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

Abstract

The model pathogen used in the development of the anti-idiotypic antibodies produced in this project was enterovirus-70. This virus is the causative agent of acute hemorrhagic conjunctivitis. In the past twenty-five years, this virus has been responsible for two worldwide pandemics of acute hemorrhagic conjunctivitis. Monoclonal antibodies (MAbs), directed against the prototype enterovirus-70 strain, J670/71, were generated and characterized in order to produce a monoclonal anti-idiotypic antibodies (MAb2s) for use as surrogate immunogens. Radio-immunoprecipitation and western immunoblot assays suggested that all the monoclonal antibodies recognize conformational epitopes on the virion surface. A neutralizing monoclonal antibody, MAb/ev-12, was selected for the production of MAb2s. Five MAb2s were selected for their capacity to inhibit the interaction of MAb/ev-12 with EV-70 in dot immunobinding inhibition and immunofluorescence assays. These five MAb2s also inhibited virus neutralization mediated by MAb/ev-12 suggesting that each recognizes a paratope associated idiotope. In competition enzyme immunosorbent assays, none of the five MAb2s recognized other neutralizing and non-neutralizing enterovirus-70 specific MAbs, thus 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 Ab3. Ab3 sera were shown to possess antibodies capable of immunoprecipitating $\sp{35}$S-labelled viral proteins in the same manner as MAb/ev-12. Nine of fifteen 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.