Search

Background Spontaneous clearance of acute hepatitis C virus (HCV) infection is more common in women than in men, independent of known risk factors. Methods To identify sex-specific genetic loci, we studied 4423 HCV-infected individuals (2903 male, 1520 female) of European, African, and Hispanic ancestry. We performed autosomal, and X chromosome sex-stratified and combined association analyses in each ancestry group. Results A male-specific region near the adenosine diphosphate–ribosylation factor–like 5B (ARL5B) gene was identified. Individuals with the C allele of rs76398191 were about 30% more likely to have chronic HCV infection than individuals with the T allele (OR, 0.69; P = 1.98 × 10−07), and this was not seen in females. The ARL5B gene encodes an interferon-stimulated gene that inhibits immune response to double-stranded RNA viruses. We also identified suggestive associations near septin 6 and ribosomal protein L39 genes on the X chromosome. In box sexes, allele G of rs12852885 was associated with a 40% increase in HCV clearance compared with the A allele (OR, 1.4; P = 2.46 × 10−06). Septin 6 facilitates HCV replication via interaction with the HCV NS5b protein, and ribosomal protein L39 acts as an HCV core interactor. Conclusions These novel gene associations support differential mechanisms of HCV clearance between the sexes and provide biological targets for treatment or vaccine development.

A major obstacle hindering the development of effective immunity against viral infections, their associated disease, and certain cancers is their inherent genomic instability. Accumulation of mutations can alter processing and presentation of antigens recognized by antibodies and T cells that can lead to immune escape variants. Use of an agent that can intrinsically combat rapidly mutating viral or cancer-associated antigens would be quite advantageous in developing effective immunity against such disease. We propose that T cells harboring cross-reactive TCRs could serve as a therapeutic agent in these instances. With the use of hepatitis C virus, known for its genomic instability as a model for mutated antigen recognition, we demonstrate cross-reactivity against immunogenic and mutagenic nonstructural protein 3:1406-1415 and nonstructural protein 3:1073-1081 epitopes in PBL-derived, TCR-gene-modified T cells. These single TCR-engineered T cells can CD8-independently recognize naturally occurring and epidemiologically relevant mutant variants. TCR-peptide MHC modeling data allow us to rationalize how TCR structural properties accommodate recognition of certain mutated epitopes and how these substitutions impact the requirement of CD8 affinity enhancement for recognition. A better understanding of such TCRs’ promiscuous behavior may allow for exploitation of these properties to develop novel, adoptive T cell-based therapies for viral infections and cancers exhibiting similar genomic instability.

The lectin galectin-9 may help establish and maintain chronic hepatitis C virus infection. Galectin-9 is elevated in the liver and sera of hepatitis C virus patients, induces apoptosis of hepatitis C virus-specific T cells, and increases inhibitory regulatory T cells. Kupffer cells stain strongly for galectin-9 protein in hepatitis C virus patients. In the current study, we determined stimuli that induce galectin-9 production by monocytes and macrophages in hepatitis C virus infection. With the use of real-time PCR and flow cytometry, we analyzed galectin-9 mRNA and protein from human monocytes cocultured with hepatitis C virus-infected cells or noninfectious hepatitis C virus subgenomic replicon cells. We focused on finding the stimuli for galectin-9 production. Additionally, we measured galectin-9 during monocyte-to-macrophage maturation. Finally, we examined galectin-9 in peripheral monocytes from hepatitis C virus patients using flow cytometry. Galectin-9 mRNA increased 8-fold when primary monocytes were exposed to hepatitis C virus--infected cells. Maximum induction required proximity or contact and did not require IFN-γ or hepatitis C virus virions. Coculture of monocytes with subgenomic replicon cells increased galectin-9 5-fold, and purified exosomes from infected cells stimulated galectin-9 production. Stimulation of monocyte TLR3, -7, and -8 increased galectin-9 production. Differentiation of monocytes to macrophages increased galectin-9, and nonclassic monocytes from hepatitis C virus patients had the highest levels of galectin-9. Hepatitis C virus-infected cells stimulated monocytes to produce galectin-9 in close proximity, possibly, in part, as a result of exosomes and endosomal TLRs. Differentiation of monocytes to macrophages increased galectin-9. Nonclassic monocytes from hepatitis C virus patients express the highest galectin-9 levels, suggesting they may contribute to elevated galectin-9 and adaptive immune inhibition in hepatitis C virus infection.

