Among the last, a significant correlation between fibrosis and all the parameters that measure the viral amino acid complexity was found. Correlation between fibrosis and serum viral load was found as well (R = 0.7). With regard to the origin of the differences in quasispecies complexity between serum and liver populations, sequence analysis argued against extrahepatic replication as a quantitatively important contributing factor and supported the idea of a differential effect or different selective forces on the virus depending on whether it is circulating in serum or replicating in the liver.

Hepatitis G virus: relevance to oral health care

OBJECTIVE

To review the current literature on the hepatitis G virus (HGV) infection, with particular attention to the aspects of interest for the dental staff.

MATERIAL AND METHODS

The authors searched for original research and review articles on specific aspects of the HGV infection including virology, epidemiology, transmission, natural history, and dental zaspects of HGV infection. The relevant articles were evaluated and reviewed.

RESULTS

HGV is a parenterally transmitted RNA virus that may cause acute, chronic, and fulminant liver disease; however, the real pathogenic potential of this virus and its possible effect on other hepatitic infections is still to be clarified. Preliminary studies have failed to demonstrate strong relationships between HGV infection and any oral disease. At present, data on the prevalence of HGV infection among health care workers are scarce. Nevertheless, in view of the potential transmission rates of HGV and the lack of effective immunization, HGV should be regarded as a potential occupational hazard for medical and dental staff.

CONCLUSION

Many virological, medical, and oral aspects of HGV infection need to be further investigated; nevertheless, until related data are available, HGV should be considered to be an infection that may be transmitted during dental care.

Hepatitis C virus-specific DNA sequences in human DNA: differentiation by means of restriction enzyme analysis at the DNA level in healthy, anti-HCV-negative individuals

This study aimed to look for further HCV-specific sequences at the DNA level of healthy, HCV-negative individuals. Here, the sequence section from nt 57 to nt 328 within the 5'-NCR was assayed. Different combinations of primers were used in the nested PCR without a preceding reverse transcriptase step, resulting in fragments of the expected molecular weight size and also shorter and longer ones. It shows that the major part of the 5'-non-coding region (5'-NCR) of the hepatitis C virus genome is present in the DNA fraction from peripheral blood mononuclear cells (PBMCs) of healthy, anti-HCV-negative individuals tested. Furthermore we designed experiments to prove the specificity of these findings, by using restriction enzymes for digest assays of the target DNA before PCR (pre-PCR digest) and of the products after PCR (post-PCR digest). In conclusion, our study indicates that the main part of the internal ribosome entry site (IRES) structure of HCV at least is contained in the DNA of the individuals tested.

De novo hepatocellular carcinoma in a hepatic allograft with recurrent hepatitis C cirrhosis

We report a case of de novo hepatocellular carcinoma (HCC) in a patient with recurrent hepatitis C (HCV) and cirrhosis 7 years after orthotopic liver transplantation (OLT). This is a previously unreported observation in the natural history of posttransplantantion HCV infection and reiterates the strong oncogenic potential of HCV.

Chronic hepatitis C in children: a clinical and immunohistochemical comparative study with adult patients

Limited information is available regarding the characteristics of the hepatitis C virus (HCV) infection in children. We compared the epidemiological background along with the virological and histological features as well as the intrahepatic immunologic phenotype of both children and adults with chronic hepatitis C (CHC). Serum samples of 24 pediatric and 32 adult patients were drawn for alanine transaminase (ALT) levels, HCV-typing, and viral load. The histological diagnosis and a semiquantitative immunohistochemical assessment were performed in all patients. The majority of children (62%) had been transfused and the mean duration of viral infection in these cases was 11 +/- 4 years, being similar in adults (11 +/- 9 years, not significant). Although genotype distribution was similar, viral load was lower in children than in adults. The mildest histological forms of chronic hepatitis along with a weak intrahepatic immunological phenotype were significantly more frequent among children than adult patients. In conclusion, in children with CHC, perinatal blood transfusion was the most frequent source of viral infection and the liver disease was characterized by both low ALT level and viral load, as well as the mildest histological and immunohistochemical forms of chronic hepatitis.

Hepatitis C virus (HCV) hypervariable region 1 complexity does not correlate with severity of liver disease, HCV type, viral load or duration of infection

BACKGROUND/AIMS

Several studies have suggested that infection with a highly heterogeneous population of hepatitis C virus correlates with a low response rate to interferon. It is still debated, however, whether or not this heterogeneity might be associated with liver disease severity. The aim of this study was to analyse hepatitis C virus genome complexity in patients with various stages of liver disease.

METHODS

We used polymerase chain reaction-single strand conformation polymorphism (SSCP) analysis to estimate the degree of complexity of the hypervariable region (HVR1) in 95 anti-HCV and serum HCV-RNA positive patients. They were divided into two groups according to Knodell's histological activity index (HAI) grading: 22 with HAI <4 and 73 with HAI> or =4, including 19 with cirrhosis.

