Detection of genomic and intermediate replicative strands of hepatitis C virus in liver tissue by in situ hybridization

Simultaneous detection of hepatitis C virus and interferon stimulated gene expression in infected human liver

Approximately 50% of patients with chronic hepatitis C (CHC) have ongoing expression of interferon stimulated genes (ISGs) in the liver. It is unclear why this endogenous antiviral response is inefficient in eradicating the infection. Several viral escape strategies have been identified in vitro, including inhibition of interferon (IFN) induction and ISG messenger RNA (mRNA) translation. The in vivo relevance of these mechanisms is unknown, because reliable methods to identify hepatitis C virus (HCV)-infected cells in human liver are lacking. We developed a highly sensitive in situ hybridization (ISH) system capable of HCV RNA and ISG mRNA detection in human liver biopsies and applied it to study the interaction of HCV with the endogenous IFN system. We simultaneously monitored HCV RNA and ISG mRNA using HCV isolate- and ISG mRNA-specific probes in liver biopsy sections from 18 CHC patients. The signals were quantified at the single-cell resolution in a series of random high-power fields. The proportion of infected hepatocytes ranged from 1%-54% and correlated with viral load, but not with HCV genotype or ISG expression. Infected cells occurred in clusters, pointing to cell-to-cell spread as the predominant mode of HCV transmission. ISG mRNAs were readily detected in HCV-infected cells, challenging previously proposed mechanisms of viral interference with the immune system. Conversely, infected cells and neighboring cells showed increased ISG mRNA levels, demonstrating that the stimulus driving ISG expression originates from HCV-infected hepatocytes.

CONCLUSION

HCV infection in human hepatocytes during CHC does not efficiently interfere with IFN induction, IFN signaling, or transcription of ISG mRNA.

HCV enters the twenty-first century

Almost one-third of Americans infected with human immunodeficiency virus (HIV) and 7 million worldwide are coinfected with hepatitis C virus (HCV). The principal route of HCV spread in the US is injection drug use but there are recent reports of outbreaks of acute HCV infection among HIV-infected men who have sex with men. With increased survival as a result of highly active antiretroviral therapy, HCV-associated liver disease has become a leading cause of death in HIV-infected individuals. Currently, telaprevir and boceprevir, both NS3/NS4A inhibitors that significantly improve sustained response when added to pegylated interferon and ribavirin, are approved only for HCV monoinfection. The optimal combination of agents, therapy durations and the timing of treatment remain major challenges in coinfected patients.

Human cell types important for hepatitis C virus replication in vivo and in vitro: old assertions and current evidence

Hepatitis C Virus (HCV) is a single stranded RNA virus which produces negative strand RNA as a replicative intermediate. We analyzed 75 RT-PCR studies that tested for negative strand HCV RNA in liver and other human tissues. 85% of the studies that investigated extrahepatic replication of HCV found one or more samples positive for replicative RNA. Studies using in situ hybridization, immunofluorescence, immunohistochemistry, and quasispecies analysis also demonstrated the presence of replicating HCV in various extrahepatic human tissues, and provide evidence that HCV replicates in macrophages, B cells, T cells, and other extrahepatic tissues. We also analyzed both short term and long term in vitro systems used to culture HCV. These systems vary in their purposes and methods, but long term culturing of HCV in B cells, T cells, and other cell types has been used to analyze replication. It is therefore now possible to study HIV-HCV co-infections and HCV replication in vitro.

Clinicopathological features of hepatitis C virus disease after living donor liver transplantation: relationship with in situ hybridisation data

AIMS

Recurrent hepatitis is a significant complication after liver transplantation for hepatitis C virus (HCV) disease. To evaluate responsiveness to treatment of HCV disease after liver transplantation, in situ hybridisation (ISH) was employed.

METHODS

Sense and anti-sense probes for HCV were synthesised, and ISH studies were performed on 19 liver biopsy specimens from 19 recipients who had undergone living donor liver transplantation for HCV disease. ISH positive cells and total hepatocytes were counted, and the percentage of positive cells was calculated. Other clinical findings were compared retrospectively with the ISH results.

RESULTS

The subjects were divided into three groups: recurrent HCV hepatitis (RHC, n = 11), acute cellular rejection (ACR, n = 5), and recurrent HCV hepatitis with ACR (MIX, n = 3). The percentage of ISH positive cells was almost the same degree (10-20%) in the three groups. The RHC group was subdivided into two sets of patients in whom serum HCV titres decreased (group D, n = 7) or did not decrease (group ND, n = 3) after 1 month of IFN therapy. The percentage of ISH positive cells in group D was significantly lower than that in group ND (p < 0.05)

CONCLUSIONS

ISH for the recipients with HCV may be useful for predicting the response to interferon therapy.

An overview about hepatitis C: a devastating virus

Hepatitis C (HCV) is the disease that has affected around 200 million people globally. HCV is a life threatening human pathogen, not only because of its high prevalence and worldwide burden but also because of the potentially serious complications of persistent HCV infection. Chronicity of the disease leads to cirrhosis, hepatocellular carcinoma and end-stage liver disease. HCV positive hepatocytes vary between less than 5% and up to 100%, indicating the high rate of replication of viral RNA. HCV has a very high mutational rate that enables it to escape the immune system. Viral diversity has two levels; the genotypes and Quasiaspecies. Major HCV genotypes constitute genotype 1, 2, 3, 4, 5 and 6 while more than 50 subtypes are known. All HCV genotypes have their particular patterns of geographical distribution and a slight drift in viral population has been observed in some parts of the globe.

Self-priming of reverse transcriptase impairs strand-specific detection of dengue virus RNA

Dengue virus infection is the most frequent arthropod-borne infection affecting humans in the world. Our understanding of the pathophysiological events leading to mild or severe outcomes of the disease remains limited by the fact that viral target cells in the human body are poorly characterized. One of the most sensitive strategies for detecting cells supporting active replication of this positive-strand RNA virus is the search for the replicative intermediate, an antigenome of negative polarity, by RT-PCR. However, a phenomenon described as 'false priming' of the reverse transcriptase (RT) prevents strand-specific detection. The results of the current study showed that this event corresponds to cDNA synthesis that is independent of any primer addition. This property was general to all RNAs tested and was not associated with small free nucleic acids, such as tRNAs and microRNAs. Rather, it corresponded to initiation of cDNA synthesis from the 3' end of the RNA template, and a model is proposed in which the template RNA snaps back upon itself and creates a transient RNA primer suitable for the RT. Such a property would explain why many assays proposed for detection of a replicative intermediate are not specific, and may help in the development of a molecular biology protocol that could allow replication studies of RNA viruses of human interest, such as dengue virus, hepatitis C virus and enteroviruses.

Roles of infection, inflammation, and the immune system in cholesterol gallstone formation

Cholesterol gallstone formation is a complex process mediated by genetic and environmental factors. Until recently, the role of the immune system in the pathogenesis of cholesterol gallstones was not considered a valid topic of research interest. This review collates and interprets an extensive body of basic literature, some of which is not customarily considered to be related to cholelithogenesis, describing the multiple facets of the immune system that appear to be involved in cholesterol cholelithogenesis. A thorough understanding of the immune interactions with biliary lipids and cholecystocytes should modify current views of the pathogenesis of cholesterol gallstones, promote further research on the pathways involved, and lead to novel diagnostic tools, treatments, and preventive measures.

