Hepatitis E virus infection of transplanted kidneys.

Immunocompromised patients are at risk of chronic hepatitis E (HEV) infection. Recurrent T cell and borderline rejections in a pediatric patient with high HEV copy numbers led us to study HEV infection within renal transplants. To investigate the frequency of renal HEV infection in transplanted patients, 15 samples from patients with contemporaneous diagnoses of HEV infection were identified at our center. Ten samples had sufficient residual paraffin tissue for immunofluorescence (IF) and RNA-fluorescence-in-situ-hybridization (RNA-FISH). The biopsy of the pediatric index patient was additionally sufficient for tissue polymerase chain reaction and electron microscopy. HEV RNA was detected in paraffin tissue of the index patient by tissue polymerase chain reaction. Subsequently, HEV infection was localized in tubular epithelial cells by IF, RNA-FISH, and electron microscopy. One additional biopsy from an adult was positive for HEV by RNA-FISH and IF. Focal IF positivity for HEV peptide was observed in 7 additional allografts. Ribavirin therapy was not successful in the pediatric index patient; after relapse, ribavirin is still administered. In the second patient, successful elimination of HEV was achieved after short-course ribavirin therapy. HEV infection is an important differential diagnosis for T cell rejection within transplanted kidneys. Immunostaining of HEV peptide does not necessarily prove acute infection. RNA-FISH seems to be a reliable method to localize HEV.