Immunohistochemistry for the diagnosis of hepatitis E virus infection

Laboratory Diagnosis of HEV Infection

Serological and nucleic acid tests for detecting hepatitis E virus (HEV) have been developed for both epidemiologic and diagnostic purposes. The laboratory diagnosis of HEV infection depends on the detection of HEV antigen or HEV RNA in the blood, stool, and other body fluids, and serum antibodies against HEV (immunoglobulin [Ig]A, IgM, and IgG). Anti-HEV IgM antibodies and low avidity IgG can be detected during the acute phase of the illness and can last approximately 12 months, representing primary infection, whereas anti-HEV IgG antibodies can last more than several years, representing remote exposure. Thus, the diagnosis of acute infection is based on the presence of anti-HEV IgM, low avidity IgG, HEV antigen, and HEV RNA, while epidemiological investigations are mainly based on anti-HEV IgG. Although significant progress has been made in developing and optimizing different formats of HEV assays, improving their sensitivity and specificity, there are many shortcomings and challenges in inter-assay concordance, validation, and standardization. This article reviews the current knowledge on the diagnosis of HEV infection, including the most common available laboratory diagnostic techniques.

Immunohistochemical diagnosis of human infectious diseases: a review

BACKGROUND

Immunohistochemistry (IHC) using monoclonal and polyclonal antibodies is a useful diagnostic method for detecting pathogen antigens in fixed tissues, complementing the direct diagnosis of infectious diseases by PCR and culture on fresh tissues. It was first implemented in a seminal publication by Albert Coons in 1941.

MAIN BODY

Of 14,198 publications retrieved from the PubMed, Google, Google Scholar and Science Direct databases up to December 2021, 230 were selected for a review of IHC techniques, protocols and results. The methodological evolutions of IHC and its application to the diagnosis of infectious diseases, more specifically lice-borne diseases, sexually transmitted diseases and skin infections, were critically examined. A total of 59 different pathogens have been detected once in 22 different tissues and organs; and yet non-cultured, fastidious and intracellular pathogens accounted for the vast majority of pathogens detected by IHC. Auto-IHC, incorporating patient serum as the primary antibody, applied to diseased heart valves surgically collected from blood culture-negative endocarditis patients, detected unidentified Gram-positive cocci and microorganisms which were subsequently identified as Coxiella burnetii, Bartonella quintana, Bartonella henselae and Tropheryma whipplei. The application of IHC to ancient tissues dated between the ends of the Ptolemaic period to over 70 years ago, have also contributed to paleomicrobiology diagnoses.

CONCLUSION

IHC plays an important role in diagnostic of infectious diseases in tissue samples. Paleo-auto-IHC derived from auto-IHC, is under development for detecting non-identified pathogens from ancient specimens.

Experimental infection of hepatitis E virus induces pancreatic necroptosis in miniature pigs

Infection by hepatitis E virus (HEV) via the oral route causes acute hepatitis. Extra-hepatic manifestations of HEV infection may stem from various causes; however, its distribution in organs such as the liver, as well as the mechanisms underlying HEV-induced cell injury, remain unclear. The objective of this study was to determine the chronological distribution of HEV in various tissues of HEV-challenged miniature pigs and to investigate the mechanisms underlying HEV-induced cell death in the pancreas and liver. Virological and serological analyses were performed on blood and faecal samples. Histopathology of the liver and extra-hepatic tissues was analysed. Cell death pathways and immune cell characterisation in inflammatory lesions were analysed using immunohistochemistry. The liver and pancreas displayed inflammation and cellular injury, and a large amount of HEV was observed in the lesions. The liver was infiltrated by T and natural killer cells. HEV was identified in all organs except the heart, and was associated with immune cells. Although the liver and the pancreas strongly expressed TNF-α and TRAIL, TUNEL assay results were negative. RIP3 and pMLKL were expressed in the pancreas. RIP3, but not pMLKL, was expressed in the liver. Pancreatitis induced in HEV-infected miniature pigs is associated with necroptosis.

Chronic Hepatitis E is associated with cholangitis

BACKGROUND AND AIMS

Sporadic hepatitis E is an emerging indigenous disease in Europe induced by genotype 3 of the virus. While the disease takes an acute self-limited course in immunocompetent individuals, under immunocompromised conditions chronic hepatitis E might develop. The histology of chronic hepatitis E has not been described in detail systematically.

