Acute liver failure of unknown pathogenesis: The hidden agenda

Viral Surveillance in Serum Samples From Patients With Acute Liver Failure By Metagenomic Next-Generation Sequencing

BACKGROUND

Twelve percent of all acute liver failure (ALF) cases are of unknown origin, often termed indeterminate. A previously unrecognized hepatotropic virus has been suspected as a potential etiologic agent.

METHODS

We compared the performance of metagenomic next-generation sequencing (mNGS) with confirmatory nucleic acid testing (NAT) to routine clinical diagnostic testing in detection of known or novel viruses associated with ALF. Serum samples from 204 adult ALF patients collected from 1998 to 2010 as part of a nationwide registry were analyzed. One hundred eighty-seven patients (92%) were classified as indeterminate, while the remaining 17 patients (8%) served as controls, with infections by either hepatitis A virus or hepatitis B virus (HBV), or a noninfectious cause for their ALF.

RESULTS

Eight cases of infection from previously unrecognized viral pathogens were detected by mNGS (4 cases of herpes simplex virus type 1, including 1 case of coinfection with HBV, and 1 case each of HBV, parvovirus B19, cytomegalovirus, and human herpesvirus 7). Several missed dual or triple infections were also identified, and assembled viral genomes provided additional information on genotyping and drug resistance mutations. Importantly, no sequences corresponding to novel viruses were detected.

CONCLUSIONS

These results suggest that ALF patients should be screened for the presence of uncommon viruses and coinfections, and that most cases of indeterminate ALF in the United States do not appear to be caused by novel viral pathogens. In the future, mNGS testing may be useful for comprehensive diagnosis of viruses associated with ALF, or to exclude infectious etiologies.

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.

Aetiology and prognostic factors in acute liver failure in India

The early prognostic indicators for acute liver failure in endemic zones for hepatitis E virus have not been determined. All consecutive patients with acute liver failure from a geographically defined region endemic for hepatitis E virus were studied over the period April 1989-April 1996. Demographic, clinical and biochemical parameters were recorded at presentation and serum samples were analysed for known viral hepatitis (A-E) markers. Multiple parameters were compared in survivors and non-survivors in a univariate analysis. All significant factors on univariate analysis were entered into a stepwise logistic regression analysis to identify independent variables of prognosis. The sensitivity and specificity of significant prognostic factors was then assessed. A total of 180 [69 males and 111 females: age (mean +/- SD) 31.1 +/- 14.7 years] with acute liver failure were studied. Of these, 131 (72.8%) patients died. Hepatitis E virus was the aetiological cause in 79 (43.9%) patients, while hepatitis A virus, hepatitis B virus, hepatitis C virus and non-A, non-E agent/'s could be incriminated in four (2.1%), 25 (13.9%), 13 (7.2%) and 56 (31.1%) patients respectively. Of 83 women in childbearing age, 49 (59.0%) were pregnant, 33 (67.3%) of these were in the third trimester. Forty-seven (95.8%) pregnant women had HEV infection. Nine variables differed significantly between survivors and non-survivors on univariate analysis. Of these, four variables which predicted the adverse outcome on multivariate analysis were non-hepatitis-E aetiology, prothrombin time >30 s, grade of coma >2 and age >40 years in that order of significance. Pregnancy per se or duration of gestation did not adversely affect the prognosis. In endemic areas, hepatitis E virus is the commonest cause of acute liver failure. Acute liver failure occurs in a high proportion of pregnant women, mostly in third trimester. Early predictors of a poor outcome are non-E aetiology, prothrombin time >30 s, grade of coma >2 and age >40 years.

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.

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.

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.

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.

No evidence of hepatitis G virus in fulminant hepatic failure in children

BACKGROUND

The cause of fulminant hepatic failure in children remains unknown, but a viral origin has been suspected in most cases. The recently discovered blood-borne virus, hepatitis G, has been suggested as a possible causative agent.

