Hepatitis C virus not found in fulminant non-A, non-B hepatitis

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.

Hepatitis C virus JFH-1 strain infection in chimpanzees is associated with low pathogenicity and emergence of an adaptive mutation

The identification of the hepatitis C virus (HCV) strain JFH-1 enabled the successful development of infectious cell culture systems. Although this strain replicates efficiently and produces infectious virus in cell culture, the replication capacity and pathogenesis in vivo are still undefined. To assess the in vivo phenotype of the JFH-1 virus, cell culture-generated JFH-1 virus (JFH-1cc) and patient serum from which JFH-1 was isolated were inoculated into chimpanzees. Both animals became HCV RNA-positive 3 days after inoculation but showed low-level viremia and no evidence of hepatitis. HCV viremia persisted 8 and 34 weeks in JFH-1cc and patient serum-infected chimpanzees, respectively. Immunological analysis revealed that HCV-specific immune responses were similarly induced in both animals. Sequencing of HCV at various times of infection indicated more substitutions in the patient serum-inoculated chimpanzee, and the higher level of sequence variations seemed to be associated with a prolonged infection in this animal. A common mutation G838R in the NS2 region emerged early in both chimpanzees. This mutation enhances viral assembly, leading to an increase in viral production in transfected or infected cells.

CONCLUSION

Our study shows that the HCV JFH-1 strain causes attenuated infection and low pathogenicity in chimpanzees and is capable of adapting in vivo with a unique mutation conferring an enhanced replicative phenotype.

In vivo study of the HC-TN strain of hepatitis C virus recovered from a patient with fulminant hepatitis: RNA transcripts of a molecular clone (pHC-TN) are infectious in chimpanzees but not in Huh7.5 cells

Both viral and host factors are thought to influence the pathogenesis of hepatitis C virus (HCV) infection. We studied strain HC-TN (genotype 1a), which caused fulminant hepatic failure in a patient and, subsequently, severe hepatitis in a chimpanzee (CH1422), to analyze the relationship between disease severity, host immune response, viral evolution, and outcome. A second chimpanzee (CH1581) was infected from CH1422 plasma, and a third chimpanzee (CH1579) was infected from RNA transcripts of a consensus cDNA of HC-TN (pHC-TN). RNA transcripts of pHC-TN did not replicate in Huh7.5 cells, which were recently found to be susceptible to infection with another fulminant HCV strain (JFH1). The courses of viremia were similar in the three animals. However, CH1581 and CH1579 developed a less severe acute hepatitis than CH1422. CH1579 and CH1422 resolved the infection, whereas CH1581 became persistently infected. CH1579 and CH1581, despite their differing outcomes, both developed significant intrahepatic cellular immune responses, but not antibodies to the envelope glycoproteins or neutralizing antibodies, during the acute infection. We analyzed the polyprotein sequences of virus recovered at five and nine time points from CH1579 and CH1581, respectively, during the first year of follow-up. High mutation rates and high proportions of nonsynonymous mutations suggested immune pressure and positive selection in both animals. Changes were not selected until after the initial decrease in virus titers and after the development of immune responses and hepatitis. Subsequently, however, mutations emerged repeatedly in both animals. Overall, our results indicate that disease severity and outcome of acute HCV infection depend primarily on the host response.

Fulminant hepatic failure

The rare but potentially devastating clinical syndrome of fulminant hepatic failure has as its components severe encephalopathy and finally cerebral edema, hemodynamic instability, renal failure, coagulopathy, profound metabolic disturbances and a particular susceptibility to bacterial and fungal infection. Despite advances in medical management, fulminant hepatic failure in its most severe form carries a high mortality rate unless urgent orthotopic liver transplantation is carried out. However, availability of cadaveric donor organs is limited and, due to the rapidly progressive clinical course in many cases, a substantial proportion of patients will die or develop contraindications to transplantation before the procedure can be performed. Consequently, recent interest has centred on living donor transplantation and the possibility of providing temporary liver support, either through auxiliary partial organ transplantation, extracorporeal perfusion or transplantation of hepatocytes, to allow time for either a liver graft to become available or native liver regeneration, on which spontaneous survival ultimately depends, to occur.

Clinical, histologic and serologic evaluation of patients with acute non-A-E hepatitis in north-eastern Brazil: is it an infectious disease?

Non-A-E hepatitis and acute cryptogenic hepatitis are the names given to the disease of patients with clinical hepatitis, but in whom serologic evidence of A-E hepatitis has not been found. Over a period of 8 years, we evaluated in Brazil 32 patients who fulfilled the criteria for this diagnosis in order to determine patterns of the clinical illness, laboratory parameters, or histologic features. Each patient was subjected to virologic tests to exclude A-E hepatitis and cytomegalovirus/Epstein-Barr virus infection. Drug-induced hepatitis and autoimmune disease were also excluded. Wilson's disease was excluded in young patients. The course of the disease was clinical/biochemical recovery in 3 months in 25 patients and persistent alanine aminotransferase (ALT) elevation in 7 patients. Three of these had chronic hepatitis, and one had severe fibrosis on liver biopsy. During the acute illness, mean peak ALT was 1267 IU/L, bilirubin was 4.0 mg/dL, and ferritin was 1393 IU/mL. GB virus type C (GBV-C) was found in six patients, and TT virus (TTV) in five patients. We conclude that, in Brazil, non-A-E hepatitis probably originates from still unidentified viruses. The course of the disease and the histologic patterns are similar to those recorded for known viruses. Continuous survey for the specific etiologic agents is needed.

