The natural history of infection with hepatitis C virus (HCV) in chimpanzees: comparison of serologic responses measured with first- and second-generation assays and relationship to HCV viremia

A Tale of Two Viruses: Immunological Insights Into HCV/HIV Coinfection

Nearly 2.3 million individuals worldwide are coinfected with human immunodeficiency virus (HIV) and hepatitis C virus (HCV). Odds of HCV infection are six times higher in people living with HIV (PLWH) compared to their HIV-negative counterparts, with the highest prevalence among people who inject drugs (PWID) and men who have sex with men (MSM). HIV coinfection has a detrimental impact on the natural history of HCV, including higher rates of HCV persistence following acute infection, higher viral loads, and accelerated progression of liver fibrosis and development of end-stage liver disease compared to HCV monoinfection. Similarly, it has been reported that HCV coinfection impacts HIV disease progression in PLWH receiving anti-retroviral therapies (ART) where HCV coinfection negatively affects the homeostasis of CD4⁺ T cell counts and facilitates HIV replication and viral reservoir persistence. While ART does not cure HIV, direct acting antivirals (DAA) can now achieve HCV cure in nearly 95% of coinfected individuals. However, little is known about how HCV cure and the subsequent resolution of liver inflammation influence systemic immune activation, immune reconstitution and the latent HIV reservoir. In this review, we will summarize the current knowledge regarding the pathogenesis of HIV/HCV coinfection, the effects of HCV coinfection on HIV disease progression in the context of ART, the impact of HIV on HCV-associated liver morbidity, and the consequences of DAA-mediated HCV cure on immune reconstitution and HIV reservoir persistence in coinfected patients.

Hepatitis C Vaccines, Antibodies, and T Cells

The development of vaccines that protect against persistent hepatitis C virus (HCV) infection remain a public health priority. The broad use of highly effective direct-acting antivirals (DAAs) is unlikely to achieve HCV elimination without vaccines that can limit viral transmission. Two vaccines targeting either the antibody or the T cell response are currently in preclinical or clinical trials. Next-generation vaccines will likely involve a combination of these two strategies. This review summarizes the state of knowledge about the immune protective role of HCV-specific antibodies and T cells and the current vaccine strategies. In addition, it discusses the potential efficacy of vaccination in DAA-cured individuals. Finally, it summarizes the challenges to vaccine development and the collaborative efforts required to overcome them.

Nonhuman primate models of human viral infections

Humans have a close phylogenetic relationship with nonhuman primates (NHPs) and share many physiological parallels, such as highly similar immune systems, with them. Importantly, NHPs can be infected with many human or related simian viruses. In many cases, viruses replicate in the same cell types as in humans, and infections are often associated with the same pathologies. In addition, many reagents that are used to study the human immune response cross-react with NHP molecules. As such, NHPs are often used as models to study viral vaccine efficacy and antiviral therapeutic safety and efficacy and to understand aspects of viral pathogenesis. With several emerging viral infections becoming epidemic, NHPs are proving to be a very beneficial benchmark for investigating human viral infections.

The Chimpanzee Model of Viral Hepatitis: Advances in Understanding the Immune Response and Treatment of Viral Hepatitis

Chimpanzees (Pan troglodytes) have contributed to diverse fields of biomedical research due to their close genetic relationship to humans and in many instances due to the lack of any other animal model. This review focuses on the contributions of the chimpanzee model to research on hepatitis viruses where chimpanzees represented the only animal model (hepatitis B and C) or the most appropriate animal model (hepatitis A). Research with chimpanzees led to the development of vaccines for HAV and HBV that are used worldwide to protect hundreds of millions from these diseases and, where fully implemented, have provided immunity for entire generations. More recently, chimpanzee research was instrumental in the development of curative therapies for hepatitis C virus infections. Over a span of 40 years, this research would identify the causative agent of NonA,NonB hepatitis, validate the molecular tools for drug discovery, and provide safety and efficacy data on the therapies that now provide a rapid and complete cure of HCV chronic infections. Several cocktails of antivirals are FDA approved that eliminate the virus following 12 weeks of once-per-day oral therapy. This represents the first cure of a chronic viral disease and, once broadly implemented, will dramatically reduce the occurrence of cirrhosis and liver cancer. The recent contributions of chimpanzees to our current understanding of T cell immunity for HCV, development of novel therapeutics for HBV, and the biology of HAV are reviewed. Finally, a perspective is provided on the events leading to the cessation of the use of chimpanzees in research and the future of the chimpanzees previously used to bring about these amazing breakthroughs in human healthcare.

The past, present and future of neutralizing antibodies for hepatitis C virus

Hepatitis C virus (HCV) is a major cause of liver disease and hepatocellular carcinoma worldwide. HCV establishes a chronic infection in the majority of cases. However, some individuals clear the virus, demonstrating a protective role for the host immune response. Although new all-oral drug combinations may soon replace traditional ribavirin-interferon therapy, the emerging drug cocktails will be expensive and associated with side-effects and resistance, making a global vaccine an urgent priority. T cells are widely accepted to play an essential role in clearing acute HCV infection, whereas the role antibodies play in resolution and disease pathogenesis is less well understood. Recent studies have provided an insight into viral neutralizing determinants and the protective role of antibodies during infection. This review provides a historical perspective of the role neutralizing antibodies play in HCV infection and discusses the therapeutic benefits of antibody-based therapies. This article forms part of a symposium in Antiviral Research on "Hepatitis C: next steps toward global eradication."

Infection of common marmosets with hepatitis C virus/GB virus-B chimeras

The development of vaccination and novel therapy for hepatitis C virus (HCV) has been hampered by the lack of suitable small-animal models. GB virus B (GBV-B), closely related to HCV, causes viral hepatitis in common marmosets (Callithrix jacchue jacchus) and might represent an attractive surrogate model for HCV infection. However, differences exist between GBV-B and HCV in spite of a short genetic distance between the two viruses. Here we report common marmosets infected with two HCV/GBV-B chimeras containing HCV structural genes coding for either whole core and envelope proteins (CE1E2p7) or full envelope proteins (E1E2p7) substituted for the counterpart elements of GBV-B. Naïve animals intrahepatically injected with chimeric RNA transcripts or intravenously injected with sera from primary infected animals produced high levels of circulating infectious chimeric viruses and they developed chronic infection. Tacrolimus-treated marmosets inoculated with a CE1E2p7 chimera had higher viral loads and long-term persistent infection. A moderate elevation of serum aspartate aminotransferase (AST) levels was observed in parallel with viral replication. Chimeras recovered from liver samples revealed 1/958 adaptive viral mutations. Histopathological changes typical of viral hepatitis were observed in liver tissues from all types of HCV chimeras-infected marmosets. HCV core and E2 proteins were detected in liver tissues from infected animals by immunohistochemical staining. Fluctuations of chimeric virus replication in marmosets with spontaneous and sporadic viral clearance might be related to specific antibody and T-cell response to HCV proteins in vivo. Replication of CE1E2p7 chimera was observed in primary hepatocyte cultures by immunofluorescent staining in vitro.

