Viral clearance in hepatitis C (1b) infection: relationship with human leukocyte antigen class II in a homogeneous population

Trans-ancestral fine-mapping of MHC reveals key amino acids associated with spontaneous clearance of hepatitis C in HLA-DQβ1

Spontaneous clearance of acute hepatitis C virus (HCV) infection is associated with single nucleotide polymorphisms (SNPs) on the MHC class II. We fine-mapped the MHC region in European (n = 1,600; 594 HCV clearance/1,006 HCV persistence) and African (n = 1,869; 340 HCV clearance/1,529 HCV persistence) ancestry individuals and evaluated HCV peptide binding affinity of classical alleles. In both populations, HLA-DQβ1Leu26 (p valueMeta = 1.24 × 10-14) located in pocket 4 was negatively associated with HCV spontaneous clearance and HLA-DQβ1Pro55 (p valueMeta = 8.23 × 10-11) located in the peptide binding region was positively associated, independently of HLA-DQβ1Leu26. These two amino acids are not in linkage disequilibrium (r2 < 0.1) and explain the SNPs and classical allele associations represented by rs2647011, rs9274711, HLA-DQB1∗03:01, and HLA-DRB1∗01:01. Additionally, HCV persistence classical alleles tagged by HLA-DQβ1Leu26 had fewer HCV binding epitopes and lower predicted binding affinities compared to clearance alleles (geometric mean of combined IC50 nM of persistence versus clearance; 2,321 nM versus 761.7 nM, p value = 1.35 × 10-38). In summary, MHC class II fine-mapping revealed key amino acids in HLA-DQβ1 explaining allelic and SNP associations with HCV outcomes. This mechanistic advance in understanding of natural recovery and immunogenetics of HCV might set the stage for much needed enhancement and design of vaccine to promote spontaneous clearance of HCV infection.

Association of HLA-DQB1*03:01 and DRB1*11:01 with spontaneous clearance of hepatitis C virus in Chinese Li ethnicity, an ethnic group genetically distinct from Chinese Han ethnicity and infected with unique HCV subtype

Specific human leukocyte antigen (HLA) class I and class II alleles have been associated with spontaneous clearance or persistent infection of hepatitis C virus (HCV), which seemed to be restricted by the host's ethnicity and viral genotype. Recently we reported a high prevalence and spontaneous clearance rate of HCV in a cohort of Chinese Li ethnicity who were infected with new variants of HCV genotype 6. In this study, we found that the distribution of HLA class I and class II alleles in HCV infected individuals of Chinese Li ethnicity (n = 143) was distinct from that of Chinese Han ethnicity which was reported in our previous study. HLA-DRB1*11:01 and DQB1*03:01 were more prevalent in Chinese Li subjects who cleared HCV spontaneously than those who were chronically infected (P = .036 and P = .024, respectively), which were consistent with our previous report regarding the Chinese Han population. Multivariate logistic regression analysis showed that DQB1*03:01 (odds ratio = 3.899, P = .017), but not DRB1*11:01, associated with HCV spontaneous clearance, independent of age, sex, and IFNL3 genotype. Because DQB1*03:01 and DRB1*11:01 were tightly linked because of linkage disequilibrium, our results clearly supported the associations of these two alleles with HCV spontaneous clearance in Chinese Li as well as Han ethnicity.

HLA Class II-DRB1 Alleles with Hepatitis C Virus Infection Outcome in Egypt: A Multicentre Family-based Study

INTRODUCTION AND AIM

Hepatitis C virus (HCV) infection is a global medical problem. HLA -DRB1 alleles have an important role in immune response against HCV. The aim of this study is to clarify the contribution of HLA -DRB1 alleles in HCV susceptibility in a multicentre family-based study.

MATERIAL AND METHODS

A total of 162 Egyptian families were recruited in this study with a total of 951 individuals (255 with chronic hepatitis C (CHC), 588 persons in the control group(-ve household contact to HCV) and 108 persons who spontaneously cleared the virus (SVC). All subjects were genotyped for HLA -DRB1 alleles by SSP-PCR and sequence based typing (SBT) methods.

RESULTS

The carriage of alleles 3:01:01 and 13:01:01 were highly significant in CHC when compared to that of control and SVC groups [OR of 3 family = 5.1289, PC (Bonferroni correction ) = 0.0002 and 5.9847, PC = 0.0001 and OR of 13 family = 4.6860, PC = 0.0002 and OR = 6.5987, PC = 0.0001 respectively]. While DRB1*040501, DRB1*040101, DRB1*7:01:01 and DRB1*110101 alleles were more frequent in SVC group than CHC patients (OR = 0.4052, PC = 0.03, OR: OR = 0.0916,PC = 0.0006, OR = 0.1833,PC = 0.0006 and OR = 0.4061, PC = 0.0001 respectively).

CONCLUSIONS

It was concluded that among the Egyptian families, HLA-DRB1*030101, and DRB1*130101 alleles associated with the risk of progression to CHC infection, while DRB1*040101, DRB1*040501, DRB1*7:01:01and DRB1*110101 act as protective alleles against HCV infection.

Role of Some Predominant Host Immunomodulators' Single Nucleotide Polymorphisms in Severity of Hepatitis B Virus and Hepatitis C Virus Infection

Hepatitis B and C infections can be either acute or chronic. The chronic infection can culminate in liver cirrhosis and hepatocellular carcinoma. Influence of the host genetic makeup on conversion of acute to chronic infection, development of cirrhosis, and hepatocellular carcinoma is an interesting area of research. Variability in different immune system genes may account for such differences in the outcome of infection. This article discusses single nucleotide polymorphisms in different host immunomodulator genes that have been frequently reported to influence the outcome of infection and severity of disease. The genetic variability could be utilized for the prediction of disease outcome and treatment responses.

Additive effects of HLA alleles and innate immune genes determine viral outcome in HCV infection

BACKGROUND

Chronic HCV infection is a leading cause of liver-related morbidity globally. The innate and adaptive immune responses are thought to be important in determining viral outcomes. Polymorphisms associated with the IFNL3 (IL28B) gene are strongly associated with spontaneous clearance and treatment outcomes.

OBJECTIVE

This study investigates the importance of HLA genes in the context of genetic variation associated with the innate immune genes IFNL3 and KIR2DS3.

DESIGN

We assess the collective influence of HLA and innate immune genes on viral outcomes in an Irish cohort of women (n=319) who had been infected from a single source as well as a more heterogeneous cohort (Swiss Cohort, n=461). In the Irish cohort, a number of HLA alleles are associated with different outcomes, and the impact of IFNL3-linked polymorphisms is profound.

RESULTS

Logistic regression was performed on data from the Irish cohort, and indicates that the HLA-A*03 (OR 0.36 (0.15 to 0.89), p=0.027) -B*27 (OR 0.12 (0.03 to 0.45), p=<0.001), -DRB1*01:01 (OR 0.2 (0.07 to 0.61), p=0.005), -DRB1*04:01 (OR 0.31 (0.12 to 0.85, p=0.02) and the CC IFNL3 rs12979860 genotypes (OR 0.1 (0.04 to 0.23), p<0.001) are significantly associated with viral clearance. Furthermore, DQB1*02:01 (OR 4.2 (2.04 to 8.66), p=0.008), KIR2DS3 (OR 4.36 (1.62 to 11.74), p=0.004) and the rs12979860 IFNL3 'T' allele are associated with chronic infection. This study finds no interactive effect between IFNL3 and these Class I and II alleles in relation to viral clearance. There is a clear additive effect, however. Data from the Swiss cohort also confirms independent and additive effects of HLA Class I, II and IFNL3 genes in their prediction of viral outcome.

CONCLUSIONS

This data supports a critical role for the adaptive immune response in the control of HCV in concert with the innate immune response.

Novel host genetic variations associated with spontaneous clearance of a single-source outbreak of HCV1b infections

Background and aims

A total of 105 patients were identified as accidentally infected with hepatitis C virus genotype 1b (HCV1b) through blood transfusion from a single blood donor. This group provides a unique patient population to study host factors involved in the spontaneous clearance of HCV and disease progression.