Case fatality rate of acute viral hepatitis in Italy: 1995-2000. An update

BACKGROUND

Fulminant hepatic failure is the most serious complication of viral hepatitis. Although this event occurs rarely, it may be fatal.

AIMS

To evaluate the case fatality rate (several deaths divided by number of cases x 100) for each viral hepatitis type in Italy from 1995 to 2000.

PATIENTS

Acute hepatitis cases identified by the surveillance system for acute viral hepatitis, which covers approximately 58% of the Italian population.

RESULTS

Twenty-five deaths (0.1%) occurred among the 18 460 acute viral hepatitis cases observed from 1995 to 2000, a rate threefold lower than the 0.3% reported during the period 1985-1994. The highest case fatality rate (0.4%) was seen for acute hepatitis B (18 deaths among 4257 cases). Only one death (0.01%) occurred among the 11 063 acute hepatitis A cases and two deaths (0.1%) among the 1536 acute hepatitis C cases. No deaths were observed among the 309 acute hepatitis A cases superimposed on chronic HBsAg carriers and the 166 superimposed on chronic HCV carriers. Intravenous drug use (22.2% of cases) and other parenteral exposures (22.2% of cases) were the most frequent non-mutually exclusive sources of infection reported by subjects who died of acute hepatitis B.

CONCLUSIONS

Analysis of surveillance system data from 1995 to 2000 indicates that, in Italy, deaths due to acute viral hepatitis are rare, but most commonly observed with acute hepatitis B. There is no evidence that acute hepatitis A may be fatal in chronic HBsAg or HCV carriers. The overall better survival rate may probably reflect improvements in the treatment of fulminant hepatitis in the last few years in Italy.

Non-A to E hepatitis

PURPOSE OF THE REVIEW

The list of possible hepatotropic viruses continues to grow with the discovery of the GB virus-C, the TT virus and the SEN virus. There is emerging data on the biology of these newly discovered :In spite of continuing research into the pathogenicity of the GB virus-C and the TT virus, definite evidence linking them to acute or chronic liver disease is lacking. The SEN virus was reported in 2000, and although there seems to be an association between virus and transfusion-related hepatitis, more data are awaited before definite conclusions can be drawn. The effect of GB virus-C, the TT virus and the SEN virus co-infection on other viral and non-viral hepatitides has also been studied in some detail. Again, there is no definite evidence so far that these viruses modify other liver diseases.

SUMMARY

At the present time, diagnostic testing for these viruses does not seem to be warranted outside of clinical studies. The discovery of these viruses, however, paves the way for further research into novel viral agents that infect humans, other among hosts.

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 activity index is a key factor in determining the natural history of chronic hepatitis C

To analyze the spontaneous pathologic progression of chronic hepatitis C, we analyzed the histopathologic semiquantitative scores (Metavir and Knodell) of sequential liver biopsies performed in untreated hepatitis C virus (HCV)-infected patients. Subjects included 35 men and 41 women, with a mean age of 41 +/- 12 years, a duration of HCV infection of 11 +/- 5 years, and an interval between liver biopsies of 3.7 +/- 2.5 years. Results obtained using the Knodell score and the Metavir score were similar. At the first biopsy, 78.9% of patients had a low activity score (A0-A1) and 82.9% had a low fibrosis score (F0-F2). At the second biopsy, the activity decreased in 9.2%, was unchanged in 72.4%, and increased in 18.5%. An increase in activity was more frequently observed in patients infected with genotype 1 (28.9%) than with others (7.7%; P =.04); the yearly progression of activity was significantly higher in patients with a low rather than high initial activity score (0.11 v -0.02; P <.01). An increase in fibrosis was noted in 13.3% of those with a low and 43.8% of those with a high initial activity score (P <.01), with a highest rate of yearly fibrosis progression (0.12 U). In multivariate analysis, only a high activity score was significantly associated with an increased risk of fibrosis progression (relative risk, 25.5; 95% confidence interval, 2.7 to 238; P =.004). Spontaneous chronic hepatitis C evolution is worsening in only 20% of patients. Fibrosis progression is significantly associated with the necroinflammatory activity suggesting that this factor should be regarded as a major clue for deciding therapy.

Sequence analysis of hepatitis C virus isolated from a fulminant hepatitis patient

Although hepatitis C virus (HCV) is a major cause of non-A non-B hepatitis, its pathogenic role in fulminant hepatitis remains controversial. A 32-year-old man contracted hepatitis. Serum ALT concentration was reached to 6,970 IU/L, the lowest prothrombin time value was 16% and jaundice and stage II encephalopathy were developed. HCV RNA was detected in this patient by reverse transcription polymerase chain reaction in sera at the acute phase, and it was undetectable during the remission phase when anti-HCV was found. The entire genome of infected HCV was recovered, cloned, and sequenced from this patient, and compared with the clones of six other chronic hepatitis patients. Phylogenetic analysis revealed a clustering around genotype 2a and a deviation from the other 2a chronic hepatitis strains. Calculating the genetic distance in each subgenomic region revealed that the 5'untranslated region (5'UTR), core, nonstructural (NS) 3, and NS5A were severely deviated. Of 20 clones of the hypervariable region (HVR), 17 showed an identical sequence with the others showing a difference of only one amino acid. HCV was isolated from a fulminant hepatitis patient and its entire genome was recovered; a clustering around genotype 2a was observed, but the sequence deviated especially in 5'UTR, core, NS3, and NS5A; and monoclonality of the HVR sequence was found not only in the fulminant hepatitis patient but in a certain percentage of chronic hepatitis patients.