CONCLUSION

Infectious HCV chimeras causing chronic hepatitis in marmosets might constitute a small primate model suitable for evaluation of virus-cell interaction, vaccination, and antiviral therapy against HCV infection.

Mechanism of hepatitis C virus infection

About 170 million persons are infected with hepatitis C virus (HCV) around the world, and nearly 80% of infected patients develop chronic liver disease that may eventually lead to liver cirrhosis or hepatocellular carcinoma. The mechanisms underlying the life cycle of HCV in the host are still largely unknown and the efforts made by researchers have been hampered by the absence of a robust system reproducing HCV infection. Moreover, there are no effective vaccines or drugs available to defend or exclude viruses because of frequent viral mutation. In 2005, several research groups have successfully established cell culture systems for HCV, pushing the basic research on HCV to a new stage. This paper will focus on HCV genome diversity, progress in culture models, HCV life cycle, and protein function to highlight the mechanism of HCV infection.

The GB viruses: a review and proposed classification of GBV-A, GBV-C (HGV), and GBV-D in genus Pegivirus within the family Flaviviridae

In 1967, it was reported that experimental inoculation of serum from a surgeon (G.B.) with acute hepatitis into tamarins resulted in hepatitis. In 1995, two new members of the family Flaviviridae, named GBV-A and GBV-B, were identified in tamarins that developed hepatitis following inoculation with the 11th GB passage. Neither virus infects humans, and a number of GBV-A variants were identified in wild New World monkeys that were captured. Subsequently, a related human virus was identified [named GBV-C or hepatitis G virus (HGV)], and recently a more distantly related virus (named GBV-D) was discovered in bats. Only GBV-B, a second species within the genus Hepacivirus (type species hepatitis C virus), has been shown to cause hepatitis; it causes acute hepatitis in experimentally infected tamarins. The other GB viruses have however not been assigned to a genus within the family Flaviviridae. Based on phylogenetic relationships, genome organization and pathogenic features of the GB viruses, we propose to classify GBV-A-like viruses, GBV-C and GBV-D as members of a fourth genus in the family Flaviviridae, named Pegivirus (pe, persistent; g, GB or G). We also propose renaming 'GB' viruses within the tentative genus Pegivirus to reflect their host origin.

HCV animal models: a journey of more than 30 years

In the 1970s and 1980s it became increasingly clear that blood transfusions could induce a form of chronic hepatitis that could not be ascribed to any of the viruses known to cause liver inflammation. In 1989, the hepatitis C virus (HCV) was discovered and found to be the major causative agent of these infections. Because of its narrow tropism, the in vivo study of this virus was, especially in the early days, limited to the chimpanzee. In the past decade, several alternative animal models have been created. In this review we review these novel animal models and their contribution to our current understanding of the biology of HCV.

Hepatitis C virus entry and neutralization

The processes of hepatitis C virus (HCV) entry and antibody-mediated neutralization are intimately linked. The high frequency of neutralizing antibodies (nAbs) that inhibit E2-CD81 interaction(s) suggests that this is a major target for the humoral immune response. The observation that HCV can transmit to naive cells by means of CD81-dependent and -independent routes in vitro awaits further investigation to assess the significance in vivo but may offer new strategies for HCV to escape nAbs. The identification of claudins in the entry process highlights the importance of cell polarity in defining routes of HCV entry and release, with recent experiments suggesting a polarized route of viral entry into cells in vitro. In this review, the authors summarize the current understanding of the mechanism(s) defining HCV entry and the role of nAbs in controlling HCV replication.

Hepatitis C virus infection--pathobiology and implications for new therapeutic options

Despite progress in therapeutic approaches for the elimination of hepatitis C, chronic hepatitis C virus infection remains an important cause of liver disease. Therapeutic intervention with the currently available interferon-based treatment regimens is quite successful, but treatment is difficult to tolerate and is contraindicated in many patients. A better understanding of the HCV biology, immunopathology, and liver disease will help to design better therapeutic strategies. The American Association for the Study of Liver Diseases sponsored a single-topic conference on hepatitis C virus infection on March 4 and 5, 2005, to enhance our current knowledge in the areas of basic and clinical research related to antiviral and immunomodulatory therapies in hepatitis C disease. The faculty consisted of 23 invited experts in the field of viral hepatitis. The program was divided into four sections including: (a) replicative mechanisms and models; (b) viral-host interactions; and (c) antiviral drug development and new strategies; and (d) back to the bedside-current issues. This report summarizes each of the presentations sections.

Acute GB virus B infection of marmosets is accompanied by mutations in the NS5A protein

GBV-B, a member of the Flaviviridae family of viruses, is the virus most closely related to HCV, and GBV-B infection in tamarin monkeys might represent a valuable surrogate animal model of HCV infection. In the current study, GBV-B was successfully transmitted to two marmosets (Callithrix jaccus). The infection resulted in viremia of 14- and 17-week duration, respectively, and was accompanied by elevation of isocitrate dehydrogenase activity. These data confirm that marmosets might represent an attractive model for GBV-B infection. The sequence of GBV-B NS5A, which was previously reported to have one of the highest mutation rates during infection in tamarins, was determined for viruses recovered from the inoculum and from marmoset blood samples obtained at weeks 1, 8, and 14 post inoculation in one marmoset and at weeks 2, 8, and 17 post inoculation in the other marmoset. In both animals, we detected four substitutions (R1945K, K2052G, F2196L, and G2268E), in the virus recovered immediately before viral clearance. Interestingly, two of these mutations (F2196L and G2268E) were described recently for viruses recovered from persistently infected tamarins. Appearance of these mutations presumably reflects a mechanism of immune escape rather than adaptation of the virus to a new host.

Evaluation of five hepatitis C virus screening tests and two supplemental assays: performance when testing sera from sexually transmitted diseases clinic attendees in the USA

The performances of five screening tests (recombinant peptide-based first and second generation tests from Abbott and Ortho, and a synthetic peptide-based test from Biochem Immunosystems) and two supplemental tests: recombinant peptide- based, Abbott neutralization test and Chiron second generation recombinant immunoblot assay (RIBA 2), were evaluated for their ability to detect hepatitis C virus (HCV) antibodies in a population of 276 individuals attending a sexually transmitted diseases (STD) clinic in the USA. Although the five screening tests produced a variable number (35-62) of repeatedly reactive samples, only 13% (36/276) were classified as true positives by the supplemental tests. Thirty-four of the 36 were reactive by all screening tests and 32 of the true positives were reactive by both supplemental tests, while 2 did not neutralize but were reactive in the RIBA 2 test. Of the remaining 2 of the true positives which were discordant by several of the screening assays, 1 was confirmed by both supplemental assays but the other required a chemiluminescent enhancement technique to show positivity in RIBA 2. The sensitivities of the first and second generation Abbott and Ortho tests ranged from 97% to 100% and that of the Biochem test was 94%. The specificities of these tests ranged from 89.2% to 99.6%. The second generation Ortho test presented 9.4% (26/276) false positives. The use of second generation Ortho as a screening test would lead to an excessive number of confirmatory false positives. the positive predictive values of the screening tests ranged from 58.1% to 97.1%. Although the synthetic peptide based Biochem test exhibited the best overall indices, the presence of 2 false negative results would prevent its use as a singular screening test. Nevertheless its high specificity may lend itself to be used as a second screening test before confirmatory testing with RIBA 2.

