Complete nucleotide sequence of spheroidin gene of Anomala cuprea entomopoxvirus

The complete nucleotide sequence of the spheroidin gene of Anomala cuprea entomopoxvirus (AcEPV) was determined. The sequence was compared with those of spheroidin genes of EPVs such as Melolontha melolontha EPV (MmEPV, Genus A), Choristoneura fumiferana EPV (CfEPV, Genus B) and Amsacta moorei EPV (AmEPV, Genus B). The gene harbored an open reading frame (ORF) of 2826 nt, with the same size as that of MmEPV belonging to the same genus, capable of coding for a polypeptide of 109.0 kDa. The predicted amino acid (aa) sequence showed a greater or moderate similarity to the corresponding sequence of the other EPVs, showing a 94, 40 and 41% aa identity with MmEPV, CfEPV and AmEPV, respectively; the identity was 89, 53 and 54% at the nucleotide level. The hydropathy plots also showed a greater similarity in organization to MmEPV and moderate similarity to the viruses of Genus B. In the polypeptide, 44 cysteine residues, which are likely to be involved in paracrystal formation and seven potential N-glycosylation sites were detected. The number of cysteine residues and N-glycosylation sites also depended on the difference in genera (A or B). Thus, the spheroidin gene of EPVs was well conserved within the same genus.