HVR1 quasispecies analysis from a long-term culture of hepatitis C virus in Hep G2 derived cells grown in a haemodialysis cartridge

Studies on the in vitro hepatitis C virus (HCV) infection are hampered by the lack of an appropriate system to culture permissive cells to be continuously infected with HCV. Trypsinization required for cell passage can lead to possible temporary loss of permissiveness for infection, whereas refreshment of the medium can result in loss of infectious particles necessary for perpetuation of the infection; it is therefore very difficult to maintain a continuous HCV infection in cell cultures. A new infection method was designed and evaluated in order to prevent these unfavourable circumstances. A cell line derived from the human hepatoblastoma cell line Hep G2 was grown in the extracapillary space of a haemodialysis cartridge, in the presence of a HCV-positive inoculum, while the culture medium was recirculated through the intracapillary space, supplying the cells with nutrients and oxygen. HCV RNA could continuously be detected in the cells up to 77 days of culture. Sequence analysis of the HCV hypervariable region 1 (HVR1) revealed that 56% and 75%, respectively, of the clones obtained from the cells at day 20 and 40 after start of the infection were different from the clones obtained from the original inoculum and that certain nucleotide positions in this region were more susceptible to mutations, leading to an alteration in amino acid sequence. As none of these sequences were present in the clones from the inoculum, it is suggested that new HCV quasispecies have emerged as a result of viral replication in the hepatocytes in vitro. This system seems a valuable tool for the in vitro evaluation of antiviral drugs.

Acute liver failure: established and putative hepatitis viruses and therapeutic implications

Any virus that can cause an acute hepatitis will, on occasion, give rise to acute liver failure. Such infections can be separated into those due to the primary hepatitis viral infections A to E and those where hepatitis occurs as part of a systemic viral infection, as with infection with, for instance, Epstein-Barr virus, cytomegalovirus, Varicella zoster virus, adenovirus and Herpes simplex virus. In general, the frequency with which the different hepatitis viruses are responsible for acute liver failure is related to their underlying prevalence in particular countries. An apparent exception is the striking geographical variation in the reported prevalence of acute liver failure due to hepatitis C virus infection, with a much higher proportion of cases generally attributed to this agent in Japan and Taiwan than in Western countries. Recent work has focused on the possible importance of mutant hepatitis B viral strains, co- and super-infection with known hepatitis viruses and certain newly described agents that may account for otherwise unexplained cases of acute liver failure. Despite an improved understanding of the pathogenesis of complicating cerebral oedema and advances in general supportive care, it is likely that the most severely affected patients with acute liver failure due to viral causes will survive only with liver transplantation, at least until approaches for promoting adequate liver regeneration are successfully developed and implemented.

Acute hepatic failure: a Western perspective

Acute hepatic failure (AHF) is an uncommon, devastating syndrome, which results in death or the need for liver transplantation in more than 50% of cases. While AHF has numerous causes, most cases are due to viral hepatitis and drug toxicity or idiosyncratic reactions. A significant group with indeterminate causation remains, despite careful investigation. In many of these cases a viral aetiology is suspected, although yet not proven. Major differences exist in the aetiology of AHF between the West and Eastern countries. A wider range of aetiologies exists in the West. Common causes include acetaminophen toxicity and idiosyncratic drug reactions, while viral hepatitis is less frequent. Hepatitis E infection is rarely seen in Western countries in contrast to its high prevalence in the East. The mainstay of AHF management is supportive care in an intensive care unit. Liver transplantation is now the standard of care in many Western liver units for individuals who have a less than 20% probability of survival. Lack of availability of donor livers at short notice remains a significant problem. Methods of liver support used while waiting for a donor liver or for the native liver to regenerate include bioartificial livers, extracorporeal liver-assist devices, extracorporeal whole organ perfusion (human and transgenic pig) and hepatocyte transplantation. The effectiveness of these methods remains unproven and awaits controlled clinical trials. Both transplantation and liver-support methods require specialized units and expensive and complicated equipment. Further research is necessary to identify modalities of therapy that would be effective as well as widely accessible.

What do we need to know about non-A-to-E viral hepatitis?

The list of potential hepatotrophic viruses continues to grow, with the recent discovery of the GB virus-C, the TT virus, and the SEN virus. Prevalence rates of the GB virus-C have ranged from 1.2% to 13% among healthy blood donors from all over the world. Higher prevalence rates have been reported among intravenous drug users. Similarly, the TT virus has a global distribution. However, in spite of numerous reports of the presence of both of these viruses in various kinds of liver diseases, definite evidence linking it to a specific disease or illness is lacking. The SEN virus is thought to be a novel viral agent that may be linked to cryptogenic chronic hepatitis, but data are awaited.

Prevalence of TT virus DNA in eastern Taiwan aborigines

We studied the prevalence of TT virus (TTV) DNA in the general population of the eastern Taiwan aborigine villages, about 11% (34 of 317). There is no association between the presence of HBsAg and TTV DNA or between the presence of HCV RNA and TTV DNA. Therefore, the infection of HBV or HCV and the presence of TTV DNA appear to be independent from each other. The association between the presence of TTV DNA and the elevated alanine aminotransferase (and/or aspartate aminotransferase) activity was also investigated. The presence of TTV DNA was not found to be correlated with abnormal liver function (P = 0.574) when age, gender, and the presence of HBsAg, HCV RNA, and HGV RNA were all considered in the assay. The sequence homology of TTV DNA fragments between different isolates from Taiwan and N22 (the clone obtained from the original prototype strain) from Japan ranged from 84 to 97%. The recombinant protein encoded by the TTV DNA fragment corresponding to the open reading frame of N22 was expressed in E. coli successfully. However, no serum response against the recombinant protein was detected.

