Structure of Rotavirus Outer-Layer Protein VP7 Bound with a Neutralizing Fab

Abstract

Summary The crystal structure of rotavirus VP7 bound with the Fab from a neutralizing monoclonal shows the mechanism by which members of a large class of neutralizing antibodies inhibit rotavirus infection, indicates how withdrawal of Ca2+ ions becomes an uncoating trigger during cell entry, and provides the “first draft” of a design for subunit immunogens. Rotavirus outer-layer protein VP7 is a principal target of protective antibodies. Removal of free Ca2+ dissociates the VP7 trimer, releases it from the virion, and initiates penetration-inducing conformational changes in the other outer-layer protein, VP4. We report the crystal structure of VP7 bound with the Fab fragment of a neutralizing monoclonal antibody. The Fab binds across the outer surface of the intersubunit contact, which is stabilized by two Ca2+ sites. Mutations that escape neutralization by other antibodies suggest that the same region bears the epitopes of most neutralizing antibodies. The monovalent Fab is sufficient to neutralize infectivity. We propose that neutralizing antibodies against VP7 act by stabilizing the trimer, thereby inhibiting the uncoating trigger for VP4 rearrangement. A disulfide-linked trimer is a potential subunit immunogen.

Human G9P[8] rotavirus strains circulating in Cameroon, 1999–2000: Genetic relationships with other G9 strains and detection of a new G9 subtype

“…Out of the 11 radical changes 9 were associated with changes in polarity with the strain 6788 being non-polar when compared to the consensus G9 strains. In VR-5/antigenic epitope A mutation in site 94 is associated with neutralization escape mutants (Aoki et al, 2009). Similar sites associated with neutralization escape mutants were observed in VR-8/ antigenic epitope C (positions 213, 217, 221) and in VR-9/antigenic epitope F (position 238).…”

“…Using the crystal structure of the RRV VP7 protein (PDB accession number 3fmg; (Aoki et al, 2009), amino acid substitutions found in Cameroonian strain RVA/Human-wt/CMR/ 6788/1999/G9P[8] were mapped spatially onto the 3D protein structure using the PyMOL Molecular Graphics System, version 1.5.0.1 (Schrodinger, 2010).…”

“…Using these models, maximum likelihood trees were constructed using PhyML 3.0 along with approximate likelihood-ratio test (aLRT) statistics for branch support (Guindon et al, 2010). Nucleotide and amino acid distance matrixes were prepared using the p-distance algorithm of MEGA version 5 software (Tamura et al, 2011).Using the crystal structure of the RRV VP7 protein (PDB accession number 3fmg; (Aoki et al, 2009), amino acid substitutions found in Cameroonian strain RVA/Human-wt/CMR/ 6788/1999/G9P[8] were mapped spatially onto the 3D protein structure using the PyMOL Molecular Graphics System, version 1.5.0.1 (Schrodinger, 2010). …”

Genomic characterization and molecular investigation of VP7 epitopes of uncommon G10P[8] group A rotavirus strains detected in Italy in 2009

“…4) (Aoki et al, 2009(Aoki et al, , 2011. The comparison investigated a total of 52 aa residues and showed the highest similarity between G10 amino acid sequences and genotypes G9 (39/52 aa) and G3 (38/ 52 aa).…”

Genetic linkage of capsid protein-encoding RNA segments in group A equine rotaviruses

“…Thus, the anchored VP4 protrudes above the surface of the VP7 layer to interact with the host cells during the attachment of the virus. Proteolytic cleavage of the spike protein VP4 into VP5 * and VP8 * is required for rotavirus infectivity, with the VP8 * domain being involved in binding to cellular receptors (Aoki et al, 2009;Chen et al, 2009;Li et al, 2009;Trask et al, 2012).…”