Associations between the human MHC and sustained virologic response in the treatment of chronic hepatitis C virus infection

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

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

Association between polymorphisms of the swine MHC-DQA gene and diarrhoea in three Chinese native piglets

Swine leucocyte antigen (SLA) is a highly polymorphic multigene family that plays a crucial role in swine immune response and disease resistance. Here, we identified polymorphisms and gene variations of SLA-DQA exon 2 using polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) and DNA sequencing analysis, and further investigated the correlation between the polymorphisms and piglet diarrhoea in three Chinese native pig breeds (Bamei, Juema and Gansu Black pigs). Consequently, 12 genotypes and 8 alleles including two novel alleles were detected. Nucleotide polymorphism was compared with the actual functional polymorphism in the peptide-binding region (PBR), binding pockets P1, P6 and P9, and the antigen-binding groove, variations in the antigen-binding groove of alleles DQA*01xa01, DQA*01xa03, DQA*01xb01, DQA*We02, DQA*03xb03 and DQA*wy06 were higher than alleles DQA*03xa01 and DQA*03xa03, while amino acid variations in peptide-binding pockets of allele DQA*03xa03 were most abundant among all alleles. The results of association analysis showed the diarrhoea score of Gansu Black pigs (-0.08 ± 0.78) was significantly higher than Bamei and Juema pigs (P < 0.01), and genotype DQA*03xa0103xa01 (0.39 ± 0.54) was significantly higher relative to other genotypes (P < 0.01), while that of genotype DQA*03xa0303xa03 (-1.31 ± 0.88) was markedly lower than scores obtained with genotypes DQA*03xa0103xa01 and DQA*03xa0101xa01 (P < 0.01), as well as DQA*01xa0101xa01 (P < 0.05), indicating that amino acid variations in the peptide-binding pockets play a more important role than the antigen-binding groove in piglet diarrhoea resistance. Further studies on other SLA molecules of native pigs are required to validate the link between this gene complex and diarrhoea.

Individualization of chronic hepatitis C treatment according to the host characteristics

Hepatitis C virus (HCV) infection is a global health problem that affects more than 170 million people worldwide. It is a major cause of cirrhosis and hepatocellular carcinoma, making the virus the most common cause of liver failure and transplantation. The standard-of-care treatment for chronic hepatitis C (CHC) has been changed during the last decade and direct acting antiviral drugs have already been used. Besides, understanding of the pathogenesis of CHC has evolved rapidly during the last years and now several host factors are known to affect the natural history and response to treatment. Recent genome-wide association studies have shown the important role of interleukin-28B and inosine triphosphatase in HCV infection. The present review article attempts to summarize the current knowledge on the role of host factors towards individualization of HCV treatment.

Impact of host and virus genome variability on HCV replication and response to interferon

Since the discovery of hepatitis C virus (HCV), treatment has proven difficult and the regimen of pegylated interferon-α and ribavirin is only effective for half of patients. Evidence suggests that host and viral genome variations play a role in either viral clearance or persistence. Powerful genomic technologies have made it possible to study genome-wide associations with treatment response, which yielded critical genetic polymorphisms that predict treatment response. This has important implications for treatment of HCV infection and opened the door to the possibility of genetic marker-guided treatment (personalized medicine). This review will focus on the recent advances in understanding host and viral genetic variations with regards to treatment and the importance for future therapeutic intervention.

Human leukocyte antigen class II alleles (DQB1 and DRB1) as predictors for response to interferon therapy in HCV genotype 4

Human leukocyte antigens class II play an important role in immune response against HCV. We investigated whether HLA class II alleles influence susceptibility to HCV infection and response to interferon therapy. HLA-DRB1 and -DQB1 loci were genotyped using PCR-SSO Luminex technology. According to our regimen, 41 (66%) of patients achieved sustained virological response to combined treatment of IFN and ribavirin. Frequencies of DQB1∗0313 allele and DRB1∗04-DRB1∗11, DQB1∗0204-DQB1∗0313, DQB1∗0309-DQB1∗0313, and DQB1∗0313-DQB1∗0319 haplotypes were significantly more frequent in nonresponders than in responders. In contrast, DQB1∗02, DQB1∗06, DRB1∗13, and DRB1∗15 alleles were significantly more frequent in responders than in nonresponders. Similarly, DRB1∗1301, DRB1∗1361, and DRB1∗1369 alleles and DRB1∗1301-DRB1∗1328, DRB1∗1301-DRB1∗1361, DRB1∗1301-DRB1∗1369, DRB1∗1328-DRB1∗1361, and DRB1∗1328-DRB1∗1369 haplotypes were significantly found only in responders. Some alleles and linkages showed significantly different distributions between patient and healthy groups. These alleles may be used as predictors for response to treatment or to susceptibility to HCV infection in the Egyptian population.

