The idiotypic network theory proposed by Jerne (1974), predicts that immunization with a given Ag will generate the production of antibodies against this Ag termed Ab1. This Ab1 can generate a series of anti-Id antibodies against Ab1 termed Ab2. Some of these Ab2 molecules can effectively mimic the three-dimensional structures of external antigens (Ab2[Beta]). Immunization with Ab2[Beta] can lead to the generation of anti-anti-Id antibodies (Ab3) that may recognize the corresponding original Ag identified by the Ab1. Because of this Ab1-like reactivity, the Ab3 is also called Ab1' to indicate that it might differ in its other idiotopes from Ab1. In this study, first we described the generation and characterization of a monoclonal anti-Id (M8G), directed to an Id on monoclonal antibody, 25C. 25C recognized an epitope referred to as glycoprotein 5 (GP5) on the PRRSV. The anti-Id M8G showed the characteristics of an internal image anti-Id. Then, M8G was used to induce an anti-anti-idiotypic antibodies (Ab3) response in murine model. Results of this study showed that the Ab3 possessed Ab1-like (Ab1') properties with specificity for the PRRSV antigen in murine model. To further investigate the Id-anti-Id network in PRRSV infection, BALB/c mice were immunized with swine auto anti-idiotypic antibody (AAb2) and the immune sera (Ab3) were tested for the presence of anti-GP5 antibodies and the expression of the Id of Ab1 specific for GP5 of PRRSV. Based on the results of this study, we concluded that immunization of mine with AAb2 led to the generation of an anti-GP5 antibody response with epitope specificity similar to that of Ab1 (Ab1') in murine model.