Host genetic determinants in hepatitis C virus infection

Enhanced TLR3 responsiveness in hepatitis C virus resistant women from the Irish anti-D cohort

Natural resistance to infection is an overlooked outcome after hepatitis C virus (HCV) exposure. Between 1977 and 1979, 1,200 Rhesus D-negative Irish women were exposed to HCV-contaminated anti-D immunoglobulin. Here, we investigate why some individuals appear to resist infection despite exposure (exposed seronegative [ESN]). We screen HCV-resistant and -susceptible donors for anti-HCV adaptive immune responses using ELISpots and VirScan to profile antibodies against all know human viruses. We perform standardized ex vivo whole blood stimulation (TruCulture) assays with antiviral ligands and assess antiviral responses using NanoString transcriptomics and Luminex proteomics. We describe an enhanced TLR3-type I interferon response in ESNs compared with seropositive women. We also identify increased inflammatory cytokine production in response to polyIC in ESNs compared with seropositive women. These enhanced responses may have contributed to innate immune protection against HCV infection in our cohort.

Impact of Toll-like Receptors 2(TLR2) and TLR 4 Gene Variations on HCV Susceptibility, Response to Treatment and Development of Hepatocellular Carcinoma in Cirrhotic HCV Patients

Background and Aims: Genetic polymorphisms of Toll-like receptors (TLRs) have been proposed to affect susceptibility to HCV infection and progression to end-stage liver disease. This study was conducted to clarify the association of SNPS of TLR2 and TLR4 with clinical outcome of hepatitis C, response to treatment and development of HCC.Methods: The current study examined 3295 individuals from 725 families that were categorized into groups comprising chronic HCV (CH), spontaneous viral clearance (SC) and control subjects. Treated patients were classified into responders (RT) and non-responders (NRT). In addition, patients with liver cirrhotic (LC), and hepatocellular carcinoma (HCC) were also included. All subjects were genotyped for five single nucleotide polymorphisms (SNPs) of TLR2 and four SNPs of TLR4 and their haplotypes using allelic discrimination real-time PCR.Results: Results demonstrated strong association with allele A of rs13105517 of TLR2 and allele C of rs10116253 of TLR4 with CH in comparison to SC group. However, The peak of risk of HCC was observed with allele C of rs3804099 of TLR2 and C allele of rs10116253 TLR4 (p < 0.001).A strong association was found with allele T of rs1816702 of TLR2 and allele A of rs5030728 of TLR4 in non responder group in comparison to responders (p < 0.001). Haplotypes CAGT of TLR4 and ATAC of TLR2 showed significant association with CH and HCC groups in comparison to other groups.Conclusions: This study shows an association of minor alleles of TLR2 and TLR4 with outcome of HCV infection, response to therapy and development of HCC in cirrhotic patients.

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.

Association of PD-1 gene with outcome of hepatitis C virus infection

Primary hepatitis C virus infection might be spontaneously cleared or become chronic. Polymorphisms in immune regulatory genes might influence the outcome. The aim of this study was to determine the frequency of genotypes and alleles of PD-1.3 and PD-1.5 gene loci in HCV infected patients and their association with the disease outcome. In this study 167 patients with chronic hepatic C and 42 individuals whose infection was spontaneously cleared, and a healthy control group comprising of 300 participants were included. The presence of chronic or spontaneously cleared infection amongst the participants was determined in advance by serologic and molecular methods. Genomic DNA was extracted using salting out method. PD-1 gene polymorphisms assay was performed using PCR-RFLP method. The frequency of alleles of PD-1.3 gene locus was significantly higher in the spontaneously cleared HCV infected group (P = 0.03) as well as the healthy control group (P = 0.04) in comparison to the chronic infected participants. In the case of PD-1.5 locus, there was no association between the frequency of inherited genotype or alleles and HCV infection outcome amongst the three groups. Haplotype analysis showed no statistically significant differences in the frequencies of different haplotypes between the three studied groups. Our finding collectively inferred that individuals with A allele at PD-1.3 locus might clear HCV infection more frequently than those with T allele. Instead, polymorphisms at PD-1.5 locus as well as haplotypes emerged from PD-1.3 G/A and PD-1.5 C/T might not be significant in the HCV infection outcome.

Association of killer cell immunoglobulin-like receptors with spontaneous clearance of hepatitis C virus in the Chinese population

BACKGROUND

Natural killer (NK) cells are critical components in innate immune response to viral infection. Killer cell immunoglobulin-like receptors (KIRs) are involved in regulating the balance of activation or inhibitory function of NK cells. However, the association of KIRs with the spontaneous clearance of hepatitis C virus (HCV) remains unclear in the Chinese population.

STUDY DESIGN AND METHODS

A total of 407 HCV-seropositive voluntary blood donors were recruited, including 203 with spontaneous viral clearance and 204 with chronic infection. The presence of KIR genes was detected individually by polymerase chain reaction with sequence-specific primers. Data of HLA and interleukin-28B (IL28B) genotypes were extracted from our previous study.

RESULTS

Our results showed that KIR2DL2, 2DS2, 2DL2/2DL3, and 2DL5A-/2DL5B+ were more frequent in subjects with HCV clearance than those with chronic infection (odds ratio [OR], 1.640, p = 0.034; OR, 1.664, p = 0.032; OR, 1.636, p = 0.040; and OR, 2.601, p = 0.012, respectively). Multivariate logistic regression analysis showed that KIR2DL5A-/2DL5B+ associated with HCV clearance (OR, 2.448, p = 0.027), independent of sex, IL28B, and other KIRs. In contrast, KIR2DL3/2DL3 (OR, 0.610, p = 0.034) as well as 2DL3/2DL3+HLA-C1 or C1C1 (OR, 0.580, p = 0.017; and OR, 0.639, p = 0.025, respectively) was found associated with chronic HCV infection. The presence of the homozygous KIR2DL3 with or without its HLA ligand increased the OR of developing chronic HCV infection in the context of IL28B.

