Induction of an immune response to the porin of Haemophilus influenzae type b by monoclonal anti-idiotypic antibodies

A novel approach to the laboratory diagnosis of Chlamydia trachomatis infections using monoclonal anti-idiotypic antibodies

We have developed a novel enzyme immunoassay (EIA) for the specific detection of Chlamydia trachomatis utilizing a monoclonal anti-idiotypic antibody to an antibody directed against a chlamydia specific epitope on 60 kDa heat-shock protein (HSP60). The basis of the assay is the inhibition of the binding of idiotype to anti-idiotype by antigen present in test samples. Two configurations of the assay were developed: a blocking EIA and a competition EIA. Greater sensitivity was observed using the competition EIA, with the assay detecting purified recombinant HSP60 and purified chlamydia in a concentration-dependent manner from 0.01 to 10 micrograms protein and from 0.5 to 12 micrograms total protein, respectively. The assay is highly specific and offers several potential advantages over currently available EIAs for the detection of this pathogen.

Monoclonal anti-idiotypes for the rapid detection of human cytomegalovirus

A novel enzyme-linked immunosorbent assay (ELISA) was developed for human cytomegalovirus (HCMV) utilizing a monoclonal anti-idiotype specific for CMVB1, an antibody to HCMV. Samples of HCMV were measured by their inhibition of the binding of CMVB1 to anti-idiotype. The ELISA detected HCMV in a concentration-dependent manner from 20 to 0.6 x 10(3) PFU/ml, with 50% inhibition at approx. 3 x 10(3) PFU/ml. These data demonstrate the potential of anti-idiotype antibodies as the basis of simple and rapid diagnostic tests for infectious agents.

Monoclonal anti-idiotypes induce neutralizing antibodies to enterovirus 70 conformational epitopes

Monoclonal antibodies (MAbs) directed against the prototype enterovirus 70 (EV-70) strain J670/71 were generated and characterized in order to produce anti-idiotypic MAbs (MAb2s) for use as surrogate immunogens. Western immunoblot and radioimmunoprecipitation assays suggested that all the MAbs recognize conformational epitopes on the virion surface. An EV-70-neutralizing antibody, MAb/ev-12 (MAb1), was selected for the production of MAb2s. Five MAb2s were selected for their capacities to inhibit the interaction of MAb/ev-12 with EV-70 in dot immunobinding inhibition and immunofluorescence assays. In addition, these five MAb2s inhibited virus neutralization mediated by MAb/ev-12, suggesting that they recognize paratope-associated idiotopes. In competition enzyme immunosorbent assays, none of the five MAb2s recognized other neutralizing and nonneutralizing EV-70-specific MAbs, demonstrating that the MAb2s were specific for private idiotopes. Immunization with each of the MAb2s was carried out for the production of anti-anti-idiotypic antibodies (Ab3). All five MAb2s induced an immune response. Moreover, results suggested that they share idiotopes, since MAb2-MAb/ev-12 binding could be inhibited by homologous as well as heterologous Ab3s. Ab3 sera were shown to possess antibodies capable of immunoprecipitating 35S-labeled viral proteins in the same manner as MAb/ev-12. Nine of 15 mice immunized with MAb2s demonstrated Ab3 neutralizing activity specific for the prototype EV-70 strain, J670/71. The potential application of MAb2s to serve as surrogate immunogens for conformational epitopes is substantiated by the results presented in this report.

Epitope analysis of an immunodominant domain on the P1 protein of Haemophilus influenzae type b using synthetic peptides and anti-idiotypic antibodies

Synthetic peptides, anti-idiotypic antibodies (anti-Id) and human and murine monoclonal antibodies (mAbs) were used to further define a major antigenic domain on the outer membrane P1 protein (OMP) of Haemophilus influenzae type b (Hib). Synthetic peptides were elaborated from the known primary sequences of the P1 protein of prototype Hib strains MinnA (OMP subtype 1H) and 8358 (OMP subtype 6U). By peptide mapping, antibodies are categorized into three groups: A, B and C. A first epitope on the P1 from strain MinnA was identified by the reactivity of one set of murine anti-P1 mAbs with the two overlapping peptides 11H and 13H, corresponding to amino acid residues 384-412 and 400-437, respectively. On the basis of their reactivity with both peptides, these mAbs were designated as group A. Anti-Id obtained from mice immunized with two group A mAbs reacted specifically with all group A mAbs. A second epitope on the same P1 protein was identified by the reactivity of the peptide 13H with another distinct set of murine anti-P1 mAbs assigned to group B. This group of mAbs did not recognize the peptide 11H. Murine anti-Id which were prepared against one group B mAb inhibited the attachment of this mAb to outer membrane preparations, whereas the binding of the other group B mAbs was not affected, suggesting that these mAbs represent a heterologous group of mAbs. The epitope(s) recognized by two human anti-P1 mAbs was (were) distinct from the ones recognized by murine mAbs since no reactivity with the peptides was observed. Similarly, the binding of the two human mAbs to the P1 antigen was not inhibited by anti-Id raised against group A or B mAbs. Interestingly, an epitope on a different P1 protein recovered from strain 8358 was identified by the reactivity of group C murine mAbs with the peptide 13U, which occupies the same position on the P1 protein as 13H but differs from the latter by 10 amino acid residues. Our studies demonstrated the presence of several distinct surface-exposed B-cell epitopes within the antigenic domain which was defined previously on the P1 protein of Hib MinnA. Furthermore, we showed the immunodominance of this region on two different P1 proteins. None of the mAbs, however, had a bacteriolytic or protective activity against Hib strains. We suggest that the surface-exposed immunodominant region on the OMP P1 of Hib do not induce protective antibodies against Hib infection.