Establishment of a Chicken Monoclonal Antibody Panel Against Mammalian Prion Protein

Monoclonal IgY antibodies: advancements and limitations for immunodiagnosis and immunotherapy applications

Due to their high specificity and scalability, Monoclonal IgY antibodies have emerged as a valuable alternative to traditional polyclonal IgY antibodies. This abstract provides an overview of the production and purification methods of monoclonal IgY antibodies, highlights their advantages over polyclonal IgY antibodies, and discusses their recent applications. Monoclonal recombinant IgY antibodies, in contrast to polyclonal IgY antibodies, offer several benefits. such as derived from a single B-cell clone, monoclonal antibodies exhibit superior specificity, ensuring consistent and reliable results. Furthermore, it explores the suitability of monoclonal IgY antibodies for low- and middle-income countries, considering their cost-effectiveness and accessibility. We also discussed future directions and challenges in using polyclonal IgY and monoclonal IgY antibodies. In conclusion, monoclonal IgY antibodies offer substantial advantages over polyclonal IgY antibodies regarding specificity, scalability, and consistent performance. Their recent applications in diagnostics, therapeutics, and research highlight their versatility.

Epitope-Based Chicken-Derived Novel Anti-PAD2 Monoclonal Antibodies Inhibit Citrullination

The aberrant upregulation of protein arginine deiminase 2- (PAD2-) catalyzed citrullination is reported in various autoimmune diseases (rheumatoid arthritis and multiple sclerosis) and several cancers. Currently, there are no anti-PAD2 monoclonal antibodies (mAbs) that can inhibit the citrullination reaction. Here, an epitope ³⁴¹YLNRGDRWIQDEIEFGY³⁵⁷ was examined as an antigenic site of PAD2. Chickens were immunized with this epitope, and the generated mAbs were screened for its reactivity against the full-length PAD2. Enzyme-linked immunosorbent assay revealed that six mAbs, which were screened from the phage display library, crossreacted with mouse PAD2. Kinetic analysis revealed that mAbs are bound to PAD2 in the nanomolar range, which indicated a strong binding. Results of the in vitro citrullination inhibition assay revealed that the half-maximal effective concentration values of mAbs for the inhibition of histone or benzoyl-L-arginine ethyl ester citrullination were in the range of 6–75 nM which supports strong inhibition capabilities. Alanine scanning of epitope revealed that the peptide fragment ³⁴⁴RGDRWIQDEIEF³⁵⁵ was responsible for generating strong antibody responses that inhibit the PAD2-catalyzed citrullination reaction. These antibodies can aid in understanding the extracellular PAD2 function and treating diseases associated with aberrant citrullination.

Generation and characterization of chicken-sourced single-chain variable fragments (scFvs) against porcine interferon-gamma (pIFN-γ)

Development of chicken-sourced antibodies offers an alternative strategy for the development of highly specific antibodies against mammalian proteins with conserved epitopes due to the phylogenetic distance between avian and mammalian species. In this study, the single-chain variable fragments (scFvs) against porcine interferon-gamma was screened and characterized from a hyperimmunized chicken phage display library. The expressed soluble scFvs exhibited highly specific recognition of porcine interferon-gamma in ELISA, Western blot, and immunofluorescence staining assays. Results of the current study indicate that it is possible to develop scFv IgY antibodies to a mammalian interferon by using Biopanning technology. Furthermore, it also confirms that monoclonal avian IgY antibody technique could be applied as a promising tool to produce immunoglobulin molecules with high specificity and affinity towards conserved mammalian epitopes or antigens.

Generation of a chickenized catalytic anti-nucleic acid antibody by complementarity-determining region grafting

In contrast to a number of studies on the humanization of non-human antibodies, the reshaping of a non-human antibody into a chicken antibody has never been attempted. Therefore, nothing is known about the animal species-dependent compatibility of the framework regions (FRs) that sustain the appropriate conformation of the complementarity-determining regions (CDRs). In this study, we attempted the reshaping of the variable domains of the mouse catalytic anti-nucleic acid antibody 3D8 (m3D8) into the FRs of a chicken antibody (“chickenization”) by CDR grafting, which is a common method for the humanization of antibodies. CDRs of the acceptor chicken antibody that showed a high homology to the FRs of m3D8 were replaced with those of m3D8, resulting in the chickenized antibody (ck3D8). ck3D8 retained the biochemical properties (DNA binding, DNA hydrolysis, and cellular internalizing activities) and three-dimensional structure of m3D8 and showed reduced immunogenicity in chickens. Our study demonstrates that CDR grafting can be applied to the chickenization of a mouse antibody, probably due to the interspecies compatibility of the FRs.

