Bovine Leukemia Virus Structural Gene Vectors Are Immunogenic and Lack Pathogenicity in a Rabbit Model

ABSTRACT Infection with a replication-competent bovine leukemia virus structural gene vector (BLV SGV) is an innovative vaccination approach to prevent disease by complex retroviruses. Previously we developed BLV SGV that constitutively expresses BLV gag, pol, and env and related cis-acting sequences but lacks tax, rex, RIII, andGIV and most of the BLV long terminal repeat sequences, including the cis-acting Tax and Rex response elements. The novel SGV virus is replication competent and replicates a selectable vector to a titer similar to that of the parental BLV in cell culture. The overall goal of this study was to test the hypothesis that infection with BLV SGV is nonpathogenic in rabbits. BLV infection of rabbits by inoculation of cell-free BLV or cell-associated BLV typically causes an immunodeficiency-like syndrome and death by 1 year postinfection. We sought to evaluate whether in vivo transfection of BLV provirus recapitulates pathogenic BLV infection and to compare BLV and BLV SGV with respect to infection, immunogenicity, and clinical outcome. Three groups of rabbits were subjected to in vivo transfection with BLV, BLV SGV, or negative control DNA. The results of our 20-month study indicate that in vivo transfection of rabbits with BLV recapitulates the fatal BLV infection produced by cell-free or cell-associated BLV. The BLV-infected rabbits exhibited sudden onset of clinical decline and immunodeficiency-like symptoms that culminated in death. BLV and BLV SGV infected peripheral blood mononuclear cells and induced similar levels of seroconversion to BLV structural proteins. However, BLV SGV exhibited a reduced proviral load and did not trigger the immunodeficiency-like syndrome. These results are consistent with the hypothesis that BLV SGV is infectious and immunogenic and lacks BLV pathogenicity in rabbits, and they support the use of this modified proviral vector delivery system for vaccines against complex retroviruses like BLV.

[1]  K. Boris-Lawrie,et al.  The 5′ RNA Terminus of Spleen Necrosis Virus Contains a Novel Posttranscriptional Control Element That Facilitates Human Immunodeficiency Virus Rev/RRE-Independent Gag Production , 1999, Journal of Virology.

[2]  Michael F. Good,et al.  Vaccine-induced cytotoxic T lymphocytes protect against retroviral challenge , 1998, Nature Medicine.

[3]  L. Ratner,et al.  Selective ablation of human T-cell lymphotropic virus type 1 p12I reduces viral infectivity in vivo. , 1998, Blood.

[4]  M A Nowak,et al.  Quantitation of HIV-1-specific cytotoxic T lymphocytes and plasma load of viral RNA. , 1998, Science.

[5]  A. Burny,et al.  In Vitro and In Vivo Oncogenic Potential of Bovine Leukemia Virus G4 Protein , 1998, Journal of Virology.

[6]  S. Cole,et al.  Reduced viral load and lack of CD4 depletion in SCID-hu mice infected with Rev-independent clones of human immunodeficiency virus type 1 , 1997, Journal of virology.

[7]  F. Ruscetti,et al.  X-I and X-II open reading frames of HTLV-I are not required for virus replication or for immortalization of primary T-cells in vitro. , 1997, Virology.

[8]  K. Shimotohno,et al.  Characterization of peripheral blood T-lymphocytes transduced with HTLV-I Tax mutants with different trans-activating phenotypes , 1997, Oncogene.

[9]  H. Temin,et al.  In vivo study of genetically simplified bovine leukemia virus derivatives that lack tax and rex , 1997, Journal of virology.

[10]  F. Dequiedt,et al.  Both wild-type and strongly attenuated bovine leukemia viruses protect peripheral blood mononuclear cells from apoptosis , 1997, Journal of virology.

[11]  T. Ross,et al.  The tax gene of human T-cell leukemia virus type 2 is essential for transformation of human T lymphocytes , 1996, Journal of virology.

[12]  S. J. Marriott,et al.  Cellular transformation by human T-cell leukemia virus type I. , 1996, FEMS microbiology letters.

[13]  H. Lewin,et al.  The prevalence of proviral bovine leukemia virus in peripheral blood mononuclear cells at two subclinical stages of infection , 1996, Journal of virology.

[14]  I. Chen,et al.  A deletion in the proximal untranslated pX region of human T-cell leukemia virus type II decreases viral replication but not infectivity in vivo. , 1996, Blood.

[15]  G. Franchini.  Molecular mechanisms of human T-cell leukemia/lymphotropic virus type I infection. , 1995, Blood.

[16]  S. Parker,et al.  Cancer gene therapy using plasmid DNA: pharmacokinetic study of DNA following injection in mice. , 1995, Human gene therapy.

