Does the hepatitis C virus replicate in cells of the hematopoietic lineage?

Chronic Hepatitis C Virus Infection and Depression

Hepatitis C virus (HCV) infection is a systemic disease with hepatic and extrahepatic manifestations, including neuropsychiatric conditions. Depression is a frequent disorder, which has been reported in one-third of patients with HCV infection and has an estimated prevalence of 1.5 to 4.0 times higher than that observed in patients with chronic hepatitis B virus infection or the general population. HCV seems to play a direct and indirect role in the development of depression. Impaired quality of life and increasing health care costs have been reported for patients with HCV infection with depression. Treatment-induced HCV clearance has been associated with improvement of depression and quality of life.

[Fulminant liver failure associated with T-cell non-Hodgkin's lymphoma and hepatitis C virus: a case report]

Hematological malignancies can affect the liver, without producing severe hepatic involvement. We report the case of a 57-year-old man with hepatitis C virus infection and mild chronic hepatitis without antiviral treatment, who developed an aggressive T-cell non-Hodgkin's lymphoma confirmed by histological studies including liver, lymph nodes and bone marrow. The patient developed massive hepatic infiltration and acute liver failure. Rescue chemotherapy was administered but the patient died soon after with severe lactic acidosis. The immunopathological features of this association and the few reports of cases presenting with acute liver failure are reviewed.

Hepatitis C virus population dynamics during infection

Hepatitis C virus (HCV) behaves as an evolving viral quasispecies in its continuously changing environment. The study of HCV quasispecies population dynamics in experimental models and infected patients can provide useful information on factors involved in the HCV life cycle and pathogenicity. HCV quasispecies variability also has therapeutic implications, as the continuous generation and selection of fitter or truly resistant variants can allow the virus to escape control by antiviral drugs.

Transmission in vitro of hepatitis C virus from persistently infected human B-cells to hepatoma cells by cell-to-cell contact

Virus cell-to-cell spread has been reported for many different viruses and may contribute to pathogenesis of viral disease. The role played by cell-to-cell contact in hepatitis C virus (HCV) transmission was studied in vitro by cell co-cultivation experiments. A human lymphoblastoid B-cell line, infected persistently with HCV in vitro (TO.FE(HCV)), was used as HCV donor [Serafino et al., 2003]; recipient cells were the human hepatoma HepG2 cell line. Both cell types were co-cultured for 48 hr to allow the cell-to-cell contacts. The hepatoma HepG2 cells are not permissive to free-virus infection, but they were infected successfully using TO.FE(HCV) cells as source of virus. The kinetics of viral RNA synthesis and the percentage of infected cells were compared in cell-mediated-and cell-free-viral infection. After co-cultivation, a consistent proportion of hepatoma cells replicated HCV and stably expressed viral antigens. Virus produced was infectious as demonstrated by the ability to reinfect fresh B-cells. This cell model shows that permissiveness to HCV infection can be achieved in vitro in non-permissive hepatoma cells by direct cell-to-cell contacts with infected human B-cells. This mechanism of virus spread may also play a pathogenic role in vivo.

Dissociation of serum and liver hepatitis C virus RNA levels in patients coinfected with human immunodeficiency virus and treated with antiretroviral drugs

We examined hepatitis C virus (HCV) RNA levels in serum, peripheral blood mononuclear cells (PBMC), and the liver for 135 patients with chronic HCV infections, 44 of whom were human immunodeficiency virus (HIV) positive and treated with highly active antiretroviral therapy (group A), 66 of whom were HIV negative (group B), with abnormal serum alanine aminotransferase (ALT) values, and 25 of whom were HIV negative, with ALT values of </=1.5 times the normal value (group C). Patients had not been treated with interferon, with or without ribavirin, at the time of the study. A statistically significant correlation between HCV RNA levels in the liver and serum was reproducibly documented, whereas this was inconsistent for serum and PBMC. A comparative evaluation of HCV RNA levels in the liver and PBMC showed significantly lower values for group A than for groups B and C (P < 0.01 and P < 0.0001, respectively). In contrast, HCV RNA levels in serum were significantly higher for group A than for group B (P < 0.001). A dissociation between HCV RNA levels in serum and the liver was found for patients with HIV-HCV coinfections. Although the relative contribution of extrahepatic reservoirs, including lymphoid cells, to HCV RNA levels in serum is unclear, it may be speculated that a low intrahepatic HCV burden is caused by restored immunocompetence after successful antiretroviral therapy in coinfected patients.