T cell response in hepatitis C virus infection

Hepatitis C virus (HCV) is a hepatotropic RNA virus that causes acute and chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma. It is widely accepted that cellular immune responses play an important role in viral clearance and disease pathogenesis. However, HCV often evades effective immune recognition and has a propensity to persist in the majority of acutely infected individuals (ca. 80%). The immunological and virological basis for the inefficiency of the cellular immune response to clear or control the virus is not known. Recent studies, however, have provided new insights into the mechanisms of viral clearance and persistence that will be discussed in detail.

Hepatitis C virus

Hepatitis C virus is a common blood-borne pathogen that is now declining as a new infection in the population. However, women and men who were infected 2 to 3 decades ago are now developing liver damage. To prevent further damage, treatment with IFN and ribavirin is available. Because of adverse events, this treatment requires close supervision over 6 to 12 months, which is often provided by a clinic nurse in collaboration with the physician and pharmacist. Educational outreach to the public and health care providers may help identify patients earlier and promote screening of high-risk groups.

Chronic hepatitis associated with GB virus B persistence in a tamarin after intrahepatic inoculation of synthetic viral RNA

Progress in understanding the pathogenesis of hepatitis C virus (HCV) has been slowed by the absence of tractable small animal models. Whereas GB virus B (GBV-B, an unclassified flavivirus) shares a phylogenetic relationship and several biologic attributes with HCV, including hepatotropism, it is not known to cause persistent infection, a hallmark of HCV. Here, we document persistent GBV-B infection in one of two healthy tamarins (Saguinus oedipus) inoculated intrahepatically with infectious synthetic RNA. High-titer viremia (108 to 109 genome equivalents per ml) and transiently elevated serum alanine transaminase activities were present from weeks 4 to 12 postinoculation in both animals. However, whereas GBV-B was eliminated from one animal by 20 weeks, the second animal remained viremic (103 to 107 genome equivalents per ml) for >2 years, with alanine transaminase levels becoming elevated again before spontaneous resolution of the infection. A liver biopsy taken late in the course of infection demonstrated hepatitis with periportal mononuclear infiltrates, hepatocellular microvesicular changes, cytoplasmic lipid droplets, and disordered mitochondrial ultrastructure, findings remarkably similar to chronic hepatitis C. GBV-B-infected hepatocytes contained numerous small vesicular membranous structures resembling those associated with expression of HCV nonstructural proteins, and sequencing of GBV-B RNA demonstrated a rate of molecular evolution comparable to that of HCV. We conclude that GBV-B is capable of establishing persistent infections in healthy tamarins, a feature that substantially enhances its value as a model for HCV. Mitochondrial structural changes and altered lipid metabolism leading to steatosis are conserved features of the pathogenesis of chronic hepatitis caused by these genetically distinct flaviviruses.

Changes in hypervariable region 1 of the envelope 2 glycoprotein of hepatitis C virus in children and adults with humoral immune defects

The N-terminal end of the hepatitis C virus (HCV) envelope glycoprotein E2 contains a stretch of 27 amino acids that exhibit increased variability. This hypervariable region 1 (HVR-1), as it is normally referred to, is thought to contain epitopes that come under humoral immune attack. In the present study, 10 patients (5 children and 5 adults) with humoral immune defects and chronic HCV infection were investigated, to see how HVR-1 sequences behave over time in these patients who are unable to produce antibodies. Amplicons of this region showed little or no variation at all over time, indicating that quasispecies variation in this region is driven by the host's humoral immune response.

Tissue culture and animal models for hepatitis C virus

In recent years, significant advances have been achieved both in the development of animal- and tissue-culture models for HCV. Among all the new systems, the small animal model based on transgenic mice with chimeric mouse-human livers and the replicon system will presumably have the most profound impact on future HCV research. Yet, in spite of this progress, much more work will be required to optimizse both systems. In case of the mouse model, breeding homozygous Alb-uPa animals is difficult because of the toxicity of the transgene, and the transplantation of primary human hepatocytes into mice a few days after birth is technically challenging. These are immunodeficient, and, therefore, it will be desirable to furnish them with components of the human immune system in order to expand the applicability of this in vivo model to questions related to pathogenesis. Advances in cryopreservation techniques are urgently needed, moreover, as this would improve the availability of primary hepatocytes and in turn also the accessibility of this small animal model. As regards the replicon system, a number of open questions remain that will hopefully be answered by future research. Why, for instance, has replication in cell culture so far been achieved only with genotype 1b isolates, whereas an isolate with proven infectivity derived from genotype 1a failed to replicate in Huh-7 cells? And why can replicons so far be propagated only in this particular cell line? Is this attributable to the lack of certain inhibitory factors, or the presence of specific activators? What are the mechanisms underlying cell-culture adaptation. and what determines whether a certain Huh-7 cell replicates HCV RNA more efficiently? Finally, the replicon system may also lead the way to the development of systems for efficient virus production in cell culture, and ultimately also a permissive cell line. These developments would at last allow us to model the complete viral life cycle, something researchers have been struggling with ever since the first identification of HCV.

Removal of cell-bound lipoproteins: a crucial step for the efficient infection of liver cells with hepatitis C virus in vitro

Hepatitis C virus (HCV) is of major social, medical and economic importance. The prevalence of HCV is approximatively 1% in most developed countries, and much higher in developing countries. HCV infection is the second major cause, after hepatitis B virus infection, for the generation of chronic liver disease and hepatocellular carcinoma. To date, the only reliable model for the study of HCV infection is the chimpanzee. Indeed, there is no robust in vitro infection system, yet. There is thus an urgent need for such an in vitro infection system in order to evaluate therapeutic agents. Here, a process is provided for infecting hepatocyte cell lines with hepatitis C virus in vitro. It is strongly suggested that cell-bound lipoproteins are playing a crucial role during the infection process. In order to obtain a robust infection, the cell-bound lipoproteins have first to be removed from their cellular receptor prior to the addition of viral inocula originating from human sera, the latter being made originally of a virus-lipoprotein complex.

