i) AEV possesses a HCV-like IRES (type
Hellen and de Breyne, 2007) distinct from
that of HAV. HAV has an IRES which is unique amongst the picornaviruses
(Brown et al., 1994).
AEV possesses a 2A distinct from HAV. The 2A protein of AEV is a member
of the H-rev107 family of proteins involved in the control of cell
proliferation (Hughes and Stanway, 2000). Similar 2A proteins are found
in members of the genera
Parechovirus and Kobuvirus
(Hughes and Stanway, 2000) and a newly sequenced unassigned
picornavirus, duck hepatitis virus (Kim
et al., 2006; Tseng
et al., 2007), but not in
hepatitis A virus. The 2A of HAV is thought to inhibit cap-dependent
gene expression by an unknown mechanism (Maltese
et al., 2000).
AEV has a 2B protein which is very different and possibly non-homologous
to that of HAV.
AEV and HAV have 3A polypeptides which share little primary sequence
identity; however, both (in common with all picornaviruses) have a
predicted transmembrane alpha-helix.
The percentage amino acid identities between AEV and HAV in the P1, P2
and P3 regions are 49.2, 28.0 and 37.3, respectively (Marvil
et al., 1999). Only the P1
region exceeds the values in the new
Study Group guidelines.
E.A., Zajac, A.J. and Lemon, S.M. (1994). In vitro characterization of
an internal ribosomal entry site (IRES) present within the 5'
nontranslated region of hepatitis A virus RNA: comparison with the IRES
of encephalomyocarditis virus. J. Virol. 68: 1066-1074.
C.U. and de Breyne, S. (2007). A distinct group of hepacivirus/pestivirus-like
internal ribosomal entry sites in members of diverse picornavirus
genera: evidence for modular exchange of functional noncoding RNA
elements by recombination. J. Virol. 81: 5850-5863.
P.J. and Stanway, G. (2000). The 2A proteins of three diverse
picornaviruses are related to each other and to the
family of proteins involved in the control of cell proliferation.
J. Gen. Virol. 81: 201-207.
Kwon, Y.K., Joh, S.J., Lindberg, A.M., Kwon, J.H., Kim, J.H. and Kim,
S.J. (2006). Molecular analysis of duck hepatitis virus type 1 reveals a
novel lineage close to the genus Parechovirus in the family
Picornaviridae. J Gen Virol. 87: 3307-3316.
E., Bucci, M., Macchia, S., Latorre, P., Pagnotti, P., Pierangeli, A.
and Pérez Bercoff, R. (2000).
cap-dependent gene expression induced by protein 2A of
hepatitis A virus. J. Gen. Virol. 81: 1373-1381.
P., Knowles, N.J., Mockett, A.P.A., Britton, P., Brown, T.D.K. and
Cavanagh, D. (1999). Avian encephalomyelitis virus is a picornavirus and
is most closely related to hepatitis A virus. J. Gen. Virol. 80:
C.H., Knowles, N.J. and Tsai, H.J. (2007). Molecular analysis of duck
hepatitis virus type 1 indicates that it should be assigned to a new
genus. Virus Res. 123: 190-203. Epub 2006 Oct 25.