Cγ lacking CH1
(Claim 1, Claim 8) | Each heavy chain constant region essentially comprises at least one heavy chain constant region gene, which is expressed without a functional CH1 domain so that generation of heavy chain-only antibody can occur. The expression of all or part of a heterologous heavy chain Cγ locus devoid of CH1 will produce optionally some or all IgG isotypes. CH1 domain functionality was absent in camelid heavy chain-only antibody due to an alternative splice site which eliminated CH1 from the processed antibody heavy chain mRNA. | A heavy chain constant region gene segment of the IgG class that has been modified or selected to exclude the CH1 domain, preventing association with immunoglobulin light chains. |
Heterologous immunoglobulin heavy chain locus
(Claim 1, Claim 8) | In the context of the present invention, the term ‘heterologous’ means a nucleotide sequence or a locus as herein described not endogenous to the mammal in which it is located or an endogenous locus which has been modified by the replacement or removal of endogenous sequences. A “heavy chain-only locus” in the context of the present invention relates to a locus encoding a VH domain comprising one or more V gene segments, one or more D gene segments and one or more J gene segments, operationally linked to one or more heavy chain effector regions (each lacking CH1 domain functionality). | A genetic construct not endogenous to the host mammal, or a modified endogenous locus, containing V, D, and J gene segments operationally linked to constant effector regions for the production of heavy chain-only antibodies. |
Human VH gene segments
(Claim 1, Claim 8) | There are over 50 human V gene segments present in the human genome of which only 39 are functional. For the derivation of heavy chain—only antibodies or soluble VH domains to be used for therapeutic applications in humans, the VDJ genes present in the locus will be derived from human germ-line sequences. Most of a VH domain is encoded by a V gene segment, but the C terminal end of each VH domain is encoded by a D gene segment and a J gene segment. | Variable region gene segments derived from the human genome that encode the heavy chain variable domain, which in this invention undergo VDJ rearrangement to form soluble antigen-binding domains. |
Naturally occurring
(Claim 1, Claim 8) | The term ‘V gene segment’ encompasses a naturally occurring V gene segment derived from a vertebrate, including camelids and human. In this approach, four natural human germ line VH gene segments (V4 natural locus) have been introduced, so relying entirely on natural selection through affinity maturation for the generation of antigen specificity and structural stability. The human V4 locus is functional and human heavy chain-only antibodies circulate in the plasma of unchallenged animals. | Gene segments derived from a vertebrate source, such as human germ-line sequences, without synthetic engineering or non-natural mutations prior to in vivo recombination. |
Transgenic non-human mammal
(Claim 1) | The transgenic mammal is preferably a rodent such as a rabbit, guinea pig, rat or mouse. Mice and rats are especially preferred. The invention yet further provides a transgenic non-human mammal comprising a heterologous heavy chain locus according to the invention. | A non-human animal, preferably a rodent like a mouse or rat, whose genome has been altered to include a functional heterologous heavy chain-only locus. |
VH gene segments
(Claim 1, Claim 8) | Most of a VH domain is encoded by a V gene segment, but the C terminal end of each VH domain is encoded by a D gene segment and a J gene segment. VDJ rearrangement in B-cells, followed by affinity maturation, provides each VH domain with its antigen-binding specificity. The human V4 locus is functional and human heavy chain-only antibodies circulate in the plasma of unchallenged animals. | Variable region gene segments that encode the majority of the heavy chain variable domain, which in this invention are human-derived and contribute to the formation of soluble heavy chain-only antibodies. |
