Resolved Hepatitis C Virus Infection Research Articles

HCV epitope, homologous to multiple human protein sequences, induces a regulatory T cell response in infected patients

Spontaneous resolution of hepatitis C virus (HCV) infection depends upon a broad T cell response to multiple viral epitopes. However, most patients fail to clear infections spontaneously and develop chronic disease. The elevated number and function of CD3(+)CD4(+)CD25(+)FoxP3(+) regulatory T cells (T(reg)) in HCV-infected patients suggest a role of Treg cells in impaired viral clearance. The factors contributing to increased Treg cell activity in chronic hepatitis C cases remain to be delineated. Immunoinformatics tools were used to predict promiscuous, highly-conserved HLA-DRB1-restricted immunogenic consensus sequences (ICS), each composed of multiple T cell epitopes. These sequences were synthesized and added to cultures of peripheral blood mononuclear cells (PBMCs), derived from patients who resolved HCV infection spontaneously, patients with persistent infection, and non-infected individuals. The cells were collected and following 5days incubation, quantified and characterized by flow cytometry. One immunogenic consensus sequence (ICS), HCV_G1_p7_794, induced a marked increase in Treg cells in PBMC cultures derived from infected patients, but not in patients who spontaneously cleared HCV or in non-infected individuals. An analogous human peptide (p7_794), on the other hand, induced a significant increase in Treg cells among PBMCs derived from both HCV-infected and non-infected individuals. JanusMatrix analyses determined that HCV_G1_p7_794 is comprised of Treg cell epitopes that exhibit extensive cross-reactivity with the human proteome. A virus-encoded peptide (HCV_G1_p7_794) with extensive human homology activates cross-reactive CD3(+)CD4(+)CD25(+)FoxP3(+) natural Treg cells, which potentially contributes to immunosuppression and to the development of chronic hepatitis C.

Need for improvements in the surveillance and management of chronic viral hepatitis in HIV patients followed in a Danish outpatient clinic.

The aim of this study was to assess hepatitis B virus (HBV) and hepatitis C virus (HCV) surveillance and management in HIV patients currently followed in an outpatient clinic at a Danish University Hospital. Patient data, including demographic characteristics, clinical findings, and hepatitis serology, were reviewed at baseline. Patients with incomplete or non-updated serology within the last 2 y were retested in the next 6 months, and the results were reviewed again at follow-up. At baseline, 84% and 74% of the 574 HIV patients were found to have incomplete and/or non-updated HBV and HCV serology, respectively. At follow-up, updated HBV serology was achieved in 535 (93%) patients; 15 (3%) patients were found to have a chronic active infection and 156 (27%) had a resolved infection, whereas 65 (11%) were vaccinated against HBV and 299 (52%) were non-immune. No patients were found to have developed chronic HBV infection following HIV diagnosis (equal to 3649 patient-y). Updated HCV serology revealed that 25 (4%) had a chronic active HCV infection and 15 (3%) had a resolved HCV infection. The anti-HCV incidence rate was 0.27/100 patient-y. A liver pathology assessment had not been performed within the last 2 y in 80% of the HBV and 32% of the HCV co-infected patients. Hepatitis screening and assessment had been inadequately performed. New cases of chronic hepatitis seem to occur infrequently. However, a more proactive hepatitis surveillance and management strategy integrated into the overall HIV health care program is warranted.

Alphavirus-based Vaccines Encoding Nonstructural Proteins of Hepatitis C Virus Induce Robust and Protective T-cell Responses

An absolute prerequisite for a therapeutic vaccine against hepatitis C virus (HCV) infection is the potency to induce HCV-specific vigorous and broad-spectrum T-cell responses. Here, we generated three HCV vaccines based on a recombinant Semliki Forest virus (rSFV) vector expressing all- or a part of the conserved nonstructural proteins (nsPs) of HCV. We demonstrated that an rSFV vector was able to encode a transgene as large as 6.1 kb without affecting its vaccine immunogenicity. Prime-boost immunizations of mice with rSFV expressing all nsPs induced strong and long-lasting NS3-specific CD8(+) T-cell responses. The strength and functional heterogeneity of the T-cell response was similar to that induced with rSFV expressing only NS3/4A. Furthermore this leads to a significant growth delay and negative selection of HCV-expressing EL4 tumors in an in vivo mouse model. In general, as broad-spectrum T-cell responses are only seen in patients with resolved HCV infection, this rSFV-based vector, which expresses all nsPs, inducing robust T-cell activity has a potential for the treatment of HCV infections.

