A peptide with similarity to baculovirus ODV-E66 binds the gut epithelium of Heliothis virescens and impedes infection with Autographa californica multiple nucleopolyhedrovirus
ABSTRACT Baculoviruses infect their lepidopteran hosts via the midgut epithelium through binding of occlusion-derived virus (ODV) and fusion between the virus envelope and microvillar membranes. To identify genes and sequences that are involved in this process, a random phage display library was screened for peptides that bound to brush border membrane vesicles (BBMV) derived from the midgut epithelium of Heliothis virescens. Seventeen peptides that bound to BBMV were recovered. Two of these, HV1 and HV2, had sequence similarity to the ODV envelope protein ODV-E66 that is found in five species of alphabaculoviruses. Chemically synthesized versions of HV1 and HV2, and two peptides (AcE66A and AcE66B) derived from similar sequences of Autographa californica multiple nucleopolyhedrovirus (AcMNPV) ODV-E66, bound to unfixed cryosections of whole midgut tissues. AcE66A, but not HV1, bound to H. virescens gut BBMV proteins on a far-Western blot. Competition assays with HV1 and purified AcMNPV ODV resulted in decreased mortality of H. virescens larvae at a dose of 1 LD(50), and a significant increase in survival time at higher virus concentrations. These results suggest a role for ODV-E66 in baculovirus infection of lepidopteran larval midgut epithelium.
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- "Finally, the data presented in this study may offer new directions in antiviral strategies based on virus–host interactions. Potential strategies have been reviewed recently by Kariithi et al. (2012) and include blocking of the initial attachment of GpSGHV to the tsetse midgut receptors using either antibodies against envelope proteins or competing peptides as reported for Autographa californica multicapsid nucleopolyhedrovirus in Heliothis virescens (Sparks et al., 2011), GpSGHV-specific gene silencing using RNA interference, inhibition of GpSGHV DNA polymerase (ORF79) by commercially available drugs (Abd-Alla et al., 2011) and blocking of RGD-directed cell adhesion as has been demonstrated for adenovirus (Bai et al., 1993). "
ABSTRACT: The Glossina pallidipes salivary gland hypertrophy virus (GpSGHV) is a dsDNA virus with rod-shaped, enveloped virions. Its 190-kb genome contains 160 putative protein-coding open reading frames (ORFs). Here, structural components, protein composition and associated aspects of GpSGHV morphogenesis and cytopathology were investigated. Four morphologically distinct structures: nucleocapsid, tegument, envelope, and helical surface projections, were observed in purified GpSGHV virions by electron microscopy. Nucleocapsids were present in virogenic stroma within the nuclei of infected salivary gland cells, whereas enveloped virions were located in the cytoplasm. The cytoplasm of infected cells appeared disordered and the plasma membranes disintegrated. Treatment of virions with 1% Nonidet P-40 efficiently partitioned the virions into envelope and nucleocapsid fractions. The fractions were separated by 12% SDS-PAGE followed by in-gel trypsin digestion and analysis of the tryptic peptides by LC-MS/MS. Using the MaxQuant program with Andromeda as a database search engine, a total of forty-five viral proteins were identified. Of these, ten and fifteen were associated with the envelope and the nucleocapsid fractions respectively, while twenty were detected in both fractions, most likely representing tegument proteins. In addition, fifty-one host-derived proteins were identified in the proteome of the virus particle, thirteen of which were verified to be incorporated into the mature virion using a proteinase K protection assay. This study provides important information about GpSGHV biology and suggests options for development of future anti-GpSGHV strategies by interfering with virus-host interactions.Journal of General Virology 10/2012; 94(Pt_1). DOI:10.1099/vir.0.047423-0 · 3.53 Impact Factor
- Abstract Book of the 44th Annual Meeting of the Society for Invertebrate Pathology; 08/2011
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ABSTRACT: The competence of the tsetse fly Glossina pallidipes (Diptera; Glossinidae) to acquire salivary gland hypertrophy virus (SGHV), to support virus replication and successfully transmit the virus depends on complex interactions between Glossina and SGHV macromolecules. Critical requisites to SGHV transmission are its replication and secretion of mature virions into the fly's salivary gland (SG) lumen. However, secretion of host proteins is of equal importance for successful transmission and requires cataloging of G. pallidipes secretome proteins from hypertrophied and non-hypertrophied SGs. After electrophoretic profiling and in-gel trypsin digestion, saliva proteins were analyzed by nano-LC-MS/MS. MaxQuant/Andromeda search of the MS data against the non-redundant (nr) GenBank database and a G. morsitans morsitans SG EST database, yielded a total of 521 hits, 31 of which were SGHV-encoded. On a false discovery rate limit of 1% and detection threshold of least 2 unique peptides per protein, the analysis resulted in 292 Glossina and 25 SGHV MS-supported proteins. When annotated by the Blast2GO suite, at least one gene ontology (GO) term could be assigned to 89.9% (285/317) of the detected proteins. Five (∼1.8%) Glossina and three (∼12%) SGHV proteins remained without a predicted function after blast searches against the nr database. Sixty-five of the 292 detected Glossina proteins contained an N-terminal signal/secretion peptide sequence. Eight of the SGHV proteins were predicted to be non-structural (NS), and fourteen are known structural (VP) proteins. SGHV alters the protein expression pattern in Glossina. The G. pallidipes SG secretome encompasses a spectrum of proteins that may be required during the SGHV infection cycle. These detected proteins have putative interactions with at least 21 of the 25 SGHV-encoded proteins. Our findings opens venues for developing novel SGHV mitigation strategies to block SGHV infections in tsetse production facilities such as using SGHV-specific antibodies and phage display-selected gut epithelia-binding peptides.PLoS Neglected Tropical Diseases 11/2011; 5(11):e1371. DOI:10.1371/journal.pntd.0001371 · 4.49 Impact Factor