Genome-wide association study of spontaneous resolution of hepatitis C virus infection: data from multiple cohorts

Chinese translation

BACKGROUND

Hepatitis C virus (HCV) infections occur worldwide and either spontaneously resolve or persist and markedly increase the person's lifetime risk for cirrhosis and hepatocellular carcinoma. Although HCV persistence occurs more often in persons of African ancestry and persons with genetic variants near interleukin-28B (IL-28B), the genetic basis is not well-understood.

OBJECTIVE

To evaluate the host genetic basis for spontaneous resolution of HCV infection.

DESIGN

2-stage, genome-wide association study.

SETTING

13 international multicenter study sites.

PATIENTS

919 persons with serum HCV antibodies but no HCV RNA (spontaneous resolution) and 1482 persons with serum HCV antibodies and HCV RNA (persistence).

MEASUREMENTS

Frequencies of 792 721 single nucleotide polymorphisms (SNPs).

RESULTS

Differences in allele frequencies between persons with spontaneous resolution and persistence were identified on chromosomes 19q13.13 and 6p21.32. On chromosome 19, allele frequency differences localized near IL-28B and included rs12979860 (overall per-allele OR, 0.45; P = 2.17 × 10-30) and 10 additional SNPs spanning 55 000 base pairs. On chromosome 6, allele frequency differences localized near genes for HLA class II and included rs4273729 (overall per-allele OR, 0.59; P = 1.71 × 10-16) near DQB1*03:01 and an additional 116 SNPs spanning 1 090 000 base pairs. The associations in chromosomes 19 and 6 were independent and additive and explain an estimated 14.9% (95% CI, 8.5% to 22.6%) and 15.8% (CI, 4.4% to 31.0%) of the variation in HCV resolution in persons of European and African ancestry, respectively. Replication of the chromosome 6 SNP, rs4272729, in an additional 745 persons confirmed the findings (P = 0.015).

LIMITATION

Epigenetic effects were not studied.

CONCLUSION

IL-28B and HLA class II are independently associated with spontaneous resolution of HCV infection, and SNPs marking IL-28B and DQB1*03:01 may explain approximately 15% of spontaneous resolution of HCV infection.

[Host's genetics in HIV disease]

In the 1990 s, the variability of responses to human immunodeficiency virus (HIV) could only be tracked by phenotypic criteria such as the number of CD4T lymphocytes, the occurrence of opportunistic infection, the disease free survival without treatment. In 1996, the viral load is the leading phenotype for genetic studies. Ever since, thanks to a better understanding of the HIV infection pathophysiology, numerous studies helped to highlight the influence of genetic variability on inter-individual response to this virus. Among the genes having an impact, we can quote the following examples: CCR5, HLA-B and HLA-C genes. Practical applications of genetics in clinical medicine include search for HLA-B*57:01 before abacavir introduction. Recently, an eradicating treatment for HIV disease after bone marrow transplantation with a donor homozygote for a CCR5 gene non-functional variant (CCR5Δ32) has been reported. Interest in genetics of chronic viral infection is not specific to HIV. It has also been used on other viral diseases and it has gained a major place on the management of diseases.

Effect of HFE gene polymorphism on sustained virological response in patients with chronic hepatitis C and elevated serum ferritin

CONTEXT

Abnormal serum ferritin levels are found in approximately 20%-30% of the patients with chronic hepatitis C and are associated with a lower response rate to interferon therapy.

OBJECTIVE

To determine if the presence of HFE gene mutations had any effect on the sustained virological response rate to interferon based therapy in chronic hepatitis C patients with elevated serum ferritin.

METHODS

A total of 44 treatment naÏve patients with histologically demonstrated chronic hepatitis C, all infected with hepatitis C virus genotype non-1 (38 genotype 3; 6 genotype 2) and serum ferritin above 500 ng/mL were treated with interferon (3 MU, 3 times a week) and ribavirin (1.000 mg, daily) for 24 weeks.

