Appeal No. 2006-3207 Page 3
Application No. 09/565,191
unlabeled competitor RNA before hybridizing the labeled RNA in a process called
“presaturation competition” might improve the results of such as assay. Id.
Several hybridization cocktails containing both labeled and unlabeled nucleic
acid probes are noted. Id. at 4-5. Details of these references are not provided, and
they have not been cited to support the Examiner’s position.
The specification describes a number of other prior art references disclosing
various hybridization assays using labeled and unlabeled probes but concludes that
these references do not “disclose, suggest or teach anything about Peptide Nucleic
Acids (PNAs).” Id. at 3-5. PNAs are described as “non-naturally occurring polyamides
which can hybridize to nucleic acids (DNA and RNA) with sequence specificity.” Id. at
5. According to the specification, a number of advantages of using PNAs as probes
have been reported in the prior art. Id. at 5-9. Reported advantages include their ability
to “provide very good discrimination of point mutations in a DNA sample.” Id. at 6.
Following its discussion of the prior art, the specification identifies a remaining
challenge, i.e., to distinguish between the exact target sequence and closely-related (or
non-target) sequences, such as those differing by only one nucleic acid. Id. at 9. “Any
hybridization to a closely related non-target sequence will result in the generation of
undesired background signal.” Id. Thus, an “object of the invention” is to address this
challenge by providing kits and compositions “suitable for the suppression of the binding
of probes to non-target sequences in hybridization assays” and “for improving
specificity, sensitivity and reliability of nucleic acid point mutation detection, analysis and
quantitiation.” Id. at 10.
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