Schistosomiasis Does Not Affect the Outcome of HCV Infection in Genotype 4-Infected Patients

Although reports suggest that Schistosoma mansoni increases hepatitis C virus (HCV) morbidity and chronicity, its impact on HCV spontaneous resolution is not clear. HCV genotype, viral load, abdominal ultrasonographic findings, and HCV-specific cell-mediated immunity (CMI) were examined among 141 healthcare workers infected with HCV (68 workers with and 73 workers without S. mansoni). HCV genotype 4 was dominate, and viral loads were 2.62 ± 0.69 × 10(6) and 4.24 ± 1.4 × 10(6) IU/mL among patients with and without coinfection, respectively (P = 0.309); 23.5% with and 32.9% without coinfection had spontaneously resolved HCV infection (P = 0.297). Interferon-γ spot-forming cells/10(6) peripheral blood mononuclear cells among responding viremic patients with and without coinfection were 716 ± 194 and 587 ± 162, whereas among aviremic patients, it was 794 ± 272 and 365 ± 36 (P > 0.05), respectively. In conclusion, there was no statistical difference in HCV spontaneous resolution, viral load, liver pathology, or CMI in patients with or without S. mansoni coinfection, suggesting that it did not impact the outcome of HCV infection.

Chronic hepatitis C virus infection

Although hepatitis B virus (HBV) and hepatitis C virus (HCV) are both hepatotropic and quite similar in terms of clinical manifestations and histopathology, their respective infections are distinct in terms of epidemiology and prognosis. Recognizing the differences between patients with HBV and HCV infection with respect to demographic characteristics, prevalence of comorbidities, and presence of lifestyle factors aids the proper treatment of these patients. We aimed to compare two populations with chronic viral liver disease (chronic HCV and chronic HBV), each of them with resolved hepatitis C. We included patients referred to a municipal reference clinic from March 2009 through May 2012. Patient data were collected using standardized questionnaires at the patients' first visit to clinic. Questionnaires included epidemiological information, presence of comorbidities, and lifestyle. A total of 756 patients were included in the study, 348 (46.0%) with chronic HCV infection, 176 (23.3%) with chronic HBV infection, and 232 (30.7%) with resolved HCV infection. Multivariate analysis including patients with chronic HCV infection and chronic HBV infection indicated that age [adjusted odds ratio (AOR)=1.06; 95% confidence interval (CI): 1.03-1.08], alcohol abuse (AOR=1.58; 95% CI: 1.01-2.49), smoking (AOR=1.64; 95% CI: 1.00-2.17), and illicit drug (AOR=2.92; 95% CI: 1.69-5.02) use were associated independently with chronic HCV infection. Multivariate analyses including patients with chronic HCV infection and those patients with resolved HCV infection, presence of at least one comorbidity (AOR=1.94; 95% CI: 1.12-3.3), illicit drug use (AOR=3.24; 95% CI: 1.90-5.54), and age (AOR=1.03; 95% CI: 1.01-1.05) were independently associated with chronic HCV infection. Age (AOR=0.98; 95% CI: 0.96-0.99) and male sex (AOR=1.93; 95% CI: 1.26-2.95) were the only variables associated significantly with chronic HBV infection in the multivariate analysis between patients with chronic HBV infection and resolved HCV infection. Our results highlight that patients with chronic HCV infection are complex and require a multidisciplinary approach during patient follow-up and clinical management.

Infection Frequency of Hepatitis C Virus and IL28B Haplotypes in Papua New Guinea, Fiji, and Kiribati

It has been estimated that there are more than 60 million Hepatitis C virus (HCV) carriers in the World Health Organisation's Western Pacific region (WHO-WPR), where liver cancer is among the top three causes of cancer death. WHO and the US Centres for Disease Control and Prevention report the prevalence of HCV in the South Pacific islands (countries within the WHO-WPR) to be high (5–10% and >2% respectively). However, since HCV is not tested for in many of these countries, there is sparse data available to support this assertion. We screened ∼2000 apparently healthy individuals from Papua New Guinea, Fiji and Kiribati and found a sero-prevalence of 2.0%, 0.1% and 0%, respectively. All sero-positive samples tested negative for HCV RNA. Curious as to why all the sero-positive individuals were negative for HCV-RNA, we also screened them for the HCV protective IL28B SNP markers rs12979860 and rs8099917. All antibody-positive participants bar one had HCV protective haplotypes. Our results suggest that HCV is present in these Pacific island countries, albeit at a prevalence lower than previous estimates. As none of our participants had undergone antiviral treatment, and therefore must have cleared infection naturally, we hypothesise that genotypes 1 and/or 4 are circulating in South Pacific Island people and that these peoples are genetically predisposed to be more likely to spontaneous resolve HCV infection than to become chronic carriers.

