Intervet, Inc. v. Merial Ltd., No. 2009-1568 (Fed. Cir. Aug. 4, 2010).

The patent at issue is directed to DNA constructs encoding a type of virus. It was undisputed that the accused product was 99.7% homologous to one of the sequences the patent holder had deposited with the USPTO. The district court entered summary judgment of noninfringement based on a claim construction that required the accused products to exactly match the deposited sequences. Additionally, the district court held that there was no infringement under the doctrine of equivalents on the basis of prosecution history estoppel.

The Federal Circuit reversed the claim construction order, vacated the summary judgment order, and remanded for further infringement analysis. In reviewing the district court’s claim construction de novo, it held that the deposited sequences were merely “representative.”

The Federal Circuit also rejected the district court’s construction, which limited the sequences covered in the claims to the representative sequences listed in an example in the specification. “[T]he [district] court erred in confining the scope of the term to the precise limits of… Example 13, and the exact DNA sequence of SEQ ID 4.” The court further rejected the argument that the claimed DNA sequences should be limited only to those strains which had actually been sequenced in the specification.

Finally, the Federal Circuit also rejected the district court’s doctrine of equivalents analysis. Although the applicants had narrowed a claim during prosecution to cover only those sequences from a particular type of virus rather than another virus, the applicants were not estopped from arguing that a viral sequence that is 99% homologous to a representative strain is equivalent to that representative strain.

Judge Dyk dissented in part, disagreeing with part of the majority’s construction of the claims, and arguing that an isolated DNA molecule is not patentable subject matter under 35 U.S.C. § 101. The issue of whether or not isolated DNA molecules are patentable subject matter is expected to be determined by the Federal Circuit en banc in Therasense, Inc. v. Becton, Dickinson & Co., Nos. 2008-1511, -1512, -1513, -1514, -1595 (Fed. Cir.).

A copy of the opinion can be found here.