Chemistry: natural resins or derivatives; peptides or proteins; – Proteins – i.e. – more than 100 amino acid residues
Reexamination Certificate
1999-01-29
2001-07-03
Celsa, Bennett (Department: 1627)
Chemistry: natural resins or derivatives; peptides or proteins;
Proteins, i.e., more than 100 amino acid residues
C530S380000, C530S386000, C530S387100, C435S005000, C435S006120, C435S007100, C435S007210, C435S007250
Reexamination Certificate
active
06255455
ABSTRACT:
FIELD OF THE INVENTION
The field of the invention is generation of binding proteins.
BACKGROUND OF THE INVENTION
The ability to produce monoclonal antibodies has revolutionized diagnostic and therapeutic medicine. Monoclonal antibodies are typically produced by immortalization of antibody-producing mouse lymphocytes thus ensuring an endless supply of cells which produce mouse antibodies. However, for many human applications, it is desirable to produce human antibodies. For example, it is preferable that antibodies which are administered to humans for either diagnostic or therapeutic purposes are human antibodies since administration of human antibodies to a human circumvents potential immune reactions to the administered antibody, which reactions may negate the purpose for which the antibody was administered.
In addition, there exists certain situations where, for diagnostic purposes, it is essential that human antibodies be used because other animals are unable to make antibodies against the antigen to be detected in the diagnostic method. For example, in order to determine the Rh phenotype of human red blood cells (RBCs), human sera that contains anti-Rh antibody must be used since other animals cannot make an antibody capable of detecting the human Rh antigen.
The production of human antibodies in vitro by immortalizing human B lymphocytes using Epstein Barr virus (EBV)-mediated transformation or cell fusion has been fraught with technical difficulties due to the relatively low efficiency of both EBV-induced transformation and cell fusion when compared with the murine system. To overcome these problems, processes have been developed for the production of human antibodies using M13 bacteriophage display (Burton et al., 1994, Adv. Immunol. 57:191-280). Essentially, a cDNA library is generated from mRNA obtained from a population of antibody-producing cells. The mRNA encodes rearranged immunoglobulin (Ig) genes and thus, the cDNA encodes the same. Amplified cDNA is cloned into M13 expression vectors creating a library of phage which express human Fab fragments on their surface. Phage which display the antibody of interest are selected by antigen binding and are propagated in bacteria to produce soluble human Fab Ig. Thus, in contrast to conventional monoclonal antibody synthesis, this procedure immortalizes DNA encoding human Ig rather than cells which express human Ig.
There are several difficulties associated with the generation of antibodies using bacteriophage. For example, many proteins cannot be purified in a non-denatured state, in that purification procedures necessarily involve solubilization of protein which may render some proteins permanently denatured with concomitant destruction of antigenic sites present thereon. Such proteins thus cannot be bound to a solid phase and therefore cannot be used to pan for phage bearing antibodies which bind to them. An example of such a protein is the human Rh antigen.
To solve the problem, a method was developed wherein intact RBCs were used as the panning antigen (Siegel et al., 1994, Blood 83:2334-2344). However, it was discovered that since phage are inherently “sticky” and RBCs express a multitude of antigens on the cell surface, a sufficient amount of phage which do not express the appropriate antibody on the surface also adhere to the RBCs, thus rendering the method impractical for isolation of phage which express antibody of desired specificity.
De Kruif et al. (1995, Proc. Natl. Acad. Sci. USA 92:3938-3942) disclose a method of isolating phage encoding antibodies, wherein antibody-expressing phage are incubated with a mixture of antigen-expressing cells and cells which do not express antigen. The antibody-expressing phage bind to the antigen-expressing cells. Following binding with phage, a fluorescently labeled antibody is added specifically to the antigen-expressing cells, which cells are removed from the mixture having antibody-expressing phage bound thereto. The isolation of fluorescently labeled cells is accomplished using the technique of fluorescently-activated cell sorting (FACS), an expensive and time-consuming procedure.
There remains a need for a method of isolating recombinant proteins, preferably antibodies, which is rapid and economical, and which will provide a vast array of protein-binding proteins useful for diagnostic and therapeutic applications in humans.
SUMMARY OF THE INVENTION
The invention relates to an isolated protein having an amino acid sequence comprising a sequence selected from the group consisting of SEQ ID NOs: 1-69 and 139-181. In one embodiment, the isolated protein is an antigen-binding protein. In one aspect, the antigen is human Rh(D) protein. In another embodiment, the binding protein has an amino acid sequence selected from the group consisting of SEQ ID NOs: 1-69 and 139-181. In one aspect, the binding protein is an antibody. In another aspect, the said antibody comprises a heavy chain having an amino acid sequence selected from the group consisting of SEQ ID NOs: 1-28 and 139-153. In still another aspect, the antibody comprises a light chain having an amino acid sequence selected from the group consisting of SEQ ID NOs: 29-69 and 154-181. In yet another aspect, the antibody comprises a heavy chain having an amino acid sequence selected from the group consisting of SEQ ID NOs: 1-28 and 139-153 and a light chain having an amino acid sequence selected from the group consisting of SEQ ID NOs: 29-69 and 154-181.
In another embodiment of the isolated binding protein, the binding protein is an antibody fusion protein.
In another embodiment of the isolated protein, the protein is substantially purified.
The invention also includes an isolated DNA encoding the isolated protein of the invention. In one embodiment, the isolated DNA has a nucleotide sequence selected from the group consisting of SEQ ID NOs: 70-138 and 182-224. In another embodiment, the DNA is substantially purified.
The invention also includes an isolated DNA encoding a protein obtained by generating a synthetic DNA library in a virus vector expressing said protein; adding a magnetic label to cells expressing said antigen-bearing moiety; incubating virus expressing said protein with said magnetically labeled cells in the presence of an excess of non-labeled cells which do not express said antigen-bearing moiety to form a mixture, wherein said virus binds to said magnetically labeled cells; isolating virus bound cells from said mixture and obtaining DNA encoding said protein therefrom. In one embodiment, the DNA has a nucleotide sequence selected from the group consisting of SEQ ID NOs: 70-138 and 182-224.
The invention further includes a substantially pure protein obtained by generating a synthetic DNA library in a virus vector expressing said protein; adding a magnetic label to cells expressing said antigen-bearing moiety; incubating virus expressing said protein with said magnetically labeled cells in the presence of an excess of non-labeled cells which do not express said antigen-bearing moiety to form a mixture, wherein said virus binds to said magnetically labeled cells; isolating virus bound cells from said mixture and isolating said protein therefrom. In one embodiment, the protein has an amino acid sequence selected from the group consisting of SEQ ID NOs: 1-69 and 139-181.
The invention also includes a substantially pure preparation of a protein obtained by expressing said protein from DNA encoding said protein, wherein said DNA is obtained by generating a synthetic DNA library in a virus vector expressing said protein; adding a magnetic label to cells expressing said antigen-bearing moiety; incubating virus expressing said protein with said magnetically labeled cells in the presence of an excess of non-labeled cells which do not express said antigen-bearing moiety to form a mixture, wherein said virus binds to said magnetically labeled cells; isolating virus bound cells from said mixture and obtaining DNA encoding said protein therefrom. In one embodiment, the protein has an amino acid sequence selected from the g
Celsa Bennett
Morgan, Lewis & Bockius, L.L.P.
The Trustees of the University of Pennsylvania
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