Synergism of Tapasin And Human Leukocyte Antigens in Resolving Hepatitis C Virus Infection

CD8+ T-cell responses to hepatitis C virus (HCV) are important in generating a successful immune response and spontaneously clearing infection. Human leukocyte antigen (HLA) class I presents viral peptides to CD8+ T cells to permit detection of infected cells, and tapasin is an important component of the peptide loading complex for HLA class I. We sought to determine if tapasin polymorphisms affected the outcome of HCV infection. Patients with resolved or chronic HCV infection were genotyped for the known G/C coding polymorphism in exon 4 of the tapasin gene. In a European, but not a US, Caucasian population, the tapasin G allele was significantly associated with the outcome of HCV infection, being found in 82.5% of resolvers versus 71.3% of persistently infected individuals (P = 0.02, odds ratio [OR] = 1.90 95% confidence interval [CI] = 1.11-3.23). This was more marked at the HLA-B locus at which heterozygosity of both tapasin and HLA-B was protective (P < 0.03). Individuals with an HLA-B allele with an aspartate at residue 114 and the tapasin G allele were more likely to spontaneously resolve HCV infection (P < 0.00003, OR = 3.2 95% CI = 1.6-6.6). Additionally, individuals with chronic HCV and the combination of an HLA-B allele with an aspartate at residue 114 and the tapasin G allele also had stronger CD8+ T-cell responses (P = 0.02, OR = 2.58, 95% CI-1.05-6.5). Tapasin alleles contribute to the outcome of HCV infection by synergizing with polymorphisms at HLA-B in a population-specific manner. This polymorphism may be relevant for peptide vaccination strategies against HCV infection.

Factors That Determine the Antiviral Efficacy of HCV-Specific CD8+ T Cells Ex Vivo

Dysfunctional CD8(+) T cells are believed to contribute to the ability of hepatitis C virus (HCV) to evade the immune response. Most studies have focused on the effector functions of HCV-specific CD8(+) T cells or their surface expression of inhibitory receptors. There is currently no information available about the ex vivo ability of HCV-specific CD8(+) T cells to inhibit viral replication (antiviral efficacy). To analyze the antiviral efficacy of virus-specific CD8(+) T cells ex vivo, we used an immunologic model based on a cell line that expresses HLA-A*02 and contains a stably replicating HCV reporter replicon. We isolated HCV-specific CD8(+) T cells from 18 HLA-A*02-positive patients with chronic HCV infection and 15 subjects with resolved HCV infection (7 spontaneous, 8 after therapy). Replicon cells were labeled with virus-specific peptides; inhibition of HCV replication was determined by measuring luciferase activity after 72 hours of coculture with virus-specific CD8(+) T cells. HCV-specific CD8(+) T cells from patients with chronic HCV infection had a significantly lower antiviral efficacy than influenza-, Epstein-Barr virus-, and cytomegalovirus-specific CD8(+) T cells. Antiviral efficacy was associated with the ability of virus-specific CD8(+) T cells to secrete interferon gamma. The antiviral efficacy of HCV-specific CD8(+) T cells was linked to surface expression of CD127 and PD-1. The cytokines interleukin-2, interleukin-7, and interleukin-15 increased the antiviral efficacy of CD127-positive but not of CD127-negative, HCV-specific CD8(+) T cells. Spontaneous, but not antiviral therapy-induced, viral clearance was associated with increased antiviral efficacy. The ability of CD8(+) T cells to inhibit HCV replication ex vivo is associated with their ability to secrete interferon gamma and their surface expression of CD127 and PD-1.

