Genetic and physicochemical analyses of a novel ferret hepatitis E virus, and clinical signs of infection after birth

A novel cluster of five ferret hepatitis E virus (HEV) strains was detected from nine laboratory ferrets (Mustela putorius furo) imported from a ferret farm in the U.S. Our detection of ferret HEV RNA and anti-HEV antibodies, and alanine aminotransferase (ALT) value assessment indicated that all of the 9 ferrets were infected with ferret HEV, and that the infection exhibited three patterns: sub-clinical infection (n = 2), acute hepatitis (n = 6) and persistent infection (n = 1). Next-generation sequence analyses of the entire genome sequences of the five strains revealed that their nucleotide sequence identities ranged from 99.5% to 99.9%, indicating that genetically similar ferret HEVs had been circulating at this the U.S. ferret farm. In contrast, the strains shared 82% and 89% nucleotide sequence identities with other ferret HEV that isolated from the Netherlands (JN998607) and the U.S. (AB890374), suggesting that these strains form a novel cluster of ferret HEV with diverse genomes depending on the region where their host. Particles with a diameter of ~ 35 nm at a density of 1.201 g/cm3 were observed in the fecal specimens by electron microscopy. There was no evidence that the particles were associated with the cell membrane. The ferret HEV RNA was not constantly detected in urine, suggesting that the excretion of ferret HEV into urine is not a common feature of HEV infection.