Protein composition of the occlusion bodies of <i>Epinotia aporema</i> granulovirus

Abstract

Within family Baculoviridae, members of the <i>Betabaculovirus</i> genus are employed as biocontrol agents against lepidopteran pests, either alone or in combination with selected members of the <i>Alphabaculovirus</i> genus. <i>Epinotia aporema</i> granulovirus (EpapGV) is a fast killing betabaculovirus that infects the bean shoot borer (<i>E. aporema</i>) 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 ac<i>110</i>-like core gene and a putative translation fusion product of ORFs <i>epap48</i> and <i>epap49</i>. Comparative studies of the proteomes available for the family <i>Baculoviridae</i> 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.