Hepatitis C Virus Late Relapse after Sustained Virologic Response from Interferon and Ribavirin Treatment as Confirmed by RNA Sequencing

Hepatitis C virus (HCV) viremia is unusual (<5%) after successful treatment, defined as sustained virologic response (SVR) or undetectable HCV PCR 12 to 24 weeks after therapy. We present a case of late virologic relapse (de novo infection was excluded by RNA sequencing) after SVR followed by spontaneous viral clearance.     

Induction of Natural Killer Cells and Interferon during Mouse Hepatitis Virus Infection of Resistant and Susceptible Inbred Mouse Strains

Following infection by mouse hepatitis virus (JHM strain), an induction of natural killer (NK) cell activity was observed in C3H mice, which are considered to be sensitive to JHM virus infection. In contrast, mice of the resistant SJL strain did not show any increase of NK cell activity after JHM virus infection. However, infection of both SJL and C3H mice with mouse hepatitis virus type 3 (MHV3) resulted in an increase of NK level, comparable to that observed with the JHM virus infection in the C3H strain. No significant differences were observed in the NK cell activity of the peritoneal exudate or spleen cells of infected mice. Low levels of interferon were detected in serum or peritoneal exudate of C3H mice infected with JHM virus 18 or 24 hours before, but no detectable early interferon production was found. Also no interferon could be detected in the resistant SJL mice. After JHM virus infection, the number of peritoneal exudate cells (PEC) was increased significantly in C3H mice but not in SJL mice. Macrophages obtained from the C3H mice supported virus replication, whereas SJL macrophages did not. Our data suggest that NK cells do not play a role in the resistance of SJL mice against JHM virus infection but may participate in the defence mechanisms against this virus in C3H mice.     

Seronegative Hepatitis C Virus Infection

Hepatitis C virus (HCV) is a major cause of liver disease worldwide. The routine diagnostics identifying HCV infection include testing for specific anti-HCV antibodies by enzyme-linked immnunosorbent assay and viral genetic material in serum or plasma. However, a small proportion of patients persistently infected with HCV, in whom anti-HCV are undetectable, constitute a serious diagnostic and possibly epidemiologic problem, as they could facilitate pathogen spread in the population. This type of infection is termed seronegative or serosilent. Seronegative HCV infection is currently of great interest to both scientists and physicians. The review presents epidemiological data concerning the prevalence of seronegative HCV infection in HIV/HCV co-infected individuals, hemodialysis patients, and blood and organ donors. The possible mechanisms behind this atypical course of infection are discussed. Furthermore, the differences between seronegative and occult infections and prolonged seroconversion are explained.     

乙型和丙型肝炎病毒感染的免疫学研究进展

世界范围内持续感染乙型肝炎病者（HBV）、丙型肝炎病毒（HCV）的患者已超过5亿。这两种病毒在病原学上有许多共同特点，但在病毒学特点上以及在慢性肝炎的免疫逃逸机制上均有着显著的差别。在早期天然免疫应答方面，HBV感染最初几周并不引起肝脏基因表达的改变，而HCV则会引起许多肝内基因表达改变。在特异性免疫应答方面，HBV和HCV感染后机体清除病毒的途径主要有特异性CTL细胞的杀伤作用、CD4^＋细胞的辅助作用、抗体的中和作用或杀伤作用。相对于HBV来说，HCV在成人更多引起慢性肝炎。     