In situ Hybridization

Hybridization is the formation of hybrid nucleic acid molecules with complementary nucleotide sequences in DNA:DNA, DNA:RNA, or RNA:RNA forms. In situ hybridization is a highly sensitive technique that allows detection and localization of specific DNA or RNA molecules in morphologically preserved isolated cells, histological tissue sections, or chromosome preparations. In situ hybridization has broad range of applications and has been used to (a) localize viral infection, (b) identify sites of gene expression, (c) analyze mRNA transcription and tissue distribution, and (d) map gene sequences in chromosomes. There are several advantages of the use of in situ hybridization including the fact that it can be applied to archival materials and frozen tissues and can be combined with immunohistochemistry to detect protein as well as mRNA of interest or phenotype of cells expressing the target genome, detecting more than one nucleic acid sequences using different labeling methods.The major steps involved in in situ hybridization are as follows: probe preparation and labeling, tissue fixation, permeabilization, hybridization, and signal detection and these are described in detail in this chapter.

Preliminary comparison of quantity, quality, and microarray performance of RNA extracted from formalin-fixed, paraffin-embedded, and unfixed frozen tissue samples

Microarrays have been used to simultaneously monitor the expression of thousands of genes from biological samples, an approach that can potentially uncover previously unrecognized functions of genes. Microarray analyses can rarely be conducted retrospectively because of the requirement for RNA to be obtained from fresh or unfixed frozen tissues. Archived pathology specimens would need to be used for retrospective analyses, and these are typically preserved as formalin-fixed, paraffin-embedded (FFPE) tissue. Formalin-fixed tissues have been shown to yield compromised RNA compared with that obtained from frozen tissue. To begin to assess the performance of RNA extracted from FFPE samples on a microarray format, we compared RNA from a model system of pelleted lipopolysaccharide-stimulated human bone marrow stromal cells that were snap frozen with RNA from FFPE cells. RNA integrity and Affymetrix quality control parameters were assessed, and differentially regulated genes were analyzed with Ingenuity Pathway Analysis software. Results demonstrate that both snap-frozen and FFPE samples yielded intact RNA suitable for amplification prior to Affymetrix GeneChip analysis. Although some transcriptional information was lost with RNA extracted from the FFPE samples, Ingenuity Pathway Analysis revealed that the major pathways identified as affected by drug treatment were similar. Results show that FFPE samples are amenable to Affymetrix GeneChip analysis, expanding the possibility for expression profiling on archived tissue blocks in pathology laboratories.

Nuclear localization of flavivirus RNA synthesis in infected cells

Flaviviral replication is believed to be exclusively cytoplasmic, occurring within virus-induced membrane-bound replication complexes in the host cytoplasm. Here we show that a significant proportion (20%) of the total RNA-dependent RNA polymerase (RdRp) activity from cells infected with West Nile virus, Japanese encephalitis virus (JEV), and dengue virus is resident within the nucleus. Consistent with this, the major replicase proteins NS3 and NS5 of JEV also localized within the nucleus. NS5 was found distributed throughout the nucleoplasm, but NS3 was present at sites of active flaviviral RNA synthesis, colocalizing with NS5, and visible as distinct foci along the inner periphery of the nucleus by confocal and immunoelectron microscopy. Both these viral replicase proteins were also present in the nuclear matrix, colocalizing with the peripheral lamina, and revealed a well-entrenched nuclear location for the viral replication complex. In keeping with this observation, antibodies to either NS3 or NS5 coimmunoprecipitated the other protein from isolated nuclei along with newly synthesized viral RNA. Taken together these data suggest an absolute requirement for both of the replicase proteins for nucleus-localized synthesis of flavivirus RNA. Thus, we conclusively demonstrate for the first time that the host cell nucleus functions as an additional site for the presence of functionally active flaviviral replicase complex.

Hepatitis C virus infection facilitates gallstone formation

BACKGROUND

Bile duct damage and hepatic steatosis are two characteristic histological findings in hepatitis C virus infection; and high prevalence of hepatitis C antibody is noted in patients with cholangiocarcinoma. The purpose of the present study was to examine the relationship between biliary diseases and hepatitis C virus infection.

METHODS

Persons who received a general checkup in Chang Gung Memorial Hospital between 2000 and 2002 were included. All of them had hemogram, serum biochemistry, hepatitis B surface antigen, hepatitis C antibody and ultrasonography studies. The prevalence of gallbladder stone, bile duct stone and gallbladder polyp/cholesterolosis were compared in different viral infection groups.

RESULTS

Of the 28 486 persons, 22 967 were negative for both hepatitis B surface antigen and hepatitis C antibody (group NBNC), 4152 were hepatitis B surface antigen carriers (broup B), 1195 were positive for hepatitis C antibody (group C), and 172 were positive for both markers. The 379 persons (1.3%) having had cholecystectomy were considered to have gallbladder stone at the time when cholecystectomy was done. Gallbladder stone was found in 6.0% persons of group NBNC, 5.4% in group B and 11.7% in group C. The prevalence of gallbladder stone in group C was found especially high for age groups 31-40 years and 61-70 years. The prevalence of bile duct stone was higher in group C (0.4%) than in group NBNC or B (both 0.1%). Stepwise logistic regression analysis showed that age, liver cirrhosis, body mass index, hepatitis C virus infection and gender were independent factors associated with gallbladder stone.

CONCLUSIONS

Hepatitis C virus infection facilitates gallstone formation.

Viral kinetics during antiviral therapy in patients with chronic hepatitis C and persistently normal ALT levels

The aim of the present study was to compare viral kinetics between patients with chronic hepatitis C and persistently normal alanine aminotransferase (ALT) levels and those with elevated ALT levels. Kinetic parameters were derived from nonlinear, least square fitting of serum hepatitis C virus RNA quantifications collected from patients with chronic hepatitis C and persistently normal (n = 20) and elevated (n = 19) ALT levels before and during treatment with 180 mug pegylated interferon alpha-2a once weekly plus daily ribavirin. Patients with chronic hepatitis C and persistently normal ALT levels showed a trend to lower pretreatment infected cell loss (delta) (P = .13) but no differences in efficacy of blocking virus production (epsilon) and infected cell loss during treatment (mdelta) compared with patients with elevated ALT levels. Differences were significant for epsilon (P = .02) and delta (P = .04) when applying updated "healthy" levels for ALT (0.75 times and 0.63 times upper limit of normal for male and female patients, respectively). A significant reduction of the kinetic parameters epsilon, delta, and mdelta was observed in patients with elevated gamma-glutamyltranspeptidase (GGT) levels compared with patients with normal GGT levels (P = .02, P = .005, and P = .02, respectively). In conclusion, viral kinetics are similar in patients with chronic hepatitis C and persistently normal ALT levels and those with elevated ALT levels. However, in patients with elevated GGT levels, a major association with reduced efficacy of blocking virus production and lower infected cell loss was observed. These data show that virological response in patients with chronic hepatitis C is less associated with baseline ALT than with GGT levels.

