Abstract: The present invention relates to the manufacture of a diverse repertoire of functional heavy chain-only antibodies that undergo affinity maturation, and uses thereof. The invention also relates to the manufacture and use of a diverse repertoire of class-specific heavy chain-only antibodies and to the manufacture and use of multivalent polypeptide complexes with antibody heavy chain functionality, preferably antibody heavy chain binding functionality, constant region effector activity and, optionally, additional effector functions. The present invention also relates to a method of generation of fully functional heavy chain-only antibodies in transgenic mice in response to antigen challenge. In particular, the present invention relates to a method for the generation of human antigen-specific, high affinity, heavy chain-only antibodies of any class, or mixture of classes and the isolation and expression of fully functional VH antigen-binding domains.

Abstract: The present invention relates to methods for engineering VH domains to improve their solubility and stability. The invention provides for the incorporation of defined amino acid substitutions based on 3-D structural information into the V segments of a heavy chain locus, expressing the locus in a non-human mammal and selecting soluble VH domains. Further stabilising or solubilising mutations maybe introduced as a result affinity maturation during B-cell maturation in vivo.

Abstract: A transgenic organism is provided comprising a polynucleotide construct encoding an intracellular antibody which disrupts the catalysis of the production of the xenoantigen galactose ? 1,3 galactose and/or a polynucleotide construct which encodes an intracellular antibody which binds specifically to a retrovirus protein, such as a PERV particle protein. Also described are methods for the production of such organisms. Cells, tissues and organs of the transgenic organism may be used in xenotransplantation.

Abstract: A transgenic organism is provided comprising a polynucleotide construct encoding an intracellular antibody which disrupts the catalysis of the production of the xenoantigen galactose ? 1,3 galactose and/or a polynucleotide construct which encodes an intracellular antibody which binds specifically to a retrovirus protein, such as a PERV particle protein. Also described are methods for the production of such organisms. Cells, tissues and organs of the transgenic organism may be used in xenotransplantation.