The patent proprietor filed an appeal after the Opposition Division (OD) had maintained its patent in amended form.
Claim 1 of the first auxiliary request read (in English translation):
Purified polypeptide comprising an amino acid sequence selected from among:(a) the sequence SEQ ID No. 2,(b) any sequence derived from SEQ ID No. 2 and capable of binding specifically to IL-l3,with the exception of the polypeptide of the following sequence:1 MARPALLGELLVLLLWTATVGQVAAATEVQPPVTNLSVSV41 ENLCTIIWTWSPPEGASPNCTLRYFSHFDDQQDKKIAPET81 HRKEELPLDEKICLQVGSQCSANESEKPSPLVKKCISPPE121 GDPESAVTELKCIWHNLSYMKCSWLPGRNTSPDTHYTLYY161 WYSSLEKSRQCENIYREGQHIACSFKLTKVEPSFEHQNVQ201 IMVKDNAGKIRPSCKIVSLTSYVKPDPPHIKHLLLKNGAL241 LVQWKNPQNFRSRCLTYEVEVNNTQTDRHNILEVEEDKCQ281 NSESDRNMEGTSCFQLPGVLADAVYTVRVRVKTNKLCFDD321 NKLWSDWSEAQSIGKEQNSTFYTTMLLTIPVFVAVAVIIL361 LFYLKRLKIIIFPPIPDPGKIFKEMFGDQNDDTLHWKKYD401 IYEKQSKEETDSVVLIENLKKAAP.(emphasis of the Board)
The Board found this disclaimer to be unallowable:
*** Translation of the French original ***
 Auxiliary request 1 is the [patent proprietor’s] preferred request. It corresponds to the precise wording of the main request considered by the OD in the impugned decision […].
 The OD has come to the conclusion that this disclaimer was not allowable because its introduction into claim 1 as granted had modified the latter so as to extend the subject-matter of the patent beyond the content of the application as filed, thereby violating A 123(2).
 The introduction of a disclaimer into claim 1 as granted aimed at restoring novelty by limiting its embodiment consisting in a purified polypeptide comprising “any sequence derived from SEQ ID No. 2 and capable of binding specifically to IL-l3” with respect to document D1.
 Document D1 is a Euro-PCT application that is comprised in the state of art within the meaning of A 54(3) EPC 1973 together with A 158 EPC 1973.
 Document D1 mainly discloses a polypeptide of murine origin designated by the term “NR4” and identified by means of the sequence indicator “SEQ ID NO:2”. An attentive examination of the examples shows that it does not correspond to the polypeptide of 426 amino acids that is represented (having the same sequence indicator) on pages 50 to 52 of the sequence listing. It rather corresponds to the polypeptide containing 424 amino acids represented on figure 1. The sentence “The NR4 cDNA is predicted to encode for a protein of 424 amino acid residues” in the context of example 6 […] and the reference to figure 1 made in examples 2, 3, and 6, are relevant in this respect. The comment regarding this figure on page 31 […] “Figure 1 is a representation of the nucleotide [SEQ ID NO:1] and predicted amino acid [SEQ ID NO:2] sequence of murine NR4” completely removes any doubt.
 Document D1 is not limited to the disclosure of this polypeptide NR4 of 424 amino acids but also extends to polypeptides having at least 50% similarity to all or part of it and have the ability of binding to IL-13 with at least low affinity […].
 Document D2 is an Australian patent application filed on October 23, 1995, i.e. prior to the priority date of the impugned patent (December 6, 1995). D2 is the earliest priority document of document D1. It precisely discloses a set of polypeptides capable of binding to IL-13, comprising a polypeptide of the SEQ ID NO:2 sequence represented in the sequence list […] corresponding to the one of figure 1 of D1, which is also capable of binding to IL-13 with low affinity, and to any polypeptide having at least 50% similarity wit said polypeptide or any part of it […].
 The polypeptides, insofar as they are capable of binding to IL-13 with low affinity, which are disclosed in the same way in both D1 and said priority document D2, are covered by claim 1 as granted. As this is an accidental disclosure (because document D1 was not available to the public on the day of filing of the patent under consideration), the [patent proprietor] may exclude them from claim 1 by means of a disclaimer (see G 1/03 ).
NB: I have the impression that the Board mixes up accidental disclosures and A 54(3) prior art. Both are mentioned in headnote 2.1 of G 1/03, but A 54(3) prior art is not necessarily accidental. According to G 1/03, “an anticipation is accidental if it is so unrelated to and remote from the claimed invention that the person skilled in the art would never have taken it into consideration when making the invention”.
 For a given claim, a disclaimer can only be allowed if it excludes the entire subject-matter that has been disclosed accidentally. However, the disclaimer of claim 1 does not exclude the polypeptides the sequence of which has at least 50% similarity with the sequence of 424 amino acids of figure 1 of document D1 or with any part of this sequence and which are capable of binding to IL-13 with low affinity. Therefore, it is not allowable within the meaning of A 123(2).
 The argument of the [patent proprietor] according to which the skilled person would have understood that the correct sequence of murine IL-13Ralpha is the sequence of 426 amino acids represented with the sequence indicator SEQ ID NO:2 in the sequence listing of document D1 but absent from document D2, and that, as a consequence, he would have ignored the sequence of 424 amino acids designated by the same sequence indicator, does not stand up to examination. The Board finds that said polypeptide of 424 amino acids is disclosed in document D1 and that this disclosure extends to any polypeptide having at least about 50% similarity with said polypeptide or with any part of it, and capable of binding to IL-13 with low affinity […]. This is a set of polypeptides each of which, in the absence of any definition of the term “variant” in the patent, represents a derivative polypeptide variant of the polypeptide of the SEQ ID NO:2 sequence of the sequence list of the patent within the definition given in paragraph  of the patent […]. In order to restore novelty for claim 1 as granted, it was thus necessary to exclude this set of polypeptides.
 It follows from this analysis that the disclaimer of claim 1 is incomplete because it does not exclude this whole set of polypeptides; it is not capable of restoring novelty with respect to document D1. As a consequence, the amendment consisting in its introduction is unallowable within the meaning of A 123(2), in conformity with G 1/03. At least for this reason, auxiliary request 1 has to be refused.
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The file wrapper can be found here.