Detection of hepatitis C virus RNA in formalin-fixed paraffin-embedded sections with digoxigenin-labeled cRNA probes

Although recent studies have analyzed Hepatitis C (HCV) infections in liver tissue by in situ hybridization (ISH), many of these studies have been of limited diagnostic utility because of the low copy numbers of HCV in formalin-fixed paraffin-embedded (FFPE) tissue and failure to correlate the ISH analysis with other methods of detecting HCV. Thirty six cases of liver biopsies from patients with known HCV antibody status including 20 cases of serum HCV positive and 16 cases of serum HCV negative were analyzed. All cases showed histologic features suggestion of HCV infection. Analyses of all 36 cases were done by RT-PCR combined with Southern hybridization (RT-PCR-SH) and in situ hybridization (ISH). A prolactin riboprobe was used as a negative control. Immunohistochemistry (IHC) with an antibody against HCV (Rb 246) was also used to analyze HCV viral protein in the tissues. Of the 20 serum antibody-positive cases, RT-PCR-SH detected 18 positive cases, while ISH and IHC detected 19 and 16 positive cases, respectively. Of the 16 serum antibody-negative cases, RT-PCR-SH detected 8 positive cases while ISH and IHC detected 8 and 11 positive cases, respectively. A positive ISH signal for HCV was also detected in some lymphocytes and bile ducts in the liver. These results show that ISH with a highly specific riboprobe is comparable to RT-PCR-SH for detection of HCV infection in liver tissue.

Full-length open reading frame of a recombinant hepatitis C virus strain from St Petersburg: proposed mechanism for its formation

The full-length ORFs for the hepatitis C virus recombinant RF1_2k/1b (N687) and the non-recombinant 1b strain N589 were sequenced. A single recombination point was found and the sizes of the genes (C, E1, E2, p7, NS2, NS3, NS4 and NS5) were according to the parental subtypes. The PKR-eIF2alpha phosphorylation site homology domain sequence of the E2 protein was identical to those of genotype 2 strains, while the IFN-alpha-sensitivity-determining region of the NS5A protein was identical to those of interferon-resistant 1b strains. For the parental strains, two hairpin structures, HS1 and HS2, were predicted for the plus-strand up- and downstream of the crossover site, which were not present in the recombinant strain. HS2 shared similarity with the motif1 hairpin of turnip crinkle virus RNA that binds to the RNA-dependent RNA polymerase and facilitates 3'-terminal extension during recombination. This study suggests that RF1_2k/1b has emerged by homologous recombination during minus-strand synthesis via template switching because of constraints imposed by the HS1 hairpin of the 3'-parental genome.

Insulin resistance and insulin secretion in chronic hepatitis C virus infection

BACKGROUND/AIMS

Diabetes mellitus (DM) is frequently observed in patients with chronic hepatitis caused by hepatitis C virus infection (CHC). The present study was designed to determine the pathogenic factors responsible for glucose intolerance in CHC patients.

METHODS

A total of 131 patients with CHC were enrolled in this study. Insulin resistance and beta-cell function were determined after 75 g oral glucose tolerance tests.

RESULTS

Glucose intolerance was detected in 27.5% (36/131) of CHC patients; 10 had DM and 26 impaired glucose tolerance. HOMA-R [insulin 0xglucose 0/22.5] was greater in patients with both impaired glucose tolerance and DM than in those with normal glucose tolerance (P<0.01). Matsuda index [10(4)/ (square root) (mean insulinxmean glucosexglucose 0xinsulin 0)] was lower in diabetic patients than in those with normal glucose tolerance (P<0.05). The insulinogenic index [Deltainsulin 30-0/Deltaglucose 30-0] and DeltaC-peptide 30 [DeltaC-peptide 30-0/Deltaglucose 30-0] were significantly lower even in patients with impaired glucose tolerance than in patients with normal glucose tolerance (P<0.01).

CONCLUSIONS

Both insulin resistance and beta-cell dysfunction contribute to glucose intolerance in CHC patients.

Improved detection of hepatocyte proliferation using antibody to the pre-replication complex: an association with hepatic fibrosis and viral replication in chronic hepatitis C virus infection

To test the hypothesis that hepatitis C virus (HCV) might induce hepatocyte proliferation directly, thereby predisposing HCV carriers to cirrhosis and hepatocellular carcinoma, we have used a new method to identify proliferating hepatocytes, employing a novel monoclonal antibody to minichromosome maintenance (Mcm) proteins, essential components of the pre-replication complex. Antibody to Ki-67, a conventional marker of cell division, was also studied. Eighty-seven patients with chronic HCV infection and a broad spectrum of histological change were studied. Proliferation was observed rarely in hepatocytes from normal liver from healthy controls (always less than 0.01%). However, proliferating hepatocytes were detected in all HCV-infected patients and the proportion of hepatocytes expressing Mcm-2 (3-40%) always exceeded that expressing Ki-67 (1-14%) and correlated positively with increasing stage of fibrosis (P = 0.0001) and viral replication (P = 0.0004). There were weaker but significant associations between the proportion of hepatocytes expressing Mcm-2 and inflammatory indices including interface hepatitis, portal tract inflammation, lobular inflammation and steatosis. There was no association between the proportion of hepatocytes expressing Mcm-2 and age, gender or past alcohol consumption, but there was a weak association with current consumption of alcohol (P = 0.0067). The proportion of Ki-67 hepatocytes did not correlate with any clinical, laboratory or histological parameter. Mcm-2 was also detected in bile duct cells, sinusoidal lining cells and infiltrating lymphocytes, but at low frequency. These data indicate first, that Mcm-2 is a more sensitive marker of hepatocyte proliferation than Ki-67, second that many hepatocytes in chronic HCV infection have entered the cell cycle and third, suggest that interference with the hepatocyte cell cycle might be an alternative approach to therapy.

Dynamics of hepatitis C virus replication in human liver

Hepatitis C virus (HCV) replication at the cellular level is not fully understood. This study describes an optimized system for quantifying replication of HCV in hepatocytes and in liver tissues. A digital image analysis method was developed to quantify signal intensities of HCV genomic and replicative-intermediate RNAs in infected human liver tissues and to examine their spatial distribution. The average number of viral genomes per productively infected hepatocyte ranged from 7 to 64 RNA molecules. The maximal concentrations of genomic and replicative-intermediate RNAs at the single cell level were 74 and 34 molecules per hepatocyte, respectively. A gradient dispersion of genomes was observed around virus-producing cells, suggesting infection of neighboring hepatocytes as one mechanism of viral spread in the liver. There was no significant difference in total hepatic load of HCV genomes between the post- and nontransplant patients, whereas serum titers in the former group were much higher that that in the latter group. HCV replication varied among infected hepatocytes, occurred in a subset of cells, and proceeded at a low level, confirming one mechanism by which individual hepatocytes are cumulatively able to generate steady state concentrations of millions of HCV genomes per milliliter of blood. Lower viral clearance rates in circulating blood may explain the phenomenon of increased serum titers of viral RNA in posttransplant immunosuppressed patients.

