Unlike other EPVs, DlEPV does not express the spheroidin protein. These results confirm that DlEPV is a true EPV and probably a member of the Group C EPVs. A digoxigenin-labeled DlEPV genomic DNA probe recognized DNA in dot-blots of male and female wasps. Western blots using a mouse polyclonal anti-DlEPV serum recognized six major protein bands in combined fractions of sucrose-purified DlEPV, at least one band in homogenates of male and female wasps, and at least two bands in host hemolymph that contained DlEPV virions. Although the RI-36-1 fragment represents a portion of the gene, it contains nucleotides that encode the NADFDGDE consensus sequence of known DNA-directed RNA polymerases. Of the deduced 772 amino acids in the DlEPV sequence, 28.4% are conserved/substituted among the four poxviruses aligned, 12.9% occur in at least one EPV, 6.5% in at least one ChPV, 3.1% in at least one EPV and one ChPV, and 49.1% occur only in DlEPV. Blast search and ClustalW alignment of the amino acids deduced from the 2316 nucleotides of a DlEPV DNA fragment cloned from an EcoR1 genomic library revealed 75–78% homology with the putative DNA-directed RNA polymerases of AmEPV, MsEPV, and two ChPV homologs of the Vac J6R gene. DlEPV DNA restriction fragment profiles differed from those reported for Amsacta moorei EPV (AmEPV) and Melanoplus sanguinipes EPV (MsEPV), the only two EPVs whose genomes have been sequenced, and from those reported for vaccinia (Vac), a vertebrate poxvirus (chordopoxvirus, ChPV).
The DlEPV virion is 250–300 nm in diameter, has a “bumpy” appearance and a unipartite double stranded DNA genome of 290–300 kb. An insect poxvirus occurs in the poison gland apparatus of female Diachasmimorpha longicaudata, a parasitic wasp of the Caribbean fruit fly, Anastrepha suspensa and other tephritid fruit flies.
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