First detection of Hepatitis E virus (Orthohepevirus C) in wild brown rats (Rattus norvegicus) from Great Britain.

Ellen G Murphy,Julian Chantrey,Malcolm Bennett,Nicola J Williams,Lorraine M Mcelhinney,Daisy Jennings,Ranieri Verin,Sylvia Grierson

doi:10.1111/zph.12581

Abstract

In the United Kingdom, there has been an increase in the number of hepatitis E virus (HEV) infections in people annually since 2010. Most of these are thought to be indigenously acquired Orthohepevirus A genotype 3 (HEV G3), which has been linked to pork production and consumption. However, the dominant subgroup circulating in British pigs differs from that which is found in people; therefore, an alternative, potentially zoonotic, source is suspected as a possible cause of these infections. Rodents, brown rats (Rattus norvegicus) in particular, have been shown to carry HEV, both the swine HEV G3 genotype and Orthohepevirus C, genotype C1 (rat HEV). To investigate the prevalence of HEV in British rodents, liver tissue was taken from 307 rodents collected from pig farms (n = 12) and other locations (n = 10). The RNA from these samples was extracted and tested using a pan‐HEV nested RT‐PCR. Limited histopathology was also performed. In this study, 8/61 (13%, 95% CI, 5–21) of brown rat livers were positive for HEV RNA. Sequencing of amplicons demonstrated all infections to be rat HEV with 87%–92% nucleotide identity to other rat HEV sequences circulating within Europe and China (224 nt ORF‐1). Lesions and necrosis were observed histologically in 2/3 samples examined. No rat HEV RNA was detected in any other species, and no HEV G3 RNA was detected in any rodent in this study. This is the first reported detection of rat HEV in Great Britain. A human case of rat HEV infection has recently been reported in Asia, suggesting that rat HEV could pose a risk to public health.

Highlights

Hepatitis E virus (HEV) is a leading cause of viral hepatitis globally, causing an estimated three million cases of acute hepatitis and 70,000 deaths annually
No hepatitis E virus (HEV) G3 RNA was detected in any of the 307 rodent livers tested, Orthohepevirus C, genotype C1 RNA was detected in 8/61 (13%, 95% CI 5–21) brown rats
HEV G3 RNA was detected in the intestinal contents, but not liver, of four house mice from one British pig farm and interpreted as the virus passing through the gut from ingested faecal matter rather than infecting the mice (Grierson et al, 2018)

Summary

| INTRODUCTION

Hepatitis E virus (HEV) is a leading cause of viral hepatitis globally, causing an estimated three million cases of acute hepatitis and 70,000 deaths annually (de Guerra, Kampa, Morsoletto, Junior, & Ivantes, 2017). Most of the reported human HEV infections were due to Orthohepevirus A genotype 3 (HEV G3) and were likely zoonotic in origin as HEV G3 has a wide host range and there is a well‐established link between HEV infection and pig meat products in industrialized countries. Rodents have been shown to be susceptible to infection with a diverse range of HEV species and could, be potential sources of human and livestock (including pig) infections (Ryll et al, 2017; Takahashi et al, 2014). In the UK, HEV G3 RNA subgroup 1 has been reported in the intestines (not livers) of house mice (Mus musculus) on one pig farm, but this is believed to be due to ingestion of virus from pig excreta rather than the mice being infected (Grierson, Rabie, Lambert, Choudhury, & Smith, 2018). Kong (HKU Med, 2018; Sridhar et al, 2018) and since other cases of human rat HEV infection reported (Andonov et al, 2019; Fleming, 2018)

| MATERIALS AND METHODS

Findings

| DISCUSSION