Hepatitis C Virus Infection Induced Vasculitis

Cryoglobulinemia are immune complexes that may induce systemic cryoglobulinemic vasculitis, a small-vessel vasculitis involving the skin, the joints, the peripheral nerve system, and the kidneys. During the last 15 years, progresses have been done after the discovery of the hepatitis C virus, the main cause of cryoglobulins. Main factors associated with cryoglobulin production are female gender, alcohol intake above 50 g/day, extensive liver fibrosis, and steatosis. Symptomatic cryoglobulins (i.e., vasculitis) are associated with older age, longer duration of infection, and main characteristics of cryoglobulin (type II, IgM kappa, high serum levels). The physiopathology is complex, and it involves humoral immunity, B- and T-cellular immunity but not the virus itself. Peg-Interféron alpha Ribavirine combination leads to a virological and clinical response of the vasculitis in about 70% of patients. In nonresponders, recent open series suggested the efficacy of Rituximab* with a good response in up to 80% of patients but a relapse in 42% after 7 months after the last infusion. For future prospects and projects, new therapeutic strategies include a combination of best antiviral treatment with Peg-Interferon plus Ribavirin and Rituximab. Multicenter controlled trials are mandatory.     

Immunoglobulin mimicry by Hepatitis C Virus envelope protein E2

Hepatitis C virus (HCV) establishes persistent infection in the majority of infected individuals. The currently accepted hypothesis of immune evasion by antigenic variation in hypervariable region 1 (HVR1) of glycoprotein E2 does not however, explain the lack of subsequent immune recognition. Here, we show that the N-terminal region of E2 is antigenically and structurally similar to human immunoglobulin (Ig) variable domains. E2 is recognized by anti-human IgG antibodies and also possesses common amino acid (aa) sequence features of the conserved v-gene framework regions of human Ig light chains in particular but also heavy chains and T cell receptors. Using a position specific scoring system, the degree of similarity of HVR1 to Ig types correlated with immune escape and persistence in humans and experimentally infected chimpanzees. We propose a unique role for threshold levels of Ig molecular mimicry in HCV biology that not only advances our concept of viral immune escape and persistent infection but also provides insight into host-dependent disease patterns.     

Induction of Cross-reactive Humoral Immune Response by Immunization with Mimotopes of the Hypervariable Region 1 of the Hepatitis C Virus

Hepatitis C Virus (HCV) is a major cause of chronic hepatitis, liver cirrhosis and hepatocellular carcinoma, worldwide, and the development of an effective vaccine represents a high priority goal. The Hyper Variable Region 1 (HVRI) of the second Envelope protein (E2) of HCV contains a principal neutralizing determinant, but it is highly variable among different isolates and it is involved in the escape from host immune response. Thus, to be effective, a vaccine should elicit a cross-reacting humoral response against the majority of viral variants. We show that it is possible to achieve a broadly cross-reactive immune response in rabbits by immunization with mimotopes of the HVRI, selected from a specialized phage library using HCV patients' sera. At least some of the cross-reacting anti-mimotope antibodies, elicited in rabbits, recognize discontinuous epitopes in a manner similar to those induced by the virus in infected patients.     

Induction of Interferon in Mice by Mycoplasmas

Interferon was induced in mice after intraperitoneal inoculation with four different mycoplasmas. Peak levels of between 100 and 300 U of interferon per ml were attained by 6 h postinfection with each of the mycoplasmas except Mycoplasma arthritidis, which induced higher titers (400 to 11,800 U/ml) by this time. A fifth mycoplasma, M. pulmonis, induced interferon inconsistently and at a later (72 to 96 h) time. Mycoplasmatales virus MVL51 and sterile mycoplasmal broth did not stimulate interferon production in vivo. All of the mycoplasmas and MVL51 failed to induce interferon in murine spleen cell, peritoneal exudate cell, or peripheral blood leukocyte cultures. Preinfecting the mycoplasmas with MVL51 or treating the organisms with trypsin or dilutions of specific antisera did not enhance their ability to induce interferon in vitro.     