Association of IL-10, IL-4, and IL-28B gene polymorphisms with spontaneous clearance of hepatitis C virus in a population from Rio de Janeiro

BackgroundCytokines play an important role in the regulation of the immune response. In hepatitis C virus (HCV) infection, cytokine levels may influence the outcome of acute HCV infection. Polymorphisms in cytokine genes have been associated to different expression levels in response to infection. This study was carried out to investigate the association of several cytokine gene polymorphisms with disease outcome in HCV-infected patients.FindingsPatients with chronic or spontaneously resolved HCV infection were included in a cross-sectional study. A comparative analysis was performed between the groups regarding frequency distribution of the following cytokines’ gene polymorphisms: IL-10 (−1082 A/G; -819 T/C; -592 A/C), IL-4 (+33C/T), IFN-γ (+874 T/A), TNF-α (−238 G/A and −308 G/A) and IL-28B (rs12979860 C/T and rs8099917 T/G). Results: Eighteen patients with spontaneous viral clearance and 161 with chronic HCV infection were included. In the comparative analysis, the GG genotype of the IL-10 polymorphism -1082A/G was more frequent in patients with spontaneous viral clearance when compared to patients with chronic HCV (41.2% vs 6.2%; p = 0.001). This association was also found for the CC genotype of the IL-4 polymorphism +33C/T (72.2% vs 36.7%; p = 0.017) and the CC and TT genotypes of the IL-28B polymorphisms rs 12979860 and rs 8099917 (88.9% vs 30.3%; p < 0.001 and 88.9% vs 49.6%; p = 0.002). The IL10 (A-1082 G) and IL-28B (Crs12979860T) gene polymorphisms showed odds ratios of 12.848 and 11.077, respectively, and thus may have a greater influence on HCV spontaneous viral clearance. The IFN-γ (+874 T/A), TNF-α (−238 G/A and −308 G/A) polymorphisms did not show significant association with spontaneous viral clearance or chronicity.ConclusionThe G allele for IL-10 (−1082 A/G), the C allele for IL-4 (+3 C/T) and the C and T alleles for IL-28B (rs12979860 and rs8099917, respectively) are associated with spontaneous viral clearance in hepatitis C infection.

Is it justifiable to transplant infected livers into haemophilia recipients?

Is it justifiable to transplant infected livers into haemophilia recipients?

Laboratory Diagnostics for Hepatitis C Virus Infection

Identification of prevalent infection by hepatitis C virus (HCV) is based serologically on detecting anti-HCV immunoglobulin G, using immunoassays, immunoblot assays, and, more recently, immunochromatography-based rapid tests. None discriminate between active and resolved HCV infection. Tests for detecting HCV RNA identify active HCV infection but are costly. Serologic assays for HCV antigens have been developed and show potential for diagnosis of active HCV infection, and their performance characteristics are undergoing evaluation. The diagnosis of acute HCV infection without the demonstration of seroconversion remains elusive.

Low perforin expression of early differentiated HCV-specific CD8+ T cells limits their hepatotoxic potential

Perforin plays a central role in the immunopathogenesis of different viral infections. However, its role in hepatitis C virus (HCV) infection has not been fully understood. Here, we analyzed two closely related questions: first, is CD8+ T cell-mediated killing of HCV-replicating human hepatoma cells mediated by perforin? Second, if so, do HCV-specific CD8+ T cells obtained from chronically HCV infected patients express and upregulate perforin? Susceptibility of HCV-replicating human hepatoma cells to the cytotoxic pathway was tested in vitro by addition of perforin substitute streptolysin O and granzyme B and by co-culture experiments with a perforin-expressing HCV-specific CD8+ T cell clone in the presence of perforin or caspase inhibitors. HCV-specific CD8+ T cells were obtained and analyzed for perforin expression and differentiation markers ex vivo from 12 chronically infected patients and 12 patients with resolved HCV infection. HCV-replicating human hepatoma cells were susceptible to cytotoxic killing in vitro and a dominant role of perforin in HCV-specific CD8+ T cell-mediated cytolysis was observed. However, HCV-specific CD8+ T cells obtained ex vivo from chronically HCV infected patients expressed only low levels of perforin and showed an impaired ability to upregulate perforin. This was tightly linked to the distinct differentiation stage of HCV-specific CD8+ T cell differentiation ex vivo since early and intermediate differentiated HCV-specific CD8+ T cells only showed weak perforin expression in contrast to late differentiated CD8+ T cells that displayed strong perforin expression. Our results suggest that perforin plays a dominant role in CD8+ T cell-mediated lysis of HCV-replicating human hepatoma cells but that lysis may be limited in human chronic viral infection by the low perforin expression of early/intermediate differentiated HCV-specific CD8+ T cells.