CONCLUSIONS

In this study we identified KIR2DL5A-/2DL5B+ associated with HCV spontaneous clearance, while KIR2DL3/2DL3, 2DL3/2DL3+HLA-C1, or C1C1 associated with chronic infection. Our study highlighted the fact that the roles of KIR and KIR-HLA contributed to the control of HCV infection by innate immune responses.

The proportion of different interleukin-17-producing T-cell subsets is associated with liver fibrosis in chronic hepatitis C

Studies have suggested the pivotal role of T helper type 1 (Th1) -related cytokines on the outcome of hepatitis C virus (HCV) infection. Nevertheless, the role of different interleukin-17 (IL-17) -secreting T cells on chronic hepatitis C (CHC) is less clear. Here, the in vivo IL-1β, IL-6, and IL-17 levels were positively correlated with both alanine transaminase (ALT) levels and hepatic lesions. When compared with the control group, CHC patients showed a lower proportion of IL-17-secreting (CD4⁺ and CD8⁺ ) T cells capable of simultaneously producing IL-21. Moreover, the percentage of IL-10-secreting Th17 cells was also lower in CHC patients. Notably, advanced liver lesions were observed among those patients with lower percentage levels of IL-17-producing T cells positive for IL-21, interferon-γ (IFN-γ) and IL-10. In contrast, the severity of hepatic damage was associated with peripheral single IL-17⁺ T cells. The percentage of IL-17⁺ IL-21^- IFN-γ⁺ (CD4⁺ and CD8⁺ ) T-cell phenotypes was positively associated with plasma CD14 levels. Finally, elevated levels of circulating CD14 were detected among CHC patients with extensive liver damage. In summary, although preliminary, our results suggest that a balance between different IL-17-producing T cells, associated with peripheral levels of CD14, may be a progress marker for liver disease in chronically HCV-infected patients.

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.

The Associations of HLA-A*02:01 and DRB1*11:01 with Hepatitis C Virus Spontaneous Clearance Are Independent of IL28B in the Chinese Population

Spontaneous clearance of hepatitis C virus (HCV) occurs in 10-40% of the infections. Specific human leukocyte antigen (HLA) alleles have been identified in associating with HCV clearance. However, data on the association of HLA with the spontaneous clearance of HCV are scarce in the Chinese population. In the current study we studied the HLA class I and class II genes in 231 Chinese voluntary blood donors who had cleared HCV infection spontaneously compared to 429 subjects with chronic HCV infections. We also studied their IL28B SNP (rs8099917) genotype, since a number of investigators have found a strong association of IL28B with spontaneous or treatment induced HCV clearance. We found that HLA-A*02:01 and DQB1*05:02 distributed differently between the two groups after Bonferroni correction (odds ratio [OR] = 1.839, Pc = 0.024 and OR = 0.547, Pc = 0.016, respectively). Multivariate logistic regression analysis suggested that A*02:01 and DRB1*11:01 (OR = 1.798, P = 0.008 and OR = 1.921, P = 0.005, respectively) were associated with HCV spontaneous clearance, independent of age, gender and IL28B polymorphism. We concluded that in the Chinese population, HLA-A*02:01 and DRB1*11:01 might be associated with the host capacity to clear HCV independent of IL28B, which suggesting that the innate and adaptive immune responses both play an important role in the control of HCV.

A novel polymorphism near HLA class II region is associated with spontaneous clearance of HCV and response to interferon treatment in Chinese patients

A recent genome-wide association study (GWAS) has identified the single-nucleotide polymorphism (SNP) rs4273729 in a 100-kbp region comprising human leukocyte antigens (HLAs) class II genes as an important predictor of hepatitis C virus (HCV) clearance in European and African populations. This study was to determine whether this polymorphism is also associated with spontaneous HCV clearance as well as response to interferon treatment in Chinese patients. Thus, 686 chronic HCV carriers, 432 individuals with spontaneous viral clearance and 243 patients with pegylated interferon-α and ribavirin (PEG IFN-α/RBV) treatment were genotyped. The rs4273729 GG genotype was strongly associated with spontaneous HCV clearance as well as better IFN/RBV treatment response compared with the GC/CC genotypes in Chinese Han population (additive model: odds ratio (OR)=0.62, 95% confidence interval (95% CI)=0.51-0.76; OR=0.58, 95% CI=0.38-0.88, respectively). Rs4273729, rs12980275, baseline HCV RNA and platelet level were independent predictors for sustained virological response (SVR). The area under the receiver-operating characteristic curve (AUC) was 0.578 when including rs4273729 alone, but the prediction value was improved significantly (AUC=0.733) when further including rs12980275, baseline viral load and baseline platelet level. In conclusion, the genetic variation of rs4273729 is associated with clearance of HCV in both the natural course and the treatment process in Chinese Han population.

An update on hepatitis C virus

Chronic hepatitis caused by hepatitis C virus infection is one of the leading causes of liver cirrhosis and hepatocellular carcinoma globally. Over the last few years, there have been significant advances in our understanding of the immunopathogenesis of this infection, as well as revolutionary developments in the therapeutic armamentarium. The introduction of a number of new oral antiviral agents is already delivering major benefits to patients as they are generally well tolerated and are associated with excellent response rates in the majority. Nonetheless, a number of clinical scenarios remain challenging and research is ongoing in these areas. In this update, we review developments in both basic as well as translational research in the field.

