Molecular detection of hepatitis E virus (HEV) in liver biopsies after liver transplantation

Abstract

We aimed to determine the rate of hepatitis E virus (HEV) infection, a recently increasingly recognized disease in the Western world, in liver transplant patients by direct molecular testing of liver tissue. A RT-PCR assay was designed for detecting the HEV open reading frame (ORF) 2/3 gene region in formalin-fixed, paraffin-embedded tissues, and applied to all liver biopsies (n ¼ 683) taken 4 weeks or later from all patients (n ¼ 282) after liver transplantation of two large academic centers. HEV-RNA was detected in ten biopsies from four different patients (rate: 1%). Histology in early HEV infection was variable including cases with only few hepatocellular apoptoses, no or only minute inflammation. Hepatitis lasted for at least 6 months in 3/4 patients. Serologic testing for HEV-RNA in a subcohort (159 patients) was positive in five patients (rate: 3%), resulting in an overall HEV detection rate of 3% (8/282). In case both liver tissue and sera of a patient were available from the same time period, all cases tested positive in one material were also tested positive in the other material, respectively. All patients had de novo autochthonous infection with HEV genotype 3. Our data confirm that HEV infection is a relevant cause of liver injury after liver transplantation. Molecular testing for HEV in routinely processed transplant liver biopsies is powerful for evaluating patients with elevated transaminases of unknown origin. Histology of HEV infection under immunosuppression in the early phase is distinct from HEV infection in immunocompetent individuals.

Detection of viral hepatitis E in clinical liver biopsies

“…In addition to the present data, PCR of archival liver biopsies has been shown recently to identify unrecognized HEV infection of small numbers of patients categorized previously as hepatitis of unknown origin, drug‐induced liver injury and among archival liver transplant biopsies . Taking all factors into account, tissue PCR testing is robust, more sensitive, easier and cheaper than in‐situ RNA testing when sufficient tissue is available.…”

“…Clearance of viraemia did not necessarily imply clearance of infection: the present identification of viral RNA in the liver by both tests in one immunosuppressed patient when contemporary point testing of serum was negative re‐emphasizes the need for follow‐up testing where the clinical setting suggests a potential for prolonged infection, particularly as serological testing is insensitive in such patients. Protzer also noted two aviraemic liver allograft patients with contemporary HEV‐RNA‐positive liver biopsies, although both appeared to eventually clear the infection biochemically . In typical self‐limited infection of immunocompetent patients, HEV is detectable in stool for 2–4 weeks after viraemia subsides, presumably reflecting dwindling hepatic viral release into bile, in which the temporary discrepancy with serum testing does not usually have a longer‐term significance.…”

“…One report describes genotype 7 (camel) HEV infection of a liver allograft . Early findings in liver allografts with accelerated fibrosis linked to chronic HEV infection included hepatocyte single cell death with no or minimal lymphocytic lobulitis, no ballooning or cholestatic features and mild portal lymphocytic infiltration . This evolved in some to mild–moderate lymphocytic portal, interface and lobular hepatitis with fibrosis, still without notable cholestatic features or ballooning .…”

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“…Histology of HEV infection under immunosuppression in the early phase is distinct from HEV infection in immunocompetent individuals. 8 Molecular testing with a reverse transcription polymerase chain reaction assay designed for detecting the HEV open reading frame 2/3 gene region in liver biopsies is another powerful tool to evaluate liver transplant recipients with elevated transaminases of unknown origin. 8 A dosage reduction of immunosuppressants is the first-line therapy that can result in a viral clearance in more than 30% of patients.…”

“…8 Molecular testing with a reverse transcription polymerase chain reaction assay designed for detecting the HEV open reading frame 2/3 gene region in liver biopsies is another powerful tool to evaluate liver transplant recipients with elevated transaminases of unknown origin. 8 A dosage reduction of immunosuppressants is the first-line therapy that can result in a viral clearance in more than 30% of patients. 5 Risk factors associated with failure of HEV clearance after acute infection included the degree of immunosuppression, the time between the last episode of acute rejection and HEV infection, time since transplant, low leucocyte count, low total-lymphocyte count, low T-cell count, and use of tacrolimus and thrombocytopenia.…”