METHOD

Six consecutive children who underwent liver transplantation for fulminant hepatic failure were studied. The children were tested for hepatitis G virus antibodies and hepatitis G virus RNA by polymerase chain reaction after excluding other causes of fulminant hepatic failure.

RESULTS

No evidence of hepatitis G virus infection was found in these patients.

CONCLUSION

Hepatitis G virus is unlikely to be a common cause of fulminant hepatic failure in pediatric patients from the upper midwestern United States.

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.

Review article: the management of acute liver failure

Acute liver failure (ALF) is a relatively uncommon but dramatic clinical syndrome with high mortality rates, in which a previously normal liver fails within days or weeks. Paracetamol overdose remains the major cause of ALF in the UK, while viral hepatitis is the commonest cause world-wide. Cerebral oedema is the leading cause of death in patients with ALF. Despite advances in intensive care and the development of new treatment modalities, ALF remains a condition of high mortality best managed in specialist centres. Orthotopic liver transplantation is the only new treatment modality that has made a significant impact in improving outcome. Bioartificial liver support systems and hepatocyte transplantation are new promising treatment options that may change the management of ALF in the future.

Fulminant hepatitis and the new G/GBV-C flavivirus

A new virus within the family Flaviviridae. 'hepatitis' G/GBV-C, has been incriminated by several authors as a causative factor of idiopathic or cryptogenic fulminant hepatitis, a syndrome of presumed viral aetiology. Review of worldwide data from 22 studies on 364 cases indicates that G/GBV-C infection is present in approximately 20% of idiopathic cases but a similar or even higher prevalence is detected in fulminant hepatitis of viral B, D or C aetiology, reflecting a high rate of parenteral viral exposure rather than a specific aetiology of fulminant hepatic failure. An aetiopathogenic role of G/GBV-C in fulminant hepatitis seems to be further refuted by the analysis of other data in the literature. The presence of G/GBV-C infection in fulminant hepatic failure is largely a result of secondary infection or coinfection. The aetiopathogenetic mystery of cryptogenic or idiopathic fulminant hepatitis remains unsolved.

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.

The natural history of hepatitis C

The natural history of hepatitis C is complex and still poorly known. Hepatitis C virus (HCV) replication can be detected very soon after exposure and, at least in the transfusional setting, it persists indefinitely in up to 90% of the cases. While liver damage during the acute phase of hepatitis is almost invariably mild (fulminant cases are exceptions), chronic sequelae of HCV infection may be severe in the long run. Chronic hepatitis C, in fact, is a long-lasting indolent process which leads to cirrhosis in approximately 20% of all infected patients. Hepatocellular carcinoma is a well-recognized complication of old infections, as are a number of extrahepatic manifestations, including type II cryoglobulinaemia. The determinants of the severity of the liver disease are still unclear. However, the risk of cirrhosis seems to be greater for patients with old infections, those infected with the genotype 1b and those with associated conditions. The latter are a heterogeneous and increasing group of 'problem' patients, including patients who are co-infected with the human immunodeficiency virus (HIV1), or who are being treated with cytotoxic or immunomodulating drugs. Data suggest that the natural history of hepatitis C is altered in patients with associated conditions, and this might have an impact on strategies of patient management and treatment.

[Study of HCV infection and viremia in patients with posttransfusion hepatitis in China]

One hundred and sixty-nine patients with posttransfusion hepatitis (PTH) were investigated for etiology with serological and PCR methods. Our result showed that HCV was the major causative agent of PTH in this study. A part of patients (24/169) were also HBV markers positive. Three patients were negative for all detected viral markers, looking forwards to progressive study. Anti-HCV was detectable from 7 days to one year after onsetting of clinical symptoms, average time 54.62 days. HCV RNA could be detected in early time of HCV infection ( 6 to 20 days later), average time 8.72 days. A follow-up study of 84 patients showed that all patients remained anti-HCV positive during the observation for 1.5 -- 3 years, but their HCV viremia had three forms: transient, persistent or intermittent. The interaction between HCV and HBV by their superinfection was unknown, awaiting further study.