METHODS

Liver biopsies from 19 immunosuppressed patients with chronic hepatitis E were collected: 17 were organ transplant recipients, one had a CD4-deficiency and one had received steroid therapy because of ulcerative colitis. Biopsies were processed with standard stains. Evaluation of histologic activity and fibrosis was performed according to Ishak. Additionally, immunohistochemistry with antibodies directed against open reading frame 2 and 3 of the virus was performed and liver biopsies were tested for hepatitis E virus RNA.

RESULTS

Biochemical data showed an increase in alanine transaminase, aspartate transaminase, gamma-glutamyl transferase and total bilirubin. Histopathology displayed typical features of chronic hepatitis with mild to moderate activity. The number of polymorphonuclear leucocytes was considerably increased and all patients had a florid cholangitis that presented as a destructive form in five of them. Hepatocytes and bile duct epithelia stained positive for hepatitis E virus by immunohistochemistry.

CONCLUSIONS

Chronic hepatitis E in immunocompromised individuals runs a similar course as hepatitis B and C and shows similar histopathology. However, the presence of destructive cholangitis in some cases accompanied by an increased number of polymorphonuclear leucocytes is markedly different. Immunohistochemically the virus is present in bile duct epithelia, seemingly the cause for cholangitis.

Role of formalin fixed paraffin embedded liver tissues in the diagnosis of viral hepatitis E in patients with undiagnosed acute liver failure

Viral hepatitis E is gaining importance as an emerging worldwide disease. Though viral hepatitis E (HEV) has been attributed as an etiology of acute liver failure (ALF), however its actual incidence and the immunopathogenesis are being under explored. The present study is aimed at detecting HEV in post mortem liver tissues of patients with undiagnosed ALF. Twenty six liver tissues of ALF patients died of unknown etiology are subjected to nested reverse transcriptase PCR with HEV ORF1 gene targeted primers and HEV RNA is detected in 30.4% (7/23) of ALF cases. Out of seven HEV RNA positive cases, three (42.8%) had HEV antigen positivity by immunohistochemistry on liver tissues using HEV ORF2 antibody. Histopathological examination by H&E staining shows multiacinar confluent hepatic necrosis, bile ductular proliferation, bridging hepatic and periportal necrosis in 4, 4, 2 and 1 cases respectively. The isolates were sequenced using RdRp gene specific primers and found to HEV genotype-1. Quantitative TaqMan real time PCR estimated the viral load ranged between 7.77 × 10³ and 1.44 × 10⁷ viral copies/µl. HEV has been associated with 30.4% (7/23) of undiagnosed ALF cases. Immuno-histochemistry along with molecular testing in FFPE biopsies might be useful for the detection of HEV in undiagnosed cases.

An Update on the Clinicopathologic Features and Pathologic Diagnosis of Hepatitis E in Liver Specimens

Infection with the hepatitis E virus (HEV) is globally seen a leading cause of hepatitis. Now increasingly recognized also in industrialized countries, hepatitis E constitutes a significant health problem worldwide. The patient's immune status determines the clinical course and histopathology of hepatitis E. In immunocompetent patients, hepatitis E usually follows an asymptomatic or subclinical course, but may also present with acute hepatitis. In contrast, immunocompromised patients may develop chronic hepatitis, and patients with preexisting liver diseases are at risk for liver decompensation with potentially fatal outcome. Whereas pathologists only occasionally encounter liver biopsies from immunocompetent individuals with hepatitis E, they are more likely exposed to biopsies from patients with preexisting liver disease or immunocompromised individuals. Histopathologic hallmarks of hepatitis E in immunocompetent patients comprise lobular disarray, lobular, and portal inflammation, as well as hepatocyte necrosis of varying extend and regeneration. Thus, it is similar to acute non-E viral hepatitis, yet further differential diagnoses include autoimmune hepatitis and drug-induced liver injury. Histopathologic findings of hepatitis E in preexisting liver disease are determined by the underlying pathology, but may be more severe. Histopathologic presentation of hepatitis E in immunocompromised patients is highly variable, ranging from minimal active hepatitis to chronic hepatitis with severe activity and progressive fibrosis. Taken together, the variability of the histologic features depending on the clinical context and the overlap with other liver diseases make the histopathologic diagnosis of hepatitis E challenging. Immunohistochemistry for HEV open reading frame 2 protein and molecular testing for HEV RNA are useful tissue-based ancillary tools.