Polymorphisms in EGFR and IL28B are associated with spontaneous clearance in an HCV-infected Iranian population

Although most hepatitis C virus (HCV)-infected individuals develop chronic infection, about 25% of them are able to clear the virus spontaneously without any therapeutic intervention. The aim of the present study was to identify genes associated with spontaneous HCV clearance in a population of Iranian patients. We genotyped 110 single-nucleotide polymorphisms (SNPs) in 59 selected--candidate--genes in a cohort of 107 HCV-infected participants who spontaneously cleared the infection and 176 participants whose infection persisted. Three out of the 110 SNPs were found to be associated with HCV outcome (P-values<0.03). rs11506105 in EGFR (epidermal growth factor receptor gene), and rs11881222 and rs12979860 in IL28B (interferon-λ3 gene). Multivariate logistic regression of the three markers showed that the A/A genotypes in both rs11506105 (EFGR) and rs11881222 (IL28B), and the C/C genotype in rs12979860 (IL28B) are associated with HCV clearance (recessive model: odds ratio (OR)=2.06, 95% confidence interval (95% CI)=1.09-3.88, P=0.025; OR=2.09, 95% CI=1.23-3.60, P=0.007; and OR=1.95, 95% CI=1.15-3.35, P=0.014 for rs11506105, rs12979860 and rs11881222, respectively). In conclusion, EGFR and IL28B SNPs are strong independent predictive markers of spontaneous viral clearance.

HLA class II alleles in Romanian patients with chronic hepatitis C

INTRODUCTION

The objective of the study was to determine the association of host human leukocyte antigen (HLA) class II genotype DRB1 alleles with the response to interferon therapy, viral loads and extent of liver fibrosis in a group of Romanian patients diagnosed with chronic hepatitis C, with different clinical outcomes. Class II HLA genes, particularly the HLA-DRB1 and DQB1 genes, have been shown to have an important role in self-limiting or persistent viral infection, in different genetic populations. In chronic hepatitis C both susceptible and protective alleles have been described, influencing the development of autoimmunity and progression to cirrhosis and hepatocellular carcinoma.

METHODS

The study included 54 patients diagnosed with chronic hepatitis C, registered and monitored from January 2014 to January 2015 at the Clinical Hospital of Infectious Diseases, Constanţa, Romania. The selected patients were positive for anti-HCV antibodies and HCV-RNA, with screening laboratory results indicating HCV genotype 1b. The method used for the assignment of alleles at HLA-DRB1 and DQB1 loci was molecular genotyping, by the sequence specific oligonucleotide (SSO) hybridization method, and when required, by the sequence specific primers method (SSP). The presence of different alleles in patients has been analyzed for statistical significance.

RESULTS

The presence of HLA-DRB1*0301 had a high frequency (14.8%) in null-responders (NR) while alleles DRB1*0701 (11.1%), DRB1*11# (22.2%) and DRB1*0101 (16.7%) were prevalent in sustained virologic responders (SVR). No significant correlation was found between the presence of HLA-DRB1* alleles and viral loads or liver fibrosis with p values not statistically significant after the Bonferroni correction.

CONCLUSION

The presented data suggest that in this group of Romanian patients, certain HLA alleles influence the therapeutic response in HCV infection and genetic predisposition may play a role in hepatitis C virus infection in those patients.

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.

IL28B gene polymorphisms in mono- and HIV-coinfected chronic hepatitis C patients

Introduction: Single-nucleotide polymorphisms (SNPs) associated with hepatitis C virus (HCV) clearance were identified near the IL28B gene. Coinfection by the human immunodeficiency virus (HIV) influences the course of HCV contributing to liver damage. Nevertheless, little is known about the relationship between these SNPs and HCV/HIV coinfection. Our aim was to estimate the frequencies of the allelic and genotypic variants of the IL28B polymorphisms rs12979860 (C/T) and rs8099917 (T/G) and their possible association with the establishment of HCV infection.

Methodology: A total of 199 non-infected controls and 230 patients with chronic hepatitis C, including 53 coinfected with HIV, participated in the study. Genotyping consisted of polymerase chain reaction and subsequent analysis of the restriction patterns resulting from exposure to endonucleases.

Results: Among the controls with established results, 47.4% (90/190) exhibited the rs12979860 CC genotype, 43.7 CT, and 8.9% TT, whereas 29.1% (66/227), 51.5%, and 19.4% of the patients exhibited the CC, CT, and TT genotypes, respectively. With respect to rs8099917, 66.8% (133/199) of the controls exhibited the TT genotype, 31.2% TG, and 2.0% GG, whereas 56.1% (129/230), 40.9%, and 3.0% of the patients exhibited the TT, TG, and GG genotypes, respectively.

Conclusion: The frequencies of the rs12979860 C allele and CC genotype and of the rs8099917 T allele and TT genotype were significantly higher among controls compared with patients, thus confirming the suggested protective effect against HCV infection. No significant difference was observed in the genotype and allelic distributions between the mono- and coinfected patients.

HLA-B alleles B*15:01 and B*15:02: opposite association with hepatitis C virus infection in Chinese voluntary blood donors

BACKGROUND

Although human leukocyte antigens (HLA) have been shown in association with the outcomes of hepatitis C virus (HCV) infection among different ethnic groups, such studies remain absent in China, where the HCV prevalence is higher than the global average.

METHODS

In this study, 426 HCV-infected and 709 uninfected blood donors were analyzed, among whom the HLA alleles were sequenced using a high-resolution genotyping method.

RESULTS

At the 2-digit level, none of the alleles showed a statistical difference between the HCV-infected and uninfected groups. However, at the 4-digit level, the HLA-B alleles B*15:01 and B*15:02 showed an opposite association with HCV infection, i.e. B*15:01 was significantly higher in the HCV-infected group (odds ratio, OR = 1.561, p = 0.010), while B*15:02 was significantly higher in the uninfected group (OR = 0.778, p = 0.016). We also identified a higher frequency of B*13:02 in the HCV-infected group (OR = 1.515, p = 0.009) and a higher frequency of B*07:05 in the uninfected group (OR = 0.299, p = 0.001).

CONCLUSIONS

The frequencies of four HLA alleles, B*07:05, B*13:02, B*15:01, and B*15:02, were found to be significantly different between the HCV-infected and uninfected blood donors in China, revealing an inverse relation of B*15:01 and B*15:02 with HCV infection. This finding suggests that the ethnic genetic variations of HLA may greatly affect the host immune responses against HCV.

