Conformational epitopes in respiratory syncytial virus G protein central conserved region
X-ray crystallography has defined conformational properties of a key functional region of the G protein of respiratory syncytial virus (RSV). Mimics of these epitopes have utility as immunogens, as tools for discovery of antibodies and other monoclonal binding agents, and as pharmacological agents to modulate activity of the host receptors for this viral protein.
1. A mutant peptide or peptidomimetic thereof, the mutant peptide or peptidomimetic comprising:
(a) amino acid residues 161-197 of respiratory syncytial virus (RSV) G protein, as set forth as SEQ ID NO: 1, with at least one amino acid substitution at amino acid residue 162, 164, 166, 177, 187, 192, or 193 thereof;
(b) amino acid residues 162-172 of RSV G protein, as set forth as SEQ ID NO: 2, with at least one amino acid substitution at amino acid residue 162, 164, or 166 thereof;
(c) amino acid residues 169-198 of RSV G protein, as set forth as SEQ ID NO: 3, with at least one amino acid substitution at amino acid residue 177, 187, 192, or 193 thereof;
(d) amino acid residues 157-197 of RSV G protein, as set forth as SEQ ID NO: 4, with at least one amino acid substitution at amino acid residue 162, 164, 166, 177, 187, 192, or 193 thereof;
(e) amino acid residues 148-197 of RSV G protein, as set forth as SEQ ID NO: 5, with at least one amino acid substitution at amino acid residue 162, 164, 166, 177, 187, 192, or 193 thereof; or
(f) amino acid residues 161-191 of RSV G protein, as set forth as SEQ ID NO: 6, with at least one amino acid substitution at amino acid residue 162, 164, 166, 177, or 187 thereof;
wherein the mutant peptide or peptidomimetic (i) comprises diminished activation of CX3CR1 (chemokine receptor responsive to fractalkine) as compared to the respective unmodified peptide comprising SEQ ID NOS: 1-6, (ii) is immunoreactive with mAb 3D3, and/or 2D10 and/or 3G12, and (iii) is chemically stabilized to maintain its native conformation when binding to mAb 3D3, and/or 2D10 and/or 3G12.
2. The mutant or peptidomimetic of claim 1 which elicits sub-nM affinity antibodies immunoreactive with an epitope of RSV G protein conserved between A and B strains of the virus.
3. The mutant or peptidomimetic of claim 1 , wherein the substituted amino acid of (a)-(f) comprises a different charge than the unsubstituted amino acid.
4. The mutant or peptidomimetic of claim 1 , wherein the substituted amino acid of (a)-(f) comprises a different size or shape than the unsubstituted amino acid.
5. The mutant or peptidomimetic of claim 1 , wherein the substituted amino acid of (a)-(f) comprises a different side chain than the unsubstituted amino acid.
6. The mutant or peptidomimetic of claim 1 , wherein the at least one substitution provided in (a)-(f) comprises a tyrosine for histidine at amino acid position 164, a lysine for glutamate at amino acid position 166, a tryptophan for serine at amino acid position 177, or arginine for serine at amino acid position 177, or combination thereof.
7. The mutant or peptidomimetic of claim 1 , wherein the at least one substitution provided in (a)-(f) comprises a lysine for glutamate at amino acid position 166 and glutamate for lysine at amino acid position 187.
8. The mutant or peptidomimetic of claim 1 , wherein the at least one substitution provided in (a) and (c) comprises a glutamate for lysine at amino acid positions 192 and 193.
9. A pharmaceutical or veterinary composition or vaccine that comprises as active agent the mutant or peptidomimetic of claim 1 .