Immune response to bovine viral diarrhea virus induced by anti-idiotypic antibodies

Semiliki forest virus vector carrying the bovine viral diarrhea virus NS3 (p80) cDNA induced immune responses in mice and expressed BVDV protein in mammalian cells

Bovine viral diarrhea virus (BVDV) is a primary pathogen responsible for bovine enteric, respiratory and reproductive failure. A genetic region is encoding the p80 (NS3) of BVDV as the most conserved protein among Pestiviruses. BVDV infection in cattle induces NS3 specific lymphocyte proliferation and humoral responses. To generate a DNA vaccine against BVDV, the gene for BVDV-NADL NS3 was cloned into an eukaryotic expression vector of Semiliki Forest virus (pSFV-1). Quadriceps muscles of BALB/c mice were injected with recombinant DNA generated statistically significant cytotoxic T-lymphocyte activity (CTL) and cell mediated immune (CMI) responses against cytopathic and noncytopathic BVDV. Whereas, the BVDV-NS3 did not generate neutralizing antibodies against BVDVin mice. pSFV-1-NS3 DNA was subjected to in vitro transcription into mRNA. The mRNA was transfected into baby hamster kidney cells (BHK-21) and Madin-Darby bovine kidney cells (MDBK). The recombinant cells were used in the detection of DNA antigen responses by immunological assays. This report establishes the ability of BVDV-NS3 DNA inoculation to induce a strong cellular immune responses in mice.

Expression of a 50 kDa putative receptor for bovine viral diarrhea virus in bovine fetal tissues

The expression of a 50 kDa bovine viral diarrhea virus putative receptor in different bovine fetal tissues from 3-month old fetuses was studied. The receptor expression was examined by immunocytochemical staining and by immunoblotting using antiidiotypic probe (anti-D89). Intense specific staining in enterocytes of the small and large intestines, cortical tubular epithelial cells of kidneys, respiratory epithelial cells of the trachea and esophageal mucosal epithelial cells was observed, demonstrating the strong expression of bovine viral diarrhea virus receptor in the tissues. Weak staining was found in cerebellum, thymus, spleen, liver, cerebrum, and lung tissues; however, heart tissues were negative. Immunoblotting results correlated with the immunoperoxidase staining assays. Thus, the expression levels of the receptor are variable in different tissues. This pattern of expression may provide clues to the pathogenic potential of bovine viral diarrhea virus in the bovine fetus.

Characterization of a putative receptor protein for bovine viral diarrhea virus

In a previous communication, we reported a 50-kDa cell surface protein from Madin-Darby bovine kidney (MDBK) cells as a putative receptor for bovine viral diarrhea virus (BVDV). The present study delineates further characterization of the receptor protein. Protease treatment of cultured MDBK cells adversely affected the receptor, thus abolishing the binding of anti-D89 (BVDV anti-idiotypes) to the cells. However, pretreatment of the cells with either phospholipases or glycosidases did not significantly change the anti-D89 binding to the cells. Additionally, pretreatment of cell monolayers with proteases decreased BVDV attachment and replication in the cells. These results suggested that the receptor for BVDV is a protein in nature, and glycosylation and phosphorylation may not play a direct role in BVDV attachment to cells. The BVDV receptor gradually regenerated on the cell surface after the protease-treated cells were cultured in normal growth medium. Regeneration of the BVDV receptor to a normal level took about 4 h as indicated by flow cytometric analysis and this process was inhibited in the presence of cycloheximide, a protein synthesis inhibitor. The 50-kDa receptor protein purified by electro-elution inhibited BVDV infection in a plaque reduction assay. It also inhibited anti-D89 binding to cells as analyzed by flow cytometry. These data demonstrated the nature of the 50-kDa protein as a specific receptor for BVDV.

A 50 kDa membrane protein from bovine kidney cells is a putative receptor for bovine viral diarrhea virus (BVDV)

A 50 kDa cell surface protein from MDBK cells has been identified as a putative receptor for bovine viral diarrhea virus (BVDV) by using a BVDV specific anti-idiotypic antibody (Anti-D89). This study delineates further characterization of the receptor protein. Protease treatment of cultured MDBK cells adversely affected the receptor thus abolishing the binding of anti-D89 to the cells. However, pretreatment of the cells with either phospholipases or glycosidases did not signficantly alter the extent of anti-D89 binding. Additionally, pretreatment of cell monolayers with proteases decreased BVDV attachment and replication in the cells. These results suggested that the receptor for BVDV is a protein in nature, and glycosylation and phosphorylation of the receptor protein may not play a direct role in BVDV attachment to cells. The BVDV receptor protein gradually regenerated on cells when they were maintained in culture following protease treatment. The purified 50 kDa receptor protein also significantly inhibited BVDV infection in a plaque reduction assay.