C3/Ig and Ig/C3 two-component-determined circulating immune complexes (TCIC) in patients with HCV infection

In the present study, we measured the levels of immunoglobulin (Ig)- and complement 3 (C3)-determined circulating immune complexes (two-component-determined CIC, or TCIC) in hepatitis C virus (HCV)-infected patients. TCIC was dissected into C3/Ig-TCIC and Ig/C3-TCIC by a reciprocal use of coating and detecting antibodies. The current study was carried out in 117 infected HCV patients and 252 healthy controls. We found that C3/Ig-TCIC elevation was a common feature in patients with HCV infection. Positive rates and levels of C3/IgG-TCIC and C3/IgM-TCIC were significantly higher in the patients with abnormal alanine aminotransferase (ALT) than patients with normal ALT (70.6% vs. 17.0%, 0.56 OD vs. 0.47 OD and 0.71 OD vs. 0.65 OD, respectively, P<0.001). However, the levels of IgM/C3-TCIC and IgA/C3-TCIC were significantly higher in individuals with HCV infection than in healthy controls, whereas the level of IgG/C3-TCIC was significantly lower in the former group than in the latter group. In summary, our results suggest that IgG and C3 TCIC may play an important role in liver cell injury during the course of HCV infection and may be a hallmark for hepatitis C pathogenesis. Elevated C3/Ig-TCIC, accompanied by decreased Ig/C3-TCIC, forms a peculiar trait in HCV infection. Our findings thus provide new insights into HCV pathogenesis.

Development of a novel nested in situ PCR-ISH method for detection of hepatitis C virus RNA in liver tissue

Hepatitis C virus (HCV) is a major cause of chronic hepatitis with liver-related death occurring in 20-25% of patients who develop cirrhosis. Detection of the virus RNA in liver is difficult since viral expression is very low. In situ polymerase chain reaction (PCR) in situ hybridisation (ISH) was developed for detection and localisation of viral RNA in formalin-fixed, paraffin-embedded liver tissue. Nested PCR technology was adapted for in situ use employing primers derived from the 5' end of the HCV genome. Seventeen liver blocks from known HCV-infected patients were examined. Viral RNA was detected in liver from eleven patients using solution phase reverse transcriptase-PCR. Of these positive samples, ten were positive by the in situ method. Positive signal was detected in the cytoplasm of hepatocytes and mononuclear cells. No Kupffer cell or bile duct epithelial positivity was observed. No positive signal was evident in any of the negative controls. A reliable method is described to demonstrate the presence and localisation of HCV RNA in liver tissue using an in situ PCR-ISH assay and it is believed that this will be a valuable tool for the understanding of HCV replication and pathogenesis.

Immunopathogenesis of hepatitis C virus infection

Hepatitis C virus, a recently identified member of the family Flaviviridae, is an important cause of chronic viral hepatitis and cirrhosis. There are similarities in the nature of the immune response to this pathogen with immunity in other flavivirus and hepatotropic virus infections, such as hepatitis B. However, the high rate of viral persistence after primary hepatitis C infection, and the observation that neutralizing antibodies are not protective, would suggest that there are a number of important differences between hepatitis C, other flaviviruses, and hepatitis B. The phenomenon of quasispecies evolution and other viral factors have been proposed to contribute to immune evasion by hepatitis C virus. In the face of established persistent infection, virus-specific cytotoxic T lymphocytes may exert some control over viral replication. However, these same effectors may also be responsible for the progressive liver damage characteristic of chronic hepatitis C infection. The nature of protective immunity, including the role of innate immune responses early after hepatitis C exposure, remains to be defined.

Hepatitis C virus infection of human hepatoma cell line 7721 in vitro

AIM: To establish a cell culture system with long-term replication of hepatitis C virus in vitro.

METHODS: Human hepatoma cell line 7721 was tested for its susceptibility to HCV by incubating with a serum from a patient with chronic hepatitis C. Cells and supernatant were harvested at various phases during the culturing periods. The presence of HCV RNA, the expression of HCV antigens in cells and/or supernatant were examined by RT-PCR, in situ hybridization and immunohisto-chemistry respectively.

RESULTS: The intracellular HCV RNA was first detected on d2 after infection and then could be intermittently detected in both cells and supernatant over a period of at least three months. The expression of HCV NS₃, CP₁₀ antigens could be observed in cells. The fresh cells could be infected by supernatant from cultured infected cells and the transmission of viral genome from HCV-infected 7721 cells to PBMCs was also observed.

CONCLUSION: The hepatoma line 7721 is not only susceptible to HCV but also supports its long-term replication in vitro.

Chronic hepatitis C virus infection without cirrhosis induces insulin resistance in patients with alpha-thalassaemia major

AIM

The aim of this study was to investigate the cause of increased incidence of impaired glucose tolerance and diabetes mellitus in patients with alpha-thalassaemia major and chronic hepatitis C virus (HCV) infection without cirrhosis of the liver.

PATIENTS AND METHODS

The study included 28 alpha-thalassaemic multi-transfused patients (14 females and 14 males; age, 25.7 +/- 6.3 years) with normal fasting glucose levels. Sixteen were seropositive for HCV and they had biopsy proven chronic hepatitis C without cirrhosis. An oral glucose tolerance test (OGTT) was performed. Glucose, insulin and C-peptide levels were measured every 30 min for 2 h. Fasting insulin resistance index (FIRI) was calculated according to the formula: FIRI = (fasting glucose x fasting insulin)/25.

RESULTS

All patients had a normal OGTT except for two HCV positive and two HCV negative patients who had impaired glucose tolerance. HCV positive patients had higher fasting insulin levels (P = 0.02), higher fasting insulin/fasting glucose ratio (P = 0.017) and higher FIRI (P = 0.016) than HCV negative patients. During the OGTT, peak insulin levels occurred at 30 min in HCV negative patients but at 60 min in HCV positive. HCV infected patients had higher mean value of insulin at 60 (P = 0.017), 90 (P = 0.04), and 120 min (P = 0.04), and higher mean increment above basal at 60 (P = 0.015), 90 (P = 0.018) and 120 min (P = 0.05). The area under the curve (AUC) of insulin was also greater in HCV positive patients as compared to HCV negative (P = 0.04), although the AUC of glucose and the glucose levels at all time points of the OGTT were similar in both groups.

CONCLUSIONS

The findings of this study show that alpha-thalassaemic patients with HCV infection without liver cirrhosis are more insulin resistant and have delayed insulin secretion compared to HCV negative alpha-thalassaemic patients. These changes in insulin action and secretion are evident before the development of impaired glucose tolerance and may explain the higher prevalence of diabetes mellitus in this group.

Hepatitis C virus in human B lymphocytes transformed by Epstein-Barr virus in vitro by in situ reverse transcriptase-polymerase chain reaction

AIM: To study persistence and replication of hepatitis C virus (HCV) in patients' peripheral blood mononuclear cells (PBMC) cultured in vitro.