Methods

Clinical markers, HCV RNA and eight single nucleotide polymorphisms (SNPs) of interleukin-28B (IL-28B) were detected. Exome capture and sequencing were analysed for association with HCV clearance.

Results

Among the 85 patients with the positive HCV antibody, 27 cases (31.8%) were HCV RNA negative over a period of 9–12 years. Of the 58 patients with positive HCV RNA, 22.4% developed chronic hepatitis, and 5.2% developed cirrhosis. Age was found to be associated with HCV1b clearance. IL-28 rs10853728 CC showed the trend. By exon sequencing, 39 SNPs were found to be significantly different in spontaneous clearance patients (p<0.001). Two SNPs in the tenascin receptor (TNR), five in the transmembrane protease serine 11A (TMPRSS11A), and one in the serine peptidase inhibitor kunitz type 2 (SPINT2) showed the closest associations (p<10⁻⁵).

Conclusions

Host genetic analyses on the unique, single source HCV1b-infected patient population has suggested that age and mutations in TNR, TMPRSS11A and SPINT2 genes may be factors associated with HCV clearance.

Prognostic factors of hepatic decompensation and hepatocellular carcinoma in patients with transfusion-acquired HCV infection

AIMS

Aim of this study was to assess if host (immunogenetic traits, age, sex), exogenous (alcohol) or viral factors (viral type, past HBV infection) might affect the progression of chronic hepatitis C to liver decompensation or the development of HCC in a cohort of patients exposed to a single blood transfusion prior to the introduction of anti-HCV screening.

METHODS

Two hundred and forty-eight patients with a history of a single exposure to blood or blood products prior to 1990 were retrospectively considered. Patients were devoid of other risk factors of liver disease or immunosuppression and naïve to antiviral therapies. Eight baseline variables were assessed: age at transfusion, sex, HBV core antibody, immunogenetic profile (DRB1*11, DRB1*1104, DRB1*07), HCV genotype and alcohol consumption.

RESULTS

The follow-up was 22 (SD: 11) years. Sixty-eight patients (27%) progressed to hepatic decompensation over a median period of 22.5 years (IQR: 14-30) and 41 patients (16%) developed HCC over a median period of 31 years (IQR: 24-38). The cumulative incidence of liver failure was 0.4% (95% CI: 0.1-3.1), 4.9% (95% CI: 2.6-9.3) and 16.2% (95% CI: 10.4-24.7) at 10, 20 and 30 years after blood transfusion respectively. By univariate analysis, only age at transfusion was correlated with the risk of decompensation. Stratifying the age of transfusion by tertiles, the incidence of hepatic decompensation was 0.7% per year in patients transfused at ≤24 years of age as compared to 1.2% and 1.9% per year in those transfused at 25-35 and >36 years of age respectively (HR: 5.5, 95% CI: 2.78-10.7, P<0.001). The risk of HCC development was correlated by univariate analysis with age at transfusion (as continuous variable, HR: 1.12, 95% CI: 1.08-1.16 per year of age, P<0.001, >36 compared to ≤24 years, HR: 10.3, 95% CI: 3.9-26.9, P<0.001) and male sex (HR: 4.2, 95% CI: 1.7-10, P=0.001). Multivariate analysis confirmed age at transfusion and male sex as independent predictors of HCC development [HR: 1.12 per year (95% CI: 1.08-1.16), P<0.001 and HR: 5.4 (95% CI: 2.2-13.2), P<0.001 respectively].

CONCLUSIONS

In patients with transfusion-acquired HCV infection, age at transfusion affects the risk for hepatic decompensation. Age at transfusion and male sex are independent risk factors for HCC development.

The effects of female sex, viral genotype, and IL28B genotype on spontaneous clearance of acute hepatitis C virus infection

Although 20%-40% of persons with acute hepatitis C virus (HCV) infection demonstrate spontaneous clearance, the time course and factors associated with clearance remain poorly understood. We investigated the time to spontaneous clearance and predictors among participants with acute HCV using Cox proportional hazards analyses. Data for this analysis were drawn from an international collaboration of nine prospective cohorts evaluating outcomes after acute HCV infection. Among 632 participants with acute HCV, 35% were female, 82% were Caucasian, 49% had interleukin-28 (IL28)B CC genotype (rs12979860), 96% had injected drugs ever, 47% were infected with HCV genotype 1, and 7% had human immunodeficiency virus (HIV) coinfection. Twenty-eight percent were HCV antibody negative/RNA positive at the time of acute HCV detection (early acute HCV). During follow-up, spontaneous clearance occurred in 173 of 632, and at 1 year after infection, 25% (95% confidence interval [CI]: 21, 29) had cleared virus. Among those with clearance, the median time to clearance was 16.5 weeks (IQR: 10.5, 33.4), with 34%, 67%, and 83% demonstrating clearance at 3, 6, and 12 months. Adjusting for age, factors independently associated with time to spontaneous clearance included female sex (adjusted hazards ratio [AHR]: 2.16; 95% CI: 1.48, 3.18), IL28B CC genotype (versus CT/TT; AHR, 2.26; 95% CI: 1.52, 3.34), and HCV genotype 1 (versus non-genotype 1; AHR: 1.56; 95% CI: 1.06, 2.30). The effect of IL28B genotype and HCV genotype on spontaneous clearance was greater among females, compared to males.

CONCLUSIONS

Female sex, favorable IL28B genotype, and HCV genotype 1 are independent predictors of spontaneous clearance. Further research is required to elucidate the observed sex-based differences in HCV control.

Effect of human leukocyte antigen class I and II alleles on hepatitis C viral load among chronic hepatitis C patients in Southern Taiwan

The viral load of hepatitis C virus (HCV) in chronic hepatitis C patients affects clinical outcomes and response to interferon treatment. Various factors may be involved in determining the viral load, including host genetic factors. The aim of this study was to investigate the relationship between HCV viral load and human leukocyte antigen (HLA) class I and class II alleles. One hundred and six HCV RNA positive subjects were enrolled, and viral load was measured. HLA-A, -B, -C, -DR, and -DQ loci were determined by sequence-based genotyping. Univariate analysis indicated that HLA-B(*)40 and HLA-C(*)07 alleles had significantly higher HCV RNA levels (P<0.05). Patients with the HLA-C(*)15 allele exhibited a trend toward a lower HCV viral load (P=0.06). After controlling for confounding factors, multivariate analysis revealed that only HLA-C(*)15 allele was identified as a significant determinant for HCV-RNA level (slope=-0.91, 95% CI: -1.58, -0.24; Holm's P<0.01). Patients expressing the HLA-C(*)15 allele had significantly lower HCV RNA levels. HCV genotype 1 was significantly associated with high HCV RNA levels (P<0.05 by Mann-Whitney U test). In conclusion, HLA-C(*)15 is an important host immunogenetic factor with an inverse association to HCV viral load in CHC patients in Taiwan. HCV genotype 1 is the viral factor that associated with high viral load.

Dendritic Cells in HIV-1 and HCV Infection: Can They Help Win the Battle?

Persistent infections with human immunodeficiency virus type 1 (HIV-1) and hepatitis C virus (HCV) are a major cause of morbidity and mortality worldwide. As sentinels of our immune system, dendritic cells (DCs) play a central role in initiating and regulating a potent antiviral immune response. Recent advances in our understanding of the role of DCs during HIV-1 and HCV infection have provided crucial insights into the mechanisms employed by these viruses to impair DC functions in order to evade an effective immune response against them. Modulation of the immunological synapse between DC and T-cell, as well as dysregulation of the crosstalk between DCs and natural killer (NK) cells, are emerging as two crucial mechanisms. This review focuses on understanding the interaction of HIV-1 and HCV with DCs not only to understand the immunopathogenesis of chronic HIV-1 and HCV infection, but also to explore the possibilities of DC-based immunotherapeutic approaches against them. Host genetic makeup is known to play major roles in infection outcome and rate of disease progression, as well as response to anti-viral therapy in both HIV-1 and HCV-infected individuals. Therefore, we highlight the genetic variations that can potentially affect DC functions, especially in the setting of chronic viral infection. Altogether, we address if DCs’ potential as critical effectors of antiviral immune response could indeed be utilized to combat chronic infection with HIV-1 and HCV.

