Hepatitis E Virus (Genotype 3) in Slurry Samples from Swine Farming Activities in Italy

Hepatitis E virus (HEV) is an emergent causative agent of acute hepatitis, transmitted by fecal-oral route. Infection with HEV is a global cause for morbidity and mortality throughout the world: it mainly causes large outbreaks in endemic areas and sporadic autochthonous cases in industrialized countries where HEV infections seem to be an emergent zoonotic disease. Infection of porcine livestock and its relationship with the human cases have been demonstrated. The present study describes an investigation on the prevalence and diversity of HEV in pig slurry in Italy. Slurry samples (24) were collected from ten farms located in North Italy during 2015 and analyzed for HEV, using four broad-range nested PCR assays targeting ORF1 (MTase), ORF2 (capsid) genes, and ORF2/3 regions. Overall, 18 samples (75%) were positive for HEV RNA, and characterized as genotype 3. Nine samples could be subtyped by ORF2 sequencing: Eight belonged to subtype 3f, while one sequence could not be characterized by blast analysis and phylogenetic analysis and may actually represent a new subtype. Furthermore, similarity of 99% was found between 3f Italian HEV sequences of human and swine origins. Real-Time PCR assay was also performed, in order to obtain quantitative data on positive samples. Two swine slurry samples were positive, containing 600 and 1000 UI per mL of sewage. The results of this study show that HEV strains belonging to zoonotic genotype 3 are widely present in swine excreta, and have high degree of identity with strains detected in autochthonous HEV cases. Improving swine farming operations safety and increasing operators' awareness of the zoonotic potential connected with the handling of swine effluents turn out to be key points in order to reduce the environmental and sanitary problem represented by the possible dissemination of HEV to water bodies.