Acute Viral Hepatitis: Beyond A, B, and C

From the standpoint of the surgical pathologist "hepatitis" is defined as the set of histologic patterns of lesions found in livers infected by hepatotropic viruses, by non-hepatotrophic viruses leading to liver inflammation in the context of systemic infection, or due to an autoimmune disease, drug, or toxin involving the liver. This article is centered on the histologic patterns of injury in acute viral hepatitis, encompassing the hepatotropic viruses A, B, C, D, and E and the "icteric hemorrhagic fevers" (dengue, hantavirus, yellow fever). A brief mention of viruses causing hepatitis in immunosuppressed patients also is presented.

Hepatitis E Virus (HEV) egress: Role of BST2 (Tetherin) and interferon induced long non- coding RNA (lncRNA) BISPR

Background

The biology of Hepatitis E Virus (HEV), a common cause of epidemic and sporadic hepatitis, is still being explored. HEV exits liver through bile, a process which is essential for its natural transmission by feco-oral route. Though the process of this polarised HEV egress is not known in detail, HEV pORF3 and hepatocyte actin cytoskeleton have been shown to play a role.

Methods

Our transcriptome analysis in Hepatitis E virus (HEV) replicon transfected Huh7 cells at 24 and 72 hrs indicated that at 24hrs, both LncBISPR and BST2, expressed by a bidirectional promoter were highly upregulated whereas at 72 hrs, BST2 expression was comparatively reduced accompanied by normal levels of BISPR. These findings were confirmed by qPCR analysis. Co-localisation of BST2 and HEV pORF2 was confirmed in HEV transfected Huh7 by confocal microscopy. To investigate the role of BISPR/BST2 in HEV life cycle, particularly virus egress, we generated Huh7 cells with ~8kb deletion in BISPR gene using Crispr-Cas9 system. The deletion was confirmed by PCR screening, Sanger sequencing and Real time PCR. Virus egress in ΔBISPR Huh7 and Huh7 cells was compared by measuring HEV positive strand RNA copy numbers in cell lysates and culture supernatants at 24 and 72 hrs post HEV replicon transfection and further validated by western blot for HEV pORF2 capsid protein.

Results

ΔBISPR Huh7 cells showed ~8 fold increase in virus egress at 24 hrs compared to Huh7 cells. No significant difference in virus egress was observed at 72hrs. Immunohistochemistry in histologically normal liver and HEV associated acute liver failure revealed BST2 overexpression in HEV infected hepatocytes and a dominant canalicular BST2 distribution in normal liver in addition to the cytoplasmic localisation reported in literature.

Conclusions

These findings lead us to believe that BISPR and BST2 may regulate egress of HEV virions into bile in vivo. This system may also be used to scale up virus production in vitro.

Laboratory Diagnosis of HEV Infection

Serological and nucleic acid tests for detecting hepatitis E virus (HEV) have been developed for both epidemiologic and diagnostic purposes. The laboratory diagnosis of HEV infection depends on the detection of HEV antigen, HEV RNA, and serum antibodies against HEV (immunoglobulin [Ig]A, IgM, and IgG). Anti-HEV IgM antibodies can be detected during the acute phase of the illness and can last approximately 4 or 5 months, representing recent exposure, whereas anti-HEV IgG antibodies can last more than 10 years, representing remote exposure. Thus, the diagnosis of acute infection is based on the presence of anti-HEV IgM, HEV antigen, and HEV RNA, while epidemiological investigations are mainly based on anti-HEV IgG. Although significant progress has been made in developing and optimizing different formats of HEV assays, improving their sensitivity and specificity, there are many shortcomings and challenges in inter-assay concordance, validation, and standardization. This article reviews the current knowledge on the diagnosis of HEV infection, including the most common available laboratory diagnostic techniques.

Visualization of hepatitis E virus RNA and proteins in the human liver

BACKGROUND & AIMS

Although hepatitis E constitutes a substantial disease burden worldwide, surprisingly little is known about the localization of hepatitis E virus (HEV) in the human liver. We therefore aimed to visualize HEV RNA and proteins in situ.

