Appeal No. 95-4481
Application No. 07/911,667
Pope analyzes various species of IgG to determine “which species of IgG is the
most sensitive and specific antigen for the detection of IgG [rheumatoid factor] by
radioimmunoassay.” See page 842.
Emlen discloses an ELISA for the detection of circulating antibodies specific for
dsDNA in which biotinylated dsDNA is immobilized in streptavidin-coated wells, the
immobilized dsDNA is used to capture antibodies specific for dsDNA, and the captured
antibodies are detected with peroxidase-labeled anti-human IgG antibodies. The
reference focuses on avoiding the problems of a number of conventional assays for
detection of anti-dsDNA antibodies, most of which rely on immobilized DNA to capture
circulating antibodies, and all of which are “plagued with the problem of purity of dsDNA,
as well as problems unique to each assay.” See the Introduction section, especially the
sentence bridging pages 91 and 92. Emlen overcomes the problems associated with the
other assays by controlling the purity and antigenicity of the immobilized dsDNA.
Pollard-Knight discloses a number of non-radioactive substances used to label
nucleic acids in hybridization assays. The labeling substances include digoxigenin, biotin
and alkaline phosphatase.
The examiner believes that it would have been obvious for one of ordinary skill in
the art “to combine the solid phase immunoadsorbent for use in a reversible sandwich
immunoassay as disclosed by Litman et al., combined with a method of purifying IgG via
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