Proteomic analysis of the Spodoptera frugiperda ascovirus 1a virion reveals 21 proteins

Abstract

The Spodoptera frugiperda ascovirus 1a (SfAV-1a) is a double-stranded DNA virus that attacks lepidopteran larvae, in which it produces enveloped virions with complex symmetry which have an average diameter of 130 nm and length of 400 nm. Here, we report identification of 21 SfAV-1a-encoded proteins that occur in the virion, as determined by nano-liquid chromatography/tandem mass spectrometry. These included a helicase (ORF009), nuclease (ORF075), ATPase (ORF047), serine/threonine-like protein kinase (ORF064), inhibitor of apoptosis-like protein (ORF015), thiol oxidoreductase-like protein (ORF061), CTD phosphatase (ORF109), major capsid protein (ORF041) and a highly basic protein, P64 (ORF048). The latter two were the most abundant. Apart from ascoviruses, the closest orthologues were found in iridoviruses, providing further evidence that ascoviruses evolved from invertebrate iridoviruses. These results establish a foundation for investigating how ascovirus virion proteins interact to form their complex asymmetrical structure, as well as for elucidating the mechanisms involved in SfAV-1a virion morphogenesis.

Symbiotic Virus at the Evolutionary Intersection of Three Types of Large DNA Viruses; Iridoviruses, Ascoviruses, and Ichnoviruses

“…There is also one protein encoded by all ascovirus genomes, homologues of SfAV1a ORF038 and DpAV4a ORF063, that is present in the virions of these viruses, yet absent in iridoviruses and phycodnaviruses. A similar situation is also encountered with homologues of the SfAV1a ORF R and P. Although these two proteins were not detected in virions [21], they might be involved in virion assembly during virogenesis. Together, the loss of the ORF encoding Vp260 homologues and the acquisition of DpAV4a ORF063, and SfAV1a R and P homologues by lateral transfer are possible candidates to explain the change in oligomerisation of ascovirus major capsid proteins that resulted in the change of virion shape from an icosahedron to a basically bacilliform shape.…”

“…In the first case, we used recent analyses of proteins present in the virions of SfAV1a [21] and TnAV6a [22] to search for homologues in the DpAV4a genome ( Fig. S5 ).…”

Global Landscape of Structural Proteins of Infectious Spleen and Kidney Necrosis Virus

“…Recently, MALDI-TOF and LC-MS/MS have been widely used in the study of virions (12,19,28,39). The protein components associated with virions from cyprinid herpesvirus 3 (CyHV-3) were identified solely using an LC-based proteomic workflow (23).…”

Proteomic analysis of Chilo iridescent virus

“…Nine CIV structural proteins have homologs in Heliothis virescens ascovirus 3e (HvAV3e), thirteen have homologs in Trichoplusia ni ascovirus 2c (TnAV2c), eleven in Spodoptera frugiperda ascovirus (SfAV1a) and six in Diadromus pulchellus ascovirus 4a (DpAV4a). The gene products of six of the eleven SfAV1a homologs were also found in the proteome of SfAV1a virions (Tan et al, 2009a). A homolog of the SfAV1a virion protein P64, which was recently shown to be a major DNA binding protein with proposed DNA condensing activity (Tan et al, 2009b) is not encoded in the CIV genome.…”