Generation of infectious and transmissible virions from a GB virus B full-length consensus clone in tamarins

The strong similarity between GB virus B (GBV-B) and hepatitis C virus (HCV) makes tamarins infected by GBV-B an acceptable surrogate animal model for HCV infection. Even more attractive, for drug discovery purposes, is the idea of constructing chimeric viruses by inserting HCV genes of interest into a GBV-B genome frame. To accomplish this, infectious cDNA clones of both viruses must be available. The characterization of several HCV molecular clones capable of infecting chimpanzees has been published, whereas only one infectious GBV-B clone inducing hepatitis in tamarins has been reported so far. Here we describe the infection of tamarins by intrahepatic injection of RNA transcribed from a genomic GBV-B clone (FL-3) and transmission of the disease from infected to naive tamarins via serum inoculation. The disease resulting from both direct and secondary infection was characterized for viral RNA titre and hepatitis parameters as well as for viral RNA distribution in the hepatic tissue. Host humoral immune response to GBV-B antigens was also monitored. The progression of the disease was compared to that induced by intravenous injection of different amounts of the non-recombinant virus.

Strategies for reliable diagnosis of hepatitis C infection: the need for a serological confirmatory assay

The aim of the study was to examine whether the diagnosis of Hepatitis C (HCV) infection can be obtained reliably without using an immunoblot-based confirmation assay. 1,708 EIA-reactive serum samples were examined retrospectively for (i) optical density value in the screening assay, (ii) reactivity in an immunoblot assay, and (iii) result by RT PCR. In 1,394 (81.0%) samples positive results were obtained by both the HCV EIA and the confirmation assay. OD-values > or = 2.2 were observed in 1026 of these samples, but covered the range from 0.4 to 2.1 in the other 368 samples. The combination of HCV EIA reactivity and indeterminate immunoblot assay was observed in 134 (7.8%) serum samples. HCV RNA was detected in 58 cases by PCR. The OD-values of these 58 samples ranged from 0.4 to >2.2. Especially reactivity against the core recombinant protein was indicative of PCR positivity. The reactivity by the HCV EIA could not be confirmed by immunoblot assay or PCR in 180 (10.5%) sera. These false reactive sera showed OD values by EIA from 0.3 to 2.1. It is concluded that no threshold values can be defined which would allow differentiation between positive, indeterminate, and false reactive result by HCV EIA without producing an unacceptably high number of false negative diagnoses. Not using immunoblot-based confirmation would result in many additional PCR examinations. Therefore, confirmation of reactive HCV EIA results by a serological confirmatory assay must remain an essential part of the diagnostic procedure.

Processing of GB virus B non-structural proteins in cultured cells requires both NS3 protease and NS4A cofactor

The identification of antivirals and vaccines against hepatitis C virus (HCV) infection is hampered by the lack of convenient animal models. The need to develop surrogate models has recently drawn attention to GB virus B (GBV-B), which produces hepatitis in small primates. In a previous study in vitro, it was shown that GBV-B NS3 protease shares substrate specificity with the HCV enzyme, known to be crucial for virus replication. In this report, GBV-B NS3 activity on GBV-B precursor proteins has been analysed in a cell-based system. It is shown that mature protein products are obtained that are compatible with the cleavage sites proposed on the basis of sequence homology with HCV and that GBV-B NS4A protein is required as a cofactor for optimal enzymatic activity. Experiments in vitro supported by a structural model mapped the region of NS4A that interacts with NS3 and showed that the GBV-B cofactor cannot be substituted for by its HCV analogue.

Induction of hepatitis C virus-specific cytotoxic T lymphocytes in mice by an intrahepatic inoculation with an expression plasmid

We assessed the possibility of intrahepatic inoculation with a plasmid encoding hepatitis C virus (HCV) proteins to elicit HCV-specific cytotoxic T lymphocytes (CTL) in mice as a conventional animal model of HCV infection. BALB/c mice were intrahepatically or intramuscularly inoculated with an expression plasmid DNA encoding HCV structural proteins under the control of the elongation factor 1-alpha promoter. Expressions of HCV-core protein and envelope proteins (E1 and E2) in hepatocytes were detected immunohistochemically 6 days after inoculation. CTL responses were examined using target cells either pulsed with a specific peptide or infected with a recombinant vaccinia virus expressing HCV structural protein. Both intrahepatically and intramuscularly DNA-inoculated mice developed CD8(+), MHC class I-restricted CTL responses that recognized the peptide pulsed as well as HCV proteins expressing target cells. These studies demonstrated the usefulness of a murine model of HCV infection induced by direct intrahepatic DNA inoculation for understanding the immunopathogenic mechanisms in HCV infection.

Priming of hepatitis C virus-specific cytotoxic T lymphocytes in mice following portal vein injection of a liver-specific plasmid DNA

The immunology of hepatitis C virus (HCV) infection should be studied in the context of HCV antigen expression in the liver, because HCV primarily infects this organ. Indeed, the nature, function, and fate of T cells primed after antigen expression in the liver might differ from those primed when antigens are expressed systemically or in other organs, because the nature of the antigen-presenting cells (APCs) involved may be different. In addition, the normal liver contains a resident population of lymphocytes that differ from those present at other sites. Thus, we investigated whether HCV-specific CD8(+) cytotoxic T cells (CTLs) could be elicited following portal vein (PV) injection of plasmid DNA in mice whose hepatic veins were transiently occluded. We show that PV injection of mice with "naked" DNA expressing the HCV-NS5a protein, under the control of a liver-specific enhancer/promoter, resulted in NS5a expression in the liver and the priming of HCV-specific CTLs. These results suggested that such a model might be relevant to the study of HCV-specific immune responses primed during natural infection.

HCV seroreactivity and detection of HCV RNA in cirrhotics

This study was carried out to determine the presence of HCV infection in cirrhotic patients and to compare their serologic profiles with detection of HCV RNA by RT-PCR. Liver function profiles were assessed and correlated with infection. Coinfection of HCV with HBV was studied in the Indian context Sera from 62 patients of biopsy confirmed cirrhosis and an equal number of asymptomatic controls were tested for HCV by two ELISA (third generation) kits and nested reverse transcription PCR using primers from the 5'NCR. Other tests included HBV serology (ELISA for HBsAg and anti-HBc) and liver function tests. Twenty-four (38.7%) cases were HCV infected, of which 17 (70.8%) had past exposure to HBV or were coinfected with HBV (either being chronically infected or carriers of HBV). There was no significant difference in the clinical and liver function profiles of HCV infected and uninfected cirrhotics. Similarly, no difference was observed in cases coinfected with both HCV and HBV compared with those infected with HCV alone. Although the difference between positivity of HCV RNA and of anti-HCV was not significant, HCV RNA and anti HCV were present together in only 7/62 (11.3%) cases. Thus testing for both antibody and HCV RNA would be more appropriate than either test alone. HBV infection was seen in about one-fourth of HCV infected cirrhotics. About one-fourth (25.8%) patients had non-B, non-C cirrhosis in whom testing for HCV variants and other recently characterized hepatitis viruses could be performed.