The Significance of Hepatitis G Virus in Serum of Patients With Sporadic Fulminant and Subfulminant Hepatitis of Unknown Etiology

Excluding acute hepatic failure caused by drugs, the etiology of fulminant hepatitis (FH) remains unknown in many patients. There are conflicting data about a possible pathogenic role for the hepatitis G virus (HGV) in patients with cryptogenic fulminant hepatitis (non–A-E FH). We investigated the presence of circulating HGV in 36 patients with well-documented non–A-E fulminant and 5 patients with subfulminant hepatitis from 3 geographic locations in the United States. Serum HGV RNA was determined by reverse transcriptase-polymerase chain reaction using primers from the NS5 region of the HGV genome. HGV RNA was also measured before and after liver transplantation in 5 patients and at different time points in 7 patients. Serum samples were recoded and reanalyzed for HGV RNA using different primer sets to assess the validity of the HGV RNA assay. HGV was present in serum of 14 of the 36 patients (38.8%) with non–A-E fulminant hepatitis. Twenty percent of patients from the Northeast, 11% of the patients from the Southeast, and 50% from the Mid-Atlantic regions of the United States had circulating HGV RNA. The use of therapeutic blood products was significantly associated with the presence of serum HGV RNA (P < .02). Retesting for HGV RNA with different primers was positive in all but 1 case. HGV RNA is not causally related to non–A-E fulminant hepatitis. The finding of HGV RNA in serum from these patients is likely related to the administration of blood product transfusion after the onset of fulminant hepatitis.

The Significance of Hepatitis G Virus in Serum of Patients With Sporadic Fulminant and Subfulminant Hepatitis of Unknown Etiology

Excluding acute hepatic failure caused by drugs, the etiology of fulminant hepatitis (FH) remains unknown in many patients. There are conflicting data about a possible pathogenic role for the hepatitis G virus (HGV) in patients with cryptogenic fulminant hepatitis (non–A-E FH). We investigated the presence of circulating HGV in 36 patients with well-documented non–A-E fulminant and 5 patients with subfulminant hepatitis from 3 geographic locations in the United States. Serum HGV RNA was determined by reverse transcriptase-polymerase chain reaction using primers from the NS5 region of the HGV genome. HGV RNA was also measured before and after liver transplantation in 5 patients and at different time points in 7 patients. Serum samples were recoded and reanalyzed for HGV RNA using different primer sets to assess the validity of the HGV RNA assay. HGV was present in serum of 14 of the 36 patients (38.8%) with non–A-E fulminant hepatitis. Twenty percent of patients from the Northeast, 11% of the patients from the Southeast, and 50% from the Mid-Atlantic regions of the United States had circulating HGV RNA. The use of therapeutic blood products was significantly associated with the presence of serum HGV RNA (P &lt; .02). Retesting for HGV RNA with different primers was positive in all but 1 case. HGV RNA is not causally related to non–A-E fulminant hepatitis. The finding of HGV RNA in serum from these patients is likely related to the administration of blood product transfusion after the onset of fulminant hepatitis.

Acute sporadic non-A, non-B hepatitis in Northeastern Brazil: etiology and natural history

In a 4-year follow-up study, patients with acute sporadic non-A, non-B (NANB) hepatitis were evaluated to determine the etiology and natural history of the disease. Acute hepatitis C virus (HCV) was detected in 13 of 43 (30%) of patients, anti-hepatitis E virus (HEV) IgG in 5 (12%), and 25 (58%) were considered non-A-E. The HCV RNA was detected in all HCV patients but none of the non-A-E cases. The initial clinical and biochemical presentation of the HCV and non-A-E cases was quite similar, although 2 of the non-A-E patients had severe disease. The 5 patients who were found to be anti-HEV IgG-reactive recovered within 6 months of follow-up. Of the 13 HCV cases, alanine transaminase (ALT) levels returned to normal in 7 (53. 8%), while 6 (46.2%) continued to show abnormal ALT after 6 months of follow-up. However, 9 (69.2%) of them remained HCV-RNA-positive, denoting virological/biochemical dissociation. Long-term follow-up showed a reappearance of HCV RNA in 2 of the 4 patients who were in virological remission performing 84% of chronicity rate. Acute non-A-E hepatitis patients were less likely to evolve toward chronicity, as compared with acute HCV cases (16% vs. 84%; P =.0001). Only 4 (16%) of the non-A-E patients were hepatitis G virus (HGV)-RNA-positive. Concerning risk factors for acquiring parenterally transmitted viruses, tattooing was the only one that could be associated with HCV transmission (P =.002). No risk factors could be identified for putative non-A-E virus transmission. Liver biopsies performed for chronic HCV patients showed a variable degree of inflammation, while the non-A-E patients presented less severe histological disease.

Fulminant hepatic failure

Fulminant hepatic failure is a disease of varied causes and a high mortality rate. A sudden onset, jaundice, hepatic encephalopathy, and multiorgan failure are the hallmarks of this syndrome. The management of patients with FHF requires a multidisciplinary approach and intense monitoring. The availability of liver transplantation has provided the means to rescue such patients from near-certain death. Early prognostication and timely availability of donor livers are requirements for a successful outcome. The development of effective artificial liver support devices may greatly prolong the window of opportunity to provide a donor liver, or alternatively, to allow the native liver to regenerate.

