Humanized antibodies with ultralong complementary determining regions

1. A bovinized human antibody comprising:

(a) a heavy chain variable domain comprising, in order:

(i) amino acids 1-95 of the amino acid sequence of SEQ ID NO: 33, wherein SEQ ID NO: 33 comprises the following amino acid substitutions: Q5R, Q6E, G31D, Y32K, and E505, wherein up to 5 additional amino acids may be substituted excluding positions 5, 6, 31, 32 and 50 of SEQ ID NO: 33; and

(ii) an ultralong CDR3 that is at least 35 amino acids in length; and

(iii) a framework region 4 (FR4); and

(b) a light chain variable domain.”

2. The bovinized human antibody of claim 1 , wherein the heavy chain variable region comprises one, two, three, four or five of the additional amino acid substitutions.”

3. The bovinized human antibody of claim 1 , wherein the light chain variable domain is a VL1-51 light chain variable domain or a variant thereof.

4. The bovinized human antibody of claim 3 , wherein the light chain variable domain comprises the amino acid sequence of SEQ ID NO: 805 with the exception of one or more amino acid substitutions at positions corresponding to positions 2, 5, 8, 12, 13, 14, 46, 47, 51, 52, and 53 in SEQ ID NO: 805.

5. The bovinized human antibody of claim 4 , wherein the amino acid substitutions are selected from S2A, TSN, PBS, Al2G, A13S, P14L, K46R, L47T, D51G, N52D, and N53T.

6. The bovinized human antibody of claim 4 , wherein the light chain variable region comprises at least two of the amino acid substitutions.

7. The bovinized human antibody of claim 1 , wherein the FR4 comprises an amino acid sequence selected from the group consisting of:

(i) WGHGTAVTVSS (SEQ ID NO: 570),

(ii) WGKGTTVTVSS (SEQ ID NO: 571),

(iii) WGRGTLVTVSS (SEQ ID NO: 573), and

(iv) WGQGLLVTVSS (SEQ ID NO: 500).

8. The bovinized human antibody of claim 1 , wherein antibody is a single-chain variable fragment.

9. The bovinized human antibody of claim 1 , wherein heavy and light chain variable domains are on different polypeptides.