The overall objective of the research in this proposal is the development of an animal model which mimics the well documented association of DNA virus with graft vs. host disease (GvHD) following clinical allogeneic bone marrow transplantation (BMT). A previously well characterized BMT model between major histocompatibility complex (MHC) matched non-MHC mismatched donor - recipient strains will be utilized as a model for transplants between HLA matched individuals. B10.D2 (H-2d) bone marrow (depleted of T-cells) together with a number of T-cells determined to be insufficient to induce graft vs. host disease (GvHD) will be used as the donor inoculum transplanted into 7.5 Gy. irradiated allogeneic BALB/c (H- 2d) recipients. Murine cytomegalovirus (MCMV) will be administered one week post BMT to these and control, including syngeneic BMT recipients. Recipients who do not survive when receiving both allogeneic T-cells and MCMV will be studied to determine the underlying basis for the 'synergistic' affects of the two pathogenic processes, i.e. GvH and viral infection. Studies are proposed to investigate the properties of infectious MCMV which are necessary with respect to its ability to induce complications following BMT. Inactivated virus and other non-infectious (including viral protein) immunogens which induce potent immune responses will be examined. Experiments are designed to determine the location and presence of infectious virus (plaque assay) and viral antigens (PCR) and compare findings with syngeneic transplant (and normal) recipients. These studies should provide novel findings as to whether the tissue distribution of infectious virus is altered in recipients (i.e. BMT) undergoing allogeneic immune (i.e. GvH) reactions. Examination of clinical signs and histopathological changes (inflammatory tissue infiltrates and tissue damage) will be compared to BMT recipients undergoing GvHD in the absence of MCMV to begin to assess whether the synergistic effect in the model system results in GvHD signs and changes. In order to assess the immunological changes occurring in MCMV infected allogeneic BMT recipients, phenotypic and functional studies will be performed prior to and following viral inoculation. Phenotypic changes which have previously been detected during GvH reactions and disease involving T-cell populations, activation markers and T-cell receptor V- beta usage will be analyzed by flow cytometric analysis. Functional studies will determine viral-induced responses. i.e anti-MCMV antibody, natural killer activity and specific T-cell mediated anti-viral responses. In total, these studies will establish a new model system which will help to elucidate the underlying mechanism whereby pathogens complicate allogeneic BMT.