Hepatitis C virus infection in the human immunodeficiency virus infected patient

Human immunodeficiency virus (HIV) and hepatitis C virus (HCV) share the same transmission routes; therefore, coinfection is frequent. An estimated 5-10 million individuals alone in the western world are infected with both viruses. The majority of people acquire HCV by injection drug use and, to a lesser extent, through blood transfusion and blood products. Recently, there has been an increase in HCV infections among men who have sex with men. In the context of effective antiretroviral treatment, liver-related deaths are now more common than Acquired Immune Deficiency Syndrome-related deaths among HIV-HCV coinfected individuals. Morbidity and mortality rates from chronic HCV infection will increase because the infection incidence peaked in the mid-1980s and because liver disease progresses slowly and is clinically silent to cirrhosis and end-stage-liver disease over a 15-20 year time period for 15%-20% of chronically infected individuals. HCV treatment has rapidly changed with the development of new direct-acting antiviral agents; therefore, cure rates have greatly improved because the new treatment regimens target different parts of the HCV life cycle. In this review, we focus on the epidemiology, diagnosis and the natural course of HCV as well as current and future strategies for HCV therapy in the context of HIV-HCV coinfection in the western world.

Genetic variants in human leukocyte antigen-DP influence both hepatitis C virus persistence and hepatitis C virus F protein generation in the Chinese Han population

Chronic hepatitis C is a serious liver disease that often results in cirrhosis or hepatocellular carcinoma. The aim of this study was to assess the association of human leukocyte antigen-DP (HLA-DP) variants with risk of chronic hepatitis C virus (HCV) or anti-F antibody generation. We selected two single nucleotide polymorphisms (SNPs) in a region including HLA-DPA1 (rs3077) and HLA-DPB1 (rs9277534) and genotyped SNPs in 702 cases and 342 healthy controls from the Chinese population using TaqMan SNP genotyping assay. Moreover, the exon 2 of the HLA-DPA1 and HLA-DPB1 genes were amplified and determined by sequencing-based typing (SBT). The results showed that rs3077 significantly increased the risk of chronic HCV infection in additive models and dominant models (odds ratio (OR) = 1.32 and 1.53). The rs3077 also contributed to decrease the risk of anti-F antibody generation in additive models and dominant models (OR = 0.46 and 0.56). Subsequent analyses revealed the risk haplotypes (DPA1*0103-DPB1*0501 and DPA1*0103-DPB1*0201) and protective haplotypes (DPA1*0202-DPB1*0501 and DPA1*0202-DPB1*0202) to chronic HCV infection. Moreover, we also found that the haplotype of DPA1*0103-DPB1*0201 and DPA1*0202-DPB1*0202 were associated with the anti-F antibody generation. Our findings show that genetic variants in HLA-DP gene are associated with chronic HCV infection and anti-F antibody generation.

Interleukin-28b CC genotype predicts early treatment response and CT/TT genotypes predicts non-response in patients infected with HCV genotype 3

Response to antiviral therapy for hepatitis C virus (HCV) depends upon the genotype and host immune response. IL28b gene mutations have been shown to modulate host antiviral immune response against genotype 1. However, the predictive value of IL28b polymorphism in genotype 3 HCV patients is largely unknown. The association of IL28b polymorphism with virological response was studied in 356 patients with genotype 3 chronic HCV undergoing treatment with peg-interferon and ribavirin and was compared with matched controls. IL28b genotyping followed by DNA sequencing was performed to identify the CC, CT, or TT genotypes. Two log reduction of HCV RNA at Day 7 (Quick Viral Response, QVR) and HCV RNA negativity at Day 28 (Rapid Viral Response, RVR) were analyzed with CC and non-CC genotypes in addition to other predictors of response. The associations of alleles with the response patterns were predicted. Sustained viral response was seen in 250 (70.2%) patients and the IL28b genotype CC/CT/TT distribution was 61.1%; 30.5%; and 8.4%, respectively. The non-CC genotypes were significantly higher in non-responders when compared to responders (67.6% vs. 38.9%, P < 0.001). Interestingly, the rapid viral response in responders was observed in 72.7% with the CC genotype and in 27.2% with the non-CC genotype (P < 0.001). Multivariate analysis showed CC genotype as an independent factor predicting the sustained viral response in patients infected with HCV genotype 3. In conclusion, the IL28b CT/TT genotype strongly correlates with treatment non-response in patients infected with HCV genotype 3 and CC genotype of IL28b is associated with higher quick viral response.

Current progress in development of hepatitis C virus vaccines

Despite major advances in the understanding and treatment of hepatitis C, a preventive vaccine remains elusive. The marked genetic diversity and multiple mechanisms of persistence of hepatitis C virus, combined with the relatively poor immune response of the infected host against the virus, are major barriers. The lack of robust and convenient model systems further hampers the effort to develop an effective vaccine. Advances in our understanding of virus-host interactions and protective immunity in hepatitis C virus infection provide an important roadmap to develop potent and broadly directed vaccine candidates targeting both humoral and cellular immune responses. Multiple approaches to generating and testing viral immunogens have met with variable success. Several candidates have advanced to clinical trials based on promising results in chimpanzees. The ultimate path to a successful preventive vaccine requires comprehensive evaluations of all aspects of protective immunity, innovative application of state-of-the-art vaccine technology and properly designed vaccine trials that can affirm definitive endpoints of efficacy.

Impact of interleukin 28B polymorphisms on spontaneous clearance of hepatitis C virus infection: a meta-analysis

BACKGROUND AND AIM

Recent studies suggested that interleukin 28B (IL28B) polymorphisms may affect spontaneous clearance (SC) of hepatitis C virus (HCV) infection. Our purpose was to update the meta-analysis to reevaluate the impact of IL28B rs12979860 and rs8099917 polymorphisms on SC in patients infected with HCV.

