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Anti-idiotypic antibodies: a new approach in prion research.

Colja Venturini A, Bresjanac M, Vranac T, Koren S, Narat M, Popović M, Curin Serbec V - BMC Immunol. (2009)

Bottom Line: Our results demonstrate that it is possible to induce a strong anti-idiotypic immune response against the V5B2 monoclonal antibody in both xenogeneic and syngeneic experimental systems.From the competition seen between polyclonal and monoclonal anti-idiotypic antibodies and the original immunogen, the P1 peptide, and even more importantly, the ultimate target antigen, PrPSc, we conclude that selected antibodies bind to the antigen-combining site of the V5B2 monoclonal antibody and might even resemble the PrPSc-specific epitope.The results of the present study not only provide an example of the successful production of Ab2 monoclonal antibodies based on a well planned strategy for selection, but should also provide a new experimental approach that is applicable to the field of prion diseases.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department for Production of Diagnostic Reagents and Research, Blood Transfusion Centre of Slovenia, Ljubljana, Slovenia. anja.venturini@ztm.si

ABSTRACT

Background: In certain cases, anti-idiotypic antibodies that recognize an antigen-combining site of an antibody can mimic the structure and/or function of certain nominal antigens. This feature makes them particularly useful if conventional experimental approaches fail to fulfil expectations, especially when the molecule of interest is infectious, toxic or difficult to isolate and purify. We suggest the application of an anti-idiotype concept to the field of prion biology, with the aim of evoking a humoral immune response against the pathological isoform of the prion protein (PrPSc). Different ways to induce anti-idiotypic responses were studied in mice and chickens using various forms of V5B2, a PrPSc-specific monoclonal antibody we have described previously.

Results: The preparation of anti-idiotypic monoclonal antibodies was achieved with well-defined strategies of immunization, selection and subsequent characterization. Our results demonstrate that it is possible to induce a strong anti-idiotypic immune response against the V5B2 monoclonal antibody in both xenogeneic and syngeneic experimental systems. From the competition seen between polyclonal and monoclonal anti-idiotypic antibodies and the original immunogen, the P1 peptide, and even more importantly, the ultimate target antigen, PrPSc, we conclude that selected antibodies bind to the antigen-combining site of the V5B2 monoclonal antibody and might even resemble the PrPSc-specific epitope. The involvement of both antigen-combining sites in the interaction between V5B2 and the most promising monoclonal anti-idiotypic antibody was further supported by molecular docking.

Conclusion: The results of the present study not only provide an example of the successful production of Ab2 monoclonal antibodies based on a well planned strategy for selection, but should also provide a new experimental approach that is applicable to the field of prion diseases.

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Related in: MedlinePlus

Ab2 monoclonal antibody selection and the binding competition in ELISA. (A) Positive and negative selection steps. Each column represents the immunoreactivity of individual Ab2 antibodies to the coated positive/negative selection antigens in the selection process. Each Ab2 antibody was used at 1 μg/ml. (B) Ab2 monoclonal antibody competition between the Ab2 antibody and the P1 peptide for the binding to V5B2. Each column represents the mean inhibition of at least three experiments ± standard deviation.
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Figure 3: Ab2 monoclonal antibody selection and the binding competition in ELISA. (A) Positive and negative selection steps. Each column represents the immunoreactivity of individual Ab2 antibodies to the coated positive/negative selection antigens in the selection process. Each Ab2 antibody was used at 1 μg/ml. (B) Ab2 monoclonal antibody competition between the Ab2 antibody and the P1 peptide for the binding to V5B2. Each column represents the mean inhibition of at least three experiments ± standard deviation.

Mentions: The nucleotide and amino-acid sequences of the variable domains of both the light and heavy chains of the anti-P1 antibodies were determined in our previous studies (manuscript in preparation). To compare not only their specificity, but also their structural determinants, the amino-acid identities and similarities between the variable regions of V5B2 and other anti-P1 monoclonal antibodies that were used for negative selection were examined. According to the identity and similarity matrices, the closest resemblance of VL and VH of V5B2 were seen with the C1/1 and K4H5 monoclonal antibodies. In particular, the VL of C1/1 was 85% identical and 91% similar to the VL of V5B2 and the VH of K4H5 was 90% identical and 93% similar to the VH of V5B2, with respect to the primary protein structures. The differences between these antibodies were predominantly restricted to the CDR regions only, as indicated by the frequencies of non-conserved substitutions (NCS) and insertions and deletions (INDEL) inside and outside these regions (Table 2). Still, all selected Ab2 antibodies exclusively recognize Fab V5B2 (Fig. 3A).


