Genomic sequencing and analysis of Clostera anachoreta granulovirus

The complete genome of Clostera anachoreta granulovirus (ClanGV) from an important pest of poplar, Clostera anachoreta (Lepidoptera: Notodontidae), was sequenced and analyzed. The circular double-stranded genome is 101,487 bp in size with a C+G content of 44.4%. It is predicted to contain 123 open reading frames (ORFs), covering 93% of the whole genome sequence. One hundred eleven ClanGV ORFs are homologues of previously reported baculovirus genes, two ORFs only exist in nucleopolyhedroviruses (NPVs), and 10 ORFs are unique to ClanGV, accounting for 3.9% of the genome in total. The average amino acid sequence identities between ClanGV and other granulovirus (GV) homologues ranged from 55.5% (PiraGV) to 43.1% (HearGV and PsunGV). ClanGV includes 16 DNA replication- and transcription-related genes, including ie-1, dnapol, helicase, lef-1, lef-2, lef-3, lef-4, lef-5, lef-6, lef-8, lef-9, lef-10, lef-11, 39K, p47 and vlf-1. Seventeen conserved structural genes and two types of apoptosis suppression proteins (P35 and IAP) have also been identified. To date, ClanGV is the second identified GV that contains the p35 gene, which is present in eight NPVs and ChocGV. Genes of chitinase and cathepsin, which are involved in the liquefaction of the host, were found in the ClanGV genome, consistent with the typical insecticidal properties of ClanGV. In the ClanGV genome, there are four homologous repeat regions, each one of which contains only 2-3 direct repeats. Phylogenetic analysis, based on the 29 core baculovirus genes, indicates that ClanGV is closely related to PhopGV, AdorGV, CpGV, CrleGV, PiraGV and ChocGV, and this agrees with the results of homology analysis and gene parity plot analysis.