METHODS

We searched PubMed, Web of Science, and Embase up to February 2013. Odds ratios (ORs) and 95% confidence intervals (CI) were calculated by fixed- or random-effects models. Heterogeneity, sensitivity analysis, and publication bias were also assessed.

RESULTS

Seventeen eligible papers were involved in this study. The SC rate was higher in patients with the rs12979860 CC (vs CT/TT OR = 2.98, 95% CI 2.53-3.50) and rs8099917 TT (vs GT/GG OR = 2.80, 95% CI 2.23-3.51) in the IL28B polymorphisms. Ethnicity stratification revealed that rs12979860 CC was associated with SC for Caucasians (vs CT/TT OR = 3.05, 95% CI 2.67-3.49), Asians (vs CT/TT OR = 1.88, 95% CI 1.33-2.66), and Africans (vs CT/TT OR = 3.15, 95% CI 2.39-4.15); rs8099917 TT was associated with SC for Caucasians (vs GT/GG OR = 2.48, 95% CI 1.96-3.15).

CONCLUSIONS

IL28B rs12979860 and rs8099917 single nucleotide polymorphisms are significantly associated with SC of HCV infection. The predictive value of rs12979860 CC was stronger in Caucasians and Africans than in Asians.

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.

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.

Glances in Immunology of HIV and HCV Infection

Since the identification of HIV and HCV much progress has been made in the understanding of their life cycle and interaction with the host immune system. Despite these viruses markedly differ in their virological properties and in their pathogenesis, they share many common features in their immune escape and survival strategy. Both viruses have developed sophisticated ways to subvert and antagonize host innate and adaptive immune responses. In the last years, much effort has been done in the study of the AIDS pathogenesis and in the development of efficient treatment strategies, and a fatal infection has been transformed in a potentially chronic pathology. Much of this knowledge is now being transferred in the HCV research field, especially in the development of new drugs, although a big difference still remains between the outcome of the two infections, being HCV eradicable after treatment, whereas HIV eradication remains at present unachievable due to the establishment of reservoirs. In this review, we present current knowledge on innate and adaptive immune recognition and activation during HIV and HCV mono-infections and evasion strategies. We also discuss the genetic associations between components of the immune system, the course of infection, and the outcome of the therapies.

Human platelet antigen genotype is associated with progression of fibrosis in chronic hepatitis C

Although progression of fibrosis in the chronic hepatitis C depends on environmental, viral, and host factors, genetic polymorphisms have been associated recently with this progression, including the expression of integrins, adhesion proteins. Some integrins expressed on the platelet membrane show polymorphic antigenic determinants called human platelet antigens (HPA), where the major ones are HPA-1, -3, -5. The association between HCV infection and HPA-5b has been demonstrated. Similarly, the HPA profile could determine if HPA is related to progression of fibrosis. The goal of this study was to evaluate the association between the frequencies of HPA-1, -3, and -5 and degree of fibrosis in HCV-infected patients. Genomic DNA from 143 HCV-infected patients was used as the source for HPA genotyping by PCR-SSP or PCR-RFLP. Progression of fibrosis was evaluated using the METAVIR scoring system, and the patients were grouped according to degree of fibrosis into G1 (n = 81, with F1, portal fibrosis without septa or F2, few septa) and G2 (n = 62, with F3, numerous septa, or F4, cirrhosis). Statistical analysis was performed using the proportional odds model. The genotypic frequency of HPA-1a/1b was significantly higher in the patients in G2. To evaluate the influence of the time of infection to the development of fibrosis and its effect on the genetic factor HPA-1, 96 patients from 143 studied were evaluated considering the time of HCV infection, and these results suggest that the HPA-1a/1b genotype promotes the development of fibrosis in HCV infection with time.

GB virus C: the good boy virus?

GB virus C (GBV-C) is a lymphotropic human virus discovered in 1995 that is related to hepatitis C virus (HCV). GBV-C infection has not been convincingly associated with any disease; however, several studies found an association between persistent GBV-C infection and improved survival in HIV-positive individuals. GBV-C infection modestly alters T cell homeostasis in vivo through various mechanisms, including modulation of chemokine and cytokine release and receptor expression, and by diminution of T cell activation, proliferation and apoptosis, all of which may contribute to improved HIV clinical outcomes. In vitro studies confirm these clinical observations and demonstrate an anti-HIV replication effect of GBV-C. This review summarizes existing data on potential mechanisms by which GBV-C interferes with HIV, and the research needed to capitalize on this epidemiological observation.

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.

HLA class II alleles and chronic hepatitis C virus infection

The aim of this study was to investigate association of human leucocyte antigens (HLA)-DRB1 and DQB1 polymorphisms with hepatitis C virus (HCV) infection and with the occurrence of severe liver fibrosis/cirrhosis in chronically infected patients. Ninety-nine white patients, from southeast Brazil, with confirmed HCV chronic infection were included in the study. Severe fibrosis/cirrhosis (METAVIR scores F3-F4) was present in 49 patients. HLA-DRB1 specificities and DRB1*11 and DQB1* alleles were determined by PCR-SSP, and their frequencies were compared between patients and a control group of 103 healthy white Brazilian individuals. The results confirmed previous reports of the association of DRB1*11 and DQB1*03 with protection from chronic HCV infection, but did not confirm their association with protection from severe fibrosis/cirrhosis. Furthermore, the results suggested that the polymorphic sites on HLA molecules responsible for protection from chronic HCV infection are encoded not only by the DRB1*1101 and DQB1*0301, as suggested in the literature, but also by other DRB1*11 and DQB1*03 alleles. Thus, we hypothesized that the common polymorphic residues shared by different DRB1*11 and/or DQB1*03 alleles might be responsible for selection of viral epitopes for presentation to CD4(+) T cells, leading to an efficient immune response against the virus.

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.

The relation of HLA genotype to hepatitis C viral load and markers of liver fibrosis in HIV-infected and HIV-uninfected women

BACKGROUND

Human leukocyte antigen (HLA) class I and II genotype is associated with clearance of hepatitis C virus (HCV) infection, but little is known regarding its relation with HCV viral load or risk of liver disease in patients with persistent HCV infection.