METHODS: Epstein-Barr virus (EBV) was used to transform the hepatitis C virus from a HCV positive patient to permanent lymphoblastoid cell lines (LCL). Positive and negative HCV RNA strands of the cultured cells and growth media were detected by reverse transcriptase-polymerase chain reaction (RT-PCR) each month. Core and NS5 proteins of HCV were further tested using immunohistochemical SP method and in situ RT-PCR.

RESULTS: HCV RNA positive strands were consistently detected the cultured cells for one year. The negative-strand RNA in LCL cells and the positive-strand RNA in supernatants were observed intermittently. Immunohistochemical results medicated expression of HCV NS3 and C proteins in LCL cytoplasm mostly. The positive signal of PCR product was dark blue and mainly localized to the LCL cytoplasm. The RT-PCR signal was eliminated by overnight RNase digestion but not DNase digestion.

CONCLUSION: HCV may exist and remain functional in a cultured cell line for a long period.

Detection and quantitation of hepatitis C virus RNA in feces of chronically infected individuals

Hepatitis C virus (HCV) RNA was detected and quantified in human fecal specimens with the Roche COBAS AMPLICOR system adapted by us for fecal specimens. HCV RNA could be detected in the feces of four of six (67%) patients chronically infected with HCV, with loads up to about 2.8 x 10(5) copies/ml of feces. The same HCV genotypes were observed in feces and plasma as determined by direct sequencing of the 5' untranslated region.

Intragraft localization of activated nuclear factor kappaB in recurrent hepatitis C virus disease following liver transplantation

Nuclear factor kappaB (NF-kappaB) is activated during viral infection and is central to the regulation of host immune responses. The NF-kappaB activation status and its morphological sources were assessed by immunohistochemistry in allograft biopsy specimens of orthotopic liver transplantation patients with recurrent hepatitis C virus (HCV). Hepatocellular NF-kappaB immunostaining was detected in HCV cases compared with controls (nontransplant: P <.001; transplant: P =.006), which correlated with the number of NF-kappaB positive hepatocytes (P =.007) and contrasted to the absent to weak staining of controls (nontransplant: P =.001; transplant: P =.009). Enhanced NF-kappaB staining of cytokeratin 19-positive bile ducts and proliferating ductules in the HCV group was in contrast to controls. Intense NF-kappaB immunoreactivity was detected in CD68-positive Kupffer cells and macrophages of all HCV specimens compared with a few controls (nontransplant: P <.001; transplant: P =.001) and contrasted to the weak staining of controls (nontransplant: P <.001; transplant: P =.001). NF-kappaB-positive immunoreactivity correlated with the number of T cell receptor (TCR) alpha/beta-positive lymphocytes (P <.001), which was not observed in controls. In those HCV cases showing evidence of necroinflammatory activity (grade) and individual features of portal inflammation, periportal inflammation/piecemeal necrosis, lobular inflammation, and fibrosis (stage), higher NF-kappaB staining intensity scores within bile ducts, proliferating ductules, hepatocytes (piecemeal necrosis: P =.016; stage: P =.030), and lymphocytes (stage: P =.044) and increased number of NF-kappaB-positive cells within bile ducts, proliferating ductules (grade, lobular inflammation, piecemeal necrosis, stage: P =.022), hepatocytes, and lymphocytes were observed. Increased staining intensity and frequency of NF-kappaB-positive cells were similarly observed in HCV-positive allografts obtained from patients under tacrolimus- compared with cyclosporine-based immunosuppression. These data implicate an immunoregulatory role of intragraft NF-kappaB activation in the pathogenesis and progression of posttransplantation HCV disease recurrence.

Human leukocyte antigen DRB1 1302 protects against bile duct damage and portal lymphocyte infiltration in patients with chronic hepatitis C

BACKGROUND/AIMS

To confirm the immune reaction of hosts in chronic hepatitis C, we examined the association of human leukocyte antigen (HLA) DR with the histopathological outcome including bile duct damage and steatosis, which are characteristic of hepatitis C virus (HCV) infection.

METHODS

One hundred and fifty-five patients with chronic HCV infection were examined. The pathological appearance of liver biopsy specimens was evaluated by both Knodell's histological activity index and examination of bile duct damage and steatosis. HLA DRB1 was determined by the polymerase chain reaction sequence-specific oligonucleotide probe method.

RESULTS

HLA DRB1 1302 was found with significantly higher frequency in patients without than with bile duct damage (34.8% vs. 4.7%, p=0.0001, p corrected by Bonferroni's inequality method=0.002). It was also found more frequently in patients without marked portal lymphocyte infiltration (28.6% vs. 7.7%, p=0.0015, p corrected by Bonferroni's method=0.03). HLA DRB1 1101 was found more frequently in patients without than with piecemeal necrosis (p=0.004). In contrast, the frequency of HLA DRB1 1502 tended to be higher in patients with than without piecemeal necrosis and marked portal lymphocyte infiltration (p=0.015 and p=0.03, respectively). HLA DRB1 1201 and 0802 were seen more frequently in bile duct damage-negative (p=0.02) and piecemeal necrosis-negative patients (p=0.03), respectively. Interestingly, serum HCV levels of HLA DRB1 1302-positive patients were significantly higher than those of 1302-negative patients (mean: 7.7 Meq/ml vs. 3.1 Meq/ml, p=0.0007).

CONCLUSION

These findings suggest that some histopathological changes in chronically HCV-infected livers could be caused by the host's immune reaction regulated by HLA DR.

In situ distribution of hepatitis C virus replicative-intermediate RNA in hepatic tissue and its correlation with liver disease

Liver failure from chronic hepatitis C is the leading indication for liver transplantation in the United States. However, the pathogenesis of liver injury resulting from chronic hepatitis C virus (HCV) infection is not well understood. To examine the relationship between HCV replication in liver tissue and hepatocellular injury, a strand-specific in situ hybridization procedure was developed. The sensitivity and specificity of digoxigenin-labeled riboprobes were optimized by analyzing Northern blots and cell lines expressing HCV RNAs. For the current study, both genomic (sense) and replicative-intermediate (antisense) HCV RNAs were detected and quantified in 8 of 8 liver tissue specimens from infected patients versus 0 of 11 liver tissue specimens from noninfected controls. The distribution pattern for HCV replicative-intermediate RNA in liver was different from that for HCV genomic RNA. HCV genomic RNA was variably distributed throughout infected livers and was located primarily in the cytoplasm of hepatocytes, with some signal in fibroblasts and/or macrophages in the surrounding fibroconnective tissue. However, HCV replicative-intermediate RNA showed a more focal pattern of distribution and was exclusively localized in the cytoplasm of hepatocytes. There was no significant relationship between the distribution pattern for HCV genomic RNA and any indices of hepatocellular injury. However, a highly significant correlation was observed between the percentage of cells staining positive for replicative-intermediate RNA and the degree of hepatic inflammatory activity (P, < 0.0001). Furthermore, the ratio of cells staining positive for HCV replicative-intermediate versus genomic RNA correlated with the histological severity of liver injury (P, 0. 0065), supporting the hypothesis that active replication of HCV in liver tissue may be a significant determinant of hepatocellular injury.

