No abstract

Clinically apparent hepatitis E infection is more common in individuals who consume at least 22 U alcohol/week. Patients with established chronic alcoholic liver disease have a low seroprevalence compared with controls. The reason for this observation is uncertain, but patients with alcoholic liver disease have clinically severe disease with a high mortality when exposed to HEV. The low seroprevalence in this group may represent a 'culled' population.

SUMMARY BackgroundIn developed countries, hepatitis E is a porcine zoonosis caused by hepatitis E virus (HEV) genotype 3. In developing countries, hepatitis E is mainly caused by genotype 1, and causes increased mortality in patients with preexisting chronic liver disease (CLD).

The interplay between host antiviral immunity and immunopathology during hepatitis E virus (HEV) infection determines important clinical outcomes. We characterized the specificity, functionality, and durability of host T‐cell responses against the full‐length HEV virus and assessed a novel “Quantiferon” assay for the rapid diagnosis of HEV infection. Eighty‐nine volunteers were recruited from Oxford, Truro (UK), and Toulouse (France), including 44 immune‐competent patients with acute HEV infection, 18 HEV‐exposed immunosuppressed organ‐transplant recipients (8 with chronic HEV), and 27 healthy volunteers. A genotype 3a peptide library (616 overlapping peptides spanning open reading frames [ORFs] 1‐3) was used in interferon‐gamma (IFN‐γ) T‐cell ELISpot assays. CD4+/CD8+ T‐cell subsets and polyfunctionality were defined using ICCS and SPICE analysis. Quantification of IFN‐γ used whole‐blood stimulation with recombinant HEV‐capsid protein in the QuantiFERON kit. HEV‐specific T‐cell responses were detected in 41/44 immune‐competent HEV exposed volunteers (median magnitude: 397 spot‐forming units/106 peripheral blood mononuclear cells), most frequently targeting ORF2. High‐magnitude, polyfunctional CD4 and CD8+ T cells were detected during acute disease and maintained to 12 years, but these declined over time, with CD8+ responses becoming more monofunctional. Low‐level responses were detectable in immunosuppressed patients. Twenty‐three novel HEV CD4+ and CD8+ T‐cell targets were mapped predominantly to conserved genomic regions. QuantiFERON testing demonstrated an inverse correlation between IFN‐γ production and the time from clinical presentation, providing 100% specificity, and 71% sensitivity (area under the receiver operator characteristic curve of 0.86) for HEV exposure at 0.3 IU/mL. Conclusion: Robust HEV‐specific T‐cell responses generated during acute disease predominantly target ORF2, but decline in magnitude and polyfunctionality over time. Defining HEV T‐cell targets will be important for the investigation of HEV‐associated autoimmune disease. (Hepatology 2016;64:1934‐1950).