Hepatitis E virus infection in wild rabbit (Oryctolagus cuniculus) in Italy and in the UK: a serological, molecular, and pathological study

A novel animal strain of HEV demonstrating zoonotic potential rabbit HEV (rHEV) has been recently identified in farmed rabbits in China. To investigate the presence of rHEV in wild rabbit population, serum and tissue samples were taken from 65 rabbits, 35 Italian and 30 from UK. Sera were submitted to a double antigen sandwich ELISA, whereas hepatic tissues and other organs to molecular and pathological investigations. Sixteen serum samples (24.6%) scored positive for anti-HEV antibodies, and six samples (9%) of hepatic tissue were positive for HEV RT-PCR, while the other organs were negative. Sequencing and phylogenetic analysis of HEV RNA-positive samples indicated that while two Italian rabbits were infected with strains closely related to wild boar and swine strains (HEV-3), the other four (2 Italian and 2 English) were clustered within rHEV clade. Megalocytosis and multifocal areas of hepatocytes degeneration and necrosis with a pericentrilobular pattern were observed in rHEV-infected rabbits. In those infected by the strain analogous to HEV-3, the lesions were mainly localized in the periportal areas and were less severe. In both cases, inflammatory infiltrates were predominantly composed of CD3-positive lymphocytes and a reduced number of macrophages. By immunohistochemistry, only liver samples taken from HEV RNA-positive rabbits scored positive for viral antigen. Our results indicated that HEV infection is present in rabbit population with different clades and is endemic in the Italian and English wild rabbit population, suggesting the possibility that this species may be infected with rHEV or swine HEV-3 strains.