Phylogenetic analysis of the full genome of rabbit hepatitis E virus (rbHEV) and molecular biologic study on the possibility of cross species transmission of rbHEV.

Rabbit HEV strains were isolated in China from farmed rabbits, which may be a reservoir of a novel genotype of HEV. However, there is little information regarding host range and zoonotic potential of rabbit HEV. A previous study from this group identified 25 specific nucleotide positions as possibly being involved in specifying the host range of HEV and/or in determining the severity of hepatitis E disease, whereas this previous analysis did not extend to the new rabbit HEVs. Consequently the complete genome of the rabbit HEV strain ch-bj-n1 was amplified as overlapping fragments using a combination of reverse-transcription-nested polymerase chain reaction and rapid amplification of cDNA ends. The resulting sequence together with two other rabbit HEVs were compared with 91 other HEV isolates representative of genotypes 1-4. Phylogenetic analysis showed that the novel rabbit HEV strain should be classified into a new HEV genotype which has a closer evolutionary relationship with genotype 3 than genotypes 1, 2 and 4, with 20 of the 25 specific nucleotide positions identified as being present in rabbit HEV genome. Alpha-helix, hydrophilicity, and surface probability plots together with antigenic index analysis of the ORF2 protein were all undertaken to investigate the antigenicity of rabbit HEV. The alpha-helix plot and antigenicity index of the rabbit ORF2 protein was nearly identical to that of genotype 1 HEV isolates from human. Furthermore, 20 possible host range determinants in rabbit HEV were identical to those isolates from zoonotic groups, which may suggest a potential possibility of cross species transmission of rabbit HEV.