Molecular Identification and Characterization of a Genotype 3 Hepatitis E Virus (HEV) Strain Detected in a Wolf Faecal Sample, Italy.

Vittorio Sarchese,Federica Di Profio,Fulvio Marsilio,Carlo Ercolini,Paola Fruci,Riccardo Orusa,Vito Martella,Barbara Di Martino,Andrea Palombieri,Serena Robetto

doi:10.3390/ani11123465

Abstract

Simple SummaryData on hepatitis E virus (HEV) strains circulating in carnivores are still limited. However, serological evidence suggests that their exposure to HEV infection is more common than expected. In addition, close relatives of Orthohepevirus C detected in rats and in human patients with persistent hepatitis have been detected in ferrets, minks, and foxes, providing a rationale for investigating the presence of HEV or HEV-like viruses in wild carnivores. Herewith, we report the identification and the nearly full-genome (7212 nucleotides) characterization of an HEV Gt3 strain detected in a faecal specimen collected from a wolf found dead in Northwestern Italy. This finding poses questions concerning the potential role of wolves as HEV mechanical, passive carriers, favouring the introduction and spread of HEV in the environment.Hepatitis E virus (HEV) infection is a major health problem worldwide. In developed countries, zoonotic transmission of HEV genotypes (Gt) 3 and 4 is caused by the ingestion of raw or undercooked meat of infected pigs and wild boars, the main reservoirs of HEV. However, additional animals may harbour HEV or HEV-related strains, including carnivores. In this study, we investigated the molecular epidemiology of orthohepeviruses in wild canids by screening a total of 136 archival faecal samples, collected from wolves (42) and red foxes (94) in Northwestern Italy. Orthohepevirus RNA was identified in a faecal specimen, collected from a wolf carcass in the province of La Spezia (Liguria Region, Italy). The nearly full-length (7212 nucleotides) genome of the strain HEV/81236/Wolf/2019/ITA (GenBank accession no. MZ463196) was determined by combining a sequence-independent single-primer amplification (SISPA) approach with the Oxford Nanopore Technologies sequencing platform. Upon phylogenetic analysis, the HEV detected in wolf was segregated into clade HEV-3.1, displaying the highest nucleotide (nt) identity (89.0–93.3%) to Gt3 strains belonging to subtype c. Interestingly, the wolf faecal sample also contained porcine astrovirus sequences, endorsing the hypothesis of a dietary origin of the HEV strain due to preying habits.

Highlights

Hepatitis E virus (HEV) is a common cause of human acute viral hepatitis [1]
BLAST and FASTA analyses of the partial RNA-dependent RNA polymerase (RdRp) and ORF2 regions revealed the highest nucleotide identity to HEV strains classified into Gt3 within the species Orthohepevirus A
Nucleotide identities to hepeviruses of species Orthohepevirus B, C, D ranged from 58.8% to 63.8% in the RdRp region and from 52.9% to 63.2% in the ORF2 gene

Summary

Introduction

Hepatitis E virus (HEV) is a common cause of human acute viral hepatitis [1]. HEV is a single-stranded, positive-sense RNA virus of about 6.4–7.2 kb in length, organized in three open reading frames (ORFs) [2] and classified in the family Hepeviridae [3]. In the last few years, identification of genetically divergent HEV strains has suggested an update of the classification of the family Hepeviridae into two genera, namely the genus. The genus Orthohepevirus is further subdivided into four distinct species, Orthohepevirus A–D, including hepeviruses of mammalian and avian origin [4]. Based on the full-length genome analysis, HEV strains within the species Orthohepevirus A have been assigned to eight distinct genotypes (Gt1-Gt8) [5], with four major Gts (1–4) implicated in human infection/disease.

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