T cell epitope mapping of JC polyoma virus-encoded proteome reveals reduced T cell responses in HLA-DRB1*04:01+ donors

JC polyomavirus (JCV) infection is highly prevalent and usually kept in a persistent state without clinical signs and symptoms. It is only during immunocompromise and especially impaired CD4(+) T cell function in the brain, as seen in AIDS patients or natalizumab-treated multiple sclerosis patients, that JCV may cause progressive multifocal leukoencephalopathy (PML), an often life-threatening brain disease. Since CD4(+) T cells likely play an important role in controlling JCV infection, we here describe the T cell response to JCV in a group of predominantly HLA-DR-heterozygotic healthy donors (HD) by using a series of overlapping 15-mer peptides spanning all JCV-encoded open reading frames. We identified immunodominant epitopes and compared T cell responses with anti-JCV VP1 antibody production and with the presence of urinary viral shedding. We observed positive JCV-specific T cell responses in 28.6% to 77.6%, humoral immune response in 42.6% to 89.4%, and urinary viral shedding in 36.4% to 45.5% of HD depending on the threshold. Four immunodominant peptides were mapped, and at least one immunogenic peptide per HLA-DRB1 allele was detected in DRB1*01(+), DRB1*07(+), DRB1*11(+), DRB1*13(+), DRB1*15(+), and DRB1*03(+) individuals. We show for the first time that JCV-specific T cell responses may be directed not only against JCV VP1 and large T antigen but also against all other JCV-encoded proteins. Heterozygotic DRB1*04:01(+) individuals showed very low T cell responses to JCV together with normal anti-VP1 antibody levels and no urinary viral shedding, indicating a dominant-negative effect of this allele on global JCV-directed T cell responses. Our data are potentially relevant for the development of vaccines against JCV.

Protective effect of HLA-DRB1 11 and predisposition of HLA-C 04 in the development of severe liver damage in Brazilian patients with chronic hepatitis C virus infection

The objective of this study was to investigate human leucocyte antigen (HLA) genes in patients chronically infected with hepatitis C virus (HCV) and to analyse the possible role of these genes in the progression of chronic hepatitis C. One hundred and forty-five (145) Brazilian patients infected only with HCV genotype 1 were evaluated. HLA class I (A, B, C) and class II (DRB1, DQA1, DQB1) typing were carried out by PCR-SSO, through Luminex technology. Associations were found with protection against development of liver damage by both DRB1 11 (5.0% versus 18.2%, P=0.0016, OR=0.23, CI 95% = 0.09-0.58; Pc=0.0208) and DRB1 11-DQA1 05-DQB1 03 haplotype (4.2% versus 15.3%, P=0.0032; OR = 0.24, CI 95% = 0.08-0.64). Liver damage was associated with HLA-C 04 in patients with <20 years of infection (38.4% versus 9.1%, P = 0.002, OR = 6.25, CI 95%=1.97-19.7; Pc=0.0238). It is concluded that HLA alleles can influence the development of liver damage in HCV type-1 chronically infected Brazilian patients.

Influence of HLA alleles in response to treatment with pegylated interferon-alpha and ribavirin in patients with chronic hepatitis C

The objective of this study was to analyse the possible role of HLA polymorphism of chronically infected hepatitis C virus patients in the response outcome to treatment with pegylated interferon-alpha plus ribavirin. To that end, 144 Brazilian patients infected only with genotype 1 of the virus were treated with pegylated interferon-alpha at 1.5 μg kg(-1) in conjunction with ribavirin (1000 mg if patient weight was <75 kg and 1250 mg if >75 kg) for 48 weeks. The patients did not have concomitant HBV or HIV infections or liver disease, did not undergo previous antiviral treatment, and were followed up for 24 weeks after the end of treatment to assure they presented a sustained virological response. Patients were classified according to response to treatment in responsive (SVR), nonresponsive (NRS) and relapsers (REL). HLA class I and class II typing were carried out through PCR-SSO using Luminex technology. A statistically higher frequency of DRB1*11 patients was observed in the SVR group (39.6% vs. 14.3%P = 0.0012; Pc = 0.0156; OR = 3.94; 95% CI = 1.8-8.8). HLA-DQB1*03 patients were also more frequent in the SVR group, but the P value lost significance after Bonferroni correction (62.3% vs. 41.7%P = 0.024; Pc = 0.14, OR = 2.3; 95% CI = 1.14-4.60). HLA class II antigens can positively influence the response to treatment with pegylated interferon-alpha and ribavirin.

Ethnicity and route of HCV infection can influence the associations of HLA with viral clearance in an ethnically heterogeneous population

Approximately 20% of hepatitis C virus (HCV) infected individuals clear the virus. Host factors that influence the course of HCV infection are still under investigation, and the data on the association of human leukocyte antigen (HLA) alleles and HCV clearance are scarce and controversial. The aims of this study were to investigate whether HLA alleles are associated with clearance of HCV infection in a highly admixed Brazilian population and whether these associations could be influenced by ethnicity and route of infection. HLA-A, -B, -C, -DRB1 and -DQB1 genotyping were performed in 135 HCV-infected Brazilian patients among which 45 cleared HCV infection (cases) and 90 had persistent viral infection (controls). Controls were matched by sex, ethnicity (withes and non-whites) and route of infection (high infectious dose or low infectious dose). No significant association was identified between HLA alleles and the outcome of HCV infection when analyzing the sample as a single group. However, a new protective association of HLA-DQB1*04 (P = 0.006; P(c) = 0.030) and a rarely described association of HLA-DRB1*08 (P = 0.004; P(c) = 0.048) were found only among white patients. The DRB1*11 allele, previously reported in homogeneous population, was associated with HCV clearance (P = 0.020) only among patients with expected high-dose exposure. These findings confirm the influence of ethnicity on the associations of HLA with spontaneous viral clearance of HCV infection and emphasize the possible influence of route of infection in this process.

Host genetics in immune-mediated hepatitis C virus clearance

Upon infection with hepatitis C virus (HCV), only few patients spontaneously clear the virus, while most patients develop chronic HCV infection. The host innate and adaptive immune response is believed to be the key determinant of viral clearance or persistence. Several host factors have been demonstrated to influence the efficiency of the antiviral immune response, including IL-28B polymorphisms, inhibitory natural killer cell receptors, as well as HLA class I and II alleles presenting viral antigens to CD8(+) and CD4(+) T cells. The understanding of the respective mechanisms is essential for the development of successful vaccination strategies against HCV.

Effect of immune pressure on hepatitis C virus evolution: insights from a single-source outbreak

The host's immune response to hepatitis C virus (HCV) can result in the selection of characteristic mutations (adaptations) that enable the virus to escape this response. The ability of the virus to mutate at these sites is dependent on the incoming virus, the fitness cost incurred by the mutation, and the benefit to the virus in escaping the response. Studies examining viral adaptation in chronic HCV infection have shown that these characteristic immune escape mutations can be observed at the population level as human leukocyte antigen (HLA)-specific viral polymorphisms. We examined 63 individuals with chronic HCV infection who were infected from a single HCV genotype 1b source. Our aim was to determine the extent to which the host's immune pressure affects HCV diversity and the ways in which the sequence of the incoming virus, including preexisting escape mutations, can influence subsequent mutations in recipients and infection outcomes.

CONCLUSION

HCV sequences from these individuals revealed 29 significant associations between specific HLA types within the new hosts and variations within their viruses, which likely represent new viral adaptations. These associations did not overlap with previously reported adaptations for genotypes 1a and 3a and possibly reflected a combination of constraint due to the incoming virus and genetic distance between the strains. However, these sites accounted for only a portion of the sites in which viral diversity was observed in the new hosts. Furthermore, preexisting viral adaptations in the incoming (source) virus likely influenced the outcomes in the new hosts.