Low risk of vertical transmission of hepatitis C virus by breast milk

To evaluate the risk of hepatitis C virus (HCV) transmission via breast milk, we collected 76 samples of breast milk from 73 chronically HCV-infected women and serum samples from their 76 perinatally HCV-exposed children. Enzyme immunoassay and strip immunoblot assay were used for detection of antibodies to HCV, and reverse transcriptase-polymerase chain reaction analysis was used for detection of HCV RNA. None of the 76 samples of breast milk contained HCV RNA, whereas 37 (59.7%) of 62 mothers tested for HCV RNA had HCV viremia. Only 1 of the 76 breast-fed infants had evidence of HCV infection. Because HCV infection in this child was detected 1 month after birth, it seems unlikely that it was transmitted by breast-feeding. These results indicate that HCV infection in pregnant women should not be a contra-indication for breast-feeding.

Assay for hepatitis C virus in peripheral blood mononuclear cells enhances sensitivity of diagnosis and monitoring of HCV-associated hepatitis

Hepatitis C virus (HCV) is a major etiological factor in chronic hepatitis affecting up to 24% of blood donors in Egypt. Since fluctuating levels of HCV RNA loads, including undetectable values, have been frequently observed in sera of chronic hepatitis patients, this study was designed to assess the sensitivity of PCR amplification for the plus- and minus-RNA strands in peripheral blood mononuclear cells (PBMC) compared to single serum PCR assay. Since the latter test detects viremia in only 79.5% of seropositive cases, the highest sensitivity for HCV diagnosis was achieved (93.20% when applying the combined triple test including PCR amplification of plus-strand in serum, together with plus-strand in PBMC and minus-strand in PBMC. The results of this study indicate that the triple test provides significant information on extrahepatic replication of HCV in a sizable sample of seropositive subjects (429 cases) and improves the assessment of HCV viremia. The cost/effectiveness and speed were upgraded by using capillary/air rapid thermal cycler. The use of the triple assay in HCV diagnosis and post-therapy monitoring is recommended.

In vitro human Th-cell responses to a recombinant hepatitis C virus antigen: failure in IL-2 production despite proliferation

Hepatitis C Virus (HCV) causes chronic infection in 80-90% of those exposed and persists despite evidence of immune recognition. To understand the immunological basis of this phenomenon, we have synthesized a non structural (NS) protein that is critical to HCV infection and replication, NS3, and used it to study in vitro helper T-cell responses from infected individuals. Strong proliferative responses were generated by peripheral T-cells isolated from a subset of chronically infected patients, but not by normal, non-infected controls. Interestingly, though gamma-interferon (gammaIfn) and IL-10 were both secreted in response to stimulation by NS3 antigen, IL-2 was not. In contrast, IL-2 was secreted in response to influenza virus vaccine antigen. Lack of IL-2 induction was confirmed by a failure to amplify IL-2 mRNA upon NS3 antigen stimulation, whereas IL-4, IL-15, and gammaIfn mRNA were seen as early as 24 h. The predominance of IL-4 and IL-10 and the lack of IL-2 suggests that in vitro responses to at least some HCV antigens are biased towards a Th2 phenotype, which may be conducive to viral persistence.

What strategy should be used for diagnosis of hepatitis C virus infection in clinical laboratories?

The aim of this study was to determine a cost-effective strategy for the diagnosis of hepatitis C virus (HCV) infection in clinical laboratories. Anti-HCV antibodies were sought in 3,014 consecutive unselected samples with two different enzyme-linked immunosorbent assays (ELISA). An immunoblot-based confirmatory assay (RIBA3.0) was performed in the samples with at least one ELISA positive or weakly positive. HCV RNA was evaluated using HCV polymerase chain reaction (PCR) in the samples with a weakly positive ELISA, discrepant results of the two ELISAs, or an indeterminate RIBA3.0 pattern. The two ELISAs gave concordant results in 2,957 (98.1%) of the 3,014 samples (negative in 87.9%, positive in 11.8%, and weakly positive in 0.3%), and discrepant results in 57 (1.9%). RIBA3.0 was positive in 338 of the 350 ELISA-positive samples (96.6%) and indeterminate in 12. Six of them were PCR-positive. Among the 8 weakly positive samples, 1 was RIBA3.0-positive, 6 were RIBA3.0-indeterminate, and 1 was RIBA3.0-negative; all were PCR-negative. Among the 57 samples with discrepant ELISA results, 4 were RIBA3.0-positive (none were PCR-positive), 22 were RIBA3.0-indeterminate (1 was PCR-positive), and 31 were RIBA3.0-negative (6 were PCR-positive). In these cases, the clinical context and PCR detection of HCV RNA allowed for definitive classification. In conclusion, one single ELISA determination is necessary for diagnosis of HCV infection in clinical laboratories, and confirmation of positive or weakly positive ELISAs with immunoblot-based confirmatory assays is no longer needed. HCV-RNA detection by PCR helps to resolve weakly positive or negative ELISA results when the clinical context is compatible with hepatitis C.

Analysis of hepatitis C virus-inoculated chimpanzees reveals unexpected clinical profiles

The clinical course of hepatitis C virus (HCV) infections in a chimpanzee cohort was examined to better characterize the outcome of this valuable animal model. Results of a cross-sectional study revealed that a low percentage (39%) of HCV-inoculated chimpanzees were viremic based on reverse transcription (RT-PCR) analysis. A correlation was observed between viremia and the presence of anti-HCV antibodies. The pattern of antibodies was dissimilar among viremic chimpanzees and chimpanzees that cleared the virus. Viremic chimpanzees had a higher prevalence of antibody reactivity to NS3, NS4, and NS5. Since an unexpectedly low percentage of chimpanzees were persistently infected with HCV, a longitudinal analysis of the virological profile of a small panel of HCV-infected chimpanzees was performed to determine the kinetics of viral clearance and loss of antibody. This study also revealed that a low percentage (33%) of HCV-inoculated chimpanzees were persistently viremic. Analysis of serial bleeds from six HCV-infected animals revealed four different clinical profiles. Viral clearance with either gradual or rapid loss of anti-HCV antibody was observed in four animals within 5 months postinoculation. A chronic-carrier profile characterized by persistent HCV RNA and anti-HCV antibody was observed in two animals. One of these chimpanzees was RT-PCR positive, antibody negative for 5 years and thus represented a silent carrier. If extrapolated to the human population, these data would imply that a significant percentage of unrecognized HCV infections may occur and that silent carriers may represent potentially infectious blood donors.