Inhibitory Molecules That Regulate Expansion and Restoration of HCV-Specific CD4 + T Cells in Patients With Chronic Infection

Inhibitory receptors such as programmed death 1 (PD-1) and cytotoxic T lymphocyte-associated antigen (CTLA)-4 mediate CD8+ T-cell exhaustion during chronic viral infection, but little is known about roles in dysfunction of CD4+ T cells. We investigated the functions of inhibitory molecules on hepatitis C virus (HCV)-, influenza-, and Epstein-Barr virus (EBV)-specific CD4+ T cells in patients with chronic infections compared with patients with resolved HCV infection and healthy donors. Expression of PD-1, CTLA-4, CD305, and CD200R were analyzed on HCV-specific CD4+ T cells, isolated from peripheral blood using major histocompatibility complex class II tetramers. We investigated the effects of in vitro inhibition of various inhibitory pathways on proliferation and cytokine production by CD4+ T cells, and we compared these effects with those from inhibition of interleukin (IL)-10 and transforming growth factor (TGF)-β1. PD-1 and CTLA-4 were up-regulated on virus-specific CD4+ T cells from patients with chronic HCV infections. PD-1 expression was lower on influenza- than on HCV-specific CD4+ T cells from subjects with chronic HCV infection, whereas CTLA-4 was expressed at similar levels, independent of their specificity. CD305 and CD200R were up-regulated in HCV resolvers. Blockade of PD-L1/2, IL-10, and TGF-β1 increased expansion of CD4+ T cells in patients with chronic HCV, whereas inhibition of IL-10 and TGF-β1 was most effective in restoring HCV-specific production of interferon gamma, IL-2, and tumor necrosis factor α. We characterized expression of inhibitory molecules on HCV-, influenza-, and EBV-specific CD4+ T cells and the effects of in vitro blockade on CD4+ T-cell expansion and cytokine production. Inhibition of PD-1, IL-10, and TGF-β1 is most efficient in restoration of HCV-specific CD4+ T cells.

Acute hepatitis A virus infection is associated with a limited type I interferon response and persistence of intrahepatic viral RNA

Hepatitis A virus (HAV) is an hepatotropic human picornavirus that is associated only with acute infection. Its pathogenesis is not well understood because there are few studies in animal models using modern methodologies. We characterized HAV infections in three chimpanzees, quantifying viral RNA by quantitative RT-PCR and examining critical aspects of the innate immune response including intrahepatic IFN-stimulated gene expression. We compared these infection profiles with similar studies of chimpanzees infected with hepatitis C virus (HCV), an hepatotropic flavivirus that frequently causes persistent infection. Surprisingly, HAV-infected animals exhibited very limited induction of type I IFN-stimulated genes in the liver compared with chimpanzees with acute resolving HCV infection, despite similar levels of viremia and 100-fold greater quantities of viral RNA in the liver. Minimal IFN-stimulated gene 15 and IFIT1 responses peaked 1-2 wk after HAV challenge and then subsided despite continuing high hepatic viral RNA. An acute inflammatory response at 3-4 wk correlated with the appearance of virus-specific antibodies and apoptosis and proliferation of hepatocytes. Despite this, HAV RNA persisted in the liver for months, remaining present long after clearance from serum and feces and revealing dramatic differences in the kinetics of clearance in the three compartments. Viral RNA was detected in the liver for significantly longer (35 to >48 wk) than HCV RNA in animals with acute resolving HCV infection (10-20 wk). Collectively, these findings indicate that HAV is far stealthier than HCV early in the course of acute resolving infection. HAV infections represent a distinctly different paradigm in virus-host interactions within the liver.

No Impact of Hepatitis C Virus Infection on Mortality Among Drug Users During the First Decade After Seroconversion

