Stabilized primate lentivirus envelope glycoproteins
A modified polypeptide corresponding to an envelope glycoprotein of a primate lentivirus is described. The polypeptide has been modified from the wild-type structure so that it has cysteine amino acid residues introduced to create disulfide bonds, a cavity is filled with hydrophobic amino acids, a Proresidue is introduced at a defined turn structure of the protein, or the hydrophobicity is increased across the interface between different domains, while retaining the overall 3-dimensional structure of a discontinuous conserved epitope of the wild-type protein. Preferably, the polypeptide has more than one of those characteristics. Preferably, the primate lentivirus is HIV, and the protein is HIV-1 gp120.
1. A modified gp120 polypeptide comprising portions of at least two conserved regions of an envelope protein selected from a the group of lentiviruses consisting of HV-1, HIV-2 and SIV, wherein at least one of the following changes relative to the wild-type gp120 protein is made:
(a) introduction of disulfide bonds to decrease the free energy of folding relative to the wild type gp120 protein;
(b) filling a cavity of the gp120 protein with hydrophobic amino acid residues; or
(c) introducing a Pro residue at a defined turn structure;
wherein the modified polypeptide maintains the overall 3-dimensional structure of a discontinuous conserved epitope of the wild-type gp120, wherein the discontinuous conserved epitope is a CD4BS epitope, CD4i epitope or 2G12 epitope.
2. The modified gp120 polypeptide of claim 1 , wherein the discontinuous conserved epitope is a CD4BS epitope or CD4i epitope.
3. The modified gp120 polypeptide of claim 1 , wherein the gp120 protein is HIV-1.
4. The modified gp120 polypeptide of claim 3 , wherein disulfide bonds are introduced between at least one of the groups of amino acids that correspond to Pro118-Ala443, Leu122-Gly431, Phe210-Gly30, or Ser256-Phe376 of the HIV-1 HXBc2 strain.
5. The modified gp120 polypeptide of claims 3 or 4 , wherein at least one amino acid residue corresponding to wild-type gp120 Ser375, Val255, Arg273, Ser481, Ser447, Asn377 of the HIV-1HXBc2 strain, Thr283, or Asp477 of the HIV-1 HXBc2 strain, has been substituted with a hydrophobic amino acid residue.
6. The modified gp120 polypeptide of claim 5 , wherein at least one of the following amino acid substitutions is present:
Trp for Ser375, Val255 or Arg 273;
Phe for Ser481;
Ile for Ser447 or Thr283;
Or Leu for Asn377 or Thr283.
7. The modified gp120 polypeptide of claim 5 , wherein a Pro residue has been introduced at a defined turn structure.
8. The modified gp120 polypeptide of claim 4 , wherein a Pro residue has been introduced at a defined turn structure.
9. The modified gp120 polypeptide of claim 3 , wherein a Pro residue has been introduced at a defined turn structure.
10. The modified gp120 polypeptide of claim 7 , wherein a Pro residue has been substituted for Ile423.
11. The modified gp120 polypeptide of claim 8 , wherein a Pro residue has been substituted for Ile423.
12. The modified gp120 polypeptide of claim 9 , wherein Pro has been substituted for Ile423.
13. The modified gp120 polypeptide of claim 1 , wherein at least two of the changes have been made.
14. The modified gp120 polypeptide of claim 1 , wherein at least three of the changes have been made.
15. The modified gp120 polypeptide of claim 1 wherein the cavity of the gp120 protein corresponds to Phe43 of the wild type HIV-1, HXBc2 strain.