A new subtype of hepatitis E virus gene 3 has emerged in Italy and several other European countries.

Abstract

In European countries, the number of locally-acquired hepatitis E virus (HEV) cases has increased in recent years, primarily linked to infections caused by HEV genotype 3 (HEV-3). The novel HEV-3 subtype 3n was initially reported in Italy; however, its distribution across other European regions remained uncertain. Here, we analyzed all HEV-3 ORF2 sequences from European countries deposited in NCBI (2016-2024). Phylogenetic analysis identified 47 HEV-3n sequences: 43 from wild boars (37 from Italy, 6 from Poland) and 4 human-derived sequences (two blood donor samples each from France and Denmark). Nucleotide sequence analysis demonstrated a 4.0-7.2% genetic distance between human and wild boar HEV-3n isolates, confirming their close evolutionary relationship. This genetic evidence, combined with the geographic distribution across Italy, Poland, France, and Denmark, provides robust molecular support for zoonotic transmission of HEV-3n from wild boars to humans. The findings indicate that HEV-3n is not restricted to Italy but has disseminated across multiple European countries, establishing wild boars as a key reservoir for human infections. This study underscores the need for integrated surveillance of HEV-3n in wildlife and human populations across Europe to mitigate zoonotic risks.