METHODS

High-resolution HLA class I and II genotyping was conducted in a prospective cohort of 519 human immunodeficiency virus (HIV)-seropositive and 100 HIV-seronegative women with persistent HCV infection. The end points were baseline HCV viral load and 2 noninvasive indexes of liver disease, fibrosis-4 (FIB-4), and the aspartate aminotransferase to platelet ratio index (APRI), measured at baseline and prospectively.

RESULTS

DQB1*0301 was associated with low baseline HCV load (β = -.4; 95% confidence interval [CI], -.6 to -.3; P < .00001), as well as with low odds of FIB-4-defined (odds ratio [OR], .5; 95% CI, .2-.9; P = .02) and APRI-defined liver fibrosis (OR, .5; 95% CI, .3-1.0; P = .06) at baseline and/or during follow-up. Most additional associations with HCV viral load also involved HLA class II alleles. Additional associations with FIB-4 and APRI primarily involved class I alleles, for example, the relation of B*1503 with APRI-defined fibrosis had an OR of 2.0 (95% CI, 1.0-3.7; P = .04).

CONCLUSIONS

HLA genotype may influence HCV viral load and risk of liver disease, including DQB1*0301, which was associated with HCV clearance in prior studies.

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.

Intrafamilial viral transmission is not the main cause of the high prevalence of hepatic C virus infection in a village, Putian county, China

BACKGROUND

The prevalence of anti-HCV in the population of a village, which is located in China's Putian County, was 28.9%.

OBJECTIVE

To investigate whether intrafamilial transmission is the main cause of the high prevalence of HCV infection in the village.

STUDY DESIGN

This study surveyed the prevalence of anti-HCV antibody and HCV RNA and analyzed the risk factors for infection. Twenty-seven families consisting of 2 or more cases who were HCV RNA-positive were selected. Genotyping of HCV isolates was performed using a restriction fragment length polymorphism (RFLP) analysis of 5'-NCR. The identity of the nucleotide sequence, the Kimura distance, and the phylogenetic trees between HCV 1b isolates from the same family were compared with that from different families using BioEdit and MEGA4.0 software.

RESULTS

Of 303 anti-HCV-positive subjects, 113 subjects were HCV RNA-positive. The frequency of some risk factors was significantly different between HCV RNA-positive and anti-HCV-negative subjects. Twenty-two pairs had subjects who were both infected with genotype 1b strains. The sequence identities between the 2 isolates from the family pairs ranged from 78.9% to 98.5% for HVR1 and from 92.4% to 97.6% for NS5B, which were not higher than the pairs from different families. The Kimura distances for family pairs ranged from 0.014 to 0.357 for HVR1 and from 0.024 to 0.081 for NS5B. They were not shorter than that from non-family pairs. Only 2 family pairs clustered in the same branch in the dendrogram obtained with NS5B sequences.

CONCLUSIONS

Intrafamilial HCV transmission is not the main cause of the high prevalence of HCV infection in the village.

Prospects for personalizing antiviral therapy for hepatitis C virus with pharmacogenetics

Chronic hepatitis C virus (HCV) infection is a major cause of liver disease worldwide. HCV infection is currently treated with IFNα plus ribavirin for 24 to 48 weeks. This demanding therapy fails in up to 50% of patients, so the use of pharmacogenetic biomarkers to predict the outcome of treatment would reduce futile treatment of non-responders and help identify patients in whom therapy would be justified. Both IFNα and ribavirin primarily act by modulating the immune system of the patient, and HCV uses multiple mechanisms to counteract the antiviral effects stimulated by therapy. Therefore, response to therapy is influenced by variations in human genes governing the immune system and by differences in HCV genes that blunt antiviral immune responses. This article summarizes recent advances in understanding how host and viral genetic variation affect outcome of therapy. The most notable human associations are polymorphisms within the IL28B gene, but variations in human leukocyte antigen and cytokine genes have also been associated with treatment outcome. The most prominent viral genetic association with outcome of therapy is that HCV genotype 1 is much less sensitive to treatment than genotypes 2 and 3, but genetic differences below the genotype level also influence outcome of therapy, presumably by modulating the ability of viral genes to blunt antiviral immune responses. Pharmacogenetic prediction of the outcome of IFN-based therapy for HCV will require integrating the efficacies of the immunosuppressive mechanisms of a viral isolate, and then interpreting the viral resistance potential in context of the genetic profile of the patient at loci associated with outcome of therapy. Direct-acting inhibitors of HCV that will be used in combination with IFNα are nearing approval, so genetic prediction for anti-HCV therapy will soon need to incorporate viral genetic markers of viral resistance to the new drugs.

IL28B CC-genotype association with HLA-DQB1*0301 allele increases the prediction of spontaneous HCV RNA clearance in thalassaemic HCV-infected patients

BACKGROUND

A single nucleotide polymorphism (SNP), upstream of the IL28B gene has been recently associated with natural clearance of HCV. In a well-characterized cohort of patients with thalassaemia major exposed to the risk of acquiring HCV infection by blood transfusions, we aimed to replicate this finding and to evaluate whether combining the IL28B genotype and HLA class II alleles allow viral clearance to be accurately predicted.

METHODS

Of 168 patients, 130 with complete clinical history were included in the analysis. According with their HCV antibodies status 13 were defined HCV resistant, and 117 infected. Infected patients were subdivided, giving 49 with self-limiting and 68 with ongoing infection.

RESULTS

IL28B CC-genotype was observed in 32 patients with self-limiting and in 23 with ongoing infection (64% versus 34%; P=0.004). HLA DQB1*0301 allele was associated with viral clearance in 36 cases (73%; P<0.0001). Both DQB1*0301 and IL28B CC-genotype were found to be independent predictors of HCV clearance (OR=5.64, 95% CI 1.52-20.9 and OR=5.76, 95% CI 2.16-15.33, respectively). With the addition of DQB1*0301, the accuracy of the prediction increased from 63% to 69%.