Identification of unique hepatitis C virus quasispecies in the central nervous system and comparative analysis of internal translational efficiency of brain, liver, and serum variants

Reports of cerebral dysfunction in chronic hepatitis C virus (HCV) infection have led to the suggestion that HCV may infect the central nervous system (CNS). We used reverse transcription-PCR, cloning, and sequencing to define quasispecies for the HCV internal ribosomal entry site (IRES) and hypervariable region 1 (HVR1) in autopsy-derived brain, liver, lymph node, and serum samples. There was evidence of tissue compartmentalization of sequences in the brain in two patients, with between 24 and 55% of brain-derived IRES sequences absent from the serum, and significant phylogenetic and phenetic clustering of the brain and lymph node HVR1 sequences. The IRES initiates cap-independent translation of the viral polyprotein. Two unique brain-derived IRES mutations (C(204)-->A and G(243)-->A), which have previously been associated with lymphoid replication and altered translational efficiency in cell culture, were found in one patient. We used a dicistronic reporter vector to test whether brain-derived variants showed altered IRES-mediated translational efficiency, which might favor CNS infection. The translational efficiencies of the brain-derived IRES sequences were generally reduced compared to those of the master serum and liver sequences in rabbit reticulocyte cell lysates and two human cell lines, HuH7 (liver) and CHME3 (microglial). The C(204)-->A and G(243)-->A mutations showed preserved translational efficiency in HuH7 cells but reduced efficiency in CHME3 cells. Our data provide evidence that the CNS is a site of HCV replication, consistent with the recent demonstration of negative-strand HCV RNA in brain, and suggest that IRES polymorphisms may be important as a viral strategy of reduced translation to favor latency in the CNS.

Hepatitis C virus genetic variability: pathogenic and clinical implications

HCV is variable because of the properties of the viral RdRp, high levels of replication, and large population sizes. The Darwinian evolution of HCV has been characterized by the emergence of the HCV genotypes, including six main types and a large number of subtypes. The study of HCV genotype epidemiology provides useful information on the worldwide HCV epidemics. The HCV genotype is an important predictor of the response to IFN-alpha-based antiviral therapy, and genotype determination is currently used to tailor treatment indications. In addition, HCV circulates and behaves in infected individuals as mixtures of closely related but distinct viral populations referred to as quasispecies. This particular nature of the virus influences its transmission, the pathogenesis of liver disease and extra-hepatic manifestations, and the outcome during and after antiviral therapy or after transplantation for HCV-related end-stage liver disease. Further studies are needed to understand better the implications of HCV quasispecies diversity in the pathophysiology of HCV infection.

Lack of in vivo blockade of Fas- and TNFR1-mediated hepatocyte apoptosis by the hepatitis C virus

In vitro data have shown that the hepatitis C virus (HCV) core protein binds to protein members of the tumour necrosis factor receptor (TNFR) superfamily. Since this interaction could be relevant to HCV persistence and oncogenesis, this study assessed whether HCV may interfere with the apoptotic cascade in vivo. Apoptosis (by TUNEL) and Fas and TNFR1 expression (by immunohistochemistry) were scored in the liver of 60 chronic hepatitis C patients. Results were compared with the liver disease grading and staging scores and the HCV replication level in serum and liver. Apoptotic hepatocytes were stained in 29 cases. Fas was expressed in 35 cases and TNFR1 in 21, 15 patients (25%) being negative for both receptors. Overall, the numbers of TUNEL-, Fas- and TNFR-positive hepatocytes did not correlate with the extent of intrahepatic CD8+ T-lymphocyte infiltration, the grading and staging of liver disease, or the serum or liver HCV RNA levels. Furthermore, when patients expressing either Fas or TNFR1 were stratified according to serum HCV RNA levels, cases with detectable hepatocyte apoptosis had higher HCV viraemias. In conclusion, an HCV-mediated, in vivo blockade of hepatocyte apoptosis via the Fas- or TNFR1-dependent pathways seems unlikely.

Detection of the negative-strand hepatitis C virus RNA in tissues: implications for pathogenesis

The replication of hepatitis C virus (HCV) RNA is believed to occur via its transcription into a complementary, genomic-length RNA, the so-called negative-strand HCV RNA. This is based on the comparison with the replication of other members of the Flaviviridae family. Detection of the negative-strand HCV RNA in human tissues by semi-quantitative, strand-specific RT-PCR has contributed to the understanding of the HCV cell tropism and of the pathogenesis of HCV-associated disease manifestations. In particular, it was shown that the levels of intrahepatic HCV RNA are not correlated to the extent of the necroinflammation, but that a significant correlation was found with the liver steatosis. These results suggest that most liver disease associated with HCV infection is mediated by the host immune response. However, in some patients, most notably those infected with HCV genotype 3, HCV may cause a cytopathic effect, consisting in the lipid accumulation within hepatocytes.

