9scw | pdb_00009scw
Crystal structure of Coxsackie B1 virus-like particle delta-palxa
Structural highlights
FunctionPOLG_CXB1J Forms an icosahedral capsid of pseudo T=3 symmetry with capsid proteins VP2 and VP3 (By similarity). The capsid is 300 Angstroms in diameter, composed of 60 copies of each capsid protein and enclosing the viral positive strand RNA genome (By similarity). Capsid protein VP1 mainly forms the vertices of the capsid (By similarity). Capsid protein VP1 interacts with host cell receptor to provide virion attachment to target host cells (By similarity). This attachment induces virion internalization (By similarity). Tyrosine kinases are probably involved in the entry process (By similarity). After binding to its receptor, the capsid undergoes conformational changes (By similarity). Capsid protein VP1 N-terminus (that contains an amphipathic alpha-helix) and capsid protein VP4 are externalized (By similarity). Together, they shape a pore in the host membrane through which viral genome is translocated to host cell cytoplasm (By similarity).[UniProtKB:P03300] Forms an icosahedral capsid of pseudo T=3 symmetry with capsid proteins VP2 and VP3 (By similarity). The capsid is 300 Angstroms in diameter, composed of 60 copies of each capsid protein and enclosing the viral positive strand RNA genome (By similarity).[UniProtKB:P03300] Forms an icosahedral capsid of pseudo T=3 symmetry with capsid proteins VP2 and VP3 (By similarity). The capsid is 300 Angstroms in diameter, composed of 60 copies of each capsid protein and enclosing the viral positive strand RNA genome (By similarity).[UniProtKB:P03300] Lies on the inner surface of the capsid shell (By similarity). After binding to the host receptor, the capsid undergoes conformational changes (By similarity). Capsid protein VP4 is released, Capsid protein VP1 N-terminus is externalized, and together, they shape a pore in the host membrane through which the viral genome is translocated into the host cell cytoplasm (By similarity).[UniProtKB:P03300] Component of immature procapsids, which is cleaved into capsid proteins VP4 and VP2 after maturation (By similarity). Allows the capsid to remain inactive before the maturation step (By similarity).[UniProtKB:P03300] Cysteine protease that cleaves viral polyprotein and specific host proteins (By similarity). It is responsible for the autocatalytic cleavage between the P1 and P2 regions, which is the first cleavage occurring in the polyprotein (By similarity). Cleaves also the host translation initiation factor EIF4G1, in order to shut down the capped cellular mRNA translation (By similarity). Inhibits the host nucleus-cytoplasm protein and RNA trafficking by cleaving host members of the nuclear pores (By similarity). Counteracts stress granule formation probably by antagonizing its assembly or promoting its dissassembly (By similarity). Cleaves and inhibits host IFIH1/MDA5, thereby inhibiting the type-I IFN production and the establishment of the antiviral state (By similarity). Cleaves and inhibits host MAVS, thereby inhibiting the type-I IFN production and the establishment of the antiviral state (By similarity).[UniProtKB:P03300][UniProtKB:P03313] Plays an essential role in the virus replication cycle by acting as a viroporin. Creates a pore in the host reticulum endoplasmic and as a consequence releases Ca2+ in the cytoplasm of infected cell. In turn, high levels of cytoplasmic calcium may trigger membrane trafficking and transport of viral ER-associated proteins to viroplasms, sites of viral genome replication.[UniProtKB:P03300] Induces and associates with structural rearrangements of intracellular membranes. Displays RNA-binding, nucleotide binding and NTPase activities. May play a role in virion morphogenesis and viral RNA encapsidation by interacting with the capsid protein VP3.[UniProtKB:P03300] Localizes the viral replication complex to the surface of membranous vesicles. Together with protein 3CD binds the Cis-Active RNA Element (CRE) which is involved in RNA synthesis initiation. Acts as a cofactor to stimulate the activity of 3D polymerase, maybe through a nucleid acid chaperone activity.[UniProtKB:P03300] Localizes the viral replication complex to the surface of membranous vesicles (By similarity). It inhibits host cell endoplasmic reticulum-to-Golgi apparatus transport and causes the disassembly of the Golgi complex, possibly through GBF1 interaction (By similarity). This would result in depletion of MHC, trail receptors and IFN receptors at the host cell surface (By similarity). Plays an essential role in viral RNA replication by recruiting ACBD3 and PI4KB at the viral replication sites, thereby allowing the formation of the rearranged membranous structures where viral replication takes place (By similarity).