Cysteine protease
The present invention relates to a novel polypeptide which displays IgG cysteine protease activity, and in vivo and ex vivo uses thereof. Uses of the polypeptide include methods for the prevention or treatment of diseases and conditions mediated by IgG, and methods for the analysis of IgG.
1. A method for the prevention or treatment of a disease or condition in a subject, which method comprises administering a polypeptide having IgG cysteine protease activity to the subject in a prophylactically or therapeutically effective amount or a method for the cleavage of IgG, the method comprising contacting a sample containing IgG with said polypeptide having IgG cysteine protease activity under conditions which permit IgG cysteine protease activity to occur; wherein said polypeptide having IgG cysteine protease activity comprises a variant of the sequence of SEQ ID NO:2, which variant:
(a) is at least 50% identical to SEQ ID NO: 2;
(b) has a cysteine (C) at the position in said variant sequence which corresponds to position 94 of SEQ ID NO: 1; and
(c) has, at the positions in said variant sequence which correspond to positions 84, 262, 284 and 286 of SEQ ID NO: 1, a lysine (K), a histidine (H), an aspartic acid (D) and an aspartic acid (D), respectively;
wherein said polypeptide produces greater quantity of IgG cleavage fragments than IdeS and/or is less immunogenic than IdeS; and wherein said variant of the sequence of SEQ ID NO: 2:
(1) has a positively charged amino acid at the position in said variant which corresponds to position 130 of SEQ ID NO: 1, optionally wherein said positively charged amino acid is arginine (R) or lysine (K); and/or
(2) has a positively charged amino acid at the position in said variant which corresponds to position 131 of SEQ ID NO: 1, optionally wherein said positively charged amino acid is arginine (R) or lysine (K); and/or
(3) does not include the contiguous sequence NQTN; and/or
(4) has deleted in its entirety the first twenty residues at the N terminus of SEQ ID NO: 2, said first twenty residues comprising the contiguous sequence DSFSANQEIR YSEVTPYHVT (SEQ ID NO: 19).
2. A method for the prevention or treatment of a disease or condition according to claim 1 , wherein said disease or condition is a disease or condition mediated in whole or in part by pathogenic IgG antibodies.
3. A method for the cleavage of IgG according to claim 1 which is carried out ex vivo and/or is conducted to generate Fc and Fab fragments and/or wherein the sample is a blood sample taken from a subject suffering from a disease or condition mediated in whole or in part by pathogenic IgG antibodies.
4. The method according to claim 2 , wherein said disease or condition is listed in Table D.
5. The method according to claim 3 , wherein said disease or condition is listed in Table D.
6. A method according to claim 1 , wherein said variant of the sequence of SEQ ID NO: 2 is at least 80% identical to SEQ ID NO: 2.
7. A method according to claim 1 , wherein said variant of the sequence of SEQ ID NO: 2 comprises or consists of the sequence of any one of SEQ ID NOs: 3 to 5 and 9 to 16, optionally wherein said variant of the sequence of SEQ ID NO: 2 includes an additional methionine at the N terminus and/or a histidine tag at the C terminus.
8. A method according to claim 1 , wherein said polypeptide produces at least 1.5 fold more IgG cleavage fragments than IdeS, when measured in the same assay.
9. A method according to claim 1 , wherein said variant of the sequence of SEQ ID NO: 2 is less immunogenic than IdeS.
10. The method according to claim 9 , wherein the immunogenicity of said variant of the sequence of SEQ ID NO: 2 is no more than 85% of the immunogenicity of IdeS when measured in the same assay.