Transmission of hepatitis C by intrahepatic inoculation with transcribed RNA

More than 1% of the world's population is chronically infected with hepatitis C virus (HCV). HCV infection can result in acute hepatitis, chronic hepatitis, and cirrhosis, which is strongly associated with development of hepatocellular carcinoma. Genetic studies of HCV replication have been hampered by lack of a bona fide infectious molecular clone. Full-length functional clones of HCV complementary DNA were constructed. RNA transcripts from the clones were found to be infectious and to cause disease in chimpanzees after direct intrahepatic inoculation. This work defines the structure of a functional HCV genome RNA and proves that HCV alone is sufficient to cause disease.

GB virus B and hepatitis C virus NS3 serine proteases share substrate specificity

GB virus B (GBV-B) is a recently discovered virus responsible for hepatitis in tamarins (Saguinus species). GBV-B belongs to the Flaviviridae family and is closely related to the human pathogen hepatitis C virus (HCV). Nonstructural protein 3 (NS3) of HCV has been shown to encompass a serine protease domain required for viral maturation. GBV-B and HCV share only about 30% of the amino acid sequence within the NS3 protease domain. The catalytic triad is conserved, and the residue Phe-154, presumed to be a crucial amino acid for determining the S1 specificity pocket of the HCV NS3 protease, is also conserved. We have expressed a synthetic gene encoding the GBV-B NS3 protease domain in Escherichia coli and have characterized the purified recombinant protein for its activity on HCV substrates. We have shown that the NS3 region of the GBV-B genome actually encodes a serine protease that, despite the low sequence homology, shares substrate specificity with the HCV NS3 protease.

Comparative features of hepatitis C virus infection in humans and chimpanzees

Several features of human HCV infection are recapitulated in the chimpanzee model. Most importantly, the frequency of persistent infection is high in both species, and virus replication occurs despite evidence of cellular and humoral immune responses. A key difference is that necroinflammatory lesions in chronically infected chimpanzees are almost always mild, whereas in humans the disease spectrum is very wide, ranging from mild to severe hepatitis and end-stage cirrhosis requiring transplantation. Understanding the basis for both the similarities and differences in persistent hepatitis C in the two species will probably be important for the development of effective prevention and therapy of HCV infection.

The quantitative humoral immune response to the hepatitis C virus is correlated with disease activity and response to interferon-alpha

BACKGROUND/AIM

Virus-host interactions may have pathogenetic significance in chronic hepatitis. Thus the humoral immune response was evaluated during the clinical course of HCV-infected patients.

METHODS

Eighteen selected chronic HCV patients received three doses of 3 or 6 MU interferon-alpha 2a weekly for 6 to 12 months and were followed up for 6 to 60 months. Anti-HCV antibody levels were serially measured either in end-point diluted sera with the Matrix-Assay or with quantitative anti-HC34-IgG and -IgM ELISA. Circulating immune complexes were assessed by flow cytometry and the results were correlated with histology, quantitative HCV-RNA levels and genotypes.

RESULTS

Nine complete responders (CR; genotypes 1a n = 4; 1b n = 1; 2a n = 1; 3a n = 3) showing sustained virus elimination and ALT normalisation had low HCV-RNA pretreatment levels (mean 14 x 10(3) copies/ml) compared to six nonresponders and three partial responders (NR/PR; genotypes 1a n = 2; 1b n = 7) who had significantly higher HCV-RNA pretreatment levels (mean 254 x 10(3) copies/ml; p < 0.01). In untreated NR/PR the HC34 core-antigen was most immunogenic, in CR the NS3-derived HC29-antigen. Pre-treatment levels of anti-HC 34-IgG and -IgM antibody levels in NR/PR were higher than in CR (IgM/IgG p = 0.05, n.s.) and these differences became significant during or after therapy (3 months therapy: IgM p < 0.02/IgG p < 0.07; end of therapy: IgM 0.006/IgG p < 0.04; 6 months post-therapy: IgM p < 0.002/IgG p < 0.004). The PR patients showed recurrent anti-HC34 antibody levels that preceded disease reactivation and detectable HCV-RNA in serum. Immune complex formation increased in some patients during treatment but did not correlate with disease activity, quantitative viraemia, antibody levels or therapy outcome.

CONCLUSION

Anti-HC34 antibodies, i.e. of the IgM-subtype, correlated quantitatively with viraemia and disease activity. Monitoring the antibody levels may predict the long-term therapy outcome during interferon-alpha treatment.

Hepatitis C virus and organ transplantation

Hepatitis C virus (HCV) is both the leading cause of cirrhosis and hepatic failure leading to liver transplantation and a cause of chronic hepatitis in approximately 10% of all transplant recipients. Beginning 5-10 years or more posttransplant, HCV causes progressive liver disease in a significant fraction of infected individuals and contributes to an increased incidence of opportunistic infection and hepatocellular carcinoma. The existence of multiple genotypes of HCV with differing biologic behaviors and the generation of antigenic diversity of the virus (quasispecies) during the course of infection, limit the capacity of the immune system to generate protective immunity. Antiviral therapy with interferon-alpha is effective in only a minority of transplant patients, and since allografts from HCV infected donors are quite efficient in transmitting the virus, great attention is paid to the appropriate use of organs from HCV-positive donors. At present, these organs should be particularly targeted for patients in emergent need of lifesaving heart, liver, or lung transplants. Issues requiring further investigation include the impact of viral superinfection on HCV-infected recipients of organs from HCV-infected donors and the use of such organs in seronegative patients who are older, diabetic, or highly sensitized, for whom quality of life issues may outweigh the long-term impact of HCV infection.

HCV replication in mononuclear cells stimulates anti-HCV-secreting B cells and reflects nonresponsiveness to interferon-alpha

Recently, it was demonstrated in chronic hepatitis C that the release of IgG and IgM anti-HCV antibodies by mononuclear cells (PBMCs) correlated with inflammatory activity, HCV persistence in serum, and negative outcome from antiviral therapy. Thus, persistent antigenic stimulation of the antibody-secreting B cells has been suggested. In this study, PBMCs were derived from 13 patients with chronic hepatitis C. Nucleic acids were extracted by the guanidine-thiocyanate-method, and plus- and minus-stranded HCV-RNAs were determined using primers from the 5'-untranslated region of HCV. Simultaneously, unstimulated PBMCs were cultured for 8 days and anti-HCV antibodies were detected in the supernatants by EIA and RIBA. Seven patients (53.8%) had both plus- and minus-stranded HCV-RNA in PBMCs, while anti-HCV antibodies were secreted in vitro. One of 2 patients with plus- but not minus-stranded HCV-RNA in PBMCs was anti-HCV positive in vitro, whereas 4 patients without HCV-infected PBMCs were anti-HCV negative in vitro. Eight patients received antiviral therapy with interferon-alpha 2b. Four nonresponders and 1 partial responder had plus- and minus-stranded HCV-RNA in PBMCs and anti-HCV secretion in vitro. On the other hand, 2 complete responders and another partial responder showed neither HCV infection of PBMCs nor anti-HCV secretion in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)