Specific human leukocyte antigen class I and II alleles associated with hepatitis C virus viremia

Studies of human leukocyte antigen (HLA) alleles and their relation with hepatitis C virus (HCV) viremia have had conflicting results. However, these studies have varied in size and methods, and few large studies assessed HLA class I alleles. Only one study conducted high-resolution class I genotyping. The current investigation therefore involved high-resolution HLA class I and II genotyping of a large multiracial cohort of U.S. women with a high prevalence of HCV and HIV. Our primary analyses evaluated associations between 12 HLA alleles identified through a critical review of the literature and HCV viremia in 758 HCV-seropositive women. Other alleles with >5% prevalence were also assessed; previously unreported associations were corrected for multiple comparisons. DRB1*0101 (prevalence ratio [PR] = 1.7; 95% confidence interval [CI] = 1.1-2.6), B*5701 (PR=2.0; 95% CI = 1.0-3.1), B*5703 (PR = 1.7; 95% CI = 1.0-2.5), and Cw*0102 (PR = 1.9; 95% CI = 1.0-3.0) were associated with the absence of HCV RNA (i.e., HCV clearance), whereas DRB1*0301 (PR = 0.4; 95% CI = 0.2-0.7) was associated with HCV RNA positivity. DQB1*0301 was also associated with the absence of HCV RNA but only among HIV-seronegative women (PR = 3.4; 95% CI = 1.2-11.8). Each of these associations was among those predicted. We additionally studied the relation of HLA alleles with HCV infection (serostatus) in women at high risk of HCV from injection drug use (N = 838), but no significant relationships were observed.

CONCLUSION

HLA genotype influences the host capacity to clear HCV viremia. The specific HLA associations observed in the current study are unlikely to be due to chance because they were a priori hypothesized.

Patient HLA-DRB1* and -DQB1* allele and haplotype association with hepatitis C virus persistence and clearance

Hepatitis C virus (HCV) infection is prevalent throughout the world and interferon (IFN)-based treatments are currently the only therapeutic option. However, depending upon variations in their human leukocyte antigen (HLA), some patients do not respond well to IFN therapy. The current study evaluated the HLA allele and haplotype distribution of 204 HCV-seropositive individuals from Islamabad, Pakistan, who were receiving standard IFN therapy. In this cohort, 150 patients (74%) showed a sustained virological response to IFN therapy, whereas 54 (26%) did not. In addition to the HCV patients, 102 unrelated healthy volunteers were used as controls. DNA was isolated from the blood of the patients and controls for HLA-DRB1 and HLA-DQB1 allele typing, whilst plasma was used for HCV detection and genotyping. HLA-DRB1*04 was found to impart a significant protective advantage [Bonferroni-corrected P value (pc)=0.047] against HCV infection. In patients on IFN therapy, HLA-DRB1*11 and -DQB1*0301 (pc=0.044) were found to be associated with viral clearance. In contrast, HLA-DRB1*07 (pc=0.008) individually or in combination with HLA-DQB1*02 was found to be associated with viral persistence. These associations of HLA with HCV persistence or clearance will be beneficial in deciding the therapeutic regimen for Pakistani patients infected with HCV genotype 3a.

Role of host genetic factors in the outcome of hepatitis C virus infection

The natural history of hepatitis C virus (HCV) infection is determined by a complex interplay between host genetic, immunological and viral factors. This review highlights genes involved in innate and adaptive immune responses associated with different outcomes of HCV infection. For example, an association of HCV clearance with certain HLA alleles has been demonstrated. The mechanisms responsible for these associations have been linked to specific T cell responses for some particular alleles (e.g., HLA-B27). Genetic associations involved in T cell regulation and function further underline the role of the adaptive immune response in the natural history of HCV infection. In addition, some genes involved in innate NK cell responses demonstrate the complex interplay between components of the immune system necessary for a successful host response to HCV infection.

Protective KIR-HLA interactions for HCV infection in intravenous drug users

Intravenous drug use has become the principal route of hepatitis C virus (HCV) transmission due to the sharing of infected needles. In this study, we analyzed the distribution of HLA-KIR genotypes among 160 Puerto Rican intravenous drug users (IDUs) with HCV infection and 92 HCV-negative Puerto Rican IDUs. We found a significant association between the presence of different combinations of KIR inhibitory receptor genes (KIR2DL2 and/or KIR2DL3, pC=0.01, OR=0.07; KIR2DL2 and/or KIR2DL3+KIR2DS4, pC=0.01, OR=0.39) and HLA-C1 homozygous genotypes (HLA-C1+KIR2DS4, pC=0.02, OR=0.43; HLA-C1+KIR2DL2+KIR2DS4, pC=0.02, OR=0.40) together with the activating receptor KIR2DS4 (HLA-C1+KIR2DS4+KIR2DL3 and/or KIR2DL2, pC=0.004, OR=0.38) with protection from HCV infection. Our findings in HCV-infected and non-infected IDUs suggest an important role for KIRs (KIR2DL2 and KIR2DL3) with group HLA-C1 molecules, in the presence of activating KIR2DS4, in protection from HCV infection. These results support the hypothesis that activator signaling, mediated by KIR2DS4, plays a determinant role in the regulation of NK cell antiviral-activity.

Distribution of the human leukocyte antigen class II alleles in Brazilian patients with chronic hepatitis C virus infection

Hepatitis C virus (HCV) infection is a global medical problem. The current standard of treatment consists of the combination of peginterferon plus ribavirin. This regimen eradicates HCV in 55% of cases. The immune response to HCV is an important determinant of disease evolution and can be influenced by various host factors. HLA class II may play an important role in immune response against HCV. The objective of the present study was to determine the distribution of HLA class II (DRB1 and DQB1) alleles, their association with chronic HCV infection and their response to interferon therapy. One hundred and two unrelated white Brazilian patients with chronic HCV infection, 52 responders (45 males and 7 females) and 50 non-responders (43 males and 7 females) to antiviral treatment, were included in the study. Healthy Brazilian bone marrow donors of Caucasian origin from the same geographic area constituted the control group (HLA-DRB1, N = 99 and HLA-DQB1, N = 222 individuals). HLA class II genotyping was performed using a low-resolution DRB1, DQB1 sequence-specific primer amplification. There were higher frequencies of HLA-DRB1*13 (26.5 vs 14.1%) and HLA-DQB1*02 (52.9 vs 38.7%) in patients compared with controls; however, these were not significantly different after P correction (Pc = 0.39 and Pc = 0.082, respectively). There was no significant difference between the phenotypic frequencies of HLA-DRB1 (17.3 vs 14.0%) and HLA-DQB1 alleles in responder and non-responder HCV patients. The HLA-DRB1*07 allele was significantly more common in HCV patients (33.3 vs 12.1%) than in controls (Pc = 0.0039), suggesting that the HLA-DRB1*07 allele is associated with chronic HCV infection.

Human leukocyte antigen class II associations with hepatitis C virus clearance and virus-specific CD4 T cell response among Caucasians and African Americans

The outcome of hepatitis C virus (HCV) infection has been associated with antiviral CD4 T cell response, human leukocyte antigens (HLA) class II genotypes, and ethnicity. However, HLA class II molecules restrict the nature of CD4 T cell response, and HLA distributions differ between ethnic groups. In this study, we asked whether HLA class II genotypes associated with HCV clearance are shared between Caucasian and African Americans and whether they contribute to enhanced antiviral CD4 T cell response. In a cohort of 93 HCV-seropositive subjects from Northeast America with defined ethnicity, virological outcome, and HCV-specific CD4 T cell proliferation, we confirm the previously reported associations between HCV clearance and two HLA types (DQB1*03, DRB1*11) while identifying a new association with DRB3*02. Strikingly, these associations were identified only among Caucasian [DQB1*03: odds ratio (OR), 10.4; P = 0.031, DRB1*11: OR, 7.0, P = 0.019; DRB3*02: OR, 8.3, P = 0.005; DQB1*03-DRB3*02: OR, 13.5, P = 0.001) but not among African American patients. Furthermore, although HLA DQB1*03, DRB1*11, and DRB3*02 genotypes were associated with increased HCV-specific CD4 T cell response in univariate analyses, these associations were lost when controlling for virological outcomes.

CONCLUSION

We conclude that the immunogenetic basis for HCV clearance differs between ethnic groups and that the association between HLA class II and HCV clearance is not directly explained by antiviral CD4 T cell response.