Conditional expression of full-length humanized anti-prion protein antibodies in Chinese hamster ovary cells

Because of their high antigen specificity and metabolic stability, genetically engineered human monoclonal antibodies are on the way to becoming one of the most promising medical diagnostics and therapeutics. In order to establish an in vitro system capable of producing such biosimilar antibodies, we used human constant chain sequences to design the novel human antibody expressing vector cassette pMAB-ABX. A bidirectional tetracycline (tet)-controllable promotor was used for harmonized expression of immunoglobulin type G (IgG) heavy and light chains. As an example we used anti-prion protein (anti-PrP) IgGs. Therefore, the variable heavy (V(H)) and light chain (V(L)) sequences of anti-PrP antibodies, previously generated in our laboratory by DNA immunization of prion protein knock-out mice, were isolated from murine hybridoma cell lines and inserted into pMAB-ABX vector. After transfection of Chinese hamster ovary (CHO) cells, a number of stable antibody producing cell clones were selected. One cell line (pMAB-ABX-13F10/3B5) stably expressing the recombinant humanized antibody (rechuAb) 13F10/3B5 was selected for detailed characterization by Western blot, immunofluorescence, and flow cytometric analyses. The full-length recombinant humanized IgG antibody showed a high level of expression in the cytoplasm. In conclusion, the new cell system described here is a suitable tool to produce functional intact full-length humanized IgG antibodies.

Towards therapeutic antibodies to membrane oncoproteins by a robust strategy using rats immunized with transfectants expressing target molecules fused to green fluorescent protein

Cell-surface molecules containing growth factor receptors, adhesion molecules and transporter proteins are often over-expressed in various cancer cells, and could be regarded as suitable targets for therapeutic monoclonal antibodies (mAb). Anti-cancer therapeutic mAb are claimed to bind these cell-surface molecules on viable cancer cells: therefore, it is necessary to produce mAb recognizing epitopes on the extracellular domains of native but not denatured proteins. We have experienced difficulty in obtaining mAb bound to viable cancer cells using synthetic peptides or recombinant proteins produced in bacteria as immunogens, although these immunogens are relatively easy to prepare. In this context, we have concluded that viable cancer cells or cells transfected with cDNA encoding target proteins are suitable immunogens for the production of anti-cancer therapeutic mAb. Furthermore, we selected rats as the immunized animals, because of their excellent capacity to generate diverse antibodies. Because many target candidates are multi-pass (type IV) membrane proteins, such as 7-pass G protein-coupled receptors and 12-pass transporter proteins belonging to the solute carrier family, and their possible immunogenic extracellular regions are very small, production of specific mAb was extremely difficult. In this review, we summarize the successful preparation and characterization of rat mAb immunized against the extracellular domain of type I, type II and type IV membrane oncoproteins fused to green fluorescent protein as an approach using reverse genetics, and also introduce the discovery of cell-death-inducing antibodies as an approach using forward genetics and a strategy to produce reshaped antibodies using mimotope peptides as the immunogen.

Phage display: a powerful technology for the generation of high specificity affinity reagents from alternative immune sources

Antibodies are critical reagents in many fundamental biochemical methods such as affinity chromatography. As our understanding of the proteome becomes more complex, demand is rising for rapidly generated antibodies of higher specificity than ever before. It is therefore surprising that few investigators have moved beyond the classical methods of antibody production in their search for new reagents. Despite their long-standing efficacy, recombinant antibody generation technologies such as phage display are still largely the tools of biotechnology companies or research groups with a direct interest in protein engineering. In this chapter, we discuss the inherent limitations of classical polyclonal and monoclonal antibody generation and highlight an attractive alternative: generating high specificity, high affinity recombinant antibodies from alternative immune sources such as chickens, via phage display.