METHODS

A panel of 12 different antibodies against HEV open reading frame (ORF) 1-3 proteins was evaluated for immunohistochemistry (IHC) and two probes for in situ hybridization (ISH) in formalin-fixed, paraffin-embedded (FFPE) HuH7 cells transfected with HEV ORF1-3 expression vectors. IHC (and partly ISH) were then applied to Hep293TT cells replicating infectious HEV and liver specimens from patients with hepatitis E (n=20) and controls (n=134).

RESULTS

Whereas ORF1-3 proteins were all detectable in transfected, HEV protein-expressing cells, only ORF2 and 3 proteins were traceable in cells replicating infectious HEV. Only the ORF2-encoded capsid protein was also unequivocally detectable in liver specimens from patients with hepatitis E. IHC for ORF2 protein revealed a patchy expression in individual or grouped hepatocytes, generally stronger in chronic compared to acute hepatitis. Besides cytoplasmic and canalicular, ORF2 protein also displayed a hitherto unknown nuclear localization. Positivity for ORF2 protein in defined areas correlated with HEV RNA detection by ISH. IHC was specific and comparably sensitive as PCR for HEV RNA.

CONCLUSIONS

ORF2 protein can be reliably visualized in the liver of patients with hepatitis E, allowing for sensitive and specific detection of HEV in FFPE samples. Its variable subcellular distribution in individual hepatocytes of the same liver suggests a redistribution of ORF2 protein during infection and interaction with nuclear components.

LAY SUMMARY

The open reading frame (ORF) 2 protein can be used to visualize the hepatitis E virus (HEV) in the human liver. This enabled us to discover a hitherto unknown localization of the HEV ORF2 protein in the nucleus of hepatocytes and to develop a test for rapid histopathologic diagnosis of hepatitis E, the most common cause of acute hepatitis worldwide.

Hepatitis E Virus and the Liver: Clinical Settings and Liver Pathology

Infection with hepatitis E virus (HEV) is a leading cause of acute hepatitis worldwide, now increasingly recognized also in nonendemic regions. Clinical manifestation of hepatitis E includes mostly asymptomatic/subclinical presentations or acute, self-limiting hepatitis, but also potentially fatal liver failure or chronic hepatitis in immunocompromised individuals. Accordingly, hepatitis E histolpathologic patterns range from an unremarkable histology over acute (cholestatic) hepatitis with variable degree of necrosis to chronic hepatitis with fibrosis. Awareness of hepatitis E and its differential diagnoses, knowledge of its clinico-pathologic manifestations and familiarity with its diagnostic tools will enable clinicians and pathologists to competently make this diagnosis.

Recombinant Hepatitis E virus like particles can function as RNA nanocarriers

Background

Assembled virus-like particles (VLPs) without genetic material, with structure similar to infectious virions, have been successfully used as vaccines. We earlier described in vitro assembly, characterisation and tissue specific receptor dependent Clathrin mediated entry of empty HEV VLPs, produced from Escherichia coli expressed HEV capsid protein (pORF2). Similar VLP’s have been described as a potential candidate vaccine (Hecolin) against HEV.

Findings

We have attempted to use such recombinant assembled Hepatitis E virus (HEV) VLPs as a carrier for heterologous RNA with protein coding sequence fused in-frame with HEV 5′ region (containing cap and encapsidation signal) and investigated, if the relevant protein could be expressed and elicit an immune response in vivo. In vitro transcribed red fluorescent protein (RFP)/Hepatitis B virus surface antigen (HBsAg) RNA, fused to 5′-HEV sequence with cap and encapsidation signal (1–249 nt), was packaged into the recombinant HEV-VLPs and incubated with five different cell lines (Huh7, A549, Vero, HeLa and SiHa). The pORF2-VLPs could specifically transfer exogenous coding RNA into Huh7 and A549 cells. In vivo, Balb/c mice were immunized (intramuscular injections) with 100 µg pORF2-VLP encapsidated with 5′-methyl-G-HEV (1–249 nt)-HBsAg RNA, blood samples were collected and screened by ELISA for anti-pORF2 and anti-HBsAg antibodies. Humoral immune response could be elicited in Balb/c mice against both HEV capsid protein and cargo RNA encoded HBsAg protein.

Conclusions

These findings suggest that other than being a possible vaccine, HEV pORF2-VLPs can be used as a promising non-replicative tissue specific gene delivery system.