Immunohistochemical detection of hepatitis C virus antigen in paraffin embedded liver biopsies from patients with chronic liver disease

A simple and reproducible immunohistochemical (IHC) staining method that adequately identifies and localizes hepatitis C virus (HCV) in human livers is still not available. We performed IHC staining using both a new monoclonal antibody against HCV and a polyclonal human anti-HCV IgG to 94 liver biopsies from HCV seropositive patients with chronic hepatitis and 15 control liver biopsies. Positive nuclear staining was consistently observed predominantly in hepatocytes and much less in lymphocytes with either antibody in 57% of anti-HCV seropositive cases but in none of the controls. However, the monoclonal antibody yielded a stronger positive reaction and in a greater proportion of hepatocytes. In 78% of the positive cases, more than a quarter of the hepatocytes showed nuclear staining. The degree of hepatic HCV load as revealed by intensity and extent of positive staining did not correlate with histological changes in the liver. The new monoclonal antibody against HCV appeared to be suitable for identifying HCV in tissues by a simple IHC stain and can be used to explore the pathogenesis of liver injury induced by this virus.

Further evidence for an association between non-insulin-dependent diabetes mellitus and chronic hepatitis C virus infection

Non-insulin-dependent diabetes mellitus (NIDDM) may be associated with chronic hepatitis C virus (HCV) infection. This was studied further in two parts. First, 1,151 patients with HCV-related cirrhosis and 181 patients with hepatitis B virus (HBV)-related cirrhosis, well matched for age, sex, and severity of cirrhosis, were reviewed retrospectively. The prevalence of diabetes mellitus was higher in HCV-related cirrhosis (23.6%) than in HBV-related cirrhosis (9.4%; odds ratio [OR], 2.78; 95% confidence interval [CI], 1.6-4.79; P =.0002). The prevalence of diabetes mellitus was associated closely with the Child-Pugh score (OR, 3.83; 95% CI, 2. 38-6.17; P <.0001) and increasing age (OR, 1.02; 95% CI, 1.00-1.03; P =.0117). Second, 235 patients with biopsy confirmed chronic HBV or HCV underwent an oral glucose tolerance test. Only 1 of 70 patients with chronic viral hepatitis without cirrhosis was diabetic. However, 31 of 127 patients with HCV-related cirrhosis (24.4%) were diabetic compared with 3 of 38 patients with HBV-related cirrhosis (7.9%, P =.0477). The major variables associated with NIDDM were cirrhosis (OR, 14.39; 95% CI, 1.91-108; P =.0096) and male sex (OR, 4.64; 95% CI, 1. 32-16.18; P =.0161). Fasting insulin levels in 30 patients with HCV-related cirrhosis and diabetes mellitus were elevated significantly, which was consistent with insulin resistance. However, acute insulin responsiveness was reduced in all patients with HCV infection and diabetes suggesting concomitant B-cell dysfunction. This study confirms an association between HCV and NIDDM.

Permissiveness of human biliary epithelial cells to infection by hepatitis C virus

The cellular tropism of hepatitis C virus (HCV) is an important but much debated issue. Permissivity to HCV of biliary cells has never been demonstrated. In this context, we used gallbladder epithelial cells (GBEC) as a model of the more proximal biliary epithelium. These cells were isolated from HCV-positive and -negative individuals and cultured for up to 40 days. Biliary cells from HCV-negative subjects were infected in vitro with various inocula. The retention of GBEC functional characteristics was assessed by the expression of cystic fibrosis transmembrane conductance regulator (CFTR). All 12 GBEC tested from HCV-negative patients were successfully infected by HCV. This was assessed by: 1) the detection of HCV-RNA positive and negative strands; 2) the detection of the viral capsid by immunofluorescence; and 3) the combination of single-strand conformation polymorphism (SSCP) and HVR1 sequence analysis demonstrating the distinct majoritary HCV genomes in serum and in GBEC. The level of HCV RNA in cell extracts and supernatants was low, but HCV infection was highly reproducible. Our results expand those showing the cellular tropism of HCV, and demonstrate the sensitivity of biliary cells to HCV infection. This might have an important impact in terms of pathogenesis and pathological features of HCV infection. In addition, given the easy access to these cells and the high reproducibility of in vitro infection, they should constitute an important tool for studies aimed at analyzing the issue of HCV penetration and neutralizing antibodies.

Direct in situ reverse transcriptase-linked polymerase chain reaction with biotinylated primers for the detection of hepatitis C virus RNA in liver biopsies

To assess the presence and the cellular distribution of hepatitis C virus (HCV) RNA in the liver of 11 patients with confirmed HCV infection, a direct in situ reverse transcriptase-linked polymerase chain reaction (RT-PCR) method was performed on formalin-fixed and paraffin-embedded biopsies. The oligonucleotide primers used were specific to the 5' non coding region. An unlabelled downstream oligonucleotide served as a primer for reverse transcription as well as PCR. The upstream oligonucleotide serving as a primer for PCR was biotinylated, allowing a direct enzymatic detection of PCR products. HCV infected cells revealed cytoplasmic staining mainly concentrated towards the interface of the nucleus and cytoplasm. Most of the stained cells were hepatocytes and sometimes Kupffer cells. The results were compared with those obtained by RT-PCR of RNA extracted from the corresponding tissue block. Extracted HCV RNA could be detected in liver tissues of nine out of 11 (82%) infected patients. The detection rate using in situ RT-PCR was 7/11 (63%). The use of labelled primers improved specificity of direct in situ methods, by preventing non-specific incorporation of labelled dNTPs into fragmented DNA. Further studies are however required in order to increase detection sensitivity of HCV infection by in situ molecular methods.

Detection of hepatitis-C virus and hepatitis-C virus replication in hepatocellular carcinoma by in situ hybridization

BACKGROUND

Although hepatitis C virus (HCV) is a major causative agent of hepatocellular carcinoma (HCC), the role of this virus in carcinogenesis is not fully understood.

METHODS

We studied HCV infection and replication by detecting plus- and minus-strand HCV RNA by in situ hybridization (ISH) in surgically resected HCCs and adjacent non-cancerous tissue obtained from 15 anti-HCV antibody-positive patients with HCC.

RESULTS

Plus-strand HCV RNA was found in 9 of 15 HCCs. Both plus- and minus-strand HCV RNA were detected in four of these nine patients. In non-cancerous tissues obtained adjacent to the HCC, plus-strand HCV RNA was found in 10 of 15 patients, whereas both plus- and minus-strand HCV RNA were detected in 7 of these 10 patients. The degree of staining by ISH did not correlate with the differentiation of the HCC, histologic classification of the non-cancerous tissue, serum HCV RNA levels, or serum transaminase levels.

CONCLUSIONS

HCV can be found in and replicates in both hepatoma cells and in non-cancerous hepatocytes in anti-HCV antibody-positive patients with HCC. The direct effects of HCV viral gene products on normal hepatocytes in the development of HCC require additional study.

Hepatotropism of GB virus C (GBV-C): GBV-C replication in human hepatocytes and cells of human hepatoma cell lines

BACKGROUND/AIMS

Recently, GB virus C (GBV-C) has been identified as another virus potentially causing viral hepatitis. However, its hepatotropism and pattern of infection in humans is still unknown. To elucidate the presence and replication of GBV-C in the human liver, we investigated tissue samples of six explanted livers from five GBV-C mono- or GBV-C/HCV co-infected patients for GBV-C RNA plus- and minus-strand RNA.

