Appeal No. 1995-4867
Application 07/993,482
appeal. Assuming this prior art suggests combining the disparate elements in the manner
required by claim 31 on appeal, we conclude that the relied upon references do not
suggest the requisite reasonable expectation of success.
For example, the examiner's rejection is premised upon modification of the “vectors
of Crowl and Maniatis.” (examiner's answer, page 5). While Crowl does describe vectors
useful for expressing human immune interferons, Crowl does not describe the secretion of
the interferon from the host cells into the culture medium. Maniatis does discuss the
secretion of foreign genes expressed in E. coli at page 433 as follows:
Vectors that allow fusion of foreign genes to DNA encoding a signal
sequence may be useful for exporting proteins out of the cytoplasm,
especially if the signal peptide is cleaved during export of the protein.
Export of the proteins may assist in subsequent purification and may serve
to isolate them from cytoplasmic proteases. However, the factors that
determine whether a given protein will be secreted when it is fused with a
particular leader peptide have not been elucidated.
Secretion of foreign proteins expressed in host cells is discussed in Chang at page 6,
lines 15-21 as follows:
“Secretion” refers to transport through the cytoplasmic membrane.
Whether or not the protein appears in the medium is dependent on the
presence or absence of an outer membrane: in the presence of outer
membrane the secreted protein will be found in the periplasm, in the
absence of outer membrane it will be in the medium.
As set forth in the paragraph bridging pages 2-3 of Chang, E. coli is a gram-negative
bacteria where the cytoplasmic membrane is encased in an outer cell membrane wall.
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