Most studies of progression of chronic hepatitis C virus (cHCV) infection were conducted in hospital settings and were therefore biased for patients with severe disease. We evaluated the long-term outcomes of hepatitis C virus (HCV) infection among injecting drug users, recruited from outside the hospital setting, and examined the effect of cHCV on mortality after seroconversion. We studied data from 106 seroconverters with a documented or estimated date of HCV seroconversion. Cox proportional hazards analysis was used to determine the effect of HCV persistence, compared with HCV clearance, on survival after HCV seroconversion. The median follow-up time was 14.8 years (interquartile range, 7.8-19.6). cHCV infection developed in 71 of the subjects (67%; 95% confidence interval [CI], 57%-76%); 33 subjects died. One HCV-related death was observed 23 years after HCV seroconversion. Most causes of death were non-natural (n = 12) or acquired immune deficiency syndrome-related (n = 8). The effect of cHCV on mortality was nonproportional over time. When survival time was analyzed separately for 0-5 years, >5-10 years, and >10 years after HCV seroconversion, the age-adjusted hazard ratios for cHCV were 0.59 (95% CI, 0.16-2.20), 1.76 (95% CI, 0.36-8.53), and 8.28 (95% CI, 1.10-64.55), respectively, compared with resolved HCV infection. cHCV infection does not affect overall mortality in the first decade after seroconversion, compared with individuals who resolve HCV infection; however, during the second decade after infection, individuals with cHCV have an increased risk for all-cause mortality. Mortality from liver-related causes was low but might have been masked by competing mortality.

A Polymorphism in IL28B Distinguishes Exposed, Uninfected Individuals From Spontaneous Resolvers of HCV Infection

Background & AimsPolymorphisms in the interleukin-28B (IL28B) gene are associated with outcomes from infection with hepatitis C virus (HCV). However, the role of these polymorphisms in protecting injection drug users who are at high risk for HCV infection but do not have detectable antibodies against HCV or HCV RNA (exposed uninfected) has not been demonstrated. We investigated whether these individuals have the IL28B genotype rs12979860-CC, which protects some individuals against HCV infection.MethodsSeventy-four exposed uninfected individuals, 89 spontaneous resolvers, and 234 chronically infected individuals were genotyped to determine single nucleotide polymorphisms at IL28B.rs12979860.ResultsExposed, uninfected individuals had a significantly lower frequency of the protective genotype (rs12979860-CC) than anti-HCV-positive spontaneous resolvers (41.9% vs 69.7%, respectively; P = .0005; odds ratio [OR], 0.31; 95% confidence interval [CI]: 0.16–0.60) but a similar frequency to patients who were chronically infected (41.9% vs 43.6%, respectively; P = ns). However, exposed, uninfected individuals had a significantly higher frequency of homozygosity for killer cell immunoglobulin-like receptor 2DL3:group 1 HLA-C (KIR2DL3:HLA-C1) than those with chronic infection (31.1% vs 13.3%, respectively; P = .0008; OR, 2.95; 95% CI: 1.59–5.49). For patients who spontaneously resolved infection, IL28B and KIR:HLA protected, independently, against chronic HCV infection, based on logistic regression and synergy analyses (synergy factor, 1.3; 95% CI: 0.37–4.75; P synergy = .6).ConclusionsIL28B and KIR2DL3:HLA-C1 are independently associated with spontaneous resolution of viremia following HCV exposure. Resistance to HCV infection in exposed uninfected cases is associated with homozygosity for KIR2DL3:HLA-C1 but not the single nucleotide polymorphism IL28B.rs12979860. Uninfected individuals are therefore a distinct population from patients who spontaneously resolve HCV infection. Distinct, nonsynergistic innate immune mechanisms can determine outcomes of HCV exposure.

GB virus C infection among young, HIV‐negative injection drug users with and without hepatitis C virus infection

Our study examined the association between GB virus C (GBV-C) and (i) hepatitis C virus (HCV) infection status, (ii) biomedical indicators of liver disease (alanine and aspartate aminotransferases) and (iii) HCV RNA level among young injection drug users (IDUs) recruited using street outreach and respondent-driven methods. Cross-sectional and longitudinal analyses were completed. GBV-C (active or resolved) infection was significantly (P < 0.05) more prevalent among HCV antibody-positive (anti-HCV+) (65.1%) than antibody-negative (anti-HCV-) (32.3%) (OR = 3.9, 95% CI: 2.3-6.9) IDUs. The prevalence of resolved GBV-C infection was highest among those with chronic HCV infection (41.9%), followed by those with resolved HCV infection (34.4%) and significantly lower (P < 0.05) among anti-HCV participants (16.9%). Although not statistically significant (P = 0.13), a similar pattern was observed for active GBV-C infection. No association between GBV-C infection status and biomedical indicators of liver disease or HCV RNA level over time was observed. In conclusion, GBV-C infection prevalence was higher among anti-HCV+ compared to anti-HCV- young IDUs, similar to prior studies among older populations. In particular, chronically HCV-infected young IDUs had an increased rate of GBV-C clearance.

