7fei
Complex of FMDV A/WH/CHA/09 and bovine neutralizing scFv antibody R55
Structural highlights
FunctionD0E7R9_9PICO Covalently linked to the 5'-end of both the positive-strand and negative-strand genomic RNAs. Acts as a genome-linked replication primer.[ARBA:ARBA00002573] Cysteine protease that generates mature viral proteins from the precursor polyprotein. In addition to its proteolytic activity, binds to viral RNA and thus influences viral genome replication. RNA and substrate bind cooperatively to the protease.[ARBA:ARBA00004047] Lies on the inner surface of the capsid shell. After binding to the host receptor, the capsid undergoes conformational changes. 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. After genome has been released, the channel shrinks.[ARBA:ARBA00033716] Mediates self-processing of the polyprotein by a translational effect termed 'ribosome skipping'. Mechanistically, 2A-mediated cleavage occurs between the C-terminal glycine and the proline of the downstream protein 2B. In the case of foot-and-mouth disease virus, the 2A oligopeptide is post-translationally 'trimmed' from the C-terminus of the upstream protein 1D by 3C proteinase.[ARBA:ARBA00002616] 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.[ARBA:ARBA00003379] RNA-directed RNA polymerase 3D-POL replicates genomic and antigenomic RNA by recognizing replications specific signals. 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.[ARBA:ARBA00004027] Publication Abstract from PubMedFoot-and-mouth disease virus (FMDV) exhibits broad antigenic diversity with poor intraserotype cross-neutralizing activity. Studies of the determinant involved in this diversity are essential for the development of broadly protective vaccines. In this work, we isolated a bovine antibody, designated R55, that displays cross-reaction with both FMDV A/AF/72 (hereafter named FMDV-AAF) and FMDV A/WH/09 (hereafter named FMDV-AWH) but only has a neutralizing effect on FMDV-AWH. Near-atomic resolution structures of FMDV-AAF-R55 and FMDV-AWH-R55 show that R55 engages the capsids of both FMDV-AAF and FMDV-AWH near the icosahedral 3-fold axis and binds to the betaB and BC/HI-loops of VP2 and to the B-B knob of VP3. The common interaction residues are highly conserved, which is the major determinant for cross-reaction with both FMDV-AAF and FMDV-AWH. In addition, the cryo-EM structure of the FMDV-AWH-R55 complex also shows that R55 binds to (VP3)E70 located at the VP3 BC-loop in an adjacent pentamer, which enhances the acid and thermal stabilities of the viral capsid. This may prevent capsid dissociation and genome release into host cells, eventually leading to neutralization of the viral infection. In contrast, R55 binds only to the FMDV-AAF capsid within one pentamer due to the (VP3)E70G variation, which neither enhances capsid stability nor neutralizes FMDV-AAF infection. The (VP3)E70G mutation is the major determinant involved in the neutralizing differences between FMDV-AWH and FMDV-AAF. The crucial amino acid (VP3)E70 is a key component of the neutralizing epitopes, which may aid in the development of broadly protective vaccines. IMPORTANCE Foot-and-mouth disease virus (FMDV) causes a highly contagious and economically devastating disease in cloven-hoofed animals, and neutralizing antibodies play critical roles in the defense against viral infections. Here, we isolated a bovine antibody (R55) using the single B cell antibody isolation technique. Enzyme-linked immunosorbent assays (ELISA) and virus neutralization tests (VNT) showed that R55 displays cross-reactions with both FMDV-AWH and FMDV-AAF but only has a neutralizing effect on FMDV-AWH. Cryo-EM structures, fluorescence-based thermal stability assays and acid stability assays showed that R55 engages the capsid of FMDV-AWH near the icosahedral 3-fold axis and informs an interpentamer epitope, which overstabilizes virions to hinder capsid dissociation to release the genome, eventually leading to neutralization of viral infection. The crucial amino acid (VP3)E70 forms a key component of neutralizing epitopes, and the determination of the (VP3)E70G mutation involved in the neutralizing differences between FMDV-AWH and FMDV-AAF could aid in the development of broadly protective vaccines. Structures of Foot-and-Mouth Disease Virus with Bovine Neutralizing Antibodies Reveal the Determinant of Intraserotype Cross-Neutralization.,He Y, Li K, Wang L, Sun Z, Cao Y, Li P, Sun P, Bao H, Zhou S, Wang S, Bai X, Liu X, Zhao L, Fan X, Liu Z, Lu Z, Yang C, Lou Z J Virol. 2021 Nov 23;95(24):e0130821. doi: 10.1128/JVI.01308-21. Epub 2021 Sep , 29. PMID:34586859[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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