Generation and characterization of chicken monoclonal antibodies against human LOX-1

Lectin-like oxidized low-density lipoprotein (LDL) receptor-1 (LOX-1) is the major receptor for oxidized LDL (oxLDL), and plays a key role in the pathogenesis of atherosclerosis and cardiovascular diseases. Monoclonal antibodies (mAbs) specific for human LOX-1 (hLOX-1) were generated by a phage display technique using chickens immunized with recombinant hLOX-1 (rhLOX-1). A total of 53 independent scFv clones reactive for rhLOX-1 were obtained. Of the 53 clones, 49 recognized the C-type lectin-like domain (CTL domain), which contributes to the binding of oxLDL. Of these, 45 clones inhibited oxLDL-binding with LOX-1. Furthermore, some of these clones cross-reacted with rabbit, pig and/or mouse LOX-1. For possible application as therapeutic agents in the future, two cross-reactive mAbs were re-constructed as chicken-human chimeric antibodies. The chimeric antibodies showed similar characteristics compared to the original antibodies, and inhibited oxLDL binding to LOX-1 expressed on CHO cells. The results obtained in this study indicate that anti-LOX-1 mAbs might be useful tools for functional analyses and development of therapeutic agents for cardiovascular indications such as atherosclerosis.

Construction of chicken-mouse chimeric antibody and immunogenicity in mice

Chicken monoclonal antibodies are potentially useful for diagnostic research and have clinical applications, as chicken show higher potential for antibody production with mammalian-conserved biological molecules. However, the applications of chicken antibodies are limited because of their immunogenicity in mammals. To overcome this problem, we have constructed a chicken-mouse chimeric antibody containing the chicken variable region and the mouse constant region. This chimeric antibody retained similar binding affinities as the parental chicken antibody. The chimeric antibody was also producible as an ascitic antibody in BALB/c mice. Furthermore, when the chimeric antibody was administered to mice, it did not provoke the mouse anti-chicken antibody response. These results indicate that the chimeric antibody is suitable for application to preclinical mouse studies.

Chicken antibody against a restrictive epitope of prion protein distinguishes normal and abnormal prion proteins

Recently, we reported the application of a recombinant chicken IgY monoclonal antibody, Ab3-15, against mammalian prion protein (PrP), for the diagnosis of bovine spongiform encephalopathy in cattle. In this study, we have characterized a soluble, single-chain variable fragment (scFv) form of this antibody, sphAb3-15 using brain homogenates from mice. This sphAb3-15 antibody recognized denatured forms of both PrP(C) and PrP(Sc), and PrP(Sc) after PK-treatment, on Western blotting. In sandwich ELISAs, on dot blots and by immunoprecipitation, sphAb3-15 efficiently bound to PrP from normal brain homogenates, but weakly bound PrP from scrapie-infected brain homogenates. These results suggest that sphAb3-15 selectively recognizes PrP(C) under native conditions and that the epitope recognized by sphAb3-15 may undergo conformational changes during the conversion of PrP(C) into PrP(Sc).

Development of recombinant chicken IgY from single chain fragment of variable region for diagnosis of BSE

We generated two recombinant chicken IgYs, designated Ab3-15 and Ab4-19, against mammalian prion protein (PrP) from the single chain fragment of variable region (scFv) antibodies. These two antibodies recognized PrP(Sc) from bovine spongiform encephalopathy (BSE) in cattle and were more sensitive than the corresponding scFv antibodies. These antibodies also recognized PrP(Sc) from other scrapie-infected mammals. These results indicate that Ab3-15 and Ab4-19 are useful for diagnosis of BSE as well as other prion diseases.

Generation of antibodies against bovine recombinant prion protein in various strains of mice

Transmissible spongiform encephalopathies (TSEs), also known as prion diseases, belong to a group of neurodegenerative disorders affecting humans and animals. To date, definite diagnosis of prion disease can only be made by analysis of tissue samples for the presence of protease-resistant misfolded prion protein (PrP(Sc)). Monoclonal antibodies (MAbs) to the prion protein provide valuable tools for TSE diagnosis, as well as for basic research on these diseases. In this communication, the development of antibodies against recombinant bovine prion protein (brecPrP) in four strains of mice (BALB/c, ND4, SJL, and NZB/NZW F(1)) is described. Immunization of autoimmunity-prone NZB/NZW F(1) and SJL mice with brecPrP was applied to overcome self-tolerance against the prion protein. ND4 and SJL mice did not develop an immune response to brecPrP. BALB/c mice produced antibody titers of 1:1,000 to 1:1,500 in an enzyme-linked immunosorbent assay (ELISA), while NZB/NZW F(1) mice responded with titers of 1:7,000 to 1:11,000. A panel of 71 anti-brecPrP MAbs recognizing continuous and discontinuous epitopes was established from BALB/c and NZB/NZW F(1) mice. Seven anti-brecPrP MAbs reacted with both the cellular form of PrP and protease K-resistant PrP(Sc) from sheep brain in Western blot assays. The epitope specificity of these MAbs was determined, and applicability to immunohistochemical detection of prions was studied. The MAbs generated will be useful tools in the development of TSE immunochemical diagnosis and for research. This is the first report of the development of anti-PrP MAbs by use of autoimmune NZB/NZW F(1) mice as an alternative approach for the generation of PrP-specific MAbs.

