The overall goal of this proposal is to investigate the origin of diversity of murine anti-PR8 influenza virus immune responses and to evaluate the effects of anti-Id antibodies in regulating these responses and in particular host defense mechanisms, in general. We have already obtained and identified monoclonal antibodies (MAb) specific for various epitopes of hemagglutinin (HA) and the HA2 subunit of PR8 virus, and by immunoprecipitation have characterized MAbs specific for viral neuraminidase (NA) and nucleoprotein (NP). In addition, we are in the process of preparing MAbs against laboratory selected antigenic variants and MAbs specific for viral HA expressed in infected cells. We now propose to extend our observations on the expression of cross-reactive idiotypes (IdX) to these antibodies. In addition,, helper and cytolytic T cell clones specific for viral HA are being prepared. The presence of IdX among MAbs specific for HA and other viral antigens and on the antigen receptor of T cell clones would indicate a common germ line gene from which antibodies and T cell receptors are derived. In further studies, we propose to analyze by Northern blotting under conditions of low and high stringency the hybridization of various germ line gene probes with mRNA from hybridomas secreting MAbs specific for different viral antigens which do or do not express IdXs, and then to sequence the RNA from the hybridomas using VK21 and different VII germ line genes. Furthermore, we will prepare monoclonal anti-Id antibodies to study their ability to alter the immune response against PR8. In these studies, the effects of monoclonal anti-Id antibodies on the immune response in vitro and on the defense reactions of BALB/c mice infected with PR8 influenza virus will be studied. Finally, we will also determine which of these anti-Id MAbs carry the internal image of the HA and thus are able to prime the animal or to evoke a secondary response in a primed animal.