Antibodies to the Buried N Terminus of Rhinovirus VP4 Exhibit Cross-Serotypic Neutralization

Abstract

Development of a vaccine for the common cold has been thwarted by the fact that there are more than 100 serotypes of human rhinovirus (HRV). We previously demonstrated that the HRV14 capsid is dynamic and transiently displays the buried N termini of viral protein 1 (VP1) and VP4. Here, further evidence for this "breathing" phenomenon is presented, using antibodies to several peptides representing the N terminus of VP4. The antibodies form stable complexes with intact HRV14 virions and neutralize infectivity. Since this region of VP4 is highly conserved among all of the rhinoviruses, antiviral activity by these anti-VP4 antibodies is cross-serotypic. The antibodies inhibit HRV16 infectivity in a temperature-and time-dependent manner consistent with the breathing behavior. Monoclonal and polyclonal antibodies raised against the 30-residue peptide do not react with peptides shorter than 24 residues, suggesting that these peptides are adopting three-dimensional conformations that are highly dependent upon the length of the peptide. Furthermore, there is evidence that the N termini of VP4 are interacting with each other upon extrusion from the capsid. A Ser5Cys mutation in VP4 yields an infectious virus that forms cysteine cross-links in VP4 when the virus is incubated at room temperature but not at 4°C. The fact that all of the VP4s are involved in this cross-linking process strongly suggests that VP4 forms specific oligomers upon extrusion. Together these results suggest that it may be possible to develop a pan-serotypic peptide vaccine to HRV, but its design will likely require details about the oligomeric structure of the exposed termini.

Antibody-induced uncoating of human rhinovirus B14

“…These structural changes lead to the formation of roughly rectangular (25 Å × 8 Å) pores around the icosahedral twofold axes through which the viral RNA and VP4 might exit (Figs. 1 and 2) (24,25). In addition, because of the rigid body movements and the disordering of residues 3172-3181 in the VP3 GH loop (the loop that links β-strands G and H), pores are opened up near the quasi-threefold axes (Fig.…”

Rhinovirus infections and immunisation induce cross-serotype reactive antibodies to VP1

“…Most antibodies generated to RV infection in humans are directed against epitopes found on surface-exposed structures of VP1, VP2 and VP3 (Carey et al, 1992). Although there is evidence that the N-terminus of VP4 may be transiently exposed at the capsid surface in a process known as capsid breathing (Lewis et al, 1998) and antibodies to this region of VP4 are cross-serotype protective (Katpally et al, 2009), naturally occurring human antibodies to VP4 have not been described. A recent study by Niespodziana et al revealed that children with RV-induced respiratory symptoms primarily generate IgG1 and IgA to N-terminal regions of VP1 and that responses to VP2, VP3 and VP4 were significantly lower .…”

Mapping of antigenic determinants on a SAT2 foot-and-mouth disease virus using chicken single-chain antibody fragments

“…These residues at the N-terminal of VP1, which have similar polar, hydroxyl-group containing side chains, are located in the internal surface of the capsid in close proximity to the N-terminal of VP2 and VP4. Neutralizing antibodies to the internal epitopes of VP1 and VP4 have been reported in poliovirus and rhinovirus (Katpally et al, 2009;Li et al, 1994;Roivainen et al, 1993). However, neutralizing antibodies to internally located epitopes of FMDV have not been reported.…”