CONCLUSIONS

In addition to IL28B CC-genotype, HLA DQB1*0301 helps in predicting natural clearance of HCV after acute infection.

Host genetic basis for hepatitis C virus clearance: a role for blood collection centers

PURPOSE OF REVIEW

Host genetic factors influencing hepatitis C virus (HCV) transmission outcomes are incompletely defined. However, vast differences observed in rates of spontaneous clearance between individuals infected with the same parental HCV strain strongly indicate a role for genetic determinants in the host immune response to HCV. This review discusses genetic association studies, particularly those published in the last year, that show gene linkages with spontaneous and treatment-induced HCV clearance. The valuable role that blood collection centers can play in increasing the sample size of HCV-confirmed seropositive donors with resolved versus persistent infections for large-scale genetic association studies is highlighted.

RECENT FINDINGS

Recent groundbreaking genome-wide association study and targeted single-nucleotide polymorphism (SNP) analysis from independent groups have demonstrated immune response gene polymorphisms, and particularly in the interleukin (IL)-28B gene, that are strongly linked to HCV clearance. The IL-28B gene encodes interferon lambda 3, an innate immune response cytokine. SNPs in the promoter region of IL-28B were first shown to be associated with HCV treatment-induced viral clearance and subsequently to be a key determinant of spontaneous HCV resolution in infected individuals. Samples from blood donors with resolved and chronic HCV infections have contributed to these findings.

SUMMARY

These genetic studies have provided the strongest evidence so far of a host genetic determinant linked to HCV clearance. Such large-scale genetic association studies will promote better understanding of HCV disease pathogenesis and assist in effective prognosis of HCV in the future. Continued and preferably expanded participation of blood centers in this research is encouraged.

Prospective follow-up of patients with acute hepatitis C virus infection in Brazil

BACKGROUND

The natural outcome of infection with hepatitis C virus (HCV) varies substantially among individuals. However, little is known about host and viral factors associated with a self-limiting or chronic evolution of HCV infection.

METHODS

From 1 January 2001 through 31 December 2008, a consecutive series of 65 patients from Rio de Janeiro, Brazil, with a well-documented diagnosis of acute HCV infection, acquired via various routes, were enrolled in this study. Patients were prospectively followed up for a median of 40 months after the estimated date of HCV infection with serial measurements of serum alanine aminotransferase, HCV RNA, and anti-HCV antibodies. Spontaneous viral clearance (SVC) was defined as undetectable levels of HCV RNA in serum, in the absence of treatment, for 3 consecutive HCV polymerase chain reaction tests within the first 6 months of follow-up. Cox proportional hazards regression was used to identify host and viral predictors of SVC.

RESULTS

The cumulative rate of SVC was 44.6% (95% confidence interval, 32.3%-57.5%). Compared with chronic HCV evolution, patients with self-limiting disease had significantly lower peak levels of anti-HCV antibodies (median, 109.0 vs 86.7 optical density-to-cutoff ratio [od/co]; P<.02), experienced disease symptoms more frequently (69.4% vs 100%; P<.001), and had lower viral load at first clinical presentation (median, 4.3 vs 0.0 log copies; P=.01). In multivariate analyses, low peak anti-HCV level (<93.5 od/co) was the only independent predictor for SVC; the hazard ratio compared with high anti-HCV levels (> or =93.5 od/co) was 2.62 (95% confidence interval, 1.11-6.19; P=.03).

CONCLUSION

Our data suggest that low levels of anti-HCV antibodies during the acute phase of HCV infection are independently related to spontaneous viral clearance.

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.

Genetic variation in IL28B is associated with chronic hepatitis C and treatment failure: a genome-wide association study

BACKGROUND & AIMS

Hepatitis C virus (HCV) induces chronic infection in 50% to 80% of infected persons; approximately 50% of these do not respond to therapy. We performed a genome-wide association study to screen for host genetic determinants of HCV persistence and response to therapy.

METHODS

The analysis included 1362 individuals: 1015 with chronic hepatitis C and 347 who spontaneously cleared the virus (448 were coinfected with human immunodeficiency virus [HIV]). Responses to pegylated interferon alfa and ribavirin were assessed in 465 individuals. Associations between more than 500,000 single nucleotide polymorphisms (SNPs) and outcomes were assessed by multivariate logistic regression.

RESULTS

Chronic hepatitis C was associated with SNPs in the IL28B locus, which encodes the antiviral cytokine interferon lambda. The rs8099917 minor allele was associated with progression to chronic HCV infection (odds ratio [OR], 2.31; 95% confidence interval [CI], 1.74-3.06; P = 6.07 x 10(-9)). The association was observed in HCV mono-infected (OR, 2.49; 95% CI, 1.64-3.79; P = 1.96 x 10(-5)) and HCV/HIV coinfected individuals (OR, 2.16; 95% CI, 1.47-3.18; P = 8.24 x 10(-5)). rs8099917 was also associated with failure to respond to therapy (OR, 5.19; 95% CI, 2.90-9.30; P = 3.11 x 10(-8)), with the strongest effects in patients with HCV genotype 1 or 4. This risk allele was identified in 24% of individuals with spontaneous HCV clearance, 32% of chronically infected patients who responded to therapy, and 58% who did not respond (P = 3.2 x 10(-10)). Resequencing of IL28B identified distinct haplotypes that were associated with the clinical phenotype.

CONCLUSIONS

The association of the IL28B locus with natural and treatment-associated control of HCV indicates the importance of innate immunity and interferon lambda in the pathogenesis of HCV infection.