RESULTS

Sustained virological response was defined as negative qualitative HCV-RNA more than 24 weeks after the end of treatment. Serum HCV-RNA was measured by qualitative in house polymerase chain reaction with a limit of detection of 200 IU/mL. HFE gene mutation was detected using restriction-enzyme digestion with RsaI (C282Y mutation analysis) and BclI (H63D mutation analysis) in 16 (37%) patients, all heterozygous (11 H63D, 2 C282Y and 3 both). Sustained virological response was achieved in 0 of 16 patients with HFE gene mutations and 11 (41%) of 27 patients without HFE gene mutations (P = 0.002; exact Fisher test).

CONCLUSION

Heterozigozity for H63D and/or C282Y HFE gene mutation predicts absence of sustained virological response to combination treatment with interferon and ribavirin in patients with chronic hepatitis C, non-1 genotype and serum ferritin levels above 500 ng/mL.

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.

Importance of host genetic factors HLA and IL28B as predictors of response to pegylated interferon and ribavirin

OBJECTIVES

Viral factors are considered the best predictors of response to treatment for chronic hepatitis C (CHC), but genetic factors are known to have an important role in this respect. This paper investigates the relationships among the host genetic factors HLA and IL28B, viral factors, and the outcome of combination therapy.

METHODS

A multicenter retrospective cohort of 428 previously untreated CHC patients was treated with pegylated interferon/ribavirin (pegIFN/RBV) for 48 weeks. In all, 378 (88%) of these patients were genotype 1 or 4, and 50 (12%) were genotype 2 or 3.

RESULTS

Multivariate logistic regression showed the rs12979860 CC genotype (adjusted odds ratio (aOR)=4.3, 95% confidence interval (95% CI): 2.6-7), the HLA-DQB1*0301 allele (aOR=2.08, 95% CI: 1.2-3.5) and age, viral genotype, and viral load levels to be significantly associated with sustained virological response (SVR). When the variable rs12979860 was eliminated, the area under the receiver operating characteristic (ROC) curve (AUC) decreased significantly (0.76 vs. 0.69; P=0.03). AUC values derived from viral factors were lower than those corresponding to host genetic factors (0.67 vs. 0.72, respectively; P=0.04). The HLA-DQB1*0301 and A*0201 alleles were associated with rs12979860 CC genotype and SVR (P<0.0001).

CONCLUSIONS

The HLA-DQB1*0301 allele and IL28B genotype are factors that are associated independently with SVR. There is a synergism between the HLA-DQB1*0301 and HLA-A*0201 alleles with polymorphism rs12979860 CC, which increases the SVR rate. IL28B genotype is the best predictor of SVR.

Herpes zoster incidence in a multicenter cohort of solid organ transplant recipients

BACKGROUND

Immunosuppressed patients are at increased risk for herpes zoster (HZ), but incidence in solid organ transplant (SOT) recipients has varied in multiple studies. To assess incidence of HZ, we examined patients who underwent SOT and received follow-up care within the large multicenter US Department of Veteran's Affairs healthcare system.

METHODS

Incident cases of HZ were determined using ICD-9 coding from administrative databases. A multivariable Cox proportional hazards model, adjusted for a priori risk factors, was used to assess demographic factors associated with development of HZ.

RESULTS

Among the 1077 eligible SOT recipients, the cohort-specific incidence rate of HZ was 22.2 per 1000 patient-years (95% confidence interval [CI], 18.1-27.4). African Americans (37.6 per 1000 [95% CI, 25.0-56.6]) and heart transplants recipients (40.0 per 1000 [95% CI, 23.2-68.9]) had the highest incidence of HZ. Patients transplanted between 2005 and 2007 had the lowest incidence (15.3 per 1000 [95% CI, 8.2-28.3]). In a multivariable model, African Americans (hazard ratio [HR] 1.88; 95% CI: 1.12, 3.17) and older transplant recipients (HR 1.13; 95% CI: 1.01, 1.27 [per 5-year increment]) had increased relative hazards of HZ.

CONCLUSIONS

These data demonstrate that HZ is a common infectious complication following SOT. Future studies focused on HZ prevention are needed in this high-risk population.