METHODS

These tissues were examined using nested RT-PCR followed by Southern blot hybridization as well as fluorescence in situ hybridization on liver cryosections. To further substantiate susceptibility of liver cells for GBV-C, in vitro infection of human hepatoma cells (HuH7, HepG2) with GBV-C mono-infected serum was performed.

RESULTS

By reverse transcription followed by nested PCR (RT-PCR), 5 of 6 liver specimens (4/5 patients) were positive for GBV-C plus-strand RNA, and viral minus-strand RNA could be detected in 4 of 6 liver specimens (4/5 patients). One liver sample was negative for GBV-C RNA. In two specimens we could identify GBV-C infection by in situ hybridization. Virus infection appeared to be restricted to hepatocytes and detection of minus-strand RNA showed viral replication in a few highly infected liver cells. In vitro infection of HepG2 or HuH7 cells confirmed these findings by a release of virions into supernatant.

CONCLUSION

In conclusion, our results establish GBV-C as a hepatotropic virus infecting human cells of hepatic origin in vivo and in vitro.

Nonspecificity of monoclonal antibody Tordji-22 for the detection of hepatitis C virus in liver transplant recipients with cholestatic hepatitis

Detection of hepatitis C virus (HCV) antigens in liver tissue provides important diagnostic and pathological information. Limited studies have been performed on tissue taken after liver transplantation for HCV. In this study, serial post-liver transplantation biopsy tissue from patients with recurrent HCV was tested, with particular interest in patients showing severe cholestatic hepatitis. HCV-related antigens were detected using the commercial monoclonal antibody, Tordji-22. Initial results were promising, showing intense positive staining, especially in areas of hepatocyte ballooning. HCV-negative donor tissue was consistently negative by staining. However, as a final control for the level of tissue damage, HCV negative posttransplantation biopsy tissue showing hepatocyte ballooning was examined. These tissues also showed positive staining. All attempts to eliminate this nonspecific interaction failed. In conclusion, Tordji-22 was associated with nonspecificity in this posttransplantation population, and care is warranted when using this monoclonal antibody.

HCV RNA levels in serum, liver, and peripheral blood mononuclear cells of chronic hepatitis C patients and their relationship to liver injury

OBJECTIVE

We sought to evaluate the relationship between HCV RNA levels in serum, liver, and peripheral blood mononuclear cells (PBMC) and the degree of liver injury in chronic hepatitis C (CHC) patients.

METHODS

Thirty-six consecutive CHC patients were included in the study. The liver damage was evaluated by the histological activity index (HAI) score. The HCV RNA levels in the three compartments studied were assessed by bDNA assay. Nineteen patients were treated with alpha-interferon 2b (IFN).

RESULTS

Serum and liver HCV RNA levels in CHC patients were significantly associated with an increasing HAI score irrespective of the HCV genotypes. Cirrhotic patients showed higher HCV RNA levels than the CHC patients with HAI score 1-4 (p < 0.05), but had lower levels than the group with HAI score > 8 (p < 0.03). Patients with HAI score 1-4 showed the lowest levels of HCV RNA in PBMC. There was a strong relation (r = 0.78; p < 0.001) between serum and liver HCV RNA levels, but not between either serum or liver HCV RNA levels and those of PBMC. Seven patients showed a response to IFN and three of these had a sustained response. Pretreatment levels of HCV RNA in PBMC of the IFN responder patients were lower than those of the nonresponder patients (p < 0.02).

CONCLUSIONS

The data indicate a relation between serum or liver HCV RNA levels and the degree of liver injury in CHC patients, and show that serum HCV RNA level mirrors the hepatic viral burden.

Detection of widespread hepatocyte infection in chronic hepatitis C

The controversial question of the extent of hepatocyte infection in chronic hepatitis C was re-examined in both chimpanzees and humans using a newly modified in situ hybridization (ISH) method for detecting hepatitis C virus (HCV) RNA. The specificity of the methodology for distinguishing positive- and negative-strand synthetic HCV RNA was at least six magnitudes greater than the reverse-transcription polymerase chain reaction (RT-PCR) assay for HCV. The sensitivity of the methodology as determined by cell culture assay was 14 +/- 2 genomic equivalents (gE) of HCV positive strand per cell, which was three magnitudes less sensitive than RT-PCR quantitation of HCV. In contrast to previous studies in both humans and chimpanzees with chronic hepatitis C, a high percentage of hepatocytes positive for both positive- and negative-strand HCV RNA was found in most specimens studied. In humans, the extent of hepatocyte infection varied with histological activity index (HAI). In the two chimpanzees studied, the liver biopsies showed minimal histological disease activity, but high percentages of hepatocytes were HCV-positive by ISH that correlated with hepatocyte ultrastructural changes associated with HCV infection. Hepatocyte infection was confirmed by RNA extraction and RT-PCR techniques for detecting HCV RNA that minimize the false detection of negative strands. In both human and chimpanzee liver biopsies showing minimal HAI, the hepatocyte concentration of HCV was estimated to be very low. These findings suggested the hypothesis that persistent infection in the liver may be caused in part by low-level HCV replication. The theoretical and clinical implications of these findings are discussed.

Detection and localization by in situ molecular biology techniques and immunohistochemistry of hepatitis C virus in livers of chronically infected patients

Hepatitis C virus (HCV) detection in the livers of chronically infected patients remains a debatable issue. We used immunohistochemistry, in situ hybridization (ISH) alone or after microwave heating with FITC-labeled probes, RT-PCR with unlabeled primers followed by ISH (RT-PCR-ISH), and in situ RT-PCR with FITC-labeled primers (in situ RT-PCRd) to localize the virus in 38 liver biopsy specimens from 21 chronically infected HCV patients treated with interferon-alpha (IFN-alpha). Biopsies were taken at the beginning and end of IFN-alpha treatment and 1 year later. Results were compared with that of HCV-PCR in serum. RT-PCR-ISH and in situ RT-PCRd showed HCV signal in all liver biopsies even in responders with seronegative HCV PCR. This signal was intranuclear, diffuse, or peripheral, in hepatocytes, bile ductule cells, and lymphocytes. Cytoplasmic signals were occasionally observed. Whereas the percentage of labeled hepatocytes remained constant, the number of labeled lymphoid follicles decreased after INF-alpha therapy. Immunohistochemistry resulted in the same pattern of positivity but it was weaker and inconstant. This study indicates the persistency of HCV latency in IFN-alpha responders 1 year after IFN-alpha treatment cessation, a finding that certainly deserves confirmation.

