Phylogenetic analysis of conserved genes within the ecdysteroid UDP-glucosyltransferase gene region of the slow-killing Adoxophyes orana granulovirus

Abstract

A physical map of the genome of Adoxophyes orana granulovirus (AoGV) was constructed for the restriction enzymes BamHI, BglII, EcoRI, PstI and SacI using restriction endonuclease analysis and DNA hybridization techniques. This enabled the size of the AoGV genome to be estimated at 100.9 kbp. A plasmid library covering 99.9% of the AoGV genome was constructed using five restriction enzymes. The ecdysteroid UDP-glucosyltransferase gene (egt) was located by hybridization with the egt gene of Cydia pomonella granulovirus. The sequence of 6000 bp of the egt region is presented and compared to the equivalent area in other GVs. Database searches showed that this region contained eight open reading frames (ORFs) similar to the baculovirus genes egt, granulin, pk-1, me53 and four ORFs of Xestia c-nigrum granulovirus (ORF 178, ORF 2, ORF 7 and ORF 8). The egt gene was shown to encode an active EGT using an EGT assay. Phylogenetic trees of the granulovirus genes egt, granulin, pk-1 and me53 were constructed using maximum parsimony and distance analyses. These analyses indicated that AoGV genes may be more closely related to other tortricid-infecting GVs than to GVs that infect other lepidopteran families.