Unprocessed foot-and-mouth disease virus capsid precursor displays discontinuous epitopes involved in viral neutralization.

Picornavirus capsids are assembled from 60 copies of a capsid precursor via a pentameric assembly intermediate or ‘pentamer’. Upon completion of virion assembly, a maturation event induces a final cleavage of the capsid precursor to create the capsid protein VP4, which is essential for capsid stability and entry into new cells. For the picornavirus foot-and-mouth disease virus (FMDV), intact capsids are temperature and acid-labile and can disassemble into pentamers. During disassembly, capsid protein VP4 is lost, presumably altering the structure and properties of the resulting pentamers. The purpose of this study was to compare the characteristics of recombinant “assembly” and “disassembly” pentamers. We generated recombinant versions of these different pentamers containing an engineered cleavage site to mimic the maturation cleavage. We compared the sedimentation and antigenic characteristics of these pentamers using sucrose density gradients and reactivity with an antibody panel. Pentamers mimicking the assembly pathway sedimented faster than those on the disassembly pathway suggesting that for FMDV, in common with other picornaviruses, assembly pentamers sediment at 14S whereas only pentamers on the disassembly pathway sediment at 12S. The reactivity with anti-VP4 antibodies was reduced for the 12S pentamers, consistent with the predicted loss of VP4. Reactivity with other antibodies was similar for both pentamers suggesting that major antigenic features may be preserved between the VP4 containing assembly pentamers and the disassembly pentamers lacking VP4.

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Structure and dynamics of the GH loop of the foot-and-mouth disease virus capsid

Journal of Molecular Graphics and Modelling ◽

10.1016/j.jmgm.2009.08.006 ◽

2009 ◽

Vol 28 (3) ◽

pp. 278-286 ◽

Cited By ~ 6

Author(s):

Hiroko Azuma ◽

Shigetaka Yoneda

Keyword(s):

Disease Virus ◽

Foot And Mouth Disease ◽

Mouth Disease ◽

Virus Capsid ◽

Structure And Dynamics ◽

Mouth Disease Virus ◽

Foot And Mouth

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Foot-and-Mouth Disease Virus Assembly: Processing of Recombinant Capsid Precursor by Exogenous Protease Induces Self-Assembly of Pentamers In Vitro in a Myristoylation-Dependent Manner

Journal of Virology ◽

10.1128/jvi.01263-09 ◽

2009 ◽

Vol 83 (21) ◽

pp. 11275-11282 ◽

Cited By ~ 27

Author(s):

Stewart Goodwin ◽

Tobias J. Tuthill ◽

Armando Arias ◽

Richard A. Killington ◽

David J. Rowlands

Keyword(s):

Disease Virus ◽

Receptor Binding ◽

Virus Assembly ◽

Foot And Mouth Disease ◽

Mouth Disease ◽

Precursor Protein ◽

Capsid Precursor ◽

Mouth Disease Virus ◽

Foot And Mouth

ABSTRACT The assembly of foot-and-mouth disease virus (FMDV) particles is poorly understood. In addition, there are important differences in the antigenic and receptor binding properties of virus assembly and dissociation intermediates, and these also remain unexplained. We have established an experimental model in which the antigenicity, receptor binding characteristics, and in vitro assembly of capsid precursor can be studied entirely from purified components. Recombinant capsid precursor protein (P1 region) was expressed in E scherichia coli as myristoylated or unmyristoylated protein. The protein sedimented in sucrose gradients at 5S and reacted with monoclonal antibodies which recognize conformational or linear antigen determinants on the virion surface. In addition, it bound the integrin αvβ6, a cellular receptor for FMDV, indicating that unprocessed recombinant capsid precursor is both structurally and antigenically similar to native virus capsid. These characteristics were not dependent on the presence of 2A at the C terminus but were altered by N-terminal myristoylation and in mutant precursors which lacked VP4. Proteolytic processing of myristoylated precursor by recombinant FMDV 3Cpro in vitro induced a shift in sedimentation from 5S to 12S, indicating assembly into pentameric capsid subunits. Nonmyristoylated precursor still assembled into higher-order structures after processing with 3Cpro, but these particles sedimented in sucrose gradients at approximately 17S. In contrast, mutant precursors lacking VP4 were antigenically distinct, were unable to form pentamers, and had reduced capacity for binding integrin receptor. These studies demonstrate the utility of recombinant capsid precursor protein for investigating the initial stages of assembly of FMDV and other picornaviruses.

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