Hepatitis C treatment among racial and ethnic groups in the IDEAL trial

Previous studies of chronic hepatitis C virus (HCV) treatment have demonstrated variations in response among racial and ethnic groups including poorer efficacy rates among African American and Hispanic patients. The individualized dosing efficacy vs flat dosing to assess optimaL pegylated interferon therapy (IDEAL) trial enrolled 3070 patients from 118 United States centres to compare treatment with peginterferon (PEG-IFN) alfa-2a and ribavirin (RBV) and two doses of PEG-IFN alfa-2b and RBV. This analysis examines treatment response among the major racial and ethnic groups in the trial. Overall, sustained virologic response (SVR) rates were 44% for white, 22% for African American, 38% for Hispanic and 59% for Asian American patients. For patients with undetectable HCV RNA at treatment week 4, the positive predictive value of SVR was 86% for white, 92% for African American, 83% for Hispanic and 89% for Asian American patients. The positive predictive values of SVR in those with undetectable HCV RNA at treatment week 12 ranged from 72% to 81%. Multivariate regression analysis using baseline characteristics demonstrated that treatment regimen was not a predictor of SVR. Despite wide-ranging SVR rates among the different racial and ethnic groups, white and Hispanic patients had similar SVR rates. In all groups, treatment response was largely determined by antiviral activity in the first 12 weeks of treatment. Therefore, decisions regarding HCV treatment should consider the predictive value of the early on-treatment response, not just baseline characteristics, such as race and ethnicity.

Intracellular expression of IRF9 Stat fusion protein overcomes the defective Jak-Stat signaling and inhibits HCV RNA replication

Interferon alpha (IFN-α) binds to a cell surface receptor that activates the Jak-Stat signaling pathway. A critical component of this pathway is the translocation of interferon stimulated gene factor 3 (a complex of three proteins Stat1, Stat2 and IRF9) to the nucleus to activate antiviral genes. A stable sub-genomic replicon cell line resistant to IFN-α was developed in which the nuclear translocation of Stat1 and Stat2 proteins was prevented due to the lack of phosphorylation; whereas the nuclear translocation of IRF9 protein was not affected. In this study, we sought to overcome defective Jak-Stat signaling and to induce an antiviral state in the IFN-α resistant replicon cell line by developing a chimera IRF9 protein fused with the trans activating domain (TAD) of either a Stat1 (IRF9-S1C) or Stat2 (IRF9-S2C) protein. We show here that intracellular expression of fusion proteins using the plasmid constructs of either IRF9-S1C or IRF9-S2C, in the IFN-α resistant cells, resulted in an increase in Interferon Stimulated Response Element (ISRE) luciferase promoter activity and significantly induced HLA-1 surface expression. Moreover, we show that transient transfection of IRF9-S1C or IRF9-S2C plasmid constructs into IFN-α resistant replicon cells containing sub-genomic HCV1b and HCV2a viruses resulted in an inhibition of viral replication and viral protein expression independent of IFN-α treatment. The results of this study indicate that the recombinant fusion proteins of IRF9-S1C, IRF9-S2C alone, or in combination, have potent antiviral properties against the HCV in an IFN-α resistant cell line with a defective Jak-Stat signaling.

IL-28A, IL-28B, and IL-29: promising cytokines with type I interferon-like properties

IL-28A, IL-28B and IL-29 (also designated type III interferons) constitute a new subfamily within the IL-10-interferon family. They are produced by virtually any nucleated cell type, particularly dendritic cells, following viral infection or activation with bacterial components, and mediate their effects via the IL-28R1/IL-10R2 receptor complex. Although IL-28/IL-29 are closer to the IL-10-related cytokines in terms of gene structure, protein structure, and receptor usage, they display type I interferon-like anti-viral and cytostatic activities. Unlike type I interferons, the target cell populations of IL-28/IL-29 are restricted and mainly include epithelial cells and hepatocytes. These properties suggest that IL-28/IL-29 are potential therapeutic alternatives to type I interferons in terms of viral infections and tumors. This review describes the current knowledge about these cytokines.