Fecal excretion of a nonenveloped DNA virus (TTV) associated with posttransfusion non-A-G hepatitis

Five patients with type B or C hepatocellular carcinoma were found to be infected with a nonenveloped DNA virus (TTV) associated with posttransfusion hepatitis of non-A-G etiology. Paired feces and serum samples from these patients were tested for TTV DNA by polymerase chain reaction with seminested primers and their sequences were compared. TTV DNA was detected in sera from all of the patients, while it was detected in feces from three patients, including two with high viral titers in serum. When feces and serum from one patient were subjected to floatation ultracentrifugation in CsCl, TTV in feces banded at a peak density of 1.35 g/cm3 and that in serum at 1.31-1.32 g/cm3. TTV isolates in three pairs of feces and serum had the identical sequence of 222 base pairs. The excretion of TTV into feces indicates that TTV would be transmitted not only parenterally but also nonparenterally by a fecal-oral route.

The distribution of HBV, HCV and HGV among livers with fulminant hepatic failure of different aetiology

BACKGROUND/AIMS

The aim of the study was to assess the impact factor of HCV and HGV in fulminant hepatic failure.

METHODS

The 5'-untranslated regions of HCV RNA and HGV RNA and a segment of the core antigen sequence of HBV were amplified after extracting the nucleic acids from snap-frozen tissue aliquots from explanted livers of 26 consecutive patients undergoing orthotopic liver transplantation for fulminant hepatic failure preoperatively diagnosed as either autoimmune (n=2), HAV/HBV (n=8), toxic (n=4) or aetiologically unknown (n=12).

RESULTS

HCV RNA was detected in five of 26 (19.2%) livers with fulminant hepatic failure. All five HCV RNA-positive livers belonged to the group of non-toxic, non-autoimmune liver failure (n=20), three of them were found in the group of liver failure with unknown aetiology (n=12) and two in the group of HBV-associated liver failure (n=7), making an HCV incidence of 25%, 25% and 28.6%, in the different groups, respectively. HGV RNA was detected in 10 of 17 (58.8%) explants and in all four groups of fulminant hepatic failure as defined preoperatively. HBV DNA was identified in six livers of 26 patients (23.1%) with fulminant hepatic failure. Neither HCV RNA nor HBV DNA was detected in the livers of patients with toxic or autoimmune fulminant hepatic failure.

CONCLUSIONS

These results indicate that HBV and HCV, but not HGV, play an aetiologic role in fulminant hepatic failure. HCV-positive cases were concentrated either in the group of otherwise unexplained fulminant hepatic failure or in the group of HBV fulminant hepatic failure. HGV-positive cases, on the other hand, were found within all four preoperatively defined groups, indicating a role as cofactor rather than as single aetiologic agent.

Chronic hepatitis C: the virus, its discovery and the natural history of the disease

The identification of hepatitis A and hepatitis B led to the recognition that a third virus was capable of causing blood-borne hepatitis. The pathogen responsible for this nonA, nonB hepatitis was identified in the late 1980s and subsequently named hepatitis C. Since the discovery of hepatitis C there has been a pandemic of research publications describing the natural history of the infection and it is now known that this virus can cause serious liver damage in a proportion of infected patients. It is now clear that the effects of infection with hepatitis C and alcohol misuse are additive and that there is an increased risk of hepatic complications in infected patients who abuse alcohol.

Hepatitis C virus infection: Review and implications for the dentist

OBJECTIVE

The purpose of this report was to review the current literature on hepatitis C virus infection, with particular attention to the aspects of interest for dental health care staff.

MATERIAL AND METHODS

The authors searched original research and review articles on specific aspects of hepatitis C virus infection, including articles on virology, epidemiology, transmission, diagnosis, natural history, extrahepatic manifestations, therapy and oral aspects of hepatitis C virus infection. The relevant material was evaluated and reviewed.

RESULTS

Hepatitis C virus is an RNA virus that is present throughout the world and has major geographic variations. The virus, transmitted mainly by means of blood contact, causes chronic hepatitis in up to 80% of cases and may give rise to hepatic cirrhosis and hepatocellular carcinoma in a significant proportion of patients. Although it is of limited efficacy, interferon alpha is currently the drug of choice in the treatment of the infection. Hepatitis C virus infection is associated with a number of extrahepatic manifestations that may include oral diseases such as lichen planus or sialadenitis. Although there are documented cases of nosocomial transmission to health care workers after percutaneous exposure, the prevalence of hepatitis C virus among dental staff members is probably similar to that in the general population.

CONCLUSION

Hepatitis C virus infection is a relatively common infection worldwide (1.4% in the US general population) that causes significant chronic hepatic disease. The dentist is thus likely to face a growing number of patients with a diagnosis of hepatitis C virus infection. For this reason it is essential for dental health care workers to be aware of the principal features of the disease and of its oral and dental implications.

[Biology of hepatitis C viruses: clinical implications]

Infection by hepatitis C virus is characterized by a high rate of chronicity and low viremia. The virus has only been recently identified; it is a positively stranded RNA virus which shows homology in its genetic organisation with the pestiviruses and flaviviruses. There is not yet an efficient culture system available. Evidence indicates that the genetic variability of the HCV genome might have important clinical implications.