Prevalence of hepatitis C antibody in patients with chronic liver disease and hepatocellular carcinoma in Korea

To investigate the contribution of hepatitis C virus (HCV) to chronic liver disease and hepatocellular carcinoma (HCC) in Korea, antibodies to HCV (anti-HCV) were tested by enzyme immunoassay in 1759 patients with chronic liver disease and HCC, and in 808 healthy adults. The prevalence of anti-HCV was 1.6% in 808 controls. Anti-HCV was present in 32 (7.7%) of 418 hepatitis B surface antigen (HBsAg)-positive and 128 (53.1%) of 241 HBsAg-negative patients with chronic hepatitis, 16 (6.0%) of 265 HBsAg-positive and 90 (30.5%) of 295 HBsAg-negative patients with liver cirrhosis, and 16 (4.8%) of 330 HBsAg-positive and 61 (29.0%) of 210 HBsAg-negative patients with HCC. Antibodies to hepatitis B core antigen (anti-HBc) were present in 80-88% of patients who were seropositive for anti-HCV and seronegative for HBsAg. Among the sera from 114 patients with HBsAg-negative and anti-HCV-positive chronic liver diseases, HBV DNA and HCV RNA were detected by polymerase chain reaction (PCR) in 54 (47.4%) and 61 (53.3%), respectively. Both HBV DNA and HCV RNA were detected in 4 (4.4%) samples. The mean age of the patients with both HBsAg and anti-HCV was not different from that of patients who were seropositive for HBsAg alone. These findings indicate that current and/or past HBV infection is still the main cause of chronic liver disease in Korea.(ABSTRACT TRUNCATED AT 250 WORDS)

Significance of IgG and IgM HCV antibody secretion in vitro in patients with chronic hepatitis C: correlation with disease activity and response to interferon-alpha

Hepatitis C virus antibodies are found in the serum of most patients with chronic hepatitis C. However, the significance of the humoral response is still uncertain. In this study, in vitro IgG and IgM anti-hepatitis C virus secretion by peripheral blood mononuclear cells of patients with chronic hepatitis C was analyzed. Peripheral-blood mononuclear cells from 21 of 36 patients (58.3%) secreted IgG anti-hepatitis C virus in vitro, as demonstrated with anti-hepatitis C virus-specific enzyme immunoassays and recombinant immunoblot assays. Ten of the 36 patients (27.8%) showed both IgG and IgM anti-hepatitis C virus core in vitro. In 9 of these 10 patients, IgM anti-hepatitis C virus was also detected in serum. Patients with in vitro IgM or IgG anti-hepatitis C virus secretion had higher ALT levels in serum than did patients without such secretion in vitro (99.5 +/- 22.1 and 85.6 +/- 34.4 vs. 38.1 +/- 37.4 U/L; p < 0.0001, p < 0.001). Furthermore, with a histology activity score it was demonstrated that patients with in vitro IgM or IgG HCV antibodies (or both) had more severe chronic active hepatitis than did patients without in vitro hepatitis C virus antibody secretion (p < 0.01). To analyze the therapy outcome, we included in this study 18 patients who had received interferon-alpha previously. Seven of eight in vitro hepatitis C virus antibody-positive patients were nonresponders, whereas the in vitro hepatitis C virus antibody-negative patients were mostly complete therapy responders (8 of 10).(ABSTRACT TRUNCATED AT 250 WORDS)

Hepatitis C: progress and problems

The hepatitis C virus (HCV), a single-stranded RNA virus, is the major cause of posttransfusion hepatitis. HCV isolates differ in nucleotide and amino acid sequences. Nucleotide changes are concentrated in hypervariable regions and may be related to immune selection. In most immunocompetent persons, HCV infection is diagnosed serologically, using antigens from conserved regions. Amplification of RNA may be necessary to detect infection in immunosuppressed patients. Transmission by known parenteral routes is frequent; other means of spread are less common and may represent inapparent, percutaneous dissemination. Infection can lead to classical acute hepatitis, but most infected persons have no history of acute disease. Once infected, most individuals apparently remain carriers of the virus, with varying degrees of hepatocyte damage and fibrosis ensuing. Chronic hepatitis may lead to cirrhosis and hepatocellular carcinoma. However, disease progression varies widely, from less than 2 years to cirrhosis in some patients to more than 30 years with only chronic hepatitis in others. Determinants important in deciding outcome are unknown. Alpha interferon, which results in sustained remission in selected patients, is the only available therapy. Long-term benefits from such therapy have not been demonstrated. Prevention of HCV infection by vaccination is likely to be challenging if ongoing viral mutation results in escape from neutralization and clearance.

Prevention of hepatitis C virus infection in chimpanzees after antibody-mediated in vitro neutralization

Hepatitis C virus (HCV) is the most important etiologic agent of non-A, non-B hepatitis and is a major cause of chronic liver disease and hepatocellular carcinoma. Development of an effective vaccine would be the most practical method for prevention of the infection, but whether infection with HCV elicits protective immunity in the host is unclear. Neutralization of HCV in vitro was attempted with plasma of a chronically infected patient, and the residual infectivity was evaluated by inoculation of eight seronegative chimpanzees. The source of HCV was plasma obtained from a patient during the acute phase of posttransfusion non-A, non-B hepatitis, which had previously been titered for infectivity in chimpanzees. Neutralization was achieved with plasma obtained from the same patient 2 yr after the onset of primary infection but not with plasma obtained 11 yr later, although both plasmas contained antibodies against nonstructural and structural (including envelope) HCV proteins. Analysis of sequential viral isolates from the same patient revealed significant genetic divergence as early as 2 yr after infection. However, the HCV recovered from the patient 2 yr after the infection had a striking sequence similarity with the HCV recovered from one of the chimpanzees inoculated with the acute-phase virus, suggesting that the progenitor of the new strain was already present 2 yr earlier. This evidence, together with the different sequences of HCV recovered from the chimpanzees that received the same inoculum, confirms that HCV is present in vivo as a quasispecies. These results provide experimental evidence in vivo that HCV infection elicits a neutralizing antibody response in humans but suggest that such antibodies are isolate-specific. This result raises concerns for the development of a broadly reactive vaccine against HCV.

Hepatitis C virus: historical perspective and current concepts

Over the past 30 years, hepatitis C has emerged from shadowy enigma to important public health problem. The existence of the etiological agent of this disease was first appreciated two decades ago but significant progress in its understanding had to await its molecular characterization within the past 5 years. The virus is a member of the family Flaviviridae and is the cause of approximately 20% of clinical viral hepatitis in the United States. While the control of the transmission of hepatitis C virus in blood and blood products has been nothing less than spectacular, the control of community-acquired hepatitis C will be a major challenge to the scientific and medical communities.

