Hepatitis E genotype 3 virus isolate from wild boar is capable of replication in non-human primate and swine kidney cells and mouse neuroblastoma cells

BACKGROUND: Wild boar-derived hepatitis E (HEV) genotype 3 virus has been successfully isolated in cell lines of human origin only. Considering the zoonotic potential and possible extrahepatic localisation of genotype 3 strain, it is important to investigate the viability of cell lines of different animal and tissue origins. Therefore, the objective of the present study was to determine the permissiveness of non-human primate (MARC-145 and Vero) and swine (PK-15) cell lines of kidney origin, and a mouse neuroblastoma (Neuro-2a) cell line for isolation of wild boar-derived HEV genotype 3. RESULTS: This study showed that MARC-145, PK-15, Neuro-2a and Vero cell lines were permissive to wild boar-derived HEV genotype 3 subtype 3i harbouring viral genome equivalents of 1.12 × 10(7) copies/ml, 2.38 × 10(5) copies/ml, 2.97 × 10(7) copies/ml and 4.01 × 10(7) copies/ml after five serial passages respectively. In all permissive cell lines, HEV was continuously recovered from growth medium between five and at least 28 days post-infection. Peak loads of HEV genome equivalents were observed on days 7, 12, 19 and 30 in MARC-145 (2.88 × 10(7) copies/ml), Vero (4.23 × 10(6) copies/ml), Neuro-2a (3.15 × 10(6) copies/ml) and PK-15 (2.24 × 10(7) copies/ml) cell lines respectively. In addition, successful virus isolation was confirmed by immunofluorescence assay targeting HEV capsid protein and sequencing of HEV isolate retrieved from cell cultures. CONCLUSIONS: This study showed that wild boar-derived HEV genotype 3 subtype 3i strain was capable of infecting cell lines of animal origin, including primate and porcine kidney cells (MARC-145, PK-15 and Vero), and mouse neuroblastoma cells (Neuro-2a), supporting the notion of the capacity of HEV genotype 3 to cross the species barrier and extra-hepatic localisation of the virus. These findings warrant further studies of tested cell lines to investigate their capacity as an efficient system for HEV propagation. HEV isolates from other wild animal hosts should be isolated on tested cell lines in order to generate more data on HEV transmission between wild animal populations and their role as sources of human infections.