6.1.2 Definition by reference to the target antigen 

An antibody can be functionally defined by the antigen it binds to, as long as the antigen is clearly defined in the claims. If the antigen is defined by a protein sequence, its definition must not use any sequence variability or open wording (e.g. "an antigen comprising …"). Otherwise the claimed subject-matter will be considered to lack novelty over any known antibody because existing antibodies will bind to the undefined region of the target antigen.

Examples of accepted antigen-defined antibody claim wording are:

– antibody binding to X 

– anti-X antibody 

– antibody reacting with X 

– antibody specific for antigen X or 

– antibody binding to antigen X consisting of the sequence defined by SEQ. ID. NO: y. 

An antibody can also be defined by its ability to bind to a well-defined antigen in combination with a negative feature, for example: "Antibody binding to antigen X and not binding to antigen Y".