Primary hepatic diffuse large B-cell lymphoma in a patient with chronic hepatitis C

Epidemiological and experimental data suggest that the hepatitis C virus infection might be associated with the development of distinct types of non-Hodgkin's lymphomas. Here, we report a case of a patient with chronic hepatitis C and type II mixed cryoglobulinemia, who developed a primary hepatic non-Hodgkin's B-cell lymphoma. A diffuse, large B-cell lymphoma was diagnosed based on morphological, immunophenotypical and molecular genetic findings. Hepatitis C virus replication, as evaluated by strand-specific reverse transcriptase-polymerase chain reaction, was detected in the nonneoplastic liver, but not in the lymphomatous tissue. High grade non-Hodgkin's lymphomas, although rare complications, have to be considered as part of the spectrum of hepatitis C virus-related hepatic lesions.

Antiapoptotic and oncogenic potentials of hepatitis C virus are linked to interferon resistance by viral repression of the PKR protein kinase

Hepatitis C virus (HCV) is prevalent worldwide and has become a major cause of liver dysfunction and hepatocellular carcinoma. The high prevalence of HCV reflects the persistent nature of infection and the large frequency of cases that resist the current interferon (IFN)-based anti-HCV therapeutic regimens. HCV resistance to IFN has been attributed, in part, to the function of the viral nonstructural 5A (NS5A) protein. NS5A from IFN-resistant strains of HCV can repress the PKR protein kinase, a mediator of the IFN-induced antiviral and apoptotic responses of the host cell and a tumor suppressor. Here we examined the relationship between HCV persistence and resistance to IFN therapy. When expressed in mammalian cells, NS5A from IFN-resistant HCV conferred IFN resistance to vesicular stomatitis virus (VSV), which normally is sensitive to the antiviral actions of IFN. NS5A blocked viral double-stranded RNA (dsRNA)-induced PKR activation and phosphorylation of eIF-2alpha in IFN-treated cells, resulting in high levels of VSV mRNA translation. Mutations within the PKR-binding domain of NS5A restored PKR function and the IFN-induced block to viral mRNA translation. The effects due to NS5A inhibition of PKR were not limited to the rescue of viral mRNA translation but also included a block in PKR-dependent host signaling pathways. Cells expressing NS5A exhibited defective PKR signaling and were refractory to apoptosis induced by exogenous dsRNA. Resistance to apoptosis was attributed to an NS5A-mediated block in eIF-2alpha phosphorylation. Moreover, cells expressing NS5A exhibited a transformed phenotype and formed solid tumors in vivo. Disruption of apoptosis and tumorogenesis required the PKR-binding function of NS5A, demonstrating that these properties may be linked to the IFN-resistant phenotype of HCV.

Detection of genomic- and minus-strand of hepatitis C virus RNA in the liver of chronic hepatitis C patients by strand-specific semiquantitative reverse-transcriptase polymerase chain reaction

Studies aimed at correlating the intrahepatic hepatitis C virus (HCV)-RNA level and anatomo-clinical features have been difficult because of sensitivity and specificity shortcomings of available techniques. We titered the genomic- and minus-strand HCV RNAs by a strand-specific, semiquantitative, genotype-independent reverse-transcriptase polymerase chain reaction (RT-PCR) in the liver tissue of 61 patients with chronic hepatitis C. Findings were correlated with the levels of HCV RNA in the serum, the HCV genotype, the expression of intrahepatic HCV antigens, the histological activity (using separate scores for the lobular and the portal/periportal necroinflammatory activity and for the fibrosis), and the response to interferon alfa (IFN-alpha) treatment. Genomic- and minus-strand HCV RNA were detected in 59 and 57 liver specimens, respectively. The HCV-RNA level in the serum correlated with the genomic-strand, but not with the minus-strand, HCV-RNA titer in the liver. No correlations were found between either strand of the intrahepatic HCV RNA and the level of expression of HCV antigens in the liver, or with the grading/staging of the underlying liver disease. The response to IFN-alpha treatment could be predicted by the serum HCV-RNA level and genotype, but not by the intrahepatic level of genomic- or minus-strand HCV RNA. These results suggest that, although the detection of the minus-strand HCV RNA reliably identifies the presence of replicating HCV in its target organ, the quantitative measurement of viremia remains the clinically meaningful "golden standard" for assessing the level of HCV replication.