Insertions and deletions in the hypervariable region of the hepatitis E virus genome in individuals with acute and chronic infection.

BACKGROUND AND AIMS: Hepatitis E virus is a major cause of acute hepatitis worldwide and can progress to chronicity in immunocompromised individuals. Various virus-host recombination events have been reported in the hypervariable region of the hepatitis E virus genome, but the patterns of assembly and selection remain unclear. METHODS: To gain further insight into viral evolution, we assessed the presence of low abundance variants in 16 samples from individuals with acute or chronic infection using a targeted next-generation sequencing approach. RESULTS: In seven samples, different variants with insertions and/or deletions were identified. Among them, eight insertions originating either from human genes or from the hepatitis E virus genome. Five different deletions could be identified. The amino acid composition of sequences with insertions showed a higher frequency of lysine and a lower abundance of proline, and additionally acetylation and ubiquitination sites were more frequent than in hepatitis E virus wild-type sequences. CONCLUSIONS: These findings suggest that the nucleotide composition of insertions and sites for post-translational modification may contribute to recombination events. Although the impact of low-level hepatitis E virus variants is uncertain, our results highlight the importance of a highly sensitive next-generation sequencing approach to capture the full diversity of hypervariable region.

Advanced sequencing approaches detected insertions of viral and human origin in the viral genome of chronic hepatitis E virus patients.

The awareness of hepatitis E virus (HEV) increased significantly in the last decade due to its unexpectedly high prevalence in high-income countries. There, infections with HEV-genotype 3 (HEV-3) are predominant which can progress to chronicity in immunocompromised individuals. Persistent infection and antiviral therapy can select HEV-3 variants; however, the spectrum and occurrence of HEV-3 variants is underreported. To gain in-depth insights into the viral population and to perform detailed characterization of viral genomes, we used a new approach combining long-range PCR with next-generation and third-generation sequencing which allowed near full-length sequencing of HEV-3 genomes. Furthermore, we developed a targeted ultra-deep sequencing approach to assess the dynamics of clinically relevant mutations in the RdRp-region and to detect insertions in the HVR-domain in the HEV genomes. Using this new approach, we not only identified several insertions of human (AHNAK, RPL18) and viral origin (RdRp-derived) in the HVR-region isolated from an exemplary sample but detected a variant containing two different insertions simultaneously (AHNAK- and RdRp-derived). This finding is the first HEV-variant recognized as such showing various insertions in the HVR-domain. Thus, this molecular approach will add incrementally to our current knowledge of the HEV-genome organization and pathogenesis in chronic hepatitis E.

Rituximab-Containing Treatment Regimens May Imply a Long-Term Risk for Difficult-To-Treat Chronic Hepatitis E.

Hepatitis E virus (HEV) infection is an emerging disease in industrialized countries which is usually characterized by a self-limited course. However, there is an increased risk of HEV persistence in immunocompromised risk populations, comprising patients following solid organ transplantation or hematological malignancies. Recently, chronic HEV infection following rituximab-containing treatment regimens has been described. Here we report five patients with chronic hepatitis E after prior rituximab therapy for various indications. We determined the immunological characteristics of these patients and analyzed the development of ribavirin (RBV) treatment failure-associated mutations in the HEV genome. One patient became chronically HEV-infected 110 months after administration of rituximab (RTX). Immunological characterization revealed that all patients exhibited significant hypogammaglobulinemia and CD4+ T cell lymphopenia. One patient permanently cleared HEV following weight-based ribavirin treatment while three patients failed to reach a sustained virological response. In depth mutational analysis confirmed the presence of specific mutations associated with RBV treatment failure in these patients. Our cases indicate that rituximab-containing treatment regimens might imply a relevant risk for persistent HEV infection even years after the last rituximab application. Moreover, we provide further evidence to prior observations suggesting that chronically HEV infected patients following RTX-containing treatment regimens might be difficult to treat.