Serological prevalence, genetic identification, and characterization of the first strains of avian hepatitis E virus from chickens in Korea

Avian hepatitis E virus (avian HEV) is associated with hepatitis-splenomegaly (HS) syndrome or big liver and spleen disease in chickens. At least three genotypes of avian HEV have been identified from chickens worldwide. A total of 297 serum samples collected from chickens in 35 flocks in Korea were tested for avian HEV antibody with an enzyme-linked immunosorbent assay. The results showed that approximately 57 % of chicken flocks and 28 % of chickens from Korea were positive for antibodies to avian HEV. Thirteen pooled fecal samples from chickens were tested for avian HEV RNA by RT-PCR, and three fecal samples were positive. The partial helicase and capsid genes of the Korean avian HEV isolates were determined, and sequence analyses revealed that the Korean avian HEV isolates were clustered together and closely related to the genotype 1 avian HEV from Australia. The complete genomic sequence of a Korean avian HEV strain HH-F9 from a broiler breeder was determined, and shown to be 6,653 nt in length, excluding the poly (A) tail, which is 1 nt shorter than the prototype avian HEV from chicken with HS syndrome in the United States. Compared to the full-length sequences of other 5 known avian HEV strains worldwide, the Korean avian HEV shared approximately 83–97 % nucleotide sequence identity. The finding that Korean avian HEV belongs to genotype 1 avian HEV which was previously identified only from chickens in Australia has significant implication in understanding the global epidemiology of avian HEV.