Publications

The Pirbright Institute publication directory contains details of selected publications written by our researchers.

There were a total of 2068 results for your search.
Mercer D K, Iqbal M, Miller P G G, McCarthy A J (1996)

Screening actinomycetes for extracellular peroxidase activity

Applied and Environmental Microbiology 62 (6), 2186-2190

Abstract

A diverse collection of actinomycete strains were screened for production of extracellular peroxidase activity by adapting a chemiluminescence analysis system developed for horseradish peroxidase-based enzyme-linked immunosorbent assay. Extracellular peroxidase activity was found to be common but quantitatively variable, and this rapid and sensitive screening system permitted identification of a small group of high-producing strains, A range of spectrophotometric assays were compared for the measurement of peroxidase activity in concentrated culture supernatants of two selected thermophilic streptomycetes, Of these, the peroxide-dependent oxidation of 2,4-dichlorophenol was identified as the most robust and reproducible assay for quantitative studies.

Abstract

Ligation of T-cell receptor (TCR) causes mature T cells to proliferate or, on re-exposure to antigen, can cause them to die by activation-induced cell death (AICD). In proliferative responses, costimulatory and adhesive interactions are required and activation of protein kinase C (PKC) has been shown to be essential. Whether or not interactions involving costimulatory signals and PKC have a role in facilitating AICD remains unclear. Here we have examined the role of CD28/B7 and leucocyte function associated antigen-1 (LFA-1)/intracellular adhesion molecule (ICAM) mediated interactions in AICD triggered by staphylococcal enterotoxin B (SEE) in murine lymph node T cells. We show that, after a primary proliferative response to SEE, LFA-1/ICAM-2 adhesive interactions can play a part in AICD following SEE rechallenge, while B7 and ICAM-1 mediated interactions are not essential for this process. In addition, using a highly selective PKC inhibitor, Ro31.8425, we show that PKC activation is essential for the regulation of AICD by SEE rechallenge.
Bell-Sakyi L, Koney E B M, Dogbey O, Sumption K J (1996)

Heartwater in Ghana: Implications for control of ticks

Tropical Animal Health and Production 28 (2), S59-S64

Abstract

Heartwater, an often fatal rickettsial disease of domestic ruminants transmitted by Amblyomma variegatum ticks, ranks with the A. variegatum-associated skin disease dermatophilosis as a major constraint to the upgrading of livestock productivity in Ghana. An epidemiological survey, using new diagnostic tests, is being carried out to determine the incidence and distribution of hear water and other tick-borne diseases in Ghanaian cattle, sheep and goats. Preliminary results from a longitudinal survey being carried out at sites in the Greater Accra Region indicating that although the vector ticks and the disease agent are widespread outside urban areas, not all animals are being exposed to heartwater during the first few months of life when an inverse age related resistance allows development of immunity without clinical disease. Thus a susceptible sub-population, at risk from heartwater, can exist even in areas of high tick challenge. The significance of these results for present and future tick and disease control strategies is discussed.

Abstract

We have developed an in vitro system in which Staphylococcal enterotoxin B (SEB) activated murine lymph node T cells undergo apoptosis following a rechallenge with SEB. Approximately 50% of the cell are induced to die following SEB rechallenge and this apoptosis is sensitive to the PKC inhibitor Ro3 1.8425 and cyclosporin A. We have also found that cells, previously activated with SEB, can be induced to undergo apoptosis with an anti-a4 mAb (9C10) in the absence of any hrther exposure to antigen. Apoptosis induced in these cells by anti-a4 mAb is inhibited by cyclosporin A and Ro3 1.8425, in a comparable way to restimulation with SEB. We suggest that VLA-4 acitvation may be an important costimulatory factor in the induction of apoptosis in activated mature T cells. This pathway may represent one of the mechanisms whereby certain integrin-cell/ECM interactions can regulate apoptosis in activated mature T cells.

Abstract

The bacteriophage T7 RNA polymerase gene was integrated into the fowlpox virus genome under the control of the vaccinia virus early/late promoter, P-7.5. The recombinant fowlpox virus, fpEFLT7pol, stably T7 RNA polymerase in avian and mammalian cells, allowing transient expression of transfected genes under the control of the T7 promoter. The recombinant fowlpox virus expressing T7 RNA polymerase offers an alternative to the widely used vaccinia virus vTF7-3, or the recently developed modified vaccinia virus Ankara (MVA) T7 RNA polymerase recombinant, a highly attenuated strain with restricted host-range. Recombinant fowlpox viruses have the advantage that as no infectious virus are produced from mammalian cells they do not have to be used under stringent microbiological safety conditions.

