Are Oligonucleotide Primers and Probes Prima Facie Obvious over Larger Prior Art Nucleic Acids?

Article excerpt

I. INTRODUCTION

While the Court of Appeals for the Federal Circuit [hereinafter CAFC] has decided that large nucleic acid sequences are nonobvious when the prior art teaches only shorter sequences, the converse question remains unaddressed, i.e. whether small nucleic acid sequences are obvious in view of the larger nucleic acid sequences that comprise them? This Comment approaches the question of "prima facie obviousness" in these smaller sequences through two hypothetical patent claims that are drawn to nucleic acid oligonucleotides. This Comment will analyze seven common prior art situations, as applied to the two hypothetical patent claims, to determine whether for each prior art situation the hypothetical claims are prima facie obvious in light of the relevant case law.

II. BACKGROUND

As the pace of advancement in biotechnology increases exponentially and the databases which store nucleic acid sequences double every year, (1) increasingly complex issues of intellectual property leave the laboratory and enter the courtroom. Nucleic acid sequences serve as a resource for the bioinformatics researcher and molecular biologist alike to design new tests and assays. (2) Some tests have been designed to diagnose diseased patients and identify the specific organism suspected of causing the symptoms, thereby leading to a specific treatment. (3) Another test has been designed to identify genetic mutations in a pig that cause enhanced litter size. The test allows farmers to select pigs with increased fecundity, which can in turn lead to reduced farm costs. (4) These tests rely on the use of small pieces of deoxyribonucleic acid (DNA), oligonucleotides, which are termed either "primers" or "probes," depending upon their use. (5)

Probes and primers are pieces of DNA which contain specific information encoded by the four nucleotide base codes, A, C, G, T (Adenine, Guanine, Cytosine, or Thymidine). (6) Probes interact with other pieces of DNA in a hybridization reaction, wherein a specific probe with a specific sequence of nucleotides will interact with a complementary sequence in a target nucleic acid. (7) Primers are a subset of probes with the further capacity to be extended in length by addition of nucleotides in a sequence-specific manner in a catalytic process employing a DNA polymerase enzyme. (8)

This Comment will address the question of whether and when oligonucleotide probes and primers are obvious under a variety of prior art situations. Figure 1 discloses the seven different nucleotide prior art situations that will be used. These sample claims will be analyzed under current case law to yield conclusions regarding the prima facie obviousness of the exemplary claims. Embedded in the CAFC case law are three approaches that are used to address the obviousness of DNA-based claims. These approaches are based upon (i) chemical case law, decisions that existed prior to the biotechnology revolution which interpret oligonucleotide claims from a chemical composition perspective; (ii) genus-species type case law, which approaches the obviousness of oligonucleotide claims as individual species in relation to the genus from which they derive; and (iii) some recent biotechnology-specific case law that is focused on issues regarding the obviousness and possession of biotechnological inventions. These three approaches will be individually applied in analyzing the level of obviousness in the exemplary claims.

III. OBVIOUSNESS ANALYSIS

A. Basic Principles

The statutory language in the Patent Act that addresses obviousness provides the starting point in analyzing the nature of each of the seven situations provided in Figure 1. The applicable section is 35 U.S.C. [section] 103(a), which states in significant part,

[a] patent may not be obtained though the invention is not

identically disclosed or described as set forth in section

102 of this title, if the differences between the subject

matter sought to be patented and the prior art are such

that the subject matter as a whole would have been obvious

at the time the invention was made to a person having ordinary

skill in the art to which said subject matter pertains. …