Protein composition of the occlusion bodies of Epinotia aporema granulovirus.

Tomás Masson,María Leticia Ferrelli,Víctor Romanowski,Matías Luis Pidre,María Laura Fabre,Brian M Ward

doi:10.1371/journal.pone.0207735

Abstract

Within family Baculoviridae, members of the Betabaculovirus genus are employed as biocontrol agents against lepidopteran pests, either alone or in combination with selected members of the Alphabaculovirus genus. Epinotia aporema granulovirus (EpapGV) is a fast killing betabaculovirus that infects the bean shoot borer (E. aporema) and is a promising biopesticide. Because occlusion bodies (OBs) play a key role in baculovirus horizontal transmission, we investigated the composition of EpapGV OBs. Using mass spectrometry-based proteomics we could identify 56 proteins that are included in the OBs during the final stages of larval infection. Our data provides experimental validation of several annotated hypothetical coding sequences. Proteogenomic mapping against genomic sequence detected a previously unannotated ac110-like core gene and a putative translation fusion product of ORFs epap48 and epap49. Comparative studies of the proteomes available for the family Baculoviridae highlight the conservation of core gene products as parts of the occluded virion. Two proteins specific for betabaculoviruses (Epap48 and Epap95) are incorporated into OBs. Moreover, quantification based on emPAI values showed that Epap95 is one of the most abundant components of EpapGV OBs.

Highlights

The family Baculoviridae comprises a diverse group of large double stranded DNA viruses that infect larvae of the insect orders Lepidoptera, Hymenoptera and Diptera [1]
occlusion bodies (OBs) on leaves that are consumed by foraging larvae reach the midgut and, after being dissolved at high pH, release the occlusion derived viruses (ODVs), which initiate infection of the epithelial cells
In this work we examined the protein content of Epinotia aporema granulovirus (EpapGV) OBs using Mass spectrometry-based (MS)-based shotgun proteomics in order to describe the composition of this virion phenotype

Summary

Introduction

The family Baculoviridae comprises a diverse group of large double stranded DNA viruses that infect larvae of the insect orders Lepidoptera, Hymenoptera and Diptera [1]. OBs on leaves that are consumed by foraging larvae reach the midgut and, after being dissolved at high pH, release the occlusion derived viruses (ODVs), which initiate infection of the epithelial cells. These infected cells produce budded viruses (BVs) that disseminate the infection systemically [3]. Based on OBs morphology, baculoviruses were first classified in two groups: Nucleopolyhedrovirus (NPV) and Granulovirus (GV) [1]. Later, they were taxonomically divided into four genera: Alphabaculovirus (lepidopteran-specific NPV), Betabaculovirus

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Discussion

Conclusion