The bovine leukemia virus tax gene contains an enhancer sequence.

Transactivator proteins of the bovine leukemia (BLV) and human T-lymphotropic (HTLV) viruses increase long terminal repeat (LTR)-directed viral gene expression and act as immortalizing oncogenes in tissue culture. We report here that the BLV tax gene sequence contains an enhancer-like activity. The X long open reading frame was cloned up-stream of the beta-globin promoter linked to the chloramphenicol acetyltransferase (CAT) gene.

Fusogenic activity of SIV (simian immunodeficiency virus) peptides located in the GP32 NH2 terminal domain.

Peptides of 12, 16 and 24 amino acids length corresponding to the NH2 terminal sequence of SIV gp32 were synthesized. Fluorescence energy transfer studies have shown that those peptides can induce lipid mixing of SUV (Small Unilamellar Vesicles) of various compositions at pH 7.4 and 37 degrees C.

Recombinant vaccinia virus expression of the bovine leukaemia virus envelope gene and protection of immunized sheep against infection.

The bovine leukaemia virus (BLV) envelope gene encoding extracellular glycoprotein gp51 and transmembrane glycoprotein gp30 was cloned into the HA locus of vaccinia virus (Copenhagen strain), downstream of the vaccinia virus early-late promoter, H6, or a triple promoter element consisting of the promoter for the vaccinia virus H6 gene, the promoter for the cowpox virus A-type inclusion (ATI) gene and the promoter for the vaccinia virus HA gene. Inoculation of rabbits or sheep with the recombinant vaccinia virus coding for gp51 and gp30 or an uncleaved env precursor induced neutralizing antibodies to BLV. These antibodies competed with monoclonal antibodies directed against gp51 epitopes F, G, and H previously shown to be of crucial importance for BLV infection.

FACS analysis of bovine leukemia virus (BLV)-infected cell lines with monoclonal antibodies (mAbs) to B cells and to monocytes/macrophages.

The eighteen monoclonal antibodies (mAbs) to B cells and the fourteen mAbs to accessory cells submitted to the workshop were analysed by FACS on three established, bovine leukemia virus (BLV)-infected bovine cell lines. Several mAbs of previously defined specificity were run in parallel. This analysis allowed us to gain further insight on the precise phenotype of those peculiar cells and to cluster the submitted mAbs according to their staining patterns.

The amino acid (157-197) peptide segment of bovine leukemia virus p34tax encompass a leucine-rich globally neutral activation domain.

The specific DNA-binding Gal4 amino-terminal portion (amino acids 1 to 147) was fused to protein segments of BLV transactivator p34tax and tested for its capacity to activate CAT-gene expression in mammalian cells. The p34tax peptide segment 157 to 197 encompasses an activating region. The segment is approximately located in the middle of p34tax and is globally neutral (net charge zero).

Nucleotide sequence of the bovine cyclic-AMP responsive DNA binding protein (CREB2) cDNA.

The bovine cyclic AMP responsive binding protein cDNA (CREB2) was isolated from a lambda-gt11 cDNA expression library using a 32P labelled oligonucleotide corresponding to the 21 bp enhancer sequence present in the BLV LTR. The deduced amino acid sequence revealed that CREB2 contains a leucine zipper structure (residue 295 to 316), a basic amino acid domain (residue 268 to 291) and several potential phosphorylation sites.

Cloning and characterization of a cDNA encoding the bovine insulin-like growth factor binding protein 1 (bIGFBP-1).

This communication reports the complete amino acid sequence (263 amino acids) for the insulin-like growth factor binding protein 1 in the bovine (bIGFBP-1). It is 70% homologous with the equivalent IGFBP-1 in human and rat.

Cloning and characterization of a cDNA encoding the beta-subunit of the bovine insulin-like growth factor-1 receptor.

This communication reports the sequence of the beta-subunit of the insulin-like growth factor-1 receptor. It shares 91.1% homology at the nucleotide level and 97.

Construction of a pigeonpox virus recombinant: expression of the Newcastle disease virus (NDV) fusion glycoprotein and protection of chickens against NDV challenge.

A pigeonpox transfer plasmid was constructed by cloning a 2.5 kb DNA fragment containing the viral thymidine kinase (TK) gene in the psp65 plasmid. The vaccinia virus P11K promoter followed by the NDV fusion (F) gene was inserted in the TK gene.

Sequence comparison between the fusion protein of human and bovine respiratory syncytial viruses.

The nucleotide sequence was determined for the fusion (F) protein-coding mRNA of the bovine respiratory syncytial virus (strain RB 94) and the amino acid sequence of the F protein was deduced for comparison with the sequence of human respiratory syncytial virus subtypes A and B (RSS-2 and 18537 strains). The human and bovine RS virus F proteins (excluding the cleaved signal peptide) share 83 to 84% homology. The greatest divergence occurred within the F2 subunit in the region preceding the cleavage activation site.

Sequence analysis of the pig phosphoglucose isomerase gene promoter region.

A cDNA for pig phosphoglucose isomerase (PGI) was used to isolate genomic clones representing the 5' portion of the corresponding gene. A total of 656 bases of the pig PGI gene were obtained that include 5'-flanking information and part of exon 1. A major transcription start was localized at 74 nucleotides from the translation start.

Orientation into the lipid bilayer of an asymmetric amphipathic helical peptide located at the N-terminus of viral fusion proteins.

The complete amino-acid sequence of viral fusion proteins has been analyzed by the Eisenberg procedure. The region surrounding the cleavage site contains a highly hydrophilic region immediately followed by a membrane-like region. Since the effective cleavage between these two domains seems required to expose the fusogenic domain (located at the N-terminal sequence of the transmembrane like region) which is assumed to interact with the lipid membrane of the host cell, we have focused our analysis on the conformation and mode of insertion of this membrane-like domain in a lipid monolayer.