[UniProtKB:P03300][UniProtKB:P03313] Acts as a primer for viral RNA replication and remains covalently bound to viral genomic RNA. VPg is uridylylated prior to priming replication into VPg-pUpU (By similarity). The oriI viral genomic sequence may act as a template for this. The VPg-pUpU is then used as primer on the genomic RNA poly(A) by the RNA-dependent RNA polymerase to replicate the viral genome (By similarity). Following genome release from the infecting virion in the cytoplasm, the VPg-RNA linkage is probably removed by host TDP2 (By similarity). During the late stage of the replication cycle, host TDP2 is excluded from sites of viral RNA synthesis and encapsidation, allowing for the generation of progeny virions (By similarity).[UniProtKB:P03300] Involved in the viral replication complex and viral polypeptide maturation. It exhibits protease activity with a specificity and catalytic efficiency that is different from protease 3C. Protein 3CD lacks polymerase activity. Protein 3CD binds to the 5'UTR of the viral genome.[UniProtKB:P03300] Replicates the viral genomic RNA on the surface of intracellular membranes. May form linear arrays of subunits that propagate along a strong head-to-tail interaction called interface-I. Covalently attaches UMP to a tyrosine of VPg, which is used to prime RNA synthesis. The positive stranded RNA genome is first replicated at virus induced membranous vesicles, creating a dsRNA genomic replication form. This dsRNA is then used as template to synthesize positive stranded RNA genomes. ss(+)RNA genomes are either translated, replicated or encapsidated.[UniProtKB:P03300] Major viral protease that mediates proteolytic processing of the polyprotein (By similarity). Cleaves host EIF5B, contributing to host translation shutoff (By similarity). Cleaves also host PABPC1, contributing to host translation shutoff (By similarity). Cleaves host NLRP1, triggers host N-glycine-mediated degradation of the autoinhibitory NLRP1 N-terminal fragment (By similarity).[UniProtKB:P03300][UniProtKB:P03303] Publication Abstract from PubMedBACKGROUND: Enteroviruses, including Coxsackie B (CVB) viruses, can cause severe diseases such as myocarditis, pancreatitis, and meningitis. Vaccines can prevent these complications, but conserved non-neutralizing epitopes in the viral capsid may limit their effectiveness. The immunodominant PALXAXETG motif, located in the VP1 N-terminus, is a highly conserved region in enteroviruses that elicits non-neutralizing antibody responses. Virus-like particles (VLPs) offer a safe and effective vaccine platform because of their structural similarity to native viruses but lack viral genetic material. Importantly, VLPs can be structurally modified to exclude specific epitopes. METHODS: Here, we produced a modified CVB1 virus-like particle (VLP) vaccine lacking 15 amino acids from the PALXAXETG motif (designated VLPDeltapalxa) using the baculovirus-insect cell expression system. To confirm the structural integrity, we determined the crystal structure of the modified VLP with 3.2 A resolution. We then conducted comprehensive immunogenicity studies in mice, including dose titration, comparison of two versus three immunizations, and post-vaccination viral challenge. In addition, we evaluated the impact of the AS04 adjuvant on the immunogenicity of unmodified and modified CVB1-VLP vaccines and the formalin-inactivated CVB1 vaccine. RESULTS: The yield of CVB1-VLPDeltapalxa was 29.5 mg/L, and the particles were shown to assemble similarly to unmodified CVB1-VLP. CVB1-VLPDeltapalxa induced robust antibody responses, with neutralizing antibody titres comparable to or exceeding those elicited by unmodified VLP or inactivated virus vaccines. A 2 microg dose was identified as optimal, providing the highest neutralizing antibody titres. A third immunization significantly increased antibody levels, and all non-adjuvanted vaccines protected the mice from CVB1 challenge after the third dose. The addition of AS04 significantly enhanced the antibody response, particularly in both VLP groups. CONCLUSIONS: We demonstrated that with targeted structural modification of the CVB1-VLP capsid, immunodominant antibody responses against the conserved PALXAXETG motif can be avoided. We demonstrate that structural modification of CVB1-VLP is a viable strategy. Since the deleted epitope is known to be non-neutralizing, its deletion may help focus the immune response on more protective targets and thereby improve vaccine efficacy. The modified VLPs, particularly when adjuvanted, offer a promising approach for developing safe and effective enterovirus vaccines. Coxsackie B1 virus-like particle vaccine modified to exclude a highly conserved immunoreactive region from the capsid induces potent neutralizing antibodies and protects against infection in mice.,Soppela S, Gonzalez-Rodriguez M, Stone VM, Mustonen I, Jouppila NVV, Lampinen V, Haikarainen T, Flodstrom-Tullberg M, Junttila IS, Hankaniemi MM J Biomed Sci. 2025 Sep 8;32(1):86. doi: 10.1186/s12929-025-01183-1. PMID:40922007[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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