Cross-Linking of Rotavirus Outer Capsid Protein VP7 by Antibodies or Disulfides Inhibits Viral Entry

Abstract

Antibodies that neutralize rotavirus infection target outer coat proteins VP4 and VP7 and inhibit viral entry. The structure of a VP7-Fab complex (S. T. Aoki, et al., Science 324:1444-1447, 2009) led us to reclassify epitopes into two binding regions at inter-and intrasubunit boundaries of the calcium-dependent trimer. It further led us to show that antibodies binding at the intersubunit boundary inhibit uncoating of the virion outer layer. We have now tested representative antibodies for each of the defined structural epitope regions and find that antibodies recognizing epitopes in either binding region neutralize by cross-linking VP7 trimers. Antibodies that bind at the intersubunit junction neutralize as monovalent Fabs, while those that bind at the intrasubunit region require divalency. The VP7 structure has also allowed us to design a disulfide cross-linked VP7 mutant which recoats double-layered particles (DLPs) as efficiently as does wild-type VP7 but which yields particles defective in cell entry as determined both by lack of infectivity and by loss of ␣-sarcin toxicity in the presence of recoated particles. We conclude that dissociation of the VP7 trimer is an essential step in viral penetration into cells.

Unexpected spreading of G12P[8] rotavirus strains among young children in a small area of central Italy

“…Trees were built using the Maximum Likelihood (ML) method and the Tamura-3 parameter as a nucleotide substitution model, as suggested by MEGA5 ModelTest, with the statistical support of 1,000 bootstrap repetitions. Amino acid alignments were performed using the BioEdit software [Hall, 1999], and based on the sequence of the prototype strain RRV [Dormitzer et al, 2002;Aoki et al, 2009Aoki et al, , 2011Zeller et al, 2012].…”

Passive Immunization

“…The outer capsid proteins VP7 and VP4 and the intermediate layer protein VP6 are likely to be the most important targets of the host neutralizing response (Aladin et al, 2012;Burns et al, 1996;Corthesy et al, 2006;Ruggeri et al, 1998). Monoclonal Abs against VP4 inhibit infection by blocking attachment (Ruggeri and Greenberg, 1991), antibodies against VP7 inhibit decapsidation (Aoki et al, 2011), and VP6 antibodies inhibit genome transcription and viral transcription in vitro (Feng et al, 2002).…”

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).…”