Research The emphasis of research in our laboratory has been on studying the immune mechanisms in virus diseases of cattle. Investigations on BIV as large animal model system for HIV: The distribution of bovine immunodeficiency virus (BIV) in bovine tissues and cells in infected calves was studied by solution phase polymerase chain reaction (SP-PCR) and PCR in situ hybridization (PCR-ISH). BIV DNA was present predominantly in neural tissues and some lymphoid tissues in BIV-infected calves. In situ hybridization with an internal biotinylated probe detected a specific BIV DNA signals in neurons, microglial cells, lymphocytes, type I and II pneumonocytes, smooth muscle cells and endothelial cells. We conclude that BIV replicates in a variety of bovine tissues in vivo and has a broad cell tropism. Studies on bovine virus diarrhea virus (BVDV): We have identified a 50 kDa cellular surface protein from MDBK cells as a putative receptor for BVDV by using a BVDV specific anti-idiotypic antibody. The presence of BVDV receptor was detected in bovine fetal tissues by immunocytochemical staining and immunoblotting using anti-D89 as a probe. The levels of expression of the BVDV receptor are variable in different tissues and the pattern of expression may provide clues to the pathogenic potential of BVDV in the bovine fetus. A genetic region encoding the P80 (NS3) of BVDV is the most conserved protein among Pesitiviruses. 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). BALB/c mice injected with recombinant DNA generated statistically significant cytotoxic T-lymphocyte activity (CTL) and cell mediated immune (CMI) responses against cytopathic and noncytopathic BVDV. However, the BVDV-NS3 did not generate neutralizing antibodies against BVDV in 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. All cp strains and most ncp BVDV strains significantly inhibited DNA synthesis in PHA-stimulated PBMC; however, only cp BVDV strains inhibited protein synthesis. The interleukin-2 receptor (IL-2R) was used as a marker for the activation status of BVDV-infected PBMC. The expression of IL-2R was preserved in virus-infected cells, even though DNA and protein synthesis was suppressed. These findings suggest a novel mechanism of virus-induced immune suppression in which BVDV inhibits basic metabolic activities of bovine PBMC. The activation signals, however, are maintained. Selected Publications Reddy, J. R., Kwang, J., Varthakavi, V., Lechtenberg, K. F. and Minocha, H. C. 1999. 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. Comparative Immunology, Microbiology & Infectious Diseases 22(4): 231-246. Li, H., Wilkerson, M., Kapil, S., Mosier, D., Shuman, W., Reddy, J. R., Loughin, T. and Minocha, H. C. 1998. The effect of different bovine viral diarrhea virus genotypes and biotypes on the metabolic activity and activation status of bovine peripheral blood mononuclear cells. Viral Immunology 11(4): 233-244. Zhang, S., Troyer, D.L., Zheng, L., Xue, W., Kapil, S., Wood, C., Kennedy, G. and Minocha, H. C. 1997. Detection of bovine immunodeficiency virus in bovine tissues by polymerase chain reaction (PCR) and PCR in situ hybridization. Virology 236: 249-257. Reddy, JR., Kwang, J., Okawamabua, O., Kapil, S., Loughin, T.M., Lechtenbeerg, K.F., Chengappa, M.M., and Minocha, H. C. 1997. Application of recombinant bovine viral diarrhea virus proteins in the diagnosis of bovine viral diarrhea infection in cattle. Vet. Microbiol. 51: 119-133. Xue, W., Zhang, S., and Minocha, H. C. 1997. Characterization of putative receptor protein for BVDV. Vet. Mcrobiol. 51:105-118. Zhang, S., Xue, W., Wood, C., Chen, Q., Kapil S., Minocha, H. C. 1997. Scrosurveillance of bovine immunodeficiency virus in Kansas cattle. J. Vet. Diagn. Invest. 9:347-351. Zhang, S., Wood, C., Xue, W., Krukenberg, S and Minocha, H. C. 1997. Immune suppression in calves with bovine immunodeficiency virus. Clin. Diag. Lab. Immu.232-235. Minocha, H. C., Xue, W., and Reddy, J. 1997. 50 KDa membrane protein from bovine kidney cells is a putative receptor for bovine viral diarrhea virus (BVDV). Adv. Exp. Med. Biol. 412:145-148.
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