Anti-idiotypic antibodies: a new approach in prion research.

Colja Venturini A, Bresjanac M, Vranac T, Koren S, Narat M, Popović M, Curin Serbec V - BMC Immunol. (2009)

Ab2 monoclonal antibody selection and the binding competition in ELISA. (A) Positive and negative selection steps. Each column represents the immunoreactivity of individual Ab2 antibodies to the coated positive/negative selection antigens in the selection process. Each Ab2 antibody was used at 1 μg/ml. (B) Ab2 monoclonal antibody competition between the Ab2 antibody and the P1 peptide for the binding to V5B2. Each column represents the mean inhibition of at least three experiments ± standard deviation.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2666643&req=5

Figure 3: Ab2 monoclonal antibody selection and the binding competition in ELISA. (A) Positive and negative selection steps. Each column represents the immunoreactivity of individual Ab2 antibodies to the coated positive/negative selection antigens in the selection process. Each Ab2 antibody was used at 1 μg/ml. (B) Ab2 monoclonal antibody competition between the Ab2 antibody and the P1 peptide for the binding to V5B2. Each column represents the mean inhibition of at least three experiments ± standard deviation.
Mentions: The nucleotide and amino-acid sequences of the variable domains of both the light and heavy chains of the anti-P1 antibodies were determined in our previous studies (manuscript in preparation). To compare not only their specificity, but also their structural determinants, the amino-acid identities and similarities between the variable regions of V5B2 and other anti-P1 monoclonal antibodies that were used for negative selection were examined. According to the identity and similarity matrices, the closest resemblance of VL and VH of V5B2 were seen with the C1/1 and K4H5 monoclonal antibodies. In particular, the VL of C1/1 was 85% identical and 91% similar to the VL of V5B2 and the VH of K4H5 was 90% identical and 93% similar to the VH of V5B2, with respect to the primary protein structures. The differences between these antibodies were predominantly restricted to the CDR regions only, as indicated by the frequencies of non-conserved substitutions (NCS) and insertions and deletions (INDEL) inside and outside these regions (Table 2). Still, all selected Ab2 antibodies exclusively recognize Fab V5B2 (Fig. 3A).

Bottom Line: Our results demonstrate that it is possible to induce a strong anti-idiotypic immune response against the V5B2 monoclonal antibody in both xenogeneic and syngeneic experimental systems.From the competition seen between polyclonal and monoclonal anti-idiotypic antibodies and the original immunogen, the P1 peptide, and even more importantly, the ultimate target antigen, PrPSc, we conclude that selected antibodies bind to the antigen-combining site of the V5B2 monoclonal antibody and might even resemble the PrPSc-specific epitope.The results of the present study not only provide an example of the successful production of Ab2 monoclonal antibodies based on a well planned strategy for selection, but should also provide a new experimental approach that is applicable to the field of prion diseases.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department for Production of Diagnostic Reagents and Research, Blood Transfusion Centre of Slovenia, Ljubljana, Slovenia. anja.venturini@ztm.si

ABSTRACT

Background: In certain cases, anti-idiotypic antibodies that recognize an antigen-combining site of an antibody can mimic the structure and/or function of certain nominal antigens. This feature makes them particularly useful if conventional experimental approaches fail to fulfil expectations, especially when the molecule of interest is infectious, toxic or difficult to isolate and purify. We suggest the application of an anti-idiotype concept to the field of prion biology, with the aim of evoking a humoral immune response against the pathological isoform of the prion protein (PrPSc). Different ways to induce anti-idiotypic responses were studied in mice and chickens using various forms of V5B2, a PrPSc-specific monoclonal antibody we have described previously.

Results: The preparation of anti-idiotypic monoclonal antibodies was achieved with well-defined strategies of immunization, selection and subsequent characterization. Our results demonstrate that it is possible to induce a strong anti-idiotypic immune response against the V5B2 monoclonal antibody in both xenogeneic and syngeneic experimental systems. From the competition seen between polyclonal and monoclonal anti-idiotypic antibodies and the original immunogen, the P1 peptide, and even more importantly, the ultimate target antigen, PrPSc, we conclude that selected antibodies bind to the antigen-combining site of the V5B2 monoclonal antibody and might even resemble the PrPSc-specific epitope. The involvement of both antigen-combining sites in the interaction between V5B2 and the most promising monoclonal anti-idiotypic antibody was further supported by molecular docking.

Conclusion: The results of the present study not only provide an example of the successful production of Ab2 monoclonal antibodies based on a well planned strategy for selection, but should also provide a new experimental approach that is applicable to the field of prion diseases.

Show MeSH
Related in: MedlinePlus