Improved detection of hepatitis C virus infection by transcription-mediated amplification technology in dialysis population

Background: Hepatitis C virus (HCV) infection remains common among patients undergoing maintenance dialysis and plays an adverse effect on survival in this population. Accurate detection of HCV viremia (HCV RNA) in dialysis patients requires a sensitive and specific diagnostic test. Methods: The Versant™ HCV RNA Qualitative Assay, based on transcription-mediated amplification (TMA) technique, was prospectively evaluated in 112 dialysis patients. Performance characteristics of the Versant HCV TMA Assay were evaluated in comparison to the Amplicor® 2.0 HCV test based on polymerase chain reaction (PCR) technique. In addition, anti-HCV serologic tests including third-generation enzyme immunoassay and Recombinant Immunoblot Assay were performed. Results: Of the 112 specimens tested, 29 were reactive by Versant HCV TMA Assay, yielding an overall prevalence of HCV viremia of 25.9%. The concordance between TMA and PCR techniques was excellent [91% (101/112)]. Eleven specimens (10%) were invalid or equivocal by PCR due to interference phenomena; all 11 specimens had valid TMA results (2 patients being TMA reactive and 9 nonreactive). Four specimens [3.6% (4/112)] that tested PCR-negative and HCV TMA nonreactive were anti-HCV seropositive, consistent with resolved HCV infection. In the group of seronegative samples, one was reactive by TMA Assay [1.25% (1/80)]. Conclusions: The HCV TMA technology seems a highly sensitive tool for detecting HCV RNA in the dialysis population, with no evidence of specimen interference. One EIA-negative but HCV-RNA-positive patient by Versant HCV TMA Assay was identified. Prospective clinical trials are under way to assess the clinical impact related to the use of HCV TMA technology in dialysis population.

Virus-specific CD4+ T cell responses in chronic HCV infection in blood and liver identified by antigen-specific upregulation of CD154

Virus-specific CD4+ T cells play a major role in hepatitis C virus (HCV) infection. Viral clearance is associated with vigorous and multispecific CD4+ T cell responses, while chronic infection has been shown to be associated with weak or absent T cell responses. Most of these studies, however, have used functional assays to analyse virus-specific CD4+ T cell responses. Therefore, the important question, of whether virus-specific CD4+ T cells are completely absent or primarily impaired in specific effector functions during chronic infection, has yet to be analysed in detail. To address this issue, a novel assay, where CD4+ T cell frequencies can be determined by de novo CD154 (CD40 ligand) expression in response to HCV antigens, was used in a cohort of chronically infected HCV patients and patients who spontaneously resolved HCV infection. These responses were compared to functional assays, such as the IFN-gamma ELISpot and flow cytometry-based proliferative assays. Our results reveal that using the CD154 assay, virus-specific CD4+ T cells are readily detectable during chronic HCV infection albeit at a lower frequency when compared to patients who spontaneously resolved the infection. Importantly, no CD4+ T cell responses were detectable from these patients when using functional assays. Finally, these cell populations were enriched in the intrahepatic compartment. Our findings suggest that HCV-specific CD4+ T cell responses are readily detectable in chronic HCV infection and enriched in the infected liver.

The potential use of Toll-like receptor agonists to restore the dysfunctional immunity induced by hepatitis C virus

Hepatitis C virus (HCV) infection is a major public health concern with approximately 3% of the world's population is infected, posing social, economical and health burden. Less than 20% of the infected individuals clear the virus during the acute infection, while the rest develop chronic infection. The treatment of choice for HCV infection is pegylated interferon-alpha (IFN-alpha) in combination with ribavarin. Despite the cost and side effects of this treatment regimen, many patients fail this therapy and develop persistent HCV infection, leading to cirrhosis and hepatocellular carcinoma. Although the mechanisms underlying the failure to resolve HCV infection are poorly understood, the incapability of patients to develop effective anti-HCV immunity is a potential cause. We hypothesize that the dysfunctional anti-HCV immunity is due to the emergence of immunosuppressive cells coinciding with a decrease in the stimulatory dendritic cells (DCs) and natural killer (NK) cells. We further hypothesize that applying agents that can correct the imbalance between the immunosuppressive cells and stimulatory cells can results in resolution of chronic HCV. In this review article, we will discuss potential approaches, focusing on the use of Toll-like receptor agonists, to block the suppressive effects of the regulatory cells and restore the stimulatory effects of DCs and NK cells.