In Intervet v. Merial, the Court of Appeals for the Federal Circuit Highlights the Critical Role Proper Markman Rulings play in Biotech Patent Infringement Cases
At issue was Merial’s patent of isolated DNA sequences from a previously unknown pathogenic porcine coronavirus (PCV). Merial differentiated four strains of PCV-2 (pathogenic) with 96% sequence homology, from a strain of PCV-1 (nonpathogenic) that had only 76% sequence homology to the PCV-2 strains. Merial identified 13 specific ORFs from a single PCV-2 strain, a single DNA isolate that Merial claimed contained an epitope specific to PCV-2, and assorted vectors and molecules designed to test for and vaccinate against PCV-2. Intervet subsequently designed and manufactured a competing vaccine against PCV-2.
The district court ruled that as Intervet’s vaccine utilized a sequence that was only 99.7% identical to one of Merial’s sequences, there was no literal infringement. Furthermore, the court ruled that prosecution history estoppel prevented Merial from claiming infringement under the doctrine of equivalents. The Federal Circuit reversed, finding errors in both the Markman rulings, and the application of prosecution history estoppel.
The reversals turned on the circuit court’s narrow interpretation of the scope of the patent. Initially, the Federal Circuit attacked the ruling that the patent extended only to the four specific PCV-2 sequences submitted. In place of this ruling, the Federal Circuit suggested that the proper scope would include all species bearing 96% sequence homology to the sample sequences. The second reversal concerned the 13 specific ORFs identified as shared aspects of PCV-2. The Federal Circuit recognized that unique mutations within a given ORF are to be expected, and that a researcher trained in genetics would interpret a claim to a specific ORF to constitute a claim to the sequence found between a start and a stop codon at the specified genetic location. Thus, the Federal Circuit ensured that the absolute letter of the patent wasn’t allowed to eviscerate the clear intent of the application.
For a discussion of the prosecution history estoppel ruling and a review of Judge Dyk’s dissent see: http://www.patentlyo.com/patent/2010/08/genus-species-doctrine-of-equivalents-and-patentable-subject-matter.html
