Novel subtypes and unexpected heterogeneity of hepatitis E viral strains
in wild boar captured in a small area in Central Italy
Abstract
Wild boar is the main sylvatic reservoir of the genotype 3 of hepatitis
E virus (HEV). The occurrence of HEV-3 human cases has been linked to
the consumption of raw or undercooked pig and wild boar meat and liver.
The zoonotic transmission of HEV-3 has been confirmed by sequencing
identical or strictly related viral strains in humans, wild boar, and
derived food. The HEV sequences classified within the HEV-3 genotype are
highly variable, and although only one serotype has been identified so
far, the observed differences allow for the further classification of
the HEV-3 genotype into subtypes, named in alphabetical order. Compared
to human and pig strains, an even higher heterogeneity is observed among
strains infecting wild boar. In the present study, the genetic
variability of eight HEV-3 strains detected in wild boars living in a
small geographical area in central Italy (Lazio and Umbria regions) was
investigated by full genome sequencing and phylogenetic analysis. The
strains were classified within the HEV-3a, HEV-3c, HEV-3f subtypes and
within two new recently proposed subtypes. Results demonstrate –
despite the relatively small geographic area of origin – an unexpected
divergence within HEV-3 strains hosted by the investigated wild boar
population and highlights the need for extensive sequencing of HEV in
reservoirs to fully understand diversity, geographical distribution and
evolution of this group of viruses.