Detection of hepatitis C and E virus genomes in sera of patients with acute viral hepatitis and fulminant hepatitis by their simultaneous amplification in PCR

A study was undertaken to investigate the role of hepatitis C virus (HCV) and hepatitis E virus (HEV), either alone or together, in the causation of sporadic acute viral hepatitis (AVH) and fulminant hepatitis (FH) by simultaneous detection of their genomes in serum samples using the reverse transcription and nested polymerase chain reaction (RT-PCR). A total of 50 patients were enrolled in the study of which 34 had AVH and 16 had sporadic FH. The serum samples were first tested for hepatitis B surface antigen (HBsAg) and immunoglobulin (Ig)M antibodies against hepatitis A virus (HAV), hepatitis B core antigen (HBcAg) and HEV and also antibodies against HCV using commercially available enzyme-linked immunosorbent assay (ELISA) kits. All samples were then subjected to RT-PCR using primers for both HCV and HEV simultaneously in the same reaction mixture. Hepatitis C or hepatitis E was diagnosed when either the antibodies or PCR or both were positive for the respective viruses. Evidence of hepatitis C was present in six of the 34 (17.6%) cases of AVH and two out of 16 (12.5%) cases of FH. Four patients in the AVH group and one of the fulminant hepatic failure (FHF) group were found to be positive by PCR and the rest by serology. But as a sole aetiological agent, HCV infection was found in only one (2.9%) case of AVH and in none of the FHF cases. Evidence of HEV infection was found in 22/34 (64.7%) and 8/16 (50%) cases of AVH and FHF, respectively. Excluding co-infection with other viruses, HEV was found to be the sole aetiological agent in 15/34 (44.1%) of AVH and 7/16 (43.7%) cases of FHF. In five (10%) (four AVH and one FHF) of the 50 cases, evidence of infection with both HCV and HEV was present. But only in two of these five cases, genomes of both HCV and HEV were co-amplified. In seven (four AVH and three FHF) out of 50 (14%) cases, no known viral agent could be detected. Our results suggest that HEV is the most common aetiological agent for both acute viral hepatitis and fulminant hepatic failure and that HCV is a rare cause of acute liver diseases although along with other viruses, evidence of either present or past HCV infection may be present in a substantial number of cases. Furthermore, advanced-stage pregnancy appears to be a potential risk factor for HEV infection and high rate of mortality in women. The study suggests that the method of simultaneous amplification of both HCV and HEV genomes could reduce the time, labour and cost involved in diagnostic work up of acute liver disease patients.

Non-A, non-B, non-C hepatitis: its significance in pediatric patients and the role of GB virus-C

OBJECTIVES

To delineate the importance of non-A, non-B, non-C (non-ABC) hepatitis, and the role of GB virus C (GBV-C) in children.

METHODS

From 1980 to 1995, acute-onset viral hepatitis was diagnosed in 166 inpatients and categorized into type A, B, C, and non-ABC hepatitis according to the serologic markers or the results of polymerase chain reaction assay for HBV DNA or HCV ribonucleic acid (RNA) in the National Taiwan University Hospital. Non-ABC hepatitis was diagnosed in 57 patients (34%). GBV-C RNA was investigated by reverse transcription and nested polymerase chain reaction in 32 of the 57 patients with non-ABC hepatitis. The clinical and laboratory features of patients with acute non-ABC hepatitis were compared with the features of those with acute hepatitis A and B.

RESULTS

The degree of abnormality in aminotransferase activities was milder in patients with non-ABC hepatitis than in those with hepatitis B; chronicity was noted in 12%. Fulminant hepatitis occurred in 16%, and the mortality rate was 56%. Young age carried a significantly higher risk of having a fulminant course (1.9 +/- 0.2 years of age vs 6.4 +/- 5.1 years of age in acute course; p < 0.05). Compared with fulminant hepatitis B, fulminant non-ABC hepatitis had a trend of a longer interval from onset to death (119.2 +/- 144.8 vs 15.2 +/- 8.4 days; p = 0.079). GBV-C RNA was detected in only two of the patients tested, both of whom had received transfusions; one had persistent viremia and fluctuating aminotransferase values.

CONCLUSIONS

Non-ABC hepatitis plays an important role in the etiology of pediatric viral hepatitis; however, the role of GBV-C is minor. A search for other unknown viral agent(s) responsible for non-ABCG hepatitis is needed.

Selection of prognostic factors of acute hepatitis type non-A, non-B for patient listing for liver transplantation

The aim of this study was to select prognostic factors from information available on admission in order to list patients for liver transplantation before the onset of hepatic encephalopathy in patients with fatal hepatitis type non-A, non-B. Information regarding patient profile and biochemical data obtained on admission was analyzed by multiple stepwise logistic regression, and independent prognostic factors related to death were selected. Four parameters were selected as independent prognostic factors. Patient age (over 50 years), serum total bilirubin level (over 10 mg/dl), peripheral leukocyte count, and prothrombin time were independently related to death. Positive predictive value, negative predictive value, and predictive accuracy were 0.86, 0.79, and 0.84, respectively. Our model is able to predict a patient's fatal outcome much earlier than other currently used models. It will be helpful for early referral to a transplant center.

How important is hepatitis C virus (HCV)-infection in persons with acute leukemia?

