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Journal of Virology, January 1999, p. 533-552, Vol. 73, No. 1
Plum Island Animal Disease Center,
Agricultural Research Service, U.S. Department of Agriculture,
Greenport, New York 11944
Received 3 August 1998/Accepted 25 September 1998
The family Poxviridae contains two subfamilies: the
Entomopoxvirinae (poxviruses of insects) and the
Chordopoxvirinae (poxviruses of vertebrates). Here we
present the first characterization of the genome of an
entomopoxvirus (EPV) which infects the North American migratory
grasshopper Melanoplus sanguinipes and other important
orthopteran pests. The 236-kbp M. sanguinipes EPV (MsEPV) genome consists of a central coding region bounded by 7-kbp inverted terminal repeats and contains 267 open reading frames (ORFs), of which
107 exhibit similarity to previously described genes. The presence of
genes not previously described in poxviruses, and in some cases in any
other known virus, suggests significant viral adaptation to the
arthropod host and the external environment. Genes predicting
interactions with host cellular mechanisms include homologues of the
inhibitor of apoptosis protein, stress response protein phosphatase 2C,
extracellular matrixin metalloproteases, ubiquitin, calcium binding
EF-hand protein, glycosyltransferase, and a triacylglyceride lipase.
MsEPV genes with putative functions in prevention and repair of DNA
damage include a complete base excision repair pathway (uracil DNA
glycosylase, AP endonuclease, DNA polymerase
0022-538X/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
The Genome of Melanoplus
sanguinipes Entomopoxvirus
, and an
NAD+-dependent DNA ligase), a photoreactivation repair
pathway (cyclobutane pyrimidine dimer photolyase), a LINE-type reverse
transcriptase, and a mutT homologue. The presence of these
specific repair pathways may represent viral adaptation for repair of
environmentally induced DNA damage. The absence of previously described
poxvirus enzymes involved in nucleotide metabolism and the
presence of a novel thymidylate synthase homologue suggest that
MsEPV is heavily reliant on host cell nucleotide pools and the de
novo nucleotide biosynthesis pathway. MsEPV and lepidopteran
genus B EPVs lack genome colinearity and exhibit a low level of amino
acid identity among homologous genes (20 to 59%), perhaps
reflecting a significant evolutionary distance between lepidopteran and
orthopteran viruses. Divergence between MsEPV and the
Chordopoxvirinae is indicated by the presence of only 49 identifiable chordopoxvirus homologues, low-level amino acid identity
among these genes (20 to 48%), and the presence in MsEPV of 43 novel
ORFs in five gene families. Genes common to both poxvirus subfamilies,
which include those encoding enzymes involved in RNA transcription and
modification, DNA replication, protein processing, virion
assembly, and virion structural proteins, define the genetic core of
the Poxviridae.
*
Corresponding author. Mailing address: Plum Island
Animal Disease Center, P.O. Box 848, Greenport, NY 11944-0848. Phone:
(516) 323-2500, ext. 330. Fax: (516) 323-2507. E-mail:
drock{at}cshore.com.
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