Appeal No. 2006-3207 Page 2
Application No. 09/565,191
Nucleic acid probes have long been used to analyze samples for the
presence of nucleic acid from a bacteria, fungi, virus or other organism.
. . . Probe-based assays are also useful in examining genetically-based
clinical conditions of interest. Nonetheless, probe-based assays have
been slow to achieve commercial success. This lack of commercial
success is, at least partially, the result of difficulties associated with
specificity, sensitivity and reliability. [Id. at 2.]
Nucleic acid hybridization is a fundamental process in molecular
biology. Sequence differences as subtle as a single base (point
mutation) in very short oligomers (< 10 base pairs “bp”) can be
sufficient to enable the discrimination of the hybridization to
complementary nucleic acid target sequences as compared with non-
target sequences. Nonetheless, nucleic acid probes of greater than 10
bp in length are generally required to obtain the sequence diversity
necessary to correctly identify a unique organism or clinical condition of
interest. However, the ability to discriminate between closely related
sequences is inversely proportional to the length of the hybridization
probe because the difference in thermal stability decreases between
wild type and mutant complexes as the probe length increases.
Consequently, the power of probe based hybridization to correctly
identify the target sequence of interest from closely related (e.g., point
mutations) non-target sequences can be very limited. [Id. at 2-3.]
The specification describes a manuscript in which “the author discussed the ‘Use
of Competitor RNA to Estimate Specificity.’” Id. at 3 (citing David E. Kennell, Principles
and Practices of Nucleic Acid Hybridization, pp. 259-301). According to the
specification, the “process is based on the principle that two identical molecules will
compete with each other for a common binding site” and is used to “assess similarities
between two RNA populations competing for a common DNA.” Id. (emphasis in
original). The process is further described as using one labeled RNA population and
one unlabeled RNA population (referred to as the “competitor population”). Id. “The
competition assay is used to estimate the degree of relation between the two RNA
species.” Id. According to the specification, Kennell suggests that hybridizing
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