Humanization of chicken monoclonal antibody using phage-display system

We describe a simple method for humanizing chicken monoclonal antibody (mAb). Humanization of mAbs by simple CDR-grafting often results in loss of affinity because certain framework residues of the antibody variable regions can participate in antigen-antibody interaction. In this study, humanization of chicken mAbs was achieved by CDR-grafting, followed by framework fine-tuning using a chicken phage-displayed mAb, phAb4-31, as a model antibody. In order to fine-tune the framework, we used the phage-displayed combinatorial library with permutation of important framework residues. After panning the humanized library, the "most humanized" variants were selected and analyzed for antigen-binding activity. All of these clones retained affinity comparable to the parental chicken mAb. These results suggest that chicken mAbs can easily be humanized, and thus humanized chicken mAbs may be practically applied as therapeutic agents.

Stable production of recombinant chicken antibody in CHO-K1 cell line

When compared with mammalian IgG, chicken IgY is advantageous in terms of cross-reactivity. In this study, two plasmids were constructed for expression of recombinant chicken IgY derived from a chicken hybridoma. The first was for expression of the light (L) chain, and the other was for the heavy (H) chain with a histidine (His) tag at the carboxy-terminal. After transfection of recombinant chicken IgY gene into Chinese hamster ovary cells, a transfectant designated HF33 that secreted the specific antibody was selected. HF33 cells produced recombinant IgY with His tag at 10-15 microg/10(6) cells/24 h. On Western blotting analysis, the recombinant IgY was detected as one band for the H chain and two bands for the L chain. The recombinant IgY was successfully purified in a one-step procedure using a nickel-affinity resin. These results indicate that the present recombinant chicken IgY is useful for further applications.

Inhibition of prion propagation in scrapie-infected mouse neuroblastoma cell lines using mouse monoclonal antibodies against prion protein

We screened six mouse monoclonal antibodies (mAbs) against prion protein (PrP), which were previously established in our laboratory, for inhibitory activity against PrP(Sc)-accumulation in scrapie-infected cell lines and identified two mAbs, 3S9 and 2H9, as possessing this inhibitory activity. mAb 3S9 recognized an epitope including 154th tyrosine in the helix 1 region of PrP, while mAb 2H9 recognized a discontinuous region that included helix 1. In three scrapie-infected cell lines infected with different mouse-adapted scrapie strains, mAb 3S9 strongly inhibited accumulation of PrP(Sc), while mAb 2H9 moderately inhibited accumulation of PrP(Sc), indicating that inhibition of prion propagation by mAbs may be dependent on PrP(Sc) characteristics. Furthermore, mAb 3S9 completely excluded PrP(Sc) from these cell lines. These results suggest that mAbs 3S9 and 2H9 might be useful for clarifying the mechanisms of prion propagation and prevention by PrP-specific antibodies, and for tracing the conversion of PrP(C) to other PrP(Sc) isoforms.

Expression vectors for chicken-human chimeric antibodies

The chicken is a useful animal for preparation of antibodies that are reactive with highly conserved mammalian molecules. For further clinical application of chicken antibodies, we constructed the novel expression vectors for chicken-human chimeric antibodies, pcSLCgamma1, pcSLCgamma4 and pcSLCkappa. These vectors had the following characteristics: (1) any chicken variable regions from hybridomas or a phage display library can be easily introduced; (2) the variable regions are able to be expressed in different immunoglobulin isotypes; and (3) the chimeric antibodies can be highly expressed in either transiently or stably transfected eukaryotic cells (COS-7 and CHO-K1 cells). Western blot analysis of the chimeric antibodies revealed that the expressed products were of the predicted size, structure and specificity. These results indicate that these vectors are useful tools for the chimerization of chicken antibodies.