Antigenic and cryo-electron microscopy structure analysis of a chimeric sapovirus capsid
<h3>ABSTRACT</h3> <p>The capsid protein (VP1) of all caliciviruses forms an icosahedral particle with two principal domains, shell (S) and protruding (P) domains, which are connected via a flexible hinge region. The S domain forms a scaffold surrounding the nucleic acid, while the...
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| Hauptverfasser: | , |
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| Dokumenttyp: | Article (Journal) |
| Sprache: | Englisch |
| Veröffentlicht: |
2016
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| In: |
Journal of virology
Year: 2015, Jahrgang: 90, Heft: 5, Pages: 2664-2675 |
| ISSN: | 1098-5514 |
| DOI: | 10.1128/JVI.02916-15 |
| Online-Zugang: | Verlag, Volltext: https://doi.org/10.1128/JVI.02916-15 Verlag, Volltext: https://jvi.asm.org/content/90/5/2664 
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| Verfasserangaben: | Naoyuki Miyazaki, David W. Taylor, Grant S. Hansman, Kazuyoshi Murata |
| Zusammenfassung: | <h3>ABSTRACT</h3> <p>The capsid protein (VP1) of all caliciviruses forms an icosahedral particle with two principal domains, shell (S) and protruding (P) domains, which are connected via a flexible hinge region. The S domain forms a scaffold surrounding the nucleic acid, while the P domains form a homodimer that interacts with receptors. The P domain is further subdivided into two subdomains, termed P1 and P2. The P2 subdomain is likely an insertion in the P1 subdomain; consequently, the P domain is divided into the P1-1, P2, and P1-2 subdomains. In order to investigate capsid antigenicity, N-terminal (N-term)/S/P1-1 and P2/P1-2 were switched between two sapovirus genotypes GI.1 and GI.5. The chimeric VP1 constructs were expressed in insect cells and were shown to self-assemble into virus-like particles (VLPs) morphologically similar to the parental VLPs. Interestingly, the chimeric VLPs had higher levels of cross-reactivities to heterogeneous antisera than the parental VLPs. In order to better understand the antigenicity from a structural perspective, we determined an intermediate-resolution (8.5-Å) cryo-electron microscopy (cryo-EM) structure of a chimeric VLP and developed a VP1 homology model. The cryo-EM structure revealed that the P domain dimers were raised slightly (∼5 Å) above the S domain. The VP1 homology model allowed us predict the S domain (67-229) and P1-1 (229-280), P2 (281-447), and P1-2 (448-567) subdomains. Our results suggested that the raised P dimers might expose immunoreactive S/P1-1 subdomain epitopes. Consequently, the higher levels of cross-reactivities with the chimeric VLPs resulted from a combination of GI.1 and GI.5 epitopes.</p><p><b>IMPORTANCE</b> We developed sapovirus chimeric VP1 constructs and produced the chimeric VLPs in insect cells. We found that both chimeric VLPs had a higher level of cross-reactivity against heterogeneous VLP antisera than the parental VLPs. The cryo-EM structure of one chimeric VLP (Yokote/Mc114) was solved to 8.5-Å resolution. A homology model of the VP1 indicated for the first time the putative S and P (P1-1, P2, and P1-2) domains. The overall structure of Yokote/Mc114 contained features common among other caliciviruses. We showed that the P2 subdomain was mainly involved in the homodimeric interface, whereas a large gap between the P1 subdomains had fewer interactions.</p> |
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| Beschreibung: | Accepted manuscript posted online 23 December 2015 Gesehen am 08.06.2020 |
| Beschreibung: | Online Resource |
| ISSN: | 1098-5514 |
| DOI: | 10.1128/JVI.02916-15 |