Interaction of NK inhibitory receptor genes with HLA-C and MHC class II alleles in Hepatitis C virus infection outcome

Natural killer cells are important in innate defense against viral infections. The interplay between stimulatory and inhibitory natural killer cell receptors and their corresponding human leukocyte antigen ligands are known to influence the outcome of acute Hepatitis C virus infection. Frequencies of NK receptor genes (8 inhibitory, 6 activating and 2 pseudogenes) and HLA class II alleles (DRB1, DQB1) were analyzed in 160 Puerto-Rican American drug users with Hepatitis C virus infection; 121 had chronic viremia (CV) and 39 were spontaneous clearance (SC). We further ruled out genetic stratification using short tandem repeats. Interaction between KIR gene receptor 2DL3/2DL3 and its ligand, C1/C1 of HLA-Cw alleles and spontaneous clearance was confirmed (p=0.03, OR=3.05). We also found a new interaction between the KIR receptor gene 2DL3 with HLA-DRB1*1201 (p=0.0001, OR=22) associated with SC, and an association of HLA DQB1*0501 (p=0.05, OR=0.30) with CV. Our findings suggested a role for MHC class II alleles in Hepatitis C virus peptide presentation to T cells together with NK ligand interaction involving pathways that will be useful for the development of immunotherapeutic interventions.

Evidence for human leukocyte antigen heterozygote advantage against hepatitis C virus infection

Outcomes of infection with hepatitis C virus (HCV) vary widely, from asymptomatic clearance to chronic infection, leading to complications that include fibrosis, cirrhosis, hepatocellular carcinoma, and liver failure. Previous studies have reported statistical associations between human leukocyte antigen (HLA) heterozygosity and favorable outcomes of infection with either hepatitis B virus (HBV) or human immunodeficiency virus (HIV) (the "heterozygote advantage"). To investigate whether HLA zygosity is associated with outcome of HCV infection, we used data from the United States Organ Procurement and Transplantation Network database of 52,435 liver transplant recipients from 1995 through 2005. Of these, 30,397 were excluded for lack of HLA data, retransplantation, known HIV infection, or insufficient information regarding HBV infection. The remaining cases were analyzed for associations between HCV infection and HLA zygosity with 1-sided Fisher's exact tests. Results show significantly lower proportions of HLA-DRB1 heterozygosity among HCV-infected than uninfected cases. The differences were more pronounced with alleles represented as functional supertypes (P = 1.05 x 10(-6)) than as low-resolution genotypes (P = 1.99 x 10(-3)). No significant associations between zygosity and HCV infection were found for other HLA loci.

CONCLUSION

These findings constitute evidence for an advantage among carriers of different supertype HLA-DRB1 alleles against HCV infection progression to end-stage liver disease in a large-scale, long-term study population. Considering HLA polymorphism in terms of supertype diversity is recommended in strategies to design association studies for robust results across populations and in trials to improve treatment options for patients with chronic viral infection. Access to deidentified clinical information relating genetic variation to viral infection improves understanding of variation in infection outcomes and might help to personalize medicine with treatment options informed in part by human genetic variation.

Clearance and persistence of hepatitis C virus in a Tunisian population: association with HLA class I and class II

Human leukocyte antigens (HLAs) of class I and class II are reported to influence the outcome of hepatitis C virus (HCV) infection. The aim of this study was to assess the role of HLA class I and class II in influencing spontaneous viral clearance or persistence in HCV-infected patients. HLA class I (A and B) typing was performed by lymphocytotoxicity test and HLA class II (DRB1) was determined by low-resolution PCR-SSP (polymerase chain reaction amplification with sequence-specific primers) for 99 subjects (48 men and 51 women). Of these, 75 had chronic infection and 24 had viral clearance. No significant differences were observed between individuals with spontaneous viral clearance or chronic HCV infection for age, sex, source of infection, and risk factors. HLAB-w35 and HLA-DRB1*08 occurred more frequently in those with viral clearance (21.7 and 16.6%, respectively) compared with those with chronic infection (5.5 and 2.6%; p < 0.04 and p < 0.01, respectively). DRB1*15 occurred more often in those with chronic infection (29.3%) compared with those with viral clearance (16.66%), but the difference did not reach statistical significance. These results support the hypothesis that specific HLA class I and class II alleles might influence the clearance or persistence of HCV infection. Both Bw35 and DRB1*08 are associated with clearance of circulating HCV whereas DRB1*15 appears to predispose to progression of liver disease in Tunisian patients. Taken together, our results and those previously reported suggest that HLA associations with the outcome of hepatitis C viremia vary in relation to the ethnicity of the population studied. Further prospective studies of larger cohorts of HCV-infected subjects are needed to evaluate, in different populations, the role of specific HLA class I and class II alleles in the outcome of HCV infection.

A comparative review of HLA associations with hepatitis B and C viral infections across global populations

Hepatitis B (HBV) and hepatitis C (HCV) viral infection or co-infection leads to risk of development of chronic infection, cirrhosis and hepatocellular carcinoma (HCC). Immigration and globalization have added to the challenges of public health concerns regarding chronic HBV and HCV infections worldwide. The aim of this study is to review existing global literature across ethnic populations on HBV and HCV related human leukocyte antigen (HLA) associations in relation to susceptibility, viral persistence and treatment. Extensive literature search was conducted to explore the HLA associations in HBV and HCV infections reported across global populations over the past decade to understand the knowledge status, weaknesses and strengths of this information in different ethnic populations. HLA DR13 is consistently associated with HBV clearance globally. HLADRB1*11/*12 alleles and DQB1*0301 are associated with HBV persistence but with HCV clearance worldwide. Consistent association of DRB1*03 and *07 is observed with HCV susceptibility and non-responsiveness to HBV vaccination across the population. HLA DR13 is protective for vertical HBV and HCV transmission in Chinese and Italian neonates, but different alleles are associated with their susceptibility in these populations. HLA class I molecule interactions with Killer cell immunoglobulin like receptors (KIR) of natural killer (NK) cells modulate HCV infection outcome via regulating immune regulatory cells and molecules. HLA associations with HBV vaccination, interferon therapy in HBV and HCV, and with extra hepatic manifestations of viral hepatitis are also discussed. Systematic studies in compliance with global regulatory standards are required to identify the HLA specific viral epitope, stage specific T cell populations interacting with different HLA alleles during disease progression and viral clearance of chronic HBV or HCV infections among different ethnic populations. These studies would facilitate stage specific therapeutic strategies for clearance of HBV and HCV infections or co-infections across global populations and aid in identification of HBV-HCV combined vaccine. HLA associations of chronic HBV or HCV development with confounding host factors including alcohol, drug abuse, insulin resistance, age and gender are lacking and warrant detailed investigation across global populations.

Monosaccharides modulate HCV E2 protein-derived peptide biological properties

A hepatitis C virus E(2) protein-derived sequence was selected for studying the effect of N-glycosylation on the peptide chain's conformational structure. The results suggested that the (534)TDVF(537) motif contained in peptide 33402 ((529)WGENDTDVFVLNNTRY(544)) had a type III beta-turn, relevant in antigen recognition of polyclonal antibodies, binding to human cells, and binding to HLA DRB1 *0401 molecules. N-Glycopeptides derived from this sequence contained monosaccharides in Asn(532). N-Glycopeptides presented differences in peptide chain structure compared to non-glycosylated peptides. Peptide 33402 specifically bound to human cells, specificity becoming lost when it was N-glycosylated. N-Glycosylation decreased antigen recognition of mouse polyclonal sera against this sequence. N-Glycopeptide binding to HLA DRB1 *0401 molecules was similar to that presented by non-glycosylated peptide, indicating that N-glycosylation did not affect binding to HLA DRB1 *0401 molecules. N-Glycosylation induced changes at structural and functional level which could be relevant for modulating human cell binding properties and antibody recognition.