[17]  H. Temin,et al.  Genetically simpler bovine leukemia virus derivatives can replicate independently of Tax and Rex , 1995, Journal of virology.

[18]  T. Ley,et al.  Development of leukemia in mice transgenic for the tax gene of human T-cell leukemia virus type I. , 1995, Proceedings of the National Academy of Sciences of the United States of America.

[19]  T. Hope,et al.  The human immunodeficiency virus type 1 Rev protein: a pivotal protein in the viral life cycle. , 1995, Current topics in microbiology and immunology.

[20]  F. Dequiedt,et al.  Attenuation of bovine leukemia virus by deletion of R3 and G4 open reading frames. , 1994, Proceedings of the National Academy of Sciences of the United States of America.

[21]  F. Dequiedt,et al.  In vivo infection of sheep by bovine leukemia virus mutants , 1993, Journal of virology.

[22]  H. Temin.  A proposal for a new approach to a preventive vaccine against human immunodeficiency virus type 1. , 1993, Proceedings of the National Academy of Sciences of the United States of America.

[23]  V. Altanerová,et al.  Envelope glycoprotein gp51 of bovine leukemia virus is differently glycosylated in cells of various species and organ origin. , 1993, Veterinary immunology and immunopathology.

[24]  S. Carpenter,et al.  Identification of alternatively spliced mRNAs encoding potential new regulatory proteins in cattle infected with bovine leukemia virus , 1993, Journal of virology.

[25]  M. Powers,et al.  Activation of bovine leukemia virus transcription in lymphocytes from infected sheep: rapid transition through early to late gene expression , 1992, Journal of virology.

[26]  A. Burny,et al.  In vivo transfection of bovine leukemia provirus into sheep. , 1992, Virology.

[27]  I. Chen,et al.  Phosphorylation regulates RNA binding by the human T-cell leukemia virus Rex protein , 1992, Journal of virology.

[28]  J. Sodroski,et al.  Role of human T-cell leukemia virus type 1 X region proteins in immortalization of primary human lymphocytes in culture , 1992, Journal of virology.

[29]  J. Rovnak,et al.  In vivo transcription of the bovine leukemia virus tax/rex region in normal and neoplastic lymphocytes of cattle and sheep , 1991, Journal of virology.

[30]  I. Chen,et al.  Human T-cell leukemia virus (HTLV) type II Rex protein binds specifically to RNA sequences of the HTLV long terminal repeat but poorly to the human immunodeficiency virus type 1 Rev-responsive element , 1991, Journal of virology.

[31]  D. Grossman,et al.  Humoral immune response of experimentally infected sheep defines two early periods of bovine leukemia virus replication. , 1990, Microbial pathogenesis.

[32]  R. Kettmann,et al.  Cooperation between bovine leukaemia virus transactivator protein and Ha‐ras oncogene product in cellular transformation. , 1990, The EMBO journal.

[33]  R. Reeves,et al.  Persistent infection of rabbits with bovine leukemia virus associated with development of immune dysfunction , 1989, Journal of virology.

[34]  V. Altanerová,et al.  Induction of immune deficiency syndrome in rabbits by bovine leukaemia virus. , 1989, AIDS.

[35]  S. Djilali,et al.  The BLV-induced leukemia--lymphosarcoma complex in sheep. , 1989, Veterinary immunology and immunopathology.

[36]  W C Greene,et al.  Comparative analysis of the HTLV-I Rex and HIV-1 Rev trans-regulatory proteins and their RNA response elements. , 1989, Genes & development.

[37]  R. Kettmann,et al.  Infection of rats with bovine leukaemia virus: establishment of a virus-producing rat cell line. , 1989, The Journal of general virology.

[38]  A. Burny,et al.  Bovine leukaemia: facts and hypotheses derived from the study of an infectious cancer. , 1988, Veterinary microbiology.

[39]  D. Derse.  trans-acting regulation of bovine leukemia virus mRNA processing , 1988, Journal of virology.

[40]  A. Burny,et al.  Experimental transmission of enzootic bovine leukosis to sheep: latency period of the tumoral disease. , 1988, Leukemia.

[41]  A. Burny,et al.  Bovine leukemia: facts and hypotheses derived from the study of an infectious cancer. , 1988, Advances in veterinary science and comparative medicine.

[42]  R. Kettmann,et al.  The bovine leukemia virus p34 is a transactivator protein. , 1987, The EMBO journal.

[43]  D. Derse.  Bovine leukemia virus transcription is controlled by a virus-encoded trans-acting factor and by cis-acting response elements , 1987, Journal of virology.

[44]  R. Kettmann,et al.  Bovine leukemia virus. , 2007, Current topics in microbiology and immunology.

[45]  C. Muscoplat,et al.  Evidence for the replication of bovine leukemia virus in the B lymphocytes. , 1977, American journal of veterinary research.