Hepatitis C virus viremia following clinical resolution of acute hepatitis C

Clinical resolution of acute hepatitis C occurs in a limited proportion of cases. However, the rate of hepatitis C virus persistence remains unclear. For this purpose, we conducted a serial study of 60 patients with hepatitis C virus infection from the early stage of the disease for 24 to 80 months (average 50 months). Fourteen cases who recovered from acute hepatitis were selected from this group for prospective analysis of the behavior of liver enzymes, anti-HCV antibodies (RIBA II, Ortho Diagnostic System) and hepatitis C virus-RNA in serum and in peripheral blood lympho-mononuclear cells by nested polymerase chain reaction. Primers were derived from the 5'-untranslated region of the hepatitis C virus genome and the amplified products were detected by gel electrophoresis and a DNA enzyme immunoassay. All patients except two showed early recovery from acute hepatitis that occurred within 3 months from clinical onset. Transaminase normalization was always preceded by clearance of serum hepatitis C virus-RNA, which remained negative throughout follow-up. During the resolution phase of the disease a progressive decline in the antibody response was observed in most of the patients. At the end of the study anti-C100 was negative in half the cases, while anti-C33 and anti-C22 became negative or borderline in five cases. Hepatitis C virus-RNA was found in the peripheral blood lympho-mononuclear cells, but not in the serum, of only one of eight patients tested.(ABSTRACT TRUNCATED AT 250 WORDS)

Peptide based enzyme immunoassays for detecting hepatitis C antibodies in sera of people at high risk

AIM

To evaluate the performance of three newly introduced enzyme immunoassays (EIAs) for hepatitis C virus (HCV) antibodies, based on synthetic oligopeptides as antigens.

METHODS

Referred serum samples (n = 173) from people representing groups at high risk of HCV infection were studied. An EIA based on second generation recombinant polypeptide antigens was used for comparison. EIA reactivities were validated by testing repeatedly reactive samples in two recombinant antigen based immunoblot assays.

RESULTS

In samples from patients with liver dysfunction and those with bleeding disorders sensitivity of the three peptide based EIAs, manufactured by Innogenetics NV, Biokit SA, and United Biomedical Inc., were all 93%; specificity and efficiency were all greater than 95%. In samples from blood donors (previously tested as positive by the Ortho and Abbott Second Generation EIA) specificity, sensitivity, and efficiency were 95% or greater in all three peptide assays. Sensitivity, specificity, and efficiency of the recombinant antigen based Ortho Second Generation EIA were 100%, 89%, and 93%, respectively, in sera of patients with liver disease and those with bleeding disorders; and 100%, 43%, and 83%, respectively, in prescreened samples from blood donors.

CONCLUSION

The peptide EIAs are more specific but less sensitive than the Ortho EIA. Peptide based EIAs should be useful in validating the specificity of Ortho EIA reactivities.

Follow-up study of acute hepatitis C

An extended follow-up study of hepatitis C virus (HVC) infection was conducted in Guangzhou and its nearby regions on patients hospitalized with acute hepatitis. Routine screening of blood donors for HCV was not yet instituted at the time of this study. HCV was found to be a common cause of the disease, and the infection had a close association with recent histories of blood transfusion. Sequential sera obtained from patients during hospitalization and after discharge were tested for the presence of HCV antibodies by the first and the second generation of commercial test kits, for levels of alanine aminotransferase (ALT), and for the presence of HCV-RNA. The development of HCV antibodies in some of the patients may be delayed for protracted period following clinical onset. HCV-RNA was only intermittently detectable both before and after seroconversion. Six of 33 patients studied showed seroreversion and 5 of them were accompanied by loss of HCV-RNA and serum ALT returned to normal levels. The disease persisted in 24 of 27 patients without seroreversion, accompanied by intermittent detection of HCV-RNA throughout the protracted course of the infection. Our results indicate that both EIA for detection of HCV antibodies and PCR for serum HCV-RNA should be used in combination for reliable diagnosis of HCV infection and screening of blood for transfusion.

Clinical significance of concomitant hepatitis C infection in patients with alcoholic liver disease

The significance of antibodies to hepatitis C virus in patients with chronic alcoholic liver disease is unclear. Prior studies have utilized the first-generation enzyme-linked immunosorbent assay, which is limited by problems with sensitivity and specificity. Hepatitis C virus infection in 137 patients with biopsy-proven alcoholic liver disease was assessed with second-generation hepatitis C virus antibody assays and reverse transcription-polymerase chain reaction for detection of hepatitis C virus RNA in the serum. The patients were categorized into three groups according to results of serological testing. Discriminant-function analysis was used to determine which factors (risk, biochemical and histological) could best differentiate the three groups. Thirty-three patients were reactive on second-generation enzyme-linked immunosorbent assay/second-generation recombinant immunoblot assay and RNA positive (group 1). Twelve were reactive on second-generation enzyme-linked immunosorbent assay/second-generation recombinant immunoblot assay but RNA negative (group 2). Eighty-six were nonreactive on second-generation enzyme-linked immunosorbent assay, and six were reactive on second-generation enzyme-linked immunosorbent assay but negative on second-generation recombinant immunoblot assay and negative for hepatitis C virus RNA (group 3). Seventy-six percent of patients in group 1 and 58% in group 2 had parenteral risk factors, compared with only 1% in group 3 (p < 0.00001). The mean ALT level was higher in group 1 patients (p < 0.05). The mean histologic activity index was significantly higher in group 1 (p = 0.0007).(ABSTRACT TRUNCATED AT 250 WORDS)

Hepatitis C virus infections in dialysis units: prevalence of HCV-RNA and antibodies to HCV

HCV infection causes serious complications in dialysis patients that lead to problems in management of patients in dialysis units. Determination of HCV-RNA is at present essential for monitoring the course of HCV infection. Reports concerning HCV-RNA in dialysis patients are mostly from Asian dialysis units; therefore, an analysis of dialysis patients in Europe was undertaken. From 1515 patients 2630 blood samples were screened for HCV-RNA and anti-HCV. Two-thirds of patients positive in an anti-HCV test containing a mixture of three antigens (EIA-II, Ortho) were further analysed for antibodies against these individual antigens. From 523 patients multiple samples were tested. Related on dialysis units from which all the attending patients were tested, mean prevalence of HCV-RNA was 8.4%, of anti-HCV 13.2%. Concerning all plasma samples from dialysis patients sent to our laboratory for investigation of HCV-RNA and anti-HCV the prevalence of HCV-RNA was 21.9%, of anti-HCV 23.1%, HCV-RNA was present in 76% of anti-HCV positive patients and in 4.1% of anti-HCV negative patients (1.3% of single and 6.8% of multiple tested patients). Acute and chronic infections with self-limited, persistent or intermittent viraemia were observed with changes and fluctuations of both HCV markers. With the exception of differences in onset of antibody production in some patients following acute infections, there were no major differences of dialysis patients compared to patients without dialysis treatment as far as antibody spectrum and detectability of HCV-RNA were concerned.