Predicting the probable outcome of treatment in HCV patients

Hepatitis C virus (HCV) is a major cause of chronic liver disease infecting more than 170 million people worldwide. HCV produces a wide gamut of manifestations varying from mild self-limiting disease to cirrhosis and hepatocellular carcinoma. A variety of viral, environmental and host genetic factors contribute to the clinical spectrum of patients infected with HCV and influence response to interferon (IFN) therapy. Predicting the probable outcome of treatment in patients with HCV infection has always been a challenging task. Treatment of HCV by pegylated interferon (peg-IFN) plus ribavirin eradicates the virus in approximately 60% of patients - HCV genotype 1 (42-51% response rates) and genotypes 2 and 3 (76-84% response rates); however, a significant number of patients do not respond to therapy or relapse following discontinuation of treatment or have significant side effects that preclude further treatment. Accurately predicting the patients who will respond to therapy is becoming increasingly important, both from the point of patient care and also with respect to the healthcare cost as clinicians need to continue treatment in patients who will respond and stop treatment in patients who are unlikely to respond. Viral RNA measurements and genotyping are used to optimize treatment as a low viral load and nongenotype 1 is more likely to be associated with sustained virological response (SVR). Rapid virological response (RVR) defined by undetectable HCV RNA at 4 weeks of treatment is increasingly being recognized as a powerful tool for predicting treatment response. A variety of host factors including single nuclear polymorphisms (SNPs) of IFN response genes, insulin resistance, obesity, ethnicity, human leukocyte antigens and difference in T-cell immune response has been found to modulate the response to antiviral treatment. The presence of severe fibrosis/cirrhosis on pretreatment liver biopsy predicts a poor response to treatment. Recent studies on gene expression profiling and characterization of the liver and serum proteome provide options to accurately predict the outcome of patients infected with HCV in the future. Future studies on the factors that predict treatment response and tailoring treatment based on this is required if we are to conquer this disease.

Hepatitis C virus and ethanol alter antigen presentation in liver cells

Alcoholic patients have a high incidence of hepatitis C virus (HCV) infection. Alcohol consumption enhances the severity of the HCV disease course and worsens the outcome of chronic hepatitis C. The accumulation of virally infected cells in the liver is related to the HCV-induced inability of the immune system to recognize infected cells and to develop the immune responses. This review covers the effects of HCV proteins and ethanol on major histocompatibility complex (MHC) class I- and class II-restricted antigen presentation. Here, we discuss the liver which functions as an immune privilege organ; factors, which affect cleavage and loading of antigenic peptides onto MHC class I and class II in hepatocytes and dendritic cells, and the modulating effects of ethanol and HCV on antigen presentation by liver cells. Altered antigen presentation in the liver limits the ability of the immune system to clear HCV and infected cells and contributes to disease progression. HCV by itself affects dendritic cell function, switching their cytokine profile to the suppressive phenotype of interleukin-10 (IL-10) and transforming growth factor beta (TGFβ) predominance, preventing cell maturation and allostimulation capacity. The synergistic action of ethanol with HCV results in the suppression of MHC class II-restricted antigen presentation. In addition, ethanol metabolism and HCV proteins reduce proteasome function and interferon signaling, thereby suppressing the generation of peptides for MHC class I-restricted antigen presentation. Collectively, ethanol exposure further impairs antigen presentation in HCV-infected liver cells, which may provide a partial explanation for exacerbations and the poor outcome of HCV infection in alcoholics.

Polymorphism in the human major histocompatibility complex and early viral decline during treatment of chronic hepatitis C

The dynamics of the viral decline immediately after the start of therapy for chronic hepatitis C virus (HCV) infection may have prognostic potential for ultimate sustained virologic response. Considerable interindividual variability in the decline has been reported, including differences by race. The human major histocompatability complex (MHC) genes encode the human leukocyte antigens, which are important in the immune response to viral infections. We examined whether carriage of specific human MHC alleles are associated with the rate of the early viral decline. Longitudinal viral level data (baseline and days 1, 2, 7, 14, and 28 of treatment), medium resolution MHC genotyping, and random coefficients models were used to examine associations between MHC class I and class II allele carriage and the dynamics of the viral decline in 180 African-Americans (AAs) and 194 Caucasian Americans (CAs) with genotype-1 HCV infection over the first 28 days of treatment with peginterferon alpha2a plus ribavirin. Baseline viral levels were similar by race, irrespective of allele carriage. However, the rate of change in the viral decline was associated with both allele and race. Among the four subgroups defined by race and specific allele, the fastest rates of decline were observed (in terms of estimated mean viral declines log(10) IU/ml during the first four weeks) in CA noncarriers for A*03 (2.75; P = 0.018), in CA carriers for Cw*03 (2.99; P = 0.046), and in CA noncarriers for DQA1*04 (2.66; P = 0.018) or DQB1*0402 (2.65; P = 0.018). MHC alleles are associated with the viral decline during the first 28 days of peginterferon therapy.