Impact of the genetic restriction of virus-specific T-cell responses in hepatitis C virus infection

The immunobiology of hepatitis C virus (HCV) is significantly influenced by the host immune response to the virus, especially by virus-specific T-cell responses. Virus-specific T cells are restricted by human leucocyte antigen class I and II molecules. Of note, associations between these polymorphic loci and outcome and course of HCV infection have been reported in large and well-documented cohorts. This review will briefly summarize these studies and focus especially on the immunological and virological basis for the reported associations. The outcome and course of HCV infection is most likely determined by a complex interplay of genetic, immunological and virological factors. A better understanding of these host-virus interactions is essential not only to gain better insights into the mechanisms of viral clearance and persistence but also for the development of new antiviral vaccine strategies.

Host and viral factors in the immunopathogenesis of primary hepatitis C virus infection

Individuals infected with hepatitis C virus (HCV) have two possible outcomes of infection, clearance or persistent infection. The focus of this review is the host mechanisms that facilitate clearance. The interaction between HCV viral components and the immune system ultimately determines the balance between the virus and host. Strong evidence points to the aspects of cellular immune response as the key determinants of outcome. The recent discovery of viral evasion strategies targeting innate immunity suggests that the interferon-alpha/beta induction pathways are also critical. A growing body of evidence has implicated polymorphisms in both innate and adaptive immune response genes as determinants of viral clearance in individuals infected with HCV.

Human leukocyte antigen class II DQB1*0301, DRB1*1101 alleles and spontaneous clearance of hepatitis C virus infection: a meta-analysis

AIM

To assess the associations of human leukocyte antigen (HLA) class II DQB1*0301 and/or DRB1*1101 allele with spontaneous hepatitis C virus (HCV) clearance by meta-analysis of individual dataset from all studies published till date.

METHODS

To clarify the impact of HLA class II polymorphisms on viral clearance, we performed a meta-analysis of the published data from 11 studies comparing the frequencies of DQB1*0301 and DRB1*1101 alleles in individuals with spontaneous resolution to those with persistent infection. As we identified the heterogeneity between studies, summary statistical data were calculated based on a random-effect model.

RESULTS

Meta-analyses yielded summary estimates-odds ratio (OR) of 2.36 [95%CI (1.62, 3.43), P<0.00001] and 2.02 [95%CI (1.56, 2.62), P<0.00001] for the effects of DQB1*0301 and DRB1*1101 alleles on spontaneous clearance of HCV, respectively.

CONCLUSION

These results support the hypothesis that specific HLA class II alleles might influence the susceptibility or resistance to persistent HCV infection. Both DQB1*0301 and DRB1*1101 are protective alleles and present HCV epitopes more effectively to CD4(+)T lymphocytes than others, and subjects with these two alleles are at a lower risk of developing chronic HCV infection. Large, multi-ethnic confirmatory and well-designed studies are needed to determine the host genetic determinants of HCV infection.

HLA-DRB1 donor-recipient mismatch affects the outcome of hepatitis C disease recurrence after liver transplantation

BACKGROUND & AIMS

This study extends our previously reported observations that various immunological factors are associated with the occurrence of histologically proven recurrent hepatitis C. The two specific issues investigated were to confirm the associations of MHC alleles and donor/recipient mismatch with the occurrence of recurrent hepatitis C in an independent cohort of newly transplanted patients and to look for immunologic and nonimmunologic variables affecting the severity of the recurrent disease.

METHODS

Two separate cohorts of consecutive patients were studied: a look-back cohort (LC) of 120 patients and a cohort for studying the disease progression (CSDP) of 190 patients. Protocol liver biopsies were obtained at least 1, 3, 5, 7, and 10 years after liver transplantation (LT).

RESULTS

A fully mismatched donor/recipient pair at the DRB1 locus was confirmed to be associated with both the recurrence of histologic hepatitis in the LC (59% vs 23%, P = .0002) and its progression beyond stage 3 in the CSPD (71.4% vs 39.3%, P = .0003). Relevant immunologic and nonimmunologic variables were included into a multivariate Cox proportional model and three variables, namely, donor age, full HLA-DRB1 donor-recipient mismatch, and HLA B14, resulted in independent risk factors for the development of severe fibrosis.

CONCLUSION

This study provides evidence that DRB1 donor-recipient mismatch affects both the occurrence and progression of recurrent hepatitis C disease. This information is clinically relevant as it may help to better allocate organs and to recognize patients at risk for progression so that specific interventions can be implemented.

Immunogenetics of viral infections

The HLA class I and II genes encode molecules that lie at the heart of the acquired immune response against infectious diseases. Associations between these polymorphic loci and genetically complex infectious diseases have been historically elusive, in contrast to the more obvious HLA associations with autoimmune diseases. High resolution molecular typing of large, clinically well-defined cohorts has begun to uncover evidence for the influence of HLA diversity on diseases of viral etiology, such as those caused by HIV-1, hepatitis B virus, hepatitis C virus and human papilloma virus. Combinations of HLA and KIR also appear to affect outcome to viral infection, supporting a role for HLA class I diversity in the innate immune response in addition to the acquired immune response.

Host immune responses in hepatitis C virus clearance

BACKGROUND AND AIM

The factors that determine the outcome of hepatitis C virus (HCV) infection are not fully understood. An increased and broadly targeted/multispecific T-cell response is thought to be paramount to a favourable outcome. Human leucocyte antigen (HLA) genes, in particular DRB1 and DQB1, are also reported to influence outcome of infection. We have previously demonstrated strong associations between DRB10101 and spontaneous viral clearance. The aim of the current study was to investigate HCV-specific T-cell response and the influence of DRB10101 in patients with long-term history of HCV clearance as compared to patients that developed persistent HCV infection.

METHODS

The proliferation of peripheral blood mononuclear cells stimulated with five non-structural and core HCV antigens and 20 synthesized HCV peptides, designed using T-cell epitope-predictive software, was determined by the incorporation of H-thymidine.

RESULTS

Although HCV-specific T-cell responses were more frequently detected and a broader range of peptides were targeted in the viral clearance group, the magnitude and breadth of the responses were not significantly different to that in the viral persistence group. The magnitude and breadth of the T-cell response was significantly associated, however, with possession of DRB10101. Furthermore DRB10101 positive individuals with viral clearance had broader HCV-specific T-cell responses.

CONCLUSION

These findings lend further credence to the importance of the host immune system to the outcome of HCV infection and provide a rationale for the role of DRB10101 in the resolution of HCV infection.

Intrafamilial transmission of hepatitis C in Egypt

The incidence of hepatitis C (HCV) infection and associated risk factors were prospectively assessed in a cohort of 6,734 Egyptians from 2 rural villages who were negative for antibodies to HCV (anti-HCV). Initial and follow-up sera were tested for anti-HCV by enzyme immunoassay (EIA), and possible incident cases were confirmed by using the microparticle enzyme immunoassay (MEIA) and tested for HCV RNA. All follow-up serum samples converting from negative to positive without detectable HCV-RNA were further tested by recombinant immunoblot assay. Over an average of 1.6 years, asymptomatic anti-HCV seroconversion occurred in 33 people (3.1/1,000 person-years [PY]), including 28 (6.8/1,000 PY) in the Nile Delta village (AES), where prevalence was 24% and 5 (0.8/1,000 PY) in the Upper Egypt village (baseline prevalence of 9%). The strongest predictor of incident HCV was having an anti-HCV-positive family member. Among those that did, incidence was 5.8/1,000 PY, compared (P < .001) with 1.0/1,000 PY; 27 of 33 incident cases had an anti-HCV-positive family member. Parenteral exposures increased the risk of HCV but were not statistically significant; 67% of seroconverters were younger than 20 years of age, and the highest incidence rate (14.1/1,000 PY) was in children younger than 10 who were living in AES households with an anti-HCV-positive parent. In conclusion, young children would especially benefit from measures reducing exposures or preventing infection with HCV.