RESULTS

The number of visible SSCP bands ranged from 1 to 7. There was no significant difference in the number of SSCP bands between patients with HAI <4 and patients with HAI> or =4 (median number of bands was 4 in both groups). The number of SSCP bands was not correlated to the biochemical activity, the genotype, the HCV-RNA titre or the duration of hepatitis C virus infection.

CONCLUSIONS

The HCV-HVR1 complexity profile alone does not correlate with the severity of liver disease, whatever the biological and virological profile of the viral infection.

Molecular epidemiology of hepatitis C in Australia

The aim of this study was to determine the distribution of hepatitis C virus (HCV) genotypes in Australian patients with hepatitis C and to identify factors associated with particular genotypes. Serum isolates of HCV-RNA were genotyped using a commercial oligonucleotide hybridization (line probe) assay. Relationships between demographic factors, mode of HCV transmission and HCV genotype were assessed by logistic regression analysis. Among 463 patients with hepatitis C, 425 tested positive for HCV-RNA and a single HCV genotype was identified in 420 cases. The patients' places of birth were Australia or New Zealand (62%), Asia (13%), Europe (12%), Mediterranean (6%), Middle East (6%) and other countries (< 1%). The most common genotypes were type 1 (52%) or type 3 (32%); type 2 (9.3%), type 4 (5.5%) and type 6 (1.7%) were less common. Patients with genotype 1b were older (48 +/- 13 years, P< 0.001) and patients with genotype 3 were younger than the remaining patients (37 +/- 11 years vs 42 +/- 12 years, P< 0.001). Among type 1 isolates, 1b was more common for patients born outside Australia compared with those born in Australia (50% vs 13%, P< 0.001) whereas non-1b subtypes were more common among Australian-born patients. Likewise, 21 of 23 (91%) patients with type 4 were from Egypt and six of seven (86%) with type 6 were from Vietnam. The relative importance of parenteral risk factors for HCV also varied according to geographic origin. Thus, a definite risk factor for HCV acquisition was identified in > 95% of Australian-born patients, but in only 33% of Asian or Mediterranean-born patients. Logistic regression analysis indicated that region of birth and risk factor (intravenous drug use or not) would allow 98% of type 4 cases and 76% of type 1b cases to be identified correctly. In summary, region of birth, patterns of migration over time and risk factors for transmission of HCV interact to determine the distribution of HCV genotypes in a multi-racial community like Australia.

Hepatitis C virus infection: Review and implications for the dentist

OBJECTIVE

The purpose of this report was to review the current literature on hepatitis C virus infection, with particular attention to the aspects of interest for dental health care staff.

MATERIAL AND METHODS

The authors searched original research and review articles on specific aspects of hepatitis C virus infection, including articles on virology, epidemiology, transmission, diagnosis, natural history, extrahepatic manifestations, therapy and oral aspects of hepatitis C virus infection. The relevant material was evaluated and reviewed.

RESULTS

Hepatitis C virus is an RNA virus that is present throughout the world and has major geographic variations. The virus, transmitted mainly by means of blood contact, causes chronic hepatitis in up to 80% of cases and may give rise to hepatic cirrhosis and hepatocellular carcinoma in a significant proportion of patients. Although it is of limited efficacy, interferon alpha is currently the drug of choice in the treatment of the infection. Hepatitis C virus infection is associated with a number of extrahepatic manifestations that may include oral diseases such as lichen planus or sialadenitis. Although there are documented cases of nosocomial transmission to health care workers after percutaneous exposure, the prevalence of hepatitis C virus among dental staff members is probably similar to that in the general population.

CONCLUSION

Hepatitis C virus infection is a relatively common infection worldwide (1.4% in the US general population) that causes significant chronic hepatic disease. The dentist is thus likely to face a growing number of patients with a diagnosis of hepatitis C virus infection. For this reason it is essential for dental health care workers to be aware of the principal features of the disease and of its oral and dental implications.

[Update on hepatitis C virus: its variability and the implications]

Hepatitis C virus (HCV) is the main etiologic factor of post-transfusional and sporadic hepatitis, called non-A non-B in the past. These infections are characterized by a very high number of chronic carriers always with a persistent viral increase, but often at a slow pace. The seriousness of liver disease differs from one individual to another, varying from an asymptomatic form with minor or no liver injuries, to cirrhosis and hepatocellular carcinoma. Physiopathological mechanisms involved in liver injuries are still poorly understood. The direct role of immune response and of possible genetic factors is still under study. This review aims at summing up the discovery of HCV, its structure, and its variability in the various genome regions in the same individual and from one individual to another. The different methods and techniques to analyze this variability are also reviewed, as well as the various suggested ways of classifying the different types. The geographical distribution and both clinical and biological consequences of this variability are also discussed.