Update: proposed reference sequences for subtypes of hepatitis E virus (species Orthohepevirus A)

Abstract

In this recommendation, we update our 2016 table of reference sequences of subtypes of hepatitis E virus (HEV; species Orthohepevirus A, family Hepeviridae) for which complete genome sequences are available (Smith et al., 2016). This takes into account subsequent publications describing novel viruses and additional proposals for subtype names; there are now eight genotypes and 36 subtypes. Although it remains difficult to define strict criteria for distinguishing between virus subtypes, and is not within the remit of the International Committee on Taxonomy of Viruses (ICTV), the use of agreed reference sequences will bring clarity and stability to researchers, epidemiologists and clinicians working with HEV.

Hepatitis E Virus Infection: Circulation, Molecular Epidemiology, and Impact on Global Health

“…Taxonomically, the family Hepeviridae is divided into the genus Orthohepevirus with the species Orthohepevirus A, B, C , and D , and the genus Piscihepevirus . The species Orthohepevirus A contains eight distinct genotypes that infect humans and other mammals [ 10 ]. It is known that HEV-1 to -4 infect humans, and rare cases of human infection with other genotypes like HEV-7 have also been described [ 11 , 143 ].…”

“…HEV-3 is common among pigs worldwide, which constitute the major reservoir for human infections [ 164 , 165 ]. HEV-4 is widely distributed in South and East Asia, where both wild and domesticated pigs serve as a reservoir [ 10 , 158 , 166 ]. Infection rates are high in people over 50 years of age [ 4 , 167 , 168 ], and seroepidemiological studies found no significant differences in HEV-IgG seropositivity according to gender [ 169 ].…”

“…HEV belongs to the genus Orthohepevirus , containing four species, namely Orthohepevirus A, B, C, and D with A containing the genotypes HEV-1 to HEV-8 [ 10 ]. The genotypes that infect humans include HEV-1 to -4, -7, and Orthohepevirus C , casually termed rat HEV [ 10 , 11 , 12 , 13 ]. HEV-1 and -2 infect only humans and cause large waterborne outbreaks due to contaminated drinking water in endemic regions of South and Southeast Asia, Africa, and Mexico [ 14 ].…”

Response to the Letter to the Editor concerning ‘Absence of hepatitis E virus circulation in wild rabbits ( Oryctolagus cuniculus ) and Iberian hares ( Lepus granatensis ) in Mediterranean ecosystems in Spain’ by Caballero‐Gómez et al. (Transbound Emerg Dis; 2020: https://doi.org/10.1111/tbed.13478)

“…Orthohepevirus A species (Smith et al, 2020) makes it difficult to use molecular assays for the diagnosis of HEV infection. Nevertheless, there are currently many in-house and commercial assays that allow for detection of the majority of the HEV strains.…”

Hepatitis E Virus: How It Escapes Host Innate Immunity

“…HEV belongs to the Hepeviridae family, a family that has two genera: the Orthohepevirus (mammalian and avian strains), with four species ( A – D ), and the Piscihepevirus (cutthroat trout virus) [ 7 , 8 ]. Humans are infected by Orthohepevirus A, although several cases of Orthohepevirus C infection have been reported recently [ 9 , 10 , 11 ].…”