Strain-specific T-cell suppression and protective immunity in patients with chronic hepatitis C virus infection

Hepatitis C virus (HCV) frequently persists with an apparently ineffective antiviral T-cell response. We hypothesized that some patients may be exposed to multiple HCV subtypes and that strain-specific T cells could contribute to the viral dynamics in this setting. To test this hypothesis, CD4 T-cell responses to three genotype 1a-derived HCV antigens and HCV antibody serotype were examined in chronically HCV infected (genotypes 1a, 1b, 2, 3, and 4) and spontaneously HCV recovered subjects. Consistent with multiple HCV exposure, 63% of patients infected with genotypes 2 to 4 (genotypes 2-4) and 36% of those infected with genotype 1b displayed CD4 T-cell responses to 1a-derived HCV antigens, while 29% of genotype 2-4-infected patients showed serotype responses to genotype 1. Detection of 1a-specific T cells in patients without active 1a infection suggested prior self-limited 1a infection with T-cell-mediated protection from 1a but not from non-1a viruses. Remarkably, CD4 T-cell responses to 1a-derived HCV antigens were weakest in patients with homologous 1a infection and greater in non-1a-infected patients: proportions of patients responding were 19% (1a), 36% (1b), and 63% (2-4) (P = 0.0006). Increased 1a-specific CD4 T-cell responsiveness in non-1a-infected patients was not due to increased immunogenicity or cross-reactivity of non-1a viruses but directly related to sequence divergence. We conclude that the T-cell response to the circulating virus is either suppressed or not induced in a strain-specific manner in chronically HCV infected patients and that, despite their ability to clear one HCV strain, patients may be reinfected with a heterologous strain that can then persist. These findings provide new insights into host-virus interactions in HCV infection that have implications for vaccine development.

DR Antigens Influence Graft Outcome and HCV Recurrence After Liver Transplantation

Hepatitis C (HCV) recurrence following liver transplantation is universal. However, the severity of recurrence is highly variable between patients. We speculated that recipient DR antigens or the level of DR mismatching between the recipient and the donor might affect the severity of HCV recurrence and allograft survival. Clinical outcome was compared between HCV+ recipients with DR2, DR3, or DR5 versus HCV+ recipients with all other DR antigens. Recipients with DR3 had reduced allograft survival (P < .02), a higher rate of HCV recurrence (P < .05), and more severe liver disease (P < .05). Recipients with DR5 had superior allograft survival (P < .05), low rates of HCV recurrence (P < .05), and benign liver disease (P < .05). Clinical outcome of recipients with DR2 was equivalent (P = Ns) to the non-DR2, -3, -5 recipients. The incidence of acute rejection was equivalent (P = Ns) in all groups. The level of DR mismatching between donor and recipient did not affect HCV recurrence or severity. However, allograft survival was better (P < .05) in recipients with zero DR mismatches. The data show that host genetic factors play an important role in HCV recurrence and allograft outcome after liver transplantation. In addition, identification of DR antigens may help predict an HCV+ patient's relative risk for severe HCV recurrence.

Host genetic determinants in hepatitis C virus infection

In addition to viral and environmental/behavioural factors, host genetic diversity is believed to contribute to the spectrum of clinical outcomes in hepatitis C virus (HCV) infection. This paper reviews the literature with respect to studies of host genetic determinants of HCV outcome and attempts to highlight trends and synthesise findings. With respect to the susceptibility to HCV infection, several studies have replicated associations of the HLA class II alleles DQB1(*)0301 and DRB1(*)11 with self-limiting infection predominantly in Caucasian populations. Meta-analyses yielded summary estimates of 3.0 (95% CI: 1.8-4.8) and 2.5 (95% CI: 1.7-3.7) for the effects of DQB1(*)0301 and DRB1(*)11 on self-limiting HCV, respectively. Studies of genetics and the response to interferon-based therapies have largely concerned single-nucleotide polymorphisms and have been inconsistent. Regarding studies of genetics and the progression of HCV-related disease, there is a trend with DRB1(*)11 alleles and less severe disease. Studies of extrahepatic manifestations of chronic HCV have shown an association between DQB1(*)11 and DR3 with the formation of cryoglobulins. Some important initial observations have been made with respect to genetic determinants of HCV outcome. Replication studies are needed for many of these associations, as well as biological data on the function of many of these polymorphisms.

Lack of a strong association between HLA class II, tumour necrosis factor and transporter associated with antigen processing gene polymorphisms and virological response to alpha-interferon treatment in patients with chronic hepatitis C

The aim of the study was to investigate whether polymorphisms of the HLA class II, tumour necrosis factor (TNF) and transporter associated with antigen processing (TAP) genes influence the response to alpha-interferon in patients with chronic hepatitis C. Twenty-seven sustained responders and 55 non-responders to alpha-interferon monotherapy were investigated. HLA-DRB1, DQA1, DQB1, TNFA, TNFB, TAP1 and TAP2 alleles were determined by PCR-based molecular techniques. Sustained virological response was defined as undetectable serum hepatitis C virus (HCV) RNA for at least 3 years after the end of treatment. Probability (P) values were corrected for the number of alleles tested (Pc). Viral genotype 1b was more frequent in responders than in non-responders (56% vs. 26%, P = 0.009). HLA-DQB1*02 occurred less frequently in responders than in non-responders (14.8% vs. 29%, Pc not significant). HLA-DRB1*11 and DQB1*0602 were found in 22.2% and 9.3% of responders and in 10.9% and 1.8% of non-responders, respectively (Pc not significant). There was no difference in the distribution of TNF alleles in the two groups. Twenty-four (88.8%) responder patients as compared with 34 (61.8%) non-responders were TAP1*0101 homozygous (Pc not significant). Thus, in European Caucasoids with chronic hepatitis C, we could not demonstrate a strong association between HLA class II, TNF, and TAP gene polymorphisms and response to interferon treatment.

Persistence of hepatitis C virus in a white population: Associations with human leukocyte antigen class 1

The aim of this study was to define novel associations between human leukocyte antigen (HLA) class 1 alleles and persistence or clearance of the hepatitis C virus (HCV) in a white population. All individuals in the study were seropositive for anti-HCV antibodies. Viral status was determined by the Roche HCV Amplicor test. HLA-A, -B, -C allelic group profile was molecularly defined by reverse line probe hybridization. The strongest individual allelic group associations with persistent HCV infection were HLA A*11 (p = 0.044) and Cw*04 (p = 0.006). However, only the HLA C*04 association survived correction for multiple comparisons. Further analysis of alleles in linkage with HLA Cw*04 revealed that the haplotype HLA A*11, Cw*04 was present in 11 individuals, 10 of whom were viremic (p = 0.05). No gene dosage effect was observed. No association between HLA class 1 allelic groups and aviremia and virus load was evident in this white population. HLA B*44 is associated with low virus load in human immunodeficiency virus disease, but this association was not evident in this HCV-infected population. Novel HLA class 1 alleles associated with persistence of HCV have been identified.

Genetic variants in the CCR gene cluster and spontaneous viral elimination in hepatitis C-infected patients

Hepatitis C virus (HCV) infection results in chronic hepatitis in more than 80% of infected patients while 10-20% of patients recover spontaneously. Host genetic factors may influence the ability to clear the virus after infection. Six single nucleotide polymorphisms and a 32 bp deletion in the genes coding for CCR3, CCR2 and CCR5 (which are all located in a cluster on chromosome 3) were investigated in 465 consecutively recruited patients infected with HCV and 370 matched controls. Genetic variants were tested for association with spontaneous viral elimination and, in the chronically infected patients, stage of fibrosis and response to antiviral therapy. The G190A polymorphism (variant allele Ile64) in the first transmembrane domain of CCR2 was under-represented in the 29 patients who had cleared the hepatitis C virus spontaneously (P = 0.018). None of the other variants in the CCR gene cluster showed association with the natural course of the infection, stage of fibrosis or response to therapy.

The influence of the human genome on chronic viral hepatitis outcome

The mechanisms that determine viral clearance or viral persistence in chronic viral hepatitis have yet to be identified. Recent advances in molecular genetics have permitted the detection of variations in immune response, often associated with polymorphism in the human genome. Differences in host susceptibility to infectious disease and disease severity cannot be attributed solely to the virulence of microbial agents. Several recent advances concerning the influence of human genes in chronic viral hepatitis B and C are discussed in this article: a) the associations between human leukocyte antigen polymorphism and viral hepatic disease susceptibility or resistance; b) protective alleles influencing hepatitis B virus (HBV) and hepatitis C virus (HCV) evolution; c) prejudicial alleles influencing HBV and HCV; d) candidate genes associated with HBV and HCV evolution; d) other genetic factors that may contribute to chronic hepatitis C evolution (genes influencing hepatic stellate cells, TGF-beta1 and TNF-alpha production, hepatic iron deposits and angiotensin II production, among others). Recent discoveries regarding genetic associations with chronic viral hepatitis may provide clues to understanding the development of end-stage complications such as cirrhosis or hepatocellular carcinoma. In the near future, analysis of the human genome will allow the elucidation of both the natural course of viral hepatitis and its response to therapy.