Production of human monoclonal IgG antibodies reacting with cytomegalovirus (CMV).

A human monoclonal antibody (MoAb) reacting with cytomegalovirus (CMV) has been produced using somatic cell hybridization between Epstein-Barr virus (EBV) infected B lymphocytes and a human-mouse heteromyeloma cell line (SHM-D33). The hybrids were selected in HAT medium containing 5 x 10(-7) ouabain. The median level of Ig production was 5 (0.

Identification and characterization of an enhancer in the coding region of the genome of human immunodeficiency virus type 1.

Transcription of human immunodeficiency virus type 1 (HIV-1) is regulated by cis-acting DNA elements located in the viral long terminal repeats, by viral transregulatory proteins, and by cellular transcription factors acting in concert to modulate the degree of viral expression. We demonstrate that a DNA fragment corresponding to the central portion of the HIV-1 genome exhibits enhancer activity when cloned upstream of the thymidine kinase promoter of herpes simplex virus. This enhancer is inducible by phorbol 12-myristate 13-acetate in HeLa cells and is independent of its position and orientation with respect to the promoter.

Cooperation between bovine leukaemia virus transactivator protein and Ha-ras oncogene product in cellular transformation.

Human T-lymphotropic viruses (HTLV-I and -II) and bovine leukaemia virus (BLV) express transactivator proteins able to increase long terminal repeat (LTR) directed viral expression. These transacting factors are though to be involved in the induction of leukaemia by these viruses. Transfection of BLV transactivator p34tax together with Ha-ras immortalizes and transforms rat embryo fibroblasts, in vitro.

B cells from bovine leukemia virus- (BLV) infected sheep with hematological disorders express the CD5 T cell marker.

Though peripheral blood B cells from healthy sheep were known to be devoid of the CD5 T cell marker, it appears from our study that most B cells from bovine leukemia virus- (BLV) infected sheep with hematological disorders express both the CD5 marker and surface IgM. The possible meaning of this T cell marker expression on B cells from BLV-infected sheep is briefly discussed.

[Evolution of plasma concentrations of testosterone and insulin-like growth factor I during the peripubertal period of cattle catheterized at the hepatic level].

To study endocrinal control of growth development in cattle during puberty, major hepatic vessels were cannulated in 8-13 week old Holstein male calves. In our experimental conditions, chronic hepatic cannulation with "grey" polyurethane catheters was performed for a long period (more than 65 d) without any rejection problems. A physiological washing solution containing at least 5 x 10(5) IU/l heparin-lithium was required to prevent cannula occlusion.

Development of a specific serological test and an efficient subunit vaccine to control bovine leukemia virus infection.

Study of the antigenic structure of the Bovine Leukemia Virus (BLV) envelope glycoprotein gp51 with a panel of mouse monoclonal antibodies (MAbs) has allowed the identification of biologically important determinants directly involved in the infectivity of BLV. Considering the various facts reported in this paper, it follows that diagnostic and vaccination procedures that make use of gp51 in a native configuration constitute a prerequisite for the design of an efficient BLV eradication program. To improve the efficacy of a serological detection test, MAbs have been selected as reagents of choice to develop a competition enzyme-linked immunosorbent assay (cELISA).

Synthesis of functional bovine leukemia virus (BLV) p34tax protein by recombinant baculoviruses.

The bovine leukemia virus (BLV) p34tax (also called tat, p34, XLOR gene product) is a 34-kDa polypeptide encoded in the 3'-terminal region of the virus. This protein is responsible for positive transcriptional trans-activation of promoter elements located within the BLV long-terminal repeat. We introduced the protein-coding region of BLV p34tax into the genome of the baculovirus Autographa californica nuclear polyhedrosis virus.

Effect of pituitary somatotropin injections on plasma insulin-like growth factor I and somatotropin profiles in growing heifers.

Effects of daily injections of pituitary-derived bovine somatotropin (bST) for 6 wk were evaluated in 10 growing heifers and compared to 9 placebo-treated control animals. Bovine somatotropin was injected at 50 micrograms/kg BW each day. Body weight and growth, plasma concentrations of insulin-like growth factor I (IGF-I) and somatotropin (ST) were assessed.

Expression of the bovine leukemia virus transactivator protein p34 by a recombinant vaccinia virus.

In order to characterize the bovine leukemia virus transactivator protein, a recombinant vaccinia virus (v-LOR) containing the BLV post-envelope long open reading frame was constructed. v-LOR was shown to encode a functional protein able to transactivate the BLV long terminal repeat-directed gene expression in the infected cells. The encountered level of transactivation was about one third of that measured in BLV-infected fetal lamb kidney cell lysates.

The GAG precursor of simian immunodeficiency virus assembles into virus-like particles.

To examine the potential role of the GAG precursor polyprotein in morphogenesis and assembly of the simian immunodeficiency virus (SIV), we have expressed the gag gene of SIVMac using a baculovirus expression vector. Infection of insect cells with recombinant virus containing the entire gag gene results in high expression of the GAG precursor protein, Pr57gag. The recombinant protein is myristylated and is released in the culture supernatant in an insoluble particulate form.

Structural and functional characterization of mutants of the bovine leukemia virus transactivator protein p34.

Mutants of the bovine leukemia virus (BLV) transactivator protein (tat, tax, p34, the XLOR gene product) were constructed by site-directed deletions, in-phase linker insertions, or fragment replacements (swapping) among BLV variants. The mutant constructs were transfected into cos cells and transiently expressed. Western blot analysis using a mixture of monoclonal antibodies to wild-type p34 revealed the presence of mutated XLOR gene products in all the mutants tested.