Relative quantification and mapping of hepatitis C virus by in situ hybridization and digital image analysis

Although several reports concerning the detection of hepatitis C virus (HCV) by in situ hybridization have been published, there are no data concerning the relative viral load in infected hepatocytes or about its relation with serum viremia levels. To address these issues, liver biopsies from 10 patients with chronic hepatitis C were analyzed by in situ hybridization and digital image analysis of hybridization signals. Serum HCV RNA levels were measured using the Amplicor Monitor test. HCV RNA was detected by in situ hybridization in the hepatocytes of the ten liver samples. The hybridization signals were mainly found in the cytoplasm. The relative viral load per infected cell fit the second order polynomial curves in all cases. The minimum and maximum relative viral load per infected hepatocyte differed in the ten cases; however, large differences were not observed in the mean relative viral load among the samples, especially when compared with the increasing values detected for copy number per milliliter in serum. The percentage of infected cells ranged from 4.8% to 87.6% in the ten cases. The percentage of positive cells correlated with the serum viremia levels. Our data suggest that HCV viremia does not depend on the relative viral load per infected cell but on the number of infected hepatocytes.

Clinical significance of intrahepatic hepatitis C virus levels in patients with chronic HCV infection

BACKGROUND

The clinical significance of a single assessment of circulating hepatitis C virus (HCV) RNA and its relation to the level of intrahepatic HCV RNA remains unclear.

AIMS

To investigate the relation between intrahepatic HCV levels and clinicopathological characteristics of chronic HCV infection.

PATIENTS

Ninety eight consecutive patients with chronic HCV infection were studied; none had received alpha interferon therapy. Of these, 12 patients were repeatedly negative for HCV RNA in serum by reverse transcriptase polymerase chain reaction (RT-PCR).

METHODS

After diagnostic laparoscopy and liver biopsy, semiquantitative analysis of intrahepatic HCV RNA levels was carried out by limiting dilution of HCV cDNA. HCV genotypes were assessed in 96 patients by restriction fragment length polymorphism analysis of HCV cDNA.

RESULTS

Ten out of 12 patients who were RT-PCR negative for HCV RNA in serum were RT-PCR positive in liver; however, this group had a significantly lower intrahepatic HCV level and serum aminotransferase level than the remaining 86 patients. Histological severity (cirrhosis: n = 10); histological activity index; HCV genotype (genotype 1: n = 41; genotype 2: n = 12; genotype 3: n = 36; genotype 4: n = 7); mode of infection (intravenous drug abuse: n = 58; post-transfusion: n = 10; haemophiliac: n = 4; sporadic: n = 26) and alcohol abuse did not affect the intrahepatic virus level. There was no correlation between patient age, duration of infection, and intrahepatic HCV level.

CONCLUSIONS

Intrahepatic virus levels were not determined by host factors (age of patient, mode or duration of infection) or by virus factors (HCV genotype). Repeatedly negative RT-PCR for HCV RNA in serum does not indicate absence of HCV from the liver.

Transgenic mouse expressing a full-length hepatitis C virus cDNA

Hepatitis C virus (HCV), a major causative agent of post transfusion non-A, non-B hepatitis (NANBH), can only infect humans and chimpanzees. We produced nine transgenic mouse lines carrying a full-length HCV cDNA with the human serum amyloid P component (hSAP) promoter that can direct liver-specific expression. In one of these lines HCV mRNA and HCV core protein were detected in the liver of the transgenic mouse, although the levels of expression were very low. In addition, HCV-related antibody was detected in the serum.

Histopathology of HCV infection

The basic morphologic features of acute and chronic viral hepatitis C are similar to those of other hepatitides; however, hepatitis C is characterized by the histologic triad of lymphoid aggregates in portal tracts, epithelial damage of small bile ducts and microvesicular and macrovesicular steatosis of hepatocytes. Significant progress has been made in the demonstration of HCV in infected liver tissues by immunohistochemical and in situ hybridization techniques. The new classification of chronic hepatitis, based on etiology, grading (extent of necroinflammatory activity) and staging (extent of fibrosis) has been widely accepted and will lead to a better understanding of the variable course and response to therapy of this enigmatic disease.

Molecular and immune mechanisms in the pathogenesis of cardiomyopathy--role of viruses, cytokines, and nitric oxide

Myocarditis is thought to be commonly caused by various viruses, and accumulating evidence links viral myocarditis with the eventual development of dilated cardiomyopathy. Recently, the importance of hepatitis C virus infection was noted in patients with dilated and hypertrophic cardiomyopathy. Cytokines are being increasingly recognized as an important factor in the pathogenesis and pathophysiology of myocarditis and cardiomyopathy. Elevated levels of circulating cytokines have been reported in patients with heart failure, and various cytokines have been shown to depress myocardial contractility in vitro and in vivo. A number of reports have shown that cytokines generated by activated immune cells cause an increase in nitric oxide (NO) via induction of NO synthase. Increased generation of NO may induce negative inotropism and myocardial damage. This review discusses the etiology and pathogenesis of myocarditis and cardiomyopathy from this point of view.

Elimination of hepatitis C virus RNA in infected human hepatocytes by adenovirus-mediated expression of ribozymes

Hepatitis C virus (HCV), a positive-strand RNA virus, is the major infectious agent responsible for causing chronic hepatitis. Currently, there is no vaccine for HCV infection, and the only therapy for chronic hepatitis C is largely ineffective. To investigate new genetic approaches to the management of HCV infection, six hammerhead ribozymes directed against a conserved region of the plus strand and minus strand of the HCV genome were isolated from a ribozyme library, characterized, and expressed from recombinant adenovirus vectors. The expressed ribozymes individually or in combination were efficient at reducing or eliminating the respective plus- or minus-strand HCV RNAs expressed in cultured cells and from primary human hepatocytes obtained from chronic HCV-infected patients. This study demonstrates the potential utility of ribozyme therapy as a strategy for the treatment of hepatitis C virus infection.

Newer aspects of pathogenesis of heart failure: hepatitis C virus infection in myocarditis and cardiomyopathy

Myocarditis is thought to be commonly caused by various viruses, and accumulating evidence links viral myocarditis with the eventual development of dilated cardiomyopathy. In many cases, however, the evidence is only circumstantial, and direct conclusive proof is not available. Polymerase chain reaction (PCR) has been used to detect enterovirus RNA in myocardial tissue, but the wide discrepancy in results emphasizes the need for further study. We evaluated patients with cardiomyopathy and myocarditis by PCR for the presence of various RNA and DNA viruses in the heart. Hepatitis C virus RNA was found in high frequency, but enterovirus RNA was detected only in low frequency. Therefore, we investigated hepatitis C virus infection in patients with dilated cardiomyopathy. Antihepatitis C virus antibody was present in the sera of 6 of 36 patients (16.7%) with dilated cardiomyopathy and in 1 of 40 patients (2.5%) with ischemic heart disease, showing a statistically significant (P < .05) difference. Hepatitis C virus RNA was present in the sera of four of the six patients, and all four had hepatitis C virus type II. The copy number of hepatitis C virus RNA in the serum was 8 x 10(2) to 2 x 10(3) genomes per 1 mL serum. Positive strands of hepatitis C virus were found in the hearts of three patients, and negative strands of hepatitis C virus were detected in the hearts of two patients. The results suggest that hepatitis C virus infection is frequently found in patients with dilated cardiomyopathy and that hepatitis C virus is an important causal agent in the pathogenesis of the disease. Antiviral therapy against hepatitis C virus may be indicated in these patients.