Natural and experimental hepatitis E virus genotype 3-infection in European wild boar is transmissible to domestic pigs

Hepatitis E virus (HEV) is the causative agent of acute hepatitis E in humans in developing countries, but sporadic and autochthonous cases do also occur in industrialised countries. In Europe, food-borne zoonotic transmission of genotype 3 (gt3) has been associated with domestic pig and wild boar. However, little is known about the course of HEV infection in European wild boar and their role in HEV transmission to domestic pigs. To investigate the transmissibility and pathogenesis of wild boar-derived HEVgt3, we inoculated four wild boar and four miniature pigs intravenously. Using quantitative real-time RT-PCR viral RNA was detected in serum, faeces and in liver, spleen and lymph nodes. The antibody response evolved after fourteen days post inoculation. Histopathological findings included mild to moderate lymphoplasmacytic hepatitis which was more prominent in wild boar than in miniature pigs. By immunohistochemical methods, viral antigens were detected mainly in Kupffer cells and liver sinusoidal endothelial cells, partially associated with hepatic lesions, but also in spleen and lymph nodes. While clinical symptoms were subtle and gross pathology was inconspicuous, increased liver enzyme levels in serum indicated hepatocellular injury. As the faecal-oral route is supposed to be the most likely transmission route, we included four contact animals to prove horizontal transmission. Interestingly, HEVgt3-infection was also detected in wild boar and miniature pigs kept in contact to intravenously inoculated wild boar. Given the high virus loads and long duration of viral shedding, wild boar has to be considered as an important HEV reservoir and transmission host in Europe.

Hepatitis E virus in patients with acute severe liver injury

AIM: To examine the incidence of hepatitis E (HepE) in individuals with acute liver injury severe enough to warrant treatment at a transplant unit.

METHODS: Hepatitis E virus (HEV) is an emerging pathogen in developed countries causing severe illness, particularly in immunocompromised patients or those with underlying chronic liver disease. HepE infection is often under diagnosed, as clinicians can be reluctant to test patients who have not travelled to regions traditionally considered hyperendemic for HepE. There are few data regarding the significance of HEV in patients with very severe acute liver injury in developed countries. Eighty patients with acute severe liver injury attending the Scottish Liver Transplant unit were tested for HEV and anti-HEV IgG and IgM. Severe acute liver injury was defined as a sudden deterioration in liver function confirmed by abnormal liver function tests and coagulopathy or presence of hepatic encephalopathy. Eighty percent of these patients were diagnosed with paracetomol overdose. No patients had a history of chronic or decompensated chronic liver disease at time of sampling. IgG positive samples were quantified against the World Health Organization anti-HEV IgG standard. Samples were screened for HEV viral RNA by quantitative reverse transcription polymerase chain reaction.

RESULTS: Four cases of hepatitis E were identified. Three of the four cases were only diagnosed on retrospective testing and were initially erroneously ascribed to drug-induced liver injury and decompensated chronic liver disease, with the cause of the decompensation uncertain. One case was caused by HEV genotype 1 in a traveller returning from Asia, the other three were autochthonous and diagnosed on retrospective testing. In two of these cases (where RNA was detected) HEV was found to be genotype 3, the most prevalent genotype in developed countries. Three patients survived, two of whom had been misdiagnosed as having drug induced liver injury. The fourth patient died from sepsis and liver failure precipitated as a result of hepatitis E infection and previously undiagnosed cirrhosis. Histopathology data to date is limited to mainly that seen for endemic HepE. All patients, with the exception of patient 1, demonstrated characteristics of HepE infection, as seen in previously described locally acquired cases.

CONCLUSION: In patients with acute severe liver injury, HEV testing should be part of the initial diagnostic investigation algorithm irrespective of suspected initial diagnosis, age or travel history.

RNA-seq based transcriptome analysis of hepatitis E virus (HEV) and hepatitis B virus (HBV) replicon transfected Huh-7 cells