Managing occupational risks for hepatitis C transmission in the health care setting

Hepatitis C virus (HCV) infection is a significant contemporary health problem in the United States and elsewhere. Because it is primarily transmitted via blood, hepatitis C infection presents risks for both nosocomial transmission to patients and occupational spread to health care workers. Recent insights into the pathogenesis, immunopathogenesis, natural history, and treatment of infection caused by this unique flavivirus provide a rationale for the use of new strategies for managing occupational hepatitis C infections when they occur. This article reviews this developing information. Recently published data demonstrate success rates in the treatment of "acute hepatitis C syndrome" that approach 100\%, and although these studies are not directly applicable to all occupational infections, they may provide important clues to optimal management strategies. In addition, the article delineates approaches to the prevention of occupational exposures and also addresses the difficult issue of managing HCV-infected health care providers. The article summarizes currently available data about the nosocomial epidemiology of HCV infection and the magnitude of risk and discusses several alternatives for managing exposure and infection. No evidence supports the use of immediate postexposure prophylaxis with immunoglobulin, immunomodulators, or antiviral agents. Based on the very limited data available, the watchful waiting and preemptive therapy strategies described in detail in this article represent reasonable interim approaches to the complex problem of managing occupational HCV infections, at least until more definitive data are obtained.

Long-term follow-up of hepatitis C virus infection: HLA class II loci influences the natural history of the disease

Hepatitis C virus (HCV) causes various grades of chronic liver disease, ranging from an asymptomatic state to cirrhosis. To assess genetic factors of disease severity, we selected two HCV patient groups according to the following stringent criteria: (i) asymptomatic carrier state (ASC) defined by HCV infection for more than 20 years, normal alanine aminotransferase levels for the past 5 years as well as normal liver histology and/or shape and (ii) liver cirrhosis (LC) as diagnosed by clinical symptoms, liver biopsy and/or ultrasonography. A total of 103 chronically infected Japanese HCV patients (43 ASC and 60 LC) were analyzed. HLA class I and II alleles were established using low resolution DNA typing. HLA-DRB1 and DQB1 genotypes were inferred upon polymerase chain reaction-restriction fragment length polymorphism analysis. Two hundred and one anti-HCV-negative ethnically matched controls were included. The frequencies of DRB1*12 (*1201 and *1202), DQB1*0301 and DRB3*03 alleles were higher in patients with ASC than in those with LC (odds ratio (OR) 11.23, OR 4.25, and OR 3.22, respectively). The frequency of DQB1*0503 were lower in ASC patients compared to LC patients (OR 0.05). No significant differences between groups were observed for age, sex, source of infection, HCV genotype or viral loads. Our findings establish that certain HLA class II alleles strongly influence disease progression following HCV infection.

MHC class II genes in HCV viral clearance of hepatitis C infected Hispanic patients

The frequency of class II human leukocyte antigen (HLA) alleles in 112 infected patients of Hispanic ancestry with serology positive for hepatitis C virus (HCV) was investigated. Our studies failed to demonstrate significant association between class II HLA alleles and the outcome of HCV infection: chronic viremia versus spontaneous viral clearance. Our results suggest that the genes responsible for the outcome are unknown, so far, and those HLA associations reported in several ethnic groups may represent genetic markers in nonrandom association with the responsible genes involved in determining viral clearance or chronic viremia following HCV infection.

Comparative rates of nucleotide sequence variation in the hypervariable region of E1/E2 and the NS5b region of hepatitis C virus in patients with a spectrum of liver disease resulting from a common source of infection

The association of the severity of liver disease and the molecular evolution of hepatitis C virus (HCV) during chronic infection remains unclear and controversial. To address this we have studied the interpatient variability in the nucleotide sequence of two regions of the HCV genome, E1/E2, which contain the hypervariable region 1 and the nonstructural NS5b region, in a cohort of Irish female patients who were all recipients of a single source of HCV genotype 1b-contaminated anti-D immunoglobulin in 1977 and 1978 and who over the subsequent 20 years developed a spectrum of liver disease. In addition, quasispecies analysis was used to evaluate intrapatient variability in the E1/E2 region in four patients with mild and four with severe disease. Phylogenetic and evolutionary rate analyses of the nucleotide sequences demonstrated that there was no significant difference between those who developed mild disease and those who had progressed to severe disease or cirrhosis. These findings suggest that other factors, either additional viral or host, may be important in the pathogenesis and clinical outcome of chronic hepatitis C virus infection.

Yield of HCV and HIV-1 NAT after screening of 3.6 million blood donations in central Europe

BACKGROUND

HCV and HIV-1 NAT of all blood donations was initiated at our institutions in January 1997 to reduce the residual risk of transfusion-transmitted virus infections. The yield of NAT after testing more than 3.6 million donations in central Europe is reported.

STUDY DESIGN AND METHODS

Automated pipetting instruments were used to pool up to 96 donor samples including those that were antibody reactive. To compensate for dilution of the individual donor samples by pooling, viruses were enriched from the pools by centrifugation at 48,000 x g. A commercial PCR (Cobas Amplicor, Roche) and an in-house PCR were applied for HCV and HIV-1 amplification, respectively.

RESULTS

Six HCV and 2 HIV-1 PCR confirmed-positive, antibody-negative donations (yield, 1 in 600,000 and 1 in 1.8 million, respectively) were identified. Thirty-nine and 11 multiple-time donors seroconverted for HCV and HIV, respectively, and look-back procedures were initiated. Archived samples from preseroconversion donations were thawed and retested by single-sample PCR and remained negative. The recipients of the blood components were traced and tested. All traced recipients were negative for HCV and HIV antibodies.

CONCLUSION

The yield of NAT in central European Red Cross blood donors was less than expected from theoretical calculations for American and German multiple-time donors. Look-back procedures for HCV and HIV indicated that no donation given before seroconversion of the donor was missed by minipool PCR. Sensitivity of minipool PCR testing after virus enrichment seems to be sufficiently high to close the diagnostic window almost completely.

The natural history of hepatitis C virus infection

The natural history of HCV infection remains ill-defined. The knowledge accumulated on the progression of HCV to date is important, however. It is now abundantly clear that the progression of disease is generally slow, and the development of cirrhosis and its complications is a possibility, not a probability as hitherto thought. Predicting the outcome remains a quandary for clinicians. Ultimately it will be possible to define the natural history of hepatitis C infection through a combination of research in the fields of virology, immunology, and molecular biology and by monitoring the biochemical and histologic progress of the disease. Only then will it be possible to intervene appropriately and develop new therapies to prevent the progression to cirrhosis and hepatocellular carcinoma.

Effect of HLA class II genotype on T helper lymphocyte responses and viral control in hepatitis C virus infection

Hepatitis C virus (HCV) infection is very common worldwide, but has a broad range of outcomes. A minority of patients are able to clear infection spontaneously, and this is thought to be due to the emergence and maintenance of effective cell-mediated immunity, particularly CD4+ T lymphocyte responses. Furthermore, genetic studies have indicated that HLA class II genotype strongly influences the outcome of infection. We have therefore investigated the influence of the protective HLA class II haplotype (DQB1*0301, which is in tight linkage disequilibrium with DRB1*1101) on the CD4+ T lymphocyte responses to HCV. We observe a strong association between this genotype and maintenance of a multispecific CD4+ T helper response. The effect on T helper responses was also maintained after combination interferon-alpha/ribavirin therapy, although the latter influenced the pattern of viral antigens to which patients responded. This is the first disease in which an association of HLA genotype with clinical outcome has been linked to an alteration of the immunological phenotype. The selection of protective peptides in those with the favourable HLA class II genotype may point in the direction of suitable vaccine candidates.