scholarly journals The Oligomerization Domain of VP3, the Scaffolding Protein of Infectious Bursal Disease Virus, Plays a Critical Role in Capsid Assembly

2003 ◽  
Vol 77 (11) ◽  
pp. 6438-6449 ◽  
Author(s):  
Antonio Maraver ◽  
Ana Oña ◽  
Fernando Abaitua ◽  
Dolores González ◽  
Roberto Clemente ◽  
...  
Keyword(s):  
Disease Virus ◽  
Infectious Bursal Disease Virus ◽  
Insect Cells ◽  
Critical Role ◽  
Recombinant Baculovirus ◽  
Particle Formation ◽  
Scaffolding Protein ◽  
Infectious Bursal Disease ◽  
Bursal Disease ◽  
Oligomerization Domain

ABSTRACT Infectious bursal disease virus (IBDV) capsids are formed by a single protein layer containing three polypeptides, pVP2, VP2, and VP3. Here, we show that the VP3 protein synthesized in insect cells, either after expression of the complete polyprotein or from a VP3 gene construct, is proteolytically degraded, leading to the accumulation of product lacking the 13 C-terminal residues. This finding led to identification of the VP3 oligomerization domain within a 24-amino-acid stretch near the C-terminal end of the polypeptide, partially overlapping the VP1 binding domain. Inactivation of the VP3 oligomerization domain, by either proteolysis or deletion of the polyprotein gene, abolishes viruslike particle formation. Formation of VP3-VP1 complexes in cells infected with a dual recombinant baculovirus simultaneously expressing the polyprotein and VP1 prevented VP3 proteolysis and led to efficient virus-like particle formation in insect cells.

Active Cross-Protection Induced by a Recombinant Baculovirus Expressing Chimeric Infectious Bursal Disease Virus Structural Proteins

1994 ◽  
Vol 38 (4) ◽  
pp. 701 ◽  
Author(s):  
D. B. Snyder ◽  
V. N. Vakharia ◽  
S. A. Mengel-Whereat ◽  
G. H. Edwards ◽  
P. K. Savage ◽  
...  
Keyword(s):  
Disease Virus ◽  
Infectious Bursal Disease Virus ◽  
Recombinant Baculovirus ◽  
Cross Protection ◽  
Infectious Bursal Disease ◽  
Structural Proteins ◽  
Bursal Disease

scholarly journals Infectious Bursal Disease Virus Capsid Assembly and Maturation by Structural Rearrangements of a Transient Molecular Switch

2007 ◽  
Vol 81 (13) ◽  
pp. 6869-6878 ◽  
Author(s):  
Daniel Luque ◽  
Irene Saugar ◽  
José F. Rodríguez ◽  
Nuria Verdaguer ◽  
Damiá Garriga ◽  
...  
Keyword(s):  
Capsid Protein ◽  
Disease Virus ◽  
Infectious Bursal Disease Virus ◽  
Scaffolding Protein ◽  
Infectious Bursal Disease ◽  
Capsid Assembly ◽  
Protein Oligomerization ◽  
Structural Protein ◽  
Bursal Disease ◽  
Α Helix

ABSTRACT Infectious bursal disease virus (IBDV), a double-stranded RNA (dsRNA) virus belonging to the Birnaviridae family, is an economically important avian pathogen. The IBDV capsid is based on a single-shelled T=13 lattice, and the only structural subunits are VP2 trimers. During capsid assembly, VP2 is synthesized as a protein precursor, called pVP2, whose 71-residue C-terminal end is proteolytically processed. The conformational flexibility of pVP2 is due to an amphipathic α-helix located at its C-terminal end. VP3, the other IBDV major structural protein that accomplishes numerous roles during the viral cycle, acts as a scaffolding protein required for assembly control. Here we address the molecular mechanism that defines the multimeric state of the capsid protein as hexamers or pentamers. We used a combination of three-dimensional cryo-electron microscopy maps at or close to subnanometer resolution with atomic models. Our studies suggest that the key polypeptide element, the C-terminal amphipathic α-helix, which acts as a transient conformational switch, is bound to the flexible VP2 C-terminal end. In addition, capsid protein oligomerization is also controlled by the progressive trimming of its C-terminal domain. The coordination of these molecular events correlates viral capsid assembly with different conformations of the amphipathic α-helix in the precursor capsid, as a five-α-helix bundle at the pentamers or an open star-like conformation at the hexamers. These results, reminiscent of the assembly pathway of positive single-stranded RNA viruses, such as nodavirus and tetravirus, add new insights into the evolutionary relationships of dsRNA viruses.

