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Abstract: A genetically distinct strain of avian hepatitis E virus (avian HEV-VA strain) was isolated from a healthy chicken in Virginia, and thus it is important to characterize and compare its pathogenicity with the prototype strain (avian HEV-prototype) isolated from a diseased chicken. Here we first constructed an infectious clone of the avian HEV-VA strain. Capped RNA transcripts from the avian HEV-VA clone were replication-competent after transfection of LMH chicken liver cells. Chickens inoculated intrahepatically with RNA transcripts of avian HEV-VA clone developed active infection as evidenced by fecal virus shedding, viremia, and seroconversion. To characterize the pathogenicity, RNA transcripts of both avian HEV-VA and avian HEV-prototype clones were intrahepatically inoculated into the livers of chickens. Avian HEV RNA was detected in feces, serum and bile samples from 10/10 avian HEV-VA-inoculated and 9/9 avian HEV-prototype-inoculated chickens although seroconversion occurred only in some chickens during the experimental period. The histopathological lesion scores were lower for avian HEV-VA group than avian HEV-prototype group in the liver at 3 and 5 weeks post-inoculation (wpi) and in the spleen at 3wpi, although the differences were not statistically significant. The liver/body weight ratio, indicative of liver enlargement, of both avian HEV-VA and avian HEV-prototype groups were significantly higher than that of the control group at 5wpi. Overall, the avian HEV-VA strain still induces histological liver lesions even though it was isolated from a healthy chicken. The results also showed that intrahepatic inoculation of chickens with RNA transcripts of avian HEV infectious clone may serve as an alternative for live virus in animal pathogenicity studies. [ABSTRACT FROM AUTHOR]

Abstract: In the present work, 262 serum samples and 29 faeces pools from chickens coming from 29 healthy flocks were analysed by RT-PCR for detection of avian HEV and by ELISA using an aHEV derived antigen for detection of anti-HEV IgG. Additionally, other 300 randomly selected serum samples were also analysed by RT-PCR. Seven serum samples were positive to RNA detection. Sequence analysis of both the helicase and the capsid genes revealed that the Spanish isolates were clustered together and close related to those strains from the United States isolated from farms with HSS. On the serology study, 26/29 flocks had at least one positive animal (89.7%) and chickens older than 40 weeks were found to have higher seropositivities compared to the rest of age groups. Within positive farms, the proportion of positive animals ranged from 20% to 80%. This is the first report of aHEV sequences in chickens from Europe. Further studies are needed to elucidate the clinical significance of avian HEV infections in Europe. [Copyright &y& Elsevier]