Human genetic variation is a determinant of recovery from acute hepatitis C virus (HCV) infection; however, to date, single-nucleotide polymorphisms (SNPs) in only a limited number of genes have been studied with respect to HCV clearance. We determined whether SNPs in 112 selected immune response genes are important for HCV clearance, by genotyping 1536 SNPs in a cohort of 343 persons with natural HCV clearance and 547 persons with HCV persistence. PLINK (version 1.05) and Haploview (version 4.1) software packages were used to perform association, permutation, and haplotype analyses stratified by African American and European American race. Of the 1536 SNPs tested, 1426 (92.8%) were successfully genotyped. In African Americans, we identified 18 SNPs located in 11 gene regions that were associated with HCV infection outcome (empirical P value, < .01). In European Americans, there were 20 SNPs located in 8 gene regions associated with HCV infection outcome. Four of the gene regions studied (TNFSF18, TANK, HAVCR1, and IL18BP) contained SNPs for which the empirical P value was

The hepatitis C virus (HCV) core protein is implicated in diverse aspects of HCV-induced pathogenesis. There is a paucity of information on core in acute hepatitis C infection.We analyzed core gene sequences and protein functions from 13 patients acutely infected with HCV genotype 1.Although core isolates differed slightly between patients, core quasispecies were relatively homogeneous within each patient. In 2 of 4 patients studied temporally, core quasispecies did not change over time. Comparison with more than 2700 published core isolates indicated that amino acid changes from a prototype reference strain found in acute core isolates were present in chronically infected persons at low frequency (6.4%; range, 0%-32%). Core isolates associated with lipid droplets to similar degrees in Huh7 cells. Core diffusion in cells was not affected by nonconservative changes F130L and G161S in the lipid targeting domain of core. Core isolates inhibited interferon-stimulated response element- and nuclear factor kappaB-dependent transcription and tumor necrosis factor alpha-induced nuclear translocation of nuclear factor kappaB and were also secreted from Huh7 cells.The data suggest that upon transmission, core quasispecies undergo genetic homogenization associated with amino acid changes that are rarely found in chronic infection and that, despite genetic variation, acute core isolates retain similar functions in vitro.

Background. Infection with hepatitis C virus (HCV) is characterized by impairment of viral effector T cell responses and a high propensity for viral persistence. Previous studies have demonstrated that chronic HCV infection is associated with an increased frequency of regulatory T (T reg ) cells, compared with that in persons whose infection resolved and in healthy persons. However, all patients in prior analyses had exposures in the distant past, precluding the ability to determine whether T reg cells play a causal role in establishing persistence during the earliest stages of infection or whether they are expanded because of viral persistence. Methods. For the first time, we longitudinally analyzed T reg cells in patients with acute HCV infection (n = 27). We used a multiparameter approach, including fluorescence-activated cell sorting analysis of cell-surface and intracellular antigens, coculture experiments with highly purified CD4 + CD25 high regulatory and CD4 + CD25 - responder cell populations, and multiplex analysis of secreted cytokines. Results. Forkhead transcription factor 3 (FoxP3) expression and T reg cell suppression were greater in patients with acute HCV infection than in healthy control subjects but were not different at the first time point among patients who subsequently developed persistence or resolved HCV infection spontaneously; however, 6 months later, the resolution of disease was associated with a relative loss of functional suppression. Conclusions. Collectively, these data indicate that patients with acute HCV infection who develop chronicity versus spontaneous resolution exhibit temporal changes in T reg cell function. It is possible that repetitive viral antigenic stimulation alters the function of T reg cells over time.

Background. Cellular immune responses play a central role in the control of hepatitis C virus (HCV) infection, and in some individuals the adaptive immune response can spontaneously eradicate HCV infection. The development of vaccine candidates to prevent the spread of this infection remains a top priority; however, understanding the correlates of effective immunological containment is an important prerequisite. Methods. Using 750 overlapping peptides, we directly characterized ex vivo total and subgenomic HCV-specific CD4 + and CD8 + T cell responses in a large cohort of participants with either chronic infection or spontaneously resolved infection. Results. In chronic infection, the frequency of total CD4 + T cells specific for HCV averaged 0.06%, compared with 0.38% in resolved infection. Total HCV-specific CD4 + and CD8 + T cell responses were strongly correlated in the setting of spontaneous resolution but not in the setting of viral persistence. NS3 protein‐specific responses comprised a significantly greater proportion of the total response in resolved infection than in chronic infection, whereas responses to different regions comprised a larger proportion of responses in chronic infection. Conclusion. Because these data comprehensively define the breadth, specificity, and threshold of the T cell response associated with spontaneous recovery from HCV infection, they have important implications in the development of multigenic vaccine candidates for this common infection. Hepatitis C virus (HCV) is the major causative agent of chronic hepatitis and has an estimated global prevalence of 3%. In the United States alone, HCV infection

Hepatitis C virus (HCV)-related cirrhosis is the leading indication for liver transplantation. Reinfection of the allograft with HCV is universal in all patients with pretransplantation viremia, and leads to histologically proven hepatitis in 50%-80% of these patients. Recent data have demonstrated significantly higher mortality among HCV-positive liver transplant recipients. For this subgroup of patients, retransplantation remains highly controversial. As current antiviral therapy is limited in efficacy and tolerability, an improved understanding of those patients at greatest risk of developing serious HCV-induced graft injury is necessary to optimize treatment.

We examined the role that immunoglobulin GM and KM allotypes-genetic markers of gamma and kappa chains, respectively-play in the outcome of hepatitis C virus (HCV) infection in white Americans. A total of 119 persons who had cleared HCV and 111 with persistent HCV infection were genotyped for the presence of several GM and KM determinants. Persistent HCV infection was more than three times as likely (odds ratio, 3.50; P= .01) in subjects who were carriers of the GM3 allele than in those who were noncarriers. These results show that particular GM alleles may be important determinants of the outcome of HCV infection.