Inherent anticipation – Is the phenotype exhibited by a transgenic plant an inherent feature?April 19, 2021

A claim is anticipated only if each and every element as set forth in the claim is found, either expressly or inherently described, in a single prior art reference. If a prior art reference expressly sets forth each of the elements of a claim, then there is typically little question of whether or not the claim is anticipated. On the other hand, inherent anticipation is not always so clear-cut. A limitation must necessarily be present for it to be deemed inherent in the prior art; the fact that it may result is not sufficient to establish anticipation.

This question of inherency can arise in plant biotechnology patent applications when claiming a plant transformed with a gene to provide a particular phenotype if a prior art reference exists that discloses a plant transformed with the same gene but to provide a different phenotype. As one example, this is precisely the situation addressed by the Patent Trial and Appeal Board (PTAB) in Ex parte Christensen (Appeal No. 2019-002834).

The claim at issue in Ex parte Christensen is reproduced below:

A plant cell comprising an exogenous nucleic acid said exogenous nucleic acid comprising a regulatory region operably linked to a nucleotide sequence encoding a polypeptide, wherein said polypeptide has 90% or greater sequence identity to the amino acid sequence of SEQ ID NO:2 and wherein a plant produced from said plant cell has an increased level of cold tolerance as compared to the corresponding level of cold tolerance of a control plant that does not comprise said nucleic acid.

The Examiner alleged that the claim was anticipated by Churchman et al. (Plant Cell. 2006 Nov;18(11):3145-57). Specifically, Churchman disclosed leaf cells transformed to express a polypeptide that shared 98.4% sequence identity with Christensen’s claimed SEQ ID NO: 2. Churchman does not mention cold tolerance at all, but the Examiner determined that its transformed plant cells would necessarily exhibit the increased level of cold tolerance claimed by Christensen.

The Christensen application itself demonstrated that not all plants transformed with the sequence had the cold tolerance phenotype. Indeed, six transformation events were analyzed and only two showed significant differences in cold tolerance relative to controls. Evidence in the form of a declaration was also submitted during prosecution to demonstrate that the claimed increase in cold tolerance is not necessarily present in Churchman’s transformed cells. The declaration notes that there are any number of reasons that a successfully transformed plant would not exhibit a phenotype including “dosage effects, threshold mechanism, differential tissue expression, genetic background dependence, transgene silencing, disruption of endogenous genes by transgene insertion, and paramutation.”

Ultimately, the evidence in the declaration carried the day. The Examiner was reversed and the case proceeded to allowance. At least in this instance, the phenotype exhibited by a transgenic plant cannot be considered an inherent feature.

Brian D. Keppler, Ph.D. is a registered Patent Agent in the MVS Biotechnology & Chemical Practice Group. To learn more, visit our MVS website, or contact Brian directly via email.