9f5p
Poliovirus type 2 (strain MEF-1) stabilised virus-like particle (PV2 SC6b) from an insect cell expression system.
Structural highlights
FunctionPOLG_POL2L Capsid proteins VP1, VP2, VP3 and VP4 form a closed capsid enclosing the viral positive strand RNA genome. VP4 lies on the inner surface of the protein shell formed by VP1, VP2 and VP3. All the three latter proteins contain a beta-sheet structure called beta-barrel jelly roll. Together they form an icosahedral capsid (T=3) composed of 60 copies of each VP1, VP2, and VP3, with a diameter of approximately 300 Angstroms. VP1 is situated at the 12 fivefold axes, whereas VP2 and VP3 are located at the quasi-sixfold axes. The interaction of five VP1 proteins in the fivefold axes results in a prominent protusion extending to about 25 Angstroms from the capsid shell. The resulting structure appears as a steep plateau encircled by a valley or cleft. This depression also termed canyon is the receptor binding site. The capsid interacts with human PVR at this site to provide virion attachment to target cell. This attachment induces virion internalization predominantly through clathrin- and caveolin-independent endocytosis in Hela cells and through caveolin-mediated endocytosis in brain microvascular endothelial cells. VP4 and VP1 subsequently undergo conformational changes leading to the formation of a pore in the endosomal membrane, thereby delivering the viral genome into the cytoplasm (By similarity). VP0 precursor is a component of immature procapsids (By similarity). Protein 2A is a cysteine protease that is responsible for the cleavage between the P1 and P2 regions. It cleaves the host translation initiation factor EIF4G1, in order to shut down the capped cellular mRNA transcription (By similarity). Protein 2B affects membrane integrity and cause an increase in membrane permeability (By similarity). Protein 2C associates with and induces structural rearrangements of intracellular membranes. It displays RNA-binding, nucleotide binding and NTPase activities (By similarity). Protein 3A, via its hydrophobic domain, serves as membrane anchor. It also inhibits endoplasmic reticulum-to-Golgi transport (By similarity). Protein 3C is a cysteine protease that generates mature viral proteins from the precursor polyprotein. In addition to its proteolytic activity, it binds to viral RNA, and thus influences viral genome replication. RNA and substrate bind co-operatively to the protease (By similarity). RNA-directed RNA polymerase 3D-POL replicates genomic and antigenomic RNA by recognizing replications specific signals (By similarity). Publication Abstract from PubMedPolioviruses have caused crippling disease in humans for centuries, prior to the successful development of vaccines in the mid-1900's, which dramatically reduced disease prevalence. Continued use of these vaccines, however, threatens ultimate disease eradication and achievement of a polio-free world. Virus-like particles (VLPs) that lack a viral genome represent a safer potential vaccine, although they require particle stabilization. Using our previously established genetic techniques to stabilize the structural capsid proteins, we demonstrate production of poliovirus VLPs of all three serotypes, from four different recombinant expression systems. We compare the antigenicity, thermostability and immunogenicity of these stabilized VLPs against the current inactivated polio vaccine, demonstrating equivalent or superior immunogenicity in female Wistar rats. Structural analyses of these recombinant VLPs provide a rational understanding of the stabilizing mutations and the role of potential excipients. Collectively, we have established these poliovirus stabilized VLPs as viable next-generation vaccine candidates for the future. Recombinant expression systems for production of stabilised virus-like particles as next-generation polio vaccines.,Sherry L, Bahar MW, Porta C, Fox H, Grehan K, Nasta V, Duyvesteyn HME, De Colibus L, Marsian J, Murdoch I, Ponndorf D, Kim SR, Shah S, Carlyle S, Swanson JJ, Matthews S, Nicol C, Lomonossoff GP, Macadam AJ, Fry EE, Stuart DI, Stonehouse NJ, Rowlands DJ Nat Commun. 2025 Jan 18;16(1):831. doi: 10.1038/s41467-025-56118-z. PMID:39827284[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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