scholarly journals Identification and Molecular Characterization of the RNA Polymerase-Binding Motif of Infectious Bursal Disease Virus Inner Capsid Protein VP3

2003 ◽  
Vol 77 (4) ◽  
pp. 2459-2468 ◽  
Author(s):  
Antonio Maraver ◽  
Roberto Clemente ◽  
Jose Francisco Rodríguez ◽  
Eleuterio Lombardo
Keyword(s):  
Rna Polymerase ◽  
Capsid Protein ◽  
Disease Virus ◽  
Infectious Bursal Disease Virus ◽  
Critical Role ◽  
Rnase A ◽  
Infectious Bursal Disease ◽  
Binding Motif ◽  
Bursal Disease

ABSTRACT Infectious bursal disease virus (IBDV), a member of the Birnaviridae family, is the causative agent of one of the most important infectious poultry diseases. Major aspects of the molecular biology of IBDV, such as assembly and replication, are as yet poorly understood. We have previously shown that encapsidation of the putative virus-encoded RNA-dependent RNA polymerase VP1 is mediated by its interaction with the inner capsid protein VP3. Here, we report the characterization of the VP1-VP3 interaction. RNase A treatment of VP1- and VP3-containing extracts does not affect the formation of VP1-VP3 complexes, indicating that formation of the complex requires the establishment of protein-protein interactions. The use of a set of VP3 deletion mutants allowed the mapping of the VP1 binding motif of VP3 within a highly charged 16-amino-acid stretch on the C terminus of VP3. This region of VP3 is sufficient to confer VP1 binding activity when fused to an unrelated protein. Furthermore, a peptide corresponding to the VP1 binding region of VP3 specifically inhibits the formation of VP1-VP3 complexes. The presence of Trojan peptides containing the VP1 binding motif in IBDV-infected cells specifically reduces infective virus production, thus showing that formation of VP1-VP3 complexes plays a critical role in IBDV replication.

scholarly journals Triplet amino acids located at positions 145/146/147 of the RNA polymerase of very virulent infectious bursal disease virus contribute to viral virulence

2014 ◽  
Vol 95 (4) ◽  
pp. 888-897 ◽  
Author(s):  
Li Gao ◽  
Kai Li ◽  
Xiaole Qi ◽  
Honglei Gao ◽  
Yulong Gao ◽  
...  
Keyword(s):  
Amino Acids ◽  
Glutamic Acid ◽  
Disease Virus ◽  
Infectious Bursal Disease Virus ◽  
Chicken Embryo Fibroblast ◽  
Critical Role ◽  
Infectious Bursal Disease ◽  
Effective Prevention ◽  
Viral Virulence ◽  
Bursal Disease

Infectious bursal disease virus (IBDV) causes an economically significant disease of chickens worldwide. The emergence of very virulent IBDV (vvIBDV) has brought more challenges for effective prevention of this disease. The molecular basis for the virulence of vvIBDV is not fully understood. In this study, 20 IBDV strains were analysed phylogenically and clustered in three branches based on their full-length B segments. The amino acid triplet located at positions 145/146/147 of VP1 was found highly conserved in branch I non-vvIBDVs as asparagine/glutamic acid/glycine (NEG), in branch II vvIBDVs as threonine/glutamic acid/glycine (TEG) and in branch III vvIBDVs as threonine/aspartic acid/asparagine (TDN). Further studies showed that the three amino acids play a critical role in the replication and pathogenicity of vvIBDV. Substitution of the TDN triplet with TEG or NEG reduced viral replication and pathogenicity of the vvIBDV HuB-1 strain in chickens. However, the replication of the attenuated IBDV Gt strain was reduced in chicken embryo fibroblast cells, whilst it was enhanced in the bursa by substituting NEG with TEG or TDN. The exchange of the three amino acids was also found to be capable of affecting the polymerase activity of VP1. The important role of segment B in the pathogenicity of IBDV was confirmed in this study. These results also provided new insights into the mechanism of the virulence of vvIBDVs and may offer new targets for their attenuation to develop potential vaccines using reverse genetics.

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