Abstract

A C terminal fragment (SR1) of SPAG-1, a sporozoite surface antigen of Theileria annulata, has been expressed as a fusion protein in the el loop of hepatitis B cope antigen (HBcAg), This recombinant antigen (HBcAg-SR1) is produced in the form of self-assembling polyhedral particles which have been visualised under the electron microscope, Cattle immunised with HBcAg-SR1 produced high titres of neutralising antibodies, A significant T cell response to both the HBcAg and SR1 determinants was observed but evidence of a T suppressor determinant in SR1 was also revealed Immunised cattle showed some evidence of protection to sporozoite challenge as assessed by severity of the disease. The significance of these findings for the development of a sub-unit vaccine against T, annulata is discussed.

Abstract

Embryonated eggs were coinfected with two strains of the coronavirus avian infectious bronchitis virus (IBV), IBV-Beaudette and IBV-M41, to investigate whether recombination between the two strains would occur. Virions were isolated from the allantoic fluid of the coinfected eggs and putative hybrid RNAs were detected by polymerase chain reaction (PCR), using strain-specific oligonucleotides. PCR products, of the expected sizes, were obtained as predicted from potential recombination events between the nucleoprotein (N) gene and the 3'-untranslated region of the two IBV genomes. Sequencing confirmed that they corresponded to hybrid RNAs. Virus produced as a result of the mixed infection was treated with an M41-specific neutralizing monoclonal antibody and passaged in Vero cells, in which IBV-Beaudette, but not IBV-M41, replicated. Hybrid RNA was still detectable after three serial passages. Since no IBV-M41 was detectable this confirmed that infectious recombinant genomes had been produced in the embryonated eggs. These findings not only support the circumstantial evidence, from sequencing studies of IBV field strains, that recombination occurs during replication of IBV and contributes to the diversity of IBV, but also show that coronavirus RNA recombination is not limited to mouse hepatitis virus.
Tchilian E Z, Anderson G, Moore N C, Owen J J, Jenkinson E J (1995)

Effects of activation on the regulation of apoptosis in lymph node T cells

Journal of Cellular Biochemistry Supplement (19B), 325
Publisher’s version:

Abstract

Nitric oxide (NO) was produced when bovine peripheral blood mononuclear cells (PBMC) or purified, adherent PBMC (macrophages) were incubated in vitro with bovine recombinant interferon gamma (Bo rIFN-?). NO was produced by cells from naive, uninfected calves as well as by cells from cattle either infected with or recovered from infection with Theileria annulata or Theileria parva. PBMC of cattle undergoing tropical theileriosis (T. annulata infection) or East Coast fever (T. parva infection) synthesized NO spontaneously in vitro. NO was also induced when PBMC of immune, but not of naive, cattle were cultured with T. annulata macroschizont-infected cell lines. Macrophages alone were not stimulated to produce NO by such infected cells. In vitro establishment of macroschizont-infected cell lines was suppressed either by incubating sporozoites with S-nitroso-N-acetyl-DL-penicillamine (SNAP), a NO releasing molecule, prior to invasion of PBMC or by pulsing developing cultures of trophozoite-infected cells with SNAP. Proliferation of established macroschizont-infected cell lines was not affected by SNAP. Taken together with the well documented roles of NO in neurotransmission, vasodilatation, cell and tissue damage and immunosuppression, the results presented here indicate that NO may not only protect cattle against T. annulata and T. parva but, if produced in excess, play a prominent role in the pathogenesis of tropical theileriosis and East Coast fever.

Abstract

A 7-kb fragment of Streptomyces rochei A2 chromosomal DNA was cloned into pAT153 and shown to confer endoglucanase (Eg1S) activity on Escherichia coli cells. In E. coli clones, the Eg1S was secreted into the periplasm. Deletion analysis revealed that an 827-bp fragment was enough for the enzymatic activity. Sequence analysis showed that the 827-bp fragment codes for the catalytic domain of the enzyme. The complete sequence of the gene (eg1S) is 1149-bp long. A signal peptide, a catalytic domain and a cellulose-binding domain were identified from the nucleotide sequence, and the Eg1S found to belong to the family H of cellulase catalytic domains. These conclusions were substantiated by determination of the N-terminal sequence of the purified protein and zymogram analysis, which revealed protein species with a molecular mass equal to that deduced from the nt sequence analysis.

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