@phdthesis{Ryll2019,
  author    = {Ren{\´e} Ryll},
  title     = {Identification and molecular characterization of small mammal-associated hepeviruses for the development of novel animal models},
  journal    = {Identifikation und molekulare charakterisierung von Kleins{\"a}uger assoziierten Hepeviren zur Entwicklung neuer Tiermodelle},
  url       = {https://nbn-resolving.org/urn:nbn:de:gbv:9-opus-29190},
  pages     = {142},
  year      = {2019},
  abstract  = {Hepeviruses are small viruses with a RNA-genome of positive polarity that form the family Hepeviridae. The family includes two genera: members of the genus Piscihepevirus were detected in fish species and members of the genus Orthohepevirus were found in different mammal and bird species. The genus Orthohepevirus contains four different species, namely Orthohepevirus A, B, C and D. The species Orthohepevirus A contains five human pathogenic genotypes, with three of them being zoonotic. The species Orthohepevirus C contains mammal-associated pathogens, which were identified in rats and carnivores. The human pathogenic genotypes are responsible for a self-limiting acute hepatitis in humans, which could become chronically in immunocompromised individuals. The main route of transmission is the consumption of undercooked meat and direct contact with HEV-positive excreta or blood. In Germany, hepatitis E is a notifiable disease since 2001 with an increased number of cases per year. Rats are the reservoir of rat-associated HEV (ratHEV), but also the zoonotic HEV-3 genotype was detected in rats. The European rabbit (Oryctolagus cuniculus) was identified as a reservoir host of a subgenotype of human pathogenic HEV-3 (HEV-3ra). For the development of small mammal animal models, the objective of this study was to evaluate different small mammal populations for novel hepeviruses and to study the presence of HEV and sequence divergence of ratHEV and rabbitHEV in rat and rabbit populations from Europe. Approximately 3000 rodents from Germany and the Czech Republic were screened by broad spectrum HEV-RT-PCR. As a result, 13 common voles (Microtus arvalis) and one bank vole (Myodes glareolus) were detected to be HEV-RNA positive. Comparison of the obtained sequences, complete genome determination and phylogenetic analysis indicated the finding of a novel common vole-associated HEV (cvHEV), which shows a high sequence divergence towards other members of the species Orthohepevirus C, but shares a high sequence similarity to a HEV-genome derived from a kestrel (Falco tinnunculus). The finding of cvHEV-RNA in a bank vole might be caused by a spillover infection. The cvHEV genome shares the hepevirus-typical open reading frames, but also has unique cvHEV-specific attributes in its genome. The investigation of 420 Norway rats (Rattus norvegicus) and 88 Black rats (Rattus rattus) identified HEV-RNA in Norway rats from eight of nine and Black rats from two of four European countries. In a single Norway rat from Belgium, a HEV-3-strain with high sequence similarities to rabbitHEV (HEV-3ra), was detected. The investigation of zoo animals revealed a ratHEV spillover infection in a Syrian brown bear (Ursus arctos syriacus). This infection was most likely caused by ratHEV-infected free-living, wild rats from the same zoo. Investigation of wild rabbit populations trapped in and around Frankfurt am Main, Germany, showed anti-HEV antibodies (34.7\%) and rabbitHEV-RNA (25\%). A high sequence similarity of rabbitHEV in the animals trapped at the urban site was observed, whereas a high sequence divergence was seen for the animals trapped at the rural trapping sites. In conclusion, hepeviruses are widespread among different small mammal populations in Europe. The broad geographical distribution of these hepeviruses should be taken into account in further public health risk assessments. Further investigations are needed to characterize the presence of cvHEV in more detail, especially by taking the population dynamics of common voles into account. The detected HEV-strains could be taken as basis for the establishment of novel HEV-animal models, which might replace the so far used swine and non-human primate models.},
  language  = {en}
}