In this study, two monoclonal antibodies, IL-A29 and CC15, are described that identify a novel bovine cell surface marker of 215/300 kDa. The antibodies reacted with a discrete population of resting lymphocytes in peripheral blood which, in young animals, constituted about 25% of the mononuclear cells. Thymus, lymph nodes and spleen contained less than 5% positive cells. These cells were negative for surface Ig, a monocyte/granulocyte marker, and the T lymphocyte antigens CD2, CD6, CD4 and CD8. Immunohistological analyses revealed the presence of IL-A29/CC15-positive lymphocytes in the thymic medulla, in the outer cortex of lymph nodes, in the marginal zones of the spleen, in the dermal and epidermal layers of the skin and in the lamina propria of the gut. The IL-A29/CC15+ cells in unfractionated blood mononuclear cells responded in autologous and allogeneic mixed lymphocyte cultures, and when purified they responded to concanavalin A in the presence of recombinant interleukin 2. These observations suggested this population of cells belonged to the T cell lineage. In order to unambiguously define their lineage, cDNA clones encoding bovine T cell receptor (TcR) and CD3 proteins were isolated. Northern blot analyses of IL-A29/CC15+ cell populations and of established cell lines of various lineages demonstrated that they expressed TcR delta and CD3 gamma, delta and epsilon mRNA: TcR alpha was not expressed, whereas only a truncated form of TcR beta mRNA was present. These results indicate that the IL-A29 and CC15 antibodies define a unique population of CD4-CD8-, gamma/delta T cells.

A cDNA library prepared from lymphocytes of a cow (E98), homozygous at major histocompatibility complex (MHC) loci (BoLA phenotype w10, KN104), was screened with a bovine MHC class I probe. Of the cDNA clones isolated, two, (2.1 and 5.1) were selected and showed divergence at both 5' and 3' termini. E98 DNA was digested with rare-cutter enzymes (Sfi I, Mlu I, Not I, and Cla I) and fragments were size-separated by field inversion gel electrophoresis (FIGE). Hybridization with an entire class I cDNA probe revealed multiple fragments generated by each enzyme. When the 3' untranslated regions (UT) of 2.1 and 5.1 were used as probes, only one fragment was revealed in each digested sample, showing locus specificity of these probes in cattle. Further, DNA of transfected mouse fibroblasts L4 (expressing KN104) and L10 (expressing w10) hybridized to the 3'UT regions of clones 2.1 and 5.1, respectively. Northern blot analysis of the mRNA of the L4 and L10 transfected cells provided further evidence that the cDNA clones 2.1 and 5.1 code for the BoLA-KN104 and BoLA-w10 class I molecules respectively, and thus these represent the products of two different genes. A long range physical mapping of the BoLA-w10 and KN104 genes was performed using FIGE analysis of DNA of an homozygous and an heterozygous animal. This analysis revealed that the BoLA-w10 and KN104 genes are separated by not more than 210 kilobases (kb) and that they are components of a multigene family spanning 1550 kb. As the w10 gene is at the BoLA-A locus we assign the KN104 gene to a B locus.

No abstract

Consensus cis-acting DNA sequences upstream of the immediate early (IE) gene of equid herpesvirus type 1 (EHV-1, strain Ab4) were identified. One copy of the conserved motif TAATGARATTC, which is the binding site for the host cellular factor Oct-1 and herpes simplex virus type 1 (HSV-I) virion protein, VmW65, complex, was identified at positions -630 to -620. Using transient transfections and chloramphenicol acetyltransferase assays the IE promoter of EHV-1 was shown to be trans-activated by VmW65 within the region -685 to +73. Ultraviolet light-inactivated EHV-1 was able to stimulate the expression of the IE gene of EHV-1 as well as HSV-1, indicating that EHV-1 possesses a protein equivalent to VmW65. The ubiquitous equid herpesvirus type 2 (EHV-2), which is not known to be a primary pathogen, was also able to trans-activate the EHV-1 and HSV-1 IE genes. Further work is being performed in order to identify the nature of the EHV-1 and EHV-2 trans-activating proteins.

Three monoclonal antibodies (MoAb), TH97A, CC13, and CC14, define a thymic differentiation antigen in cattle. The antigen is expressed on 50-60% of bovine thymocytes, located mainly in the cortical areas, but is not expressed on peripheral blood mononuclear cells (PBMC). In cryostat sections of lymph node, the antibodies react with large dendritic-like cells in the paracortical regions. They also react with a proportion of the large 'frilly' cells in afferent lymph and with dendritic-like cells in the dermis. The antibodies apparently do not react with cells in the epidermis. Biochemical analysis of the antigen recognized by MoAb TH97A reveals two bands of 44 kDa and 12 kDa under reducing conditions. These polypeptides are distinct from bovine class I major histocompatibility complex molecules reactive with the MoAb w6/32. The tissue distribution of positive cells together with results of biochemical analyses indicate that the antigen recognized by these MoAb is the bovine analogue of the human CD1.