Hepatitis C virus (HCV)-infection is common in persons with leukemia. Blood transfusions are the typical source and HCV-related chronic hepatitis a common outcome. Development of HCV-infection and -related hepatitis raises important questions about subsequent leukemia treatment including the natural history of the infection and need for treatment modification. Although the natural history of HCV-infection and -related hepatitis in this setting is unknown, data from normal persons with HCV-infection suggest that short-term survival is not likely to be decreased in persons with leukemia and these complications. In contrast, long-term survival may decrease because of a high rate of chronic hepatitis, cirrhosis, and possibly hepatocellular carcinoma. There are no convincing data that HCV-infection or -related hepatitis or alterations in anti-leukemia drug dose or schedule prompted by abnormal liver function tests, alter leukemia outcome. Consequently, it is uncertain whether drug doses and/or schedule should be modified in persons with leukemia and HCV-infection or -related hepatitis. Short-term outcome of blood cell and bone marrow transplants is also unaffected by HCV-infection or -related hepatitis.

Case fatality rate of acute hepatitis in Italy: results from a 10 year surveillance

Using data from the surveillance system for acute viral hepatitis we have evaluated the case fatality rate of viral hepatitis in Italy. 71 deaths (0.3%) occurred among the 21,553 reported acute viral hepatitis cases from 1985-1994. None reported history of exposure to drugs or toxins. The highest case fatality rate was observed for B and NANB hepatitis (0.5%). One death occurred among the 6,353 (0.02%) hepatitis A cases and 1 among the 909 (0.1%) anti-HCV positive NANB hepatitis cases. The case fatality for Delta hepatitis was 0.2% (1/422). Case fatality rate was similar in both sexes; increasing with age; 0.03% were < 15 years of age, 0.1%, 15-24 year-old, and 0.5%, > or = 25 years. Subjects older than 24 years of age accounted for 81.4% of total deaths. Intravenous drug use, blood transfusion and other parenteral exposures were the three most frequent non-mutually exclusive sources of infection reported by subjects who died from B and NANB hepatitis. These findings indicate that the survival rate of acute B and NANB hepatitis is lower than that of acute hepatitis A; moreover in Italy, as in other Western countries, acute HCV seems to cause liver failure only rarely.

Hepatitis C virus: molecular biology and genetic variability

The pathogenetic mechanisms of hepatitis C virus (HCV) infection are poorly known. An understanding of HCV biology and the potential clinical impact of HCV genetic variability is essential to managing, treating, and preventing HCV infections. HCV is a member of the Flaviviridae viral family. Its genome is a positive, single-strand RNA molecule. The structure of the HCV particles is poorly known due to the lack of an efficient cell culture system as well as a striking heterogeneity in density. The core protein may have a regulatory role on both viral and cellular gene expression. The mechanisms of HCV-RNA replication may include synthesis of negative strand intermediates, which drive synthesis of new positive RNA genomes. New procedures have been developed to better identify and characterize the HCV-RNA genome. The mechanisms of HCV persistence are currently unknown, although it is known that HCV chronicity develops despite humoral and cellular responses to HCV proteins. HCV-RNA shows significant genetic variability with an estimated rate of nucleotide change of approximately 10(-3) substitutions/site/year. Currently, three major HCV genotypes and three to seven minor subtypes can be distinguished. The geographical distribution of these genotypes and subtypes varies significantly. It appears that poor clinical response to interferon (IFN) is more common with HCV genotype 1. In addition, some studies have shown an association between chronic infection, severe chronic hepatitis, and cirrhosis with subtype 1b. Further, there is evidence for a potential direct effect of HCV in liver carcinogenesis, with subtype 1b possibly being an independent risk factor for hepatic carcinoma development. HCV-RNA circulates as a population of RNA molecules, which creates a heterogeneity referred to as "quasispecies." It is possible that some HCV strains might have direct clinical implications. It may be that highly heterogeneous populations observed prior to treatment might correlate with a lower rate of response to IFN therapy.

Hepatitis C virus density heterogeneity and viral titre in acute and chronic infection: a comparison of immunodeficient and immunocompetent patients

BACKGROUND

Heterogeneities in the buoyant density of hepatitis C virus RNA have been reported in different groups of patients, and have been attributed to differential binding of viral particles to beta-lipoproteins and IgG, and the presence of hepatitis C virus nucleocapsids in circulation. It may be that hepatitis C virus density heterogeneity correlates with the severity of liver disease, hepatitis C virus RNA titre, and the immunocompetence of the patient.

METHODS AND RESULTS

We have analysed five immunodeficient patients (one with hypogammaglobulinaemia and selective IgA deficiency, one with X-linked agammaglobulinaemia, three with common variable immunodeficiency) who have been acutely infected with the same batch of intravenous immunoglobulin contaminated with hepatitis C virus (genotype 1a). The course of hepatitis C virus infection in these patients was compared to one immunocompetent patient who presented with acute hepatitis C virus and progressed to chronic disease, and seven immunocompetent patients with chronic hepatitis C. Serum samples were analysed by differential flotation ultracentrifugation in NaCl solution (density 1.063 g/ml). The high and low density fractions were tested for the presence of RNA by RT-PCR. Serum samples were also quantified for hepatitis C virus RNA (Amplicor HCV Monitor kit, Roche Diagnostic Systems). Three quarters of the acutely infected patients analysed presented with low density hepatitis C virus. Low density hepatitis C virus was absent in most chronic infections but persisted in two patients with common variable immunodeficiency. High density hepatitis C virus was detected in the chronic phase in all acutely infected patients in whom the disease persisted, and was present in all samples from PCR-positive patients with chronic infection. Immunodeficient patients had significantly higher hepatitis C virus RNA titres on presentation than immunocompetent patients, but there was no correlation between titre and clinical course of infection.