Changes in Hepatitis C Virus Genotype Distribution in Chronic Hepatitis C Infection Patients

Purpose: Identification of hepatitis C virus (HCV) genotypes is very important in the selection of antiviral treatment, dose adjustment of antiviral agents, determining the treatment duration and following-up of treatment response. We aimed to determine the distribution pattern of HCV genotypes in chronic hepatitis C infection (CHC) patients. Materials and Methods: We have included 106 CHC patients who were positive in the anti-HCV and HCV-RNA tests performed in our hospital during the 16-month period. Anti-HCV assays were performed on device using a chemiluminescent microparticle immunoassay, while HCV-RNA tests and HCV genotyping assays were performed by real-time polymerase chain reaction. Results: Of the 106 cases; genotype 1b was detected in 67.0%, genotype 3 was detected in 16.0%, genotype 1a was detected in 14.2% and genotype 2 was detected in 2.8% patients. Genotypes 4, 5 and 6 were not detected in our study group. There were no statistically significant differences between the gender and age groups according to the HCV genotype distribution. The genotype 3 detection rate (16%) was the highest rate among the studies compared with the other studies in our country. Conclusions: Events that cause social changes such as war and immigration and intense commercial and touristic activities affect and alter the HCV genotype distribution in HCV-infected patients. For this reason, further multicentre studies are required reflecting all the regions in order to determine the genotype distribution in HCV-infected patients at regular intervals.     

Cyclosporin A Inhibits Induction but Not Production of Gamma Interferon Induced by Epstein–Barr Virus

Cyclosporin A (CsA) interferes with various T-cell functions in vitro and is a potent inhibitor of T-cell-dependent reactions in vivo, such as graft rejection and control of virus infections. Since human gamma interferon (Hu IFN-gamma) is synthesized by T cells and has a controlling role in regulation of Epstein-Barr virus (EBV) infection, we have studied the effects of CsA on EBV-induced cellular Hu IFN-gamma release. CsA inhibited dose-dependently the EBV-induced Hu IFN-gamma response, studied at the cellular level in human blood lymphocytes. These effects were not due to toxicity of CsA, since at inhibitory levels cellular EBV infection measured as polyclonal IgM production proceeded unaffected. CsA did not affect the number of spontaneous Hu IFN-gamma-secreting cells, nor did it have any inhibitory effect if added after virus exposure. It is concluded that CsA inhibits induction but not production of cellular Hu IFN-gamma.     

Evidence That Hepatitis C Virus Resistance to Interferon Is Mediated through Repression of the PKR Protein Kinase by the Nonstructural 5A Protein

Hepatitis C virus (HCV) is the major cause of non-A non-B hepatitis and a leading cause of liver dysfunction worldwide. While the current therapy for chronic HCV infection is parenteral administration of type 1 interferon (IFN), only a fraction of HCV-infected individuals completely respond to treatment. Previous studies have correlated the IFN sensitivity of strain HCV-1b with mutations within a discrete region of the viral nonstructural 5A protein (NS5A), termed the interferon sensitivity determining region (ISDR), suggesting that NS5A may contribute to the IFN-resistant phenotype of HCV. To determine the importance of HCV NS5A and the NS5A ISDR in mediating HCV IFN resistance, we tested whether the NS5A protein could regulate the IFN-induced protein kinase, PKR, a mediator of IFN-induced antiviral resistance and a target of viral and cellular inhibitors. Using multiple approaches, including biochemical, transfection, and yeast genetics analyses, we can now report that NS5A represses PKR through a direct interaction with the protein kinase catalytic domain and that both PKR repression and interaction requires the ISDR. Thus, inactivation of PKR may be one mechanism by which HCV avoids the antiviral effects of IFN. Finally, the inhibition of the PKR protein kinase by NS5A is the first described function for this HCV protein.     

Immune Mechanisms and the Action of Interferon in Chronic Hepatitis B Virus Infection

Cytotoxic T lymphocytes can eliminate cells infected with hepatitis B virus. A defect of T lymphocyte-mediated cytolysis seems to exist in chronic hepatitis B infection. T cell-mediated lysis is dependent on HLA antigens of the infected host and this may explain the increased or decreased frequency of particular HLA antigens in chronic carriers of hepatitis B virus. This virus may decrease the concentration of HLA antigens expressed on liver cells. Interferon increases the HLA antigen expression on T lymphocytes and hepatocytes, thereby enhancing T lymphocyte-mediated lysis of infected liver cells and elimination of the hepatitis B virus.     

