Appeal No. 1998-1987
Application No. 07/915,783
a suspension in water” of a parasite-containing material,2 “adding a non-ionic
detergent to the suspension,” and “separating and recovering the antigenic
factor(s) from the aqueous medium.” Claim 68 requires no particular purification
step(s) or degree of purification in the claimed compositions.
Both Kilejian and Epstein teach immunoprecipitation of antigens from
plasmodial parasites. In the process disclosed by Kilejian, plasmodial
merozoites and a “membrane-enriched fraction prepared from schizonts” were
used to immunize rabbits. Page 3695, right-hand column. After the rabbits had
developed plasmodial-specific antibodies, antisera (“immune sera”) were
collected. Id. The antibody-containing immune sera were then mixed with
“protein A covalently coupled with Sepharose CL-4B,” to form antibody/protein
A/Sepharose beads. Page 3696, sentence bridging the columns. In the
meantime, Plasmodium falciparum “parasites were solubilized in . . . 1% Nonidet
P-40 (NP-40) in phosphate-buffered saline.” Id., left-hand column.3 The “NP-40
extract (200 µl; 400-600 µg of protein) was added to the washed beads. . . .
Unbound extract was removed by three washes with 0.5 M LiCl/10 mM Tris-HCl,
pH 8, and one wash with 1% NP-40 buffer. Immunocomplexes were eluted.” Id.,
right-hand column.
Epstein discloses a similar immunoprecipitation protocol. Mice were
immunized with merozoites and used to produce plasmodial-specific monoclonal
2 Specifically, “intact starting plasmodial parasite released from a quantity of red blood
cells, intact red blood cells containing the blood stage of the starting plasmodial parasite,
merozoites which released themselves from red blood cells, tissues having blood infected
with said starting plasmodial parasite, [or] tissues having starting plasmodial parasite
infected blood.” Claim 68.
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