CONCLUSIONS

Heterogeneities in the buoyant density of hepatitis C virus RNA have been identified in the patient groups studied. Low density hepatitis C virus is detected more often in acute infection and high density hepatitis C virus is detected more often in chronic infection. Despite acute infection via the same route of infection with the same hepatitis C virus strain, the five immunodeficient patients studied all followed a different clinical course.

Hepatitis B and C viruses and primary liver cancer

The data presented indicate that viral agents (namely, HBV and HCV) are major environmental aetiological factors for human primary liver cancer. It is important to elucidate the molecular mechanisms further because HCC is one of the few examples of virus-related human cancers. In addition, the available evidence points to the possibility of at least partial prevention of the tumour by large-scale vaccination.

Fulminant hepatitis caused by hepatitis C virus during treatment for multiple sclerosis

A 55-year-old woman was treated at our hospital for multiple sclerosis. Therapy consisted of glucocorticosteroids and cyclosporin. In the 7th week after these drugs were discontinued the patient developed acute liver failure due to fulminant hepatitis (FH) and died. Post-mortem examination showed massive liver necrosis. Serologic examination was negative for hepatitis B virus-related markers. Antihepatitis C virus (anti-HCV) antibody and serum HCV RNA were negative on admission, but HCV RNA appeared concurrently with the onset of FH. Although HCV infection rarely causes FH, it was considered to be the cause of FH in this patient, since there were no other causes of acute liver injury. We suspect that underlying immunologic abnormalities in conjunction with HCV infection may have precipitated the FH.

Fulminant hepatitis on withdrawal of chemotherapy in carriers of hepatitis C virus

BACKGROUND

Fulminant hepatitis on withdrawal of chemotherapy has been described in chronic hepatitis B virus infection, but not in hepatitis C virus (HCV) infection. The relation between HCV and immune response to this virus, and disease severity, has not been examined. We present two patients with HCV who developed fulminant liver failure after chemotherapy was stopped.

PATIENTS AND FINDINGS

Two patients with chronic HCV infection and malignant lymphoma received chemotherapy (cyclophosphamide, adriamycin, vincristine, bleomycin, etoposide, and prednisolone in patient 1; doxorubicin, bleomycin, vinblastine, and dacarbazine in patient 2), on withdrawal of which both developed fulminant hepatitis. Alanine aminotransferase (ALT) concentrations were greatly raised (6030 and 3870 IU/L in patients 1 and 2, respectively), and serum HCV-RNA was low in both patients when severe disease developed (10(2) genome equivalents per mL). Patient 1 died, and necropsy showed massive liver necrosis.

INTERPRETATION

The findings suggest an immune-mediated mechanism for hepatocyte damage in HCV infection. Careful monitoring of ALT concentrations is necessary in such patients during and after chemotherapy.

Fulminant hepatitis in patients undergoing liver transplantation: evidence for a non-A, non-B, non-C, non-D, and non-E syndrome

Fulminant hepatic failure (FHF) in the absence of serum markers of hepatitis A (HAV) or B (HBV) infection or another cause is called non-A, non-B (NANB) FHF. The pathogenetic role of viral infection in NANB FHF remains controversial. To better define this relationship, we studied patients who underwent orthotopic liver transplantation (OLT) for FHF. Thirty-six patients with FHF underwent transplantation between 1987 and 1992. Pre-OLT serum was available for 24 patients, 14 with NANB FHF (all female; mean age, 32 years), and 10 (3 males, 7 females; mean age, 20 years) with a defined origin for FHF who formed the control group. Sera were tested using polymerase chain reaction for HAV, HCV, HDV, and HEV RNA and HBV DNA, and also serologically for antibodies to these viruses. In the NANB group, pre-OLT serum was negative for all viruses tested. Four patients in the control group had HBV serologically, 2 with HBV DNA in serum. One of these 4 also had hepatitis C and one hepatitis D infection. There was no difference in intensive care unit or hospital stay between the groups. The only significant difference in laboratory data was for peak creatinine pre-OLT (0.94 mg/dL in NANB v 1.62 mg/dL; P < .05). Two patients in the NANB groups and 3 in the control group required early retransplantation for graft primary nonfunction. One case of NANB FHF appeared to recur at 6 months but not after subsequent retransplantation. NANB FHF is not associated with hepatitis A, B, C, D, or E in plasma. It has a later age of onset but a similar clinical course to other forms of FHF and appears to preferentially affect women.

Hepatitis C virus infection: clinical aspects and treatment with interferon alfa

Screening for antibodies to hepatitis C virus (HCV) has substantially reduced the risk of HCV infection from transfusion of blood and blood products. Nevertheless, new infections may continue to occur. These infections may be caused by donor infections that escape detection or by insufficient decontamination of blood products during preparation. Frequently, HCV infection becomes chronic, is clinically silent, and can be associated with extrahepatic illnesses and liver cancer. A recent outbreak of HCV infection in patients who received intravenous immunoglobulin has permitted study of this infection in immunocompromised hosts. Some evidence indicates that this infection is more virulent in these patients, and our experience at Children's Hospital, Boston, Massachusetts, substantiates this finding. In this article, epidemiology and modes of transmission of HCV, pathogenesis of HCV infections, differential diagnosis, and clinical features of HCV infection in both children and adults are discussed. Particular attention is given to the serologic findings seen in the spectrum of diseases associated with chronic HCV infection. The mechanisms of action of interferon alfa treatment of HCV infections are discussed. However, results of interferon alfa treatment of patients with HCV infection at Children's Hospital are preliminary.