The complete genome of a baculovirus isolated from an insect of medical interest: Lonomia obliqua (Lepidoptera: Saturniidae).

C. W. Aragão-Silva,R. H. P. Moraes,M. S. Andrade,J. L. C. Wolff,S. N. Báo,B. M. Ribeiro,J. E. A. Fernandes,F. L. Melo,F. S. Morgado,D. M. P. Ardisson-Araújo

doi:10.1038/srep23127

Abstract

Lonomia obliqua (Lepidoptera: Saturniidae) is a species of medical importance due to the severity of reactions caused by accidental contact with the caterpillar bristles. Several natural pathogens have been identified in L. obliqua, and among them the baculovirus Lonomia obliqua multiple nucleopolyhedrovirus (LoobMNPV). The complete genome of LoobMNPV was sequenced and shown to have 120,022 bp long with 134 putative open reading frames (ORFs). Phylogenetic analysis of the LoobMNPV genome showed that it belongs to Alphabaculovirus group I (lepidopteran-infective NPV). A total of 12 unique ORFs were identified with no homologs in other sequenced baculovirus genomes. One of these, the predicted protein encoded by loob035, showed significant identity to an eukaryotic transcription terminator factor (TTF2) from the Lepidoptera Danaus plexippus, suggesting an independent acquisition through horizontal gene transfer. Homologs of cathepsin and chitinase genes, which are involved in host integument liquefaction and viral spread, were not found in this genome. As L. obliqua presents a gregarious behavior during the larvae stage the impact of this deletion might be neglectable.

Highlights

120 Open Reading Frames (ORFs) were found in other baculoviruses and among those, three ORFs (loob[078], loob[100] and loob113) showed higher identity with orthologs from betabaculoviruses (Table S1), confirming that horizontal transference between alphabaculovirus and betabaculovirus is a common event, as previously documented[11]
According to a previous study[31], baculovirus Global Transactivator (GTA) play an important role in transcriptional activation of viral genes and were probably originated by horizontal gene transfer (HGT) from the host to the common ancestor of the clade that includes AcMNPV, Bombyx mori nucleopolyhedrovirus (BmNPV), Orgyia pseudotsugata multicapsid nucleopolyhedrovirus (OpMNPV), and Epiphyas postvittana nucleopolyhedrovirus (EppoNPV)
We have found that the loob[035], terminator factor type 2 (TTF2), and GTA genes are members of the SNF2 family

Summary

Introduction

We have performed a phylogenetic analysis (Fig. 3) based on the concatenated amino acid sequence alignment of 37 baculovirus core genes of 72 baculovirus species available in GenBank (Table S2). Based on the phylogenetic results we have selected some of the closest relatives of LoobMNPV, including AcMNPV, Antheraea pernyi nucleopolyhedrovirus (AnpeNPV), Maruca vitrata nucleopolyhedrovirus (MaviNPV), Dendrolimus kikuchii nucleopolyhedrovirus (DekiNPV) and ThorNPV for comparative genomics.

Results

Conclusion