Characterization of the cellular immune response in hepatitis C virus infection

Hepatitis C virus (HCV), a hepatotropic RNA virus, is a major causative agent of chronic hepatitis, liver cirrhosis, and hepatocellular carcinomas. The host immune responses, especially cellular immune responses, play an important role in viral clearance, liver injury, and persistent HCV infection. A thorough characterization of the HCV cellular immune responses is important for understanding the interplays between host immune system and viral components, as well as for developing effective therapeutic and prophylactic HCV vaccines. Recent advances that provide better understanding the cell immune responses in HCV infection are summarized in this article.

Influence of selected HLA tissue compatibility antigens on the course and efficacy of viral hepatitis C treatment--actual knowledge position

Hepatitis C virus (HCV) infection is a common problem. Combined treatment with interferon and ribavirin improved treatment efficacy, but still high percentage of infected patients has not reached virus elimination. It was found that HCV infection course, but also treatment efficacy among other things can depend on patient's individual factors, including MHC genes structure for HLA tissue compatibility antigens. Many connections between HLA system and HCV infection course were noted. There are some reports concerning connections between MHC structure and results of chronic hepatitis C treatment with interferon. In future, results of investigations connected with this problem can allow to verify qualification criteria for treatment with alpha-interferon, because actual knowledge position has been too inconspicuous to have practical significance.

Variants in interferon-alpha pathway genes and response to pegylated interferon-Alpha2a plus ribavirin for treatment of chronic hepatitis C virus infection in the hepatitis C antiviral long-term treatment against cirrhosis trial

Combination treatment with pegylated-interferon-alpha (PEG IFN-alpha) and ribavirin, the current recommended therapy for chronic hepatitis C virus (HCV) infection, results in a sustained virological response (SVR) in only about half of patients. Because genes involved in the interferon-alpha pathway may affect antiviral responses, we analyzed the relationship between variants in these genes and SVR among participants in the Hepatitis C Antiviral Long-Term treatment Against Cirrhosis (HALT-C) trial. Patients had advanced chronic hepatitis C that had previously failed to respond to interferon-based treatment. Participants were treated with peginterferon-alpha2a and ribavirin during the trial. Subjects with undetectable HCV RNA at week 72 were considered to have had an SVR. Subjects with detectable HCV RNA at week 20 were considered nonresponders. We used TaqMan assays to genotype 56 polymorphisms found in 13 genes in the interferon-alpha pathway. This analysis compares genotypes for participants with an SVR to nonresponders. The primary analysis was restricted to European American participants because a priori statistical power was low among the small number (n = 131) of African American patients. We used logistic regression to control the effect of other variables that are associated with treatment response. Among 581 European American patients, SVR was associated with IFNAR1 IVS1-22G (adjusted odds ratio, 0.57; P = 0.02); IFNAR2 Ex2-33C (adjusted odds ratio, 2.09; P = 0.02); JAK1 IVS22+112T (adjusted odds ratio, 1.66; P = 0.04); and ADAR Ex9+14A (adjusted odds ratio, 1.67; P = 0.03). For the TYK2-2256A promoter region variant, a borderline association was present among European American participants (OR, 1.51; P = 0.05) and a strong relationship among African American patients; all 10 with SVR who were genotyped for TYK2 -2256 carried the A variant compared with 68 of 120 (57%) nonresponders (P = 0.006).

CONCLUSION

Genetic polymorphisms in the interferon-alpha pathway may affect responses to antiviral therapy of chronic hepatitis C.

Human leukocyte antigen polymorphisms in Italian primary biliary cirrhosis: a multicenter study of 664 patients and 1992 healthy controls

Genetic factors are critical in determining susceptibility to primary biliary cirrhosis (PBC), but there has not been a clear association with human leukocyte antigen (HLA) genes. We performed a multicenter case-control study and analyzed HLA class II DRB1 associations using a large cohort of 664 well-defined cases of PBC and 1992 controls of Italian ancestry. Importantly, healthy controls were rigorously matched not only by age and sex, but also for the geographical origin of the proband four grandparents (Northern, Central, and Southern Italy). After correction for multiple testing, DRB1*08 [odds ratio (OR), 3.3; 95% confidence interval (CI), 2.4-4.5] and DRB1*02 (OR 0.9; 95% CI 0.8-1.2) were significantly associated with PBC, whereas alleles DRB1*11 (OR 0.4; 95% CI 0.3-0.4) and DRB1*13 (OR 0.7; 95% CI 0.6-0.9) were protective. When subjects were stratified according to their grandparental geographical origin, only the associations with DRB1*08 and DRB1*11 were common to all three areas. Associated DRB1 alleles were found only in a minority of patients, whereas an additive genetic model is supported by the gene dosage effect for DRB1*11 allele and the interaction of DRB1*11,*13, and *08. Lastly, no significant associations were detected between specific DRB1 alleles and relevant clinical features represented by the presence of cirrhosis or serum autoantibodies. In conclusion, we confirm the role for HLA to determine PBC susceptibility and suggest that the effect of HLA is limited to patient subgroups. We suggest that a large whole-genome approach is required to identify further genetic elements contributing to the loss of tolerance in this disease.

Adaptive immune responses to hepatitis C virus: from viral immunobiology to a vaccine

Hepatitis C virus (HCV) causes chronic infection in approximately two-thirds of cases, leading to chronic hepatitis, liver cirrhosis, liver disease, liver failure, and hepatocellular carcinoma in a substantial proportion of the 170 million HCV-infected individuals worldwide. It is generally accepted that the cellular immune response plays the most important role in determining the outcome of HCV infection. First, vigorous, multispecific and sustained CD4+ and CD8+ T-cell responses are associated with viral clearance. Second, depletion studies in chimpanzees, the only other host of HCV besides humans, have shown that both CD4+ and CD8+ T-cells are required for virus elimination. Third, the host's human leukocyte antigen alleles, which restrict the repertoire of CD4+ and CD8+ T-cell responses, influence the outcome of infection. Of note, protective immunity has been demonstrated in population-based studies, as well as in experimentally infected chimpanzees. Thus, a detailed understanding of the mechanisms contributing to the failure of the antiviral immune response should allow successful development of prophylactic and therapeutic vaccination strategies.