Pathogenesis of hepatitis B virus (HBV) and hepatitis E virus (HEV) infection is as varied as they appear similar; while HBV causes an acute and/or chronic liver disease and hepatocellular carcinoma, HEV mostly causes an acute self-limiting disease. In both infections, host responses are crucial in disease establishment and/or virus clearance. In the wake of worsening prognosis described during HEV super-infection over chronic HBV hepatitis, we investigated the host responses by studying alterations in gene expression in liver cells (Huh-7 cell line) by transfection with HEV replicon only (HEV-only), HBV replicon only (HBV-only) and both HBV and HEV replicons (HBV+HEV). Virus replication was validated by strand-specific real-time RT-PCR for HEV and HBsAg ELISA of the culture supernatants for HBV. Indirect immunofluorescence for the respective viral proteins confirmed infection. Transcription profiling was carried out by RNA Sequencing (RNA-Seq) analysis of the poly-A enriched RNA from the transfected cells. Averages of 600 million bases within 5.6 million reads were sequenced in each sample and ∼15,800 genes were mapped with at least one or more reads. A total of 461 genes in HBV+HEV, 408 in HBV-only and 306 in HEV-only groups were differentially expressed as compared to mock transfection control by two folds (p<0.05) or more. Majority of the significant genes with altered expression clustered into immune-associated, signal transduction, and metabolic process categories. Differential gene expression of functionally important genes in these categories was also validated by real-time RT-PCR based relative gene-expression analysis. To our knowledge, this is the first report of in vitro replicon transfected RNA-Seq based transcriptome analysis to understand the host responses against HEV and HBV.

Hepatitis E in liver biopsies from patients with acute hepatitis of clinically unexplained origin

Hepatitis E virus (HEV) is a small RNA virus and the infectious agent of hepatitis E that occurs worldwide either as epidemics in Asia caused by genotype 1 and 2 or as sporadic disease in industrialized countries induced by genotype 3 and 4. The frequency might be underestimated in central Europe as a cause of acute hepatitis. Therefore, we analyzed on liver biopsies, if cases of acute hepatitis with clinically unknown or obscure diagnosis were actually caused by the infection with HEV. We included 221 liver biopsies retrieved from the files of the institute of pathology during the years 2000 till 2010 that were taken from patients with acute hepatitis of obscure or doubtful diagnosis. From all biopsies RNA was extracted, prepared, and subjected to RT-PCR with specific primers. Amplified RNA was detected in 7 patients, sequenced and the genotype 3 could be determined in four of the seven of positive specimens from 221 samples. Histopathology of the biopsies revealed a classic acute hepatitis with cholestatic features and in some cases confluent necrosis in zone 3. Histology in a cohort of matched patients was less severe and showed more eosinophils. The analysis of the immune response by subtyping of liver infiltrating lymphocytes showed circumstantial evidence of adaptive immune reaction with CD 8 positive CTLs being the dominant lymphocyte population. In conclusion, in doubtful cases of acute hepatitis of unknown origin, HEV infection should be considered as etiology in central Europe. We demonstrate for the first time that the diagnosis can be made in paraffin-embedded liver biopsies reliably when no serum is available and also the genotype can be determined. The analysis of the immune response by subtyping of liver infiltrating lymphocytes indicates an adaptive mechanism suggesting in analogy with HAV, HBV and HCV that the virus itself is not cytopathic but liver damage is due to immune reaction.

Torque Teno virus in children who underwent orthotopic liver transplantation: new insights about a common pathogen

BACKGROUND

 Torque Teno virus (TTV) is a ubiquitous infectious agent. Transplant recipients are at risk of hepatitis E virus (HEV) infection and could be vulnerable to TTV-associated adverse effects. The aim of this study was to evaluate the influence of immunosuppression and HEV infection on TTV replication and liver injury in pediatric patients after orthotopic liver transplantation (OLT).

METHODS

 Pediatric recipients of liver transplants were classified into the following 2 groups: (1) those with normal serum aminotransferases levels and (2) those with persistently increased serum aminotransferases levels and histological features of chronic hepatitis of unknown etiology. The TTV load was assessed in 342 serum samples by use of TaqMan real-time polymerase chain reaction, along with TTV genogroups and coinfection with HEV.

RESULTS

 TTV DNA was detected in 96% of tested serum samples. Viral load was significantly lower in patients with features of chronic hepatitis, of whom 78% had liver fibrosis scores of ≥2. Viral load decreased during posttransplantation follow-up. Viral load and genogroups were influenced by immunosuppression. Lower viral load was observed in patients coinfected with HEV.

CONCLUSIONS

 TTV infection is widespread, and its replication is closely related to immune status and viral coinfection. High TTV viremia is not associated with hepatitis after OLT, but, conversely, liver inflammatory activity impairs TTV replication.

Hepatitis E masquerading as drug-induced liver injury

The patient presented below gives us the opportunity to discuss challenges in the diagnosis of drug-induced liver injury in an era of increasing awareness of hepatitis E.