TRAIL诱导乙型肝炎病毒转染细胞株凋亡的实验研究

目的 探讨人肿瘤坏死因子相关凋亡诱导配体（TNF-related apoptosis inducing ligand，TRAIL）对HBV稳定转染的肝癌细胞株HepG2．2．15的凋亡诱导效果。方法应用MTT法了解TRAIL对HepG2．2．15细胞的诱导效果，琼脂糖凝胶电泳、流式细胞术和Caspase．3酶活性分析TRAIL诱导HepG2．2．15细胞凋亡过程。结果TRAIL（0．1μg／mL）作用于HepG2．2．15细胞株12、24、36h后，细胞抑制率分别为17．91％、41．26％、59．85％；PI单染亚二倍体含量12h后为21．8％，高于对照组的8．7％；24h后DNA电泳200bp处出现特异性条带；6h后Caspase-3酶活性为对照组的4．76倍。结论TRAIL诱导后，HBV稳定转染的肝癌细胞株HepG2．2．15发生凋亡     

应用非同位素原位杂交检测肝组织中丙型肝炎病毒基因的分布

为了研究丙型肝炎患者肝组织中丙型肝炎病毒（ＨＣＶ）基因的分布，我们应用地高辛标记的ＨＣＶ基因５＇端非翻译区的探针（长度为３２个寡核苷酸），对２４例急、慢性丙型肝炎患者活检的肝组织石蜡包埋切片进行了原位核酸杂交检测。结果显示：ＨＣＶ基因阳性的肝组织标本有１１例，检出率是４５．８％（１１／２４）。ＨＣＶ基因主要分布于肝细胞浆，偶见于肝细胞核内。此外在肝血窦的ｋｕｐｆｆｅｒ细胞、小血管内皮细胞和汇管区附近均有明显的ＨＣＶ基因阳性染色，而对照组均未发现ＨＣＶ基因阳性信号。     

Diversity of Hepatitis C Virus Quasispecies Evaluated by Denaturing Gradient Gel Electrophoresis

Denaturing gradient gel electrophoresis (DGGE) was used to study the diversity of hepatitis C virus (HCV) quasispecies. Optimized DGGE running conditions were applied to screen for variations in sequences cloned from amplicons originating from the nonstructural 5b (NS5b) gene of HCV in blood of hemophilia patients, intravenous drug users, and blood donors (five specimens from each study group, ca. 40 clones studied per specimen). Clones identified by DGGE as unique were sequenced. NS5b sequence entropy and mean genetic distance in hemophiliacs did not differ significantly from those in the other groups, pointing to a lack of correlation between HCV diversity and the multiplicity of past HCV exposures. DGGE was also applied to investigate variation in the HCV envelope 2/hypervariable region 1 (E2/HVR-1) in serum samples serially taken from two patients during the seroconversion phase of HCV infection. E2/HVR-1 sequence entropy changes were small and not correlated with rising anti-HCV antibody levels, reflecting mutational changes not mediated by antibody selection.     

丙型肝炎病毒抗原检测试剂在临床诊断中的初步应用

本文利用重组丙型肝炎病毒(HCV)多表位复合抗原免疫动物制备抗HCV多克隆抗体,建立HCAgELISA检测方法,对不同的临床样品进行检测,分析不同临床样品HCAg检出率,并与荧光定量PCR结果进行对比。95份HCAb阳性的样品中,51份样品HCAg阳性,阳性率为53.7%;88份重症肝病患者血清中检出HCAg阳性33份,阳性率为37.5%,均明显高于其它样品(P<0.05);73份肝功异常但HCAb阴性血清样品,检出HCAg阳性8份,阳性率为11.0%;HCAg与HCAb之间存在相关性(r=0.5076,P<0.01),HCAg与HCV-RNA符合率为85.7%。HCAg ELISA检测可作为临床HCV诊断的检测指标,为临床早期诊断及治疗预后提供依据。