Leaching of four different antibacterials from oil- and alginate-coated fish-feed pellets

Leaching of oxytetracycline, oxolinic acid, amoxycillin and the potentiated sulphonamide trimethoprim/ sulphamethoxazote (TMP/SMX) from surface-coated fish-feed pellets, surrounded with either cod liver oil or with calcium-alginate, was investigated. Despite the low water temperature (12°C), losses of amoxycillin, oxytetracycline and TMP/SMX from the oil-coated feed were high with 41.6-67.3% of the drugs lost after 15 min immersion. By contrast, less than 20% of oxolinic acid was lost within the same interval. When calcium-alginate was used, leaching rates were found to be considerably lower. Losses of TMP/SMX. amoxycillin and oxytetracycline ranged from 6.3 to 24.1% within 15 min. Leaching of oxolinic acid was completely prevented by the alginate.     

Characterisation and biological activity of monoclonal antibodies specific for Pasteurella haemolytica A1 capsule and lipopolysaccharide.

Monoclonal antibodies (mAb) against both Pasteurella haemolytica A1 capsule and lipopolysaccharide (LPS) were produced. Anti-capsule mAb reacted with the homologous A1 serotype only, whereas mAb against LPS reacted with P. haemolytica serotypes A2, A5, A8, A12, A14 and A16 but not with 33 bacterial species or rough LPS mutant strains tested. Both capsule and LPS antigens were visualised on the surface of bacteria by immunogold electron microscopy. Neither of the mAbs demonstrated antibody-dependent complement-mediated killing in vitro but both facilitated phagocytosis in vitro.     

Use of ammonium tetrathiomolybdate in the treatment of copper poisoning in sheep

Intravenous administration of ammonium tetrathiomolybdate (three doses on alternate days) appeared to be an effective means of containing the acute phase of copper toxicity in sheep, whether this arose from continuous ingestion of high copper feeds or by injudicious use of copper preparations for the control of copper deficiency. No adverse effects were recorded on lamb numbers, birth weight or survival of lambs born to ewes of normal to low copper status when the treatment was applied at sensitive periods of the reproductive cycle. Decreases in 'available' plasma copper and in liver damage occurred rapidly in response to intravenous tetrathiomolybdate and it is suggested that all animals at risk be treated.     

Characterization of a galectin-like activity from the parasitic nematode, Haemonchus contortus, which modulates ovine eosinophil migration in vitro

The development of eosinophilia is a characteristic feature of helminth infection, although the exact nature of the interaction between eosinophils and parasites remains to be fully defined. Previously, it has been reported that Haemonchus contortus and other nematodes produce eosinophil-specific chemoattractants. This paper describes studies aimed at isolating and identifying the factor(s) responsible. Initial studies showed that soluble extracts of infective larvae (L3) of H. contortus provoked a chemokinetic, rather than chemotactic, response in ovine bone marrow eosinophils in vitro. This activity was inhibited by lactose to a markedly greater extent than sucrose suggesting a galectin-like identity. Lactose affinity chromatography of soluble H. contortus extracts resulted in the isolation a specific bound fraction which retained biological activity. SDS-PAGE gel electrophoresis indicated a single Coomassie-stained band at between 31 and 41kDa. Subsequent, mass spectrometric analysis confirmed that the bound fraction contained a mixture of nematode galectins. The results confirm that H. contortus larvae produce several galectin-like proteins, at least one of which demonstrates eosinophil chemokinetic activity in vitro. The possibility of the parasite-derived factor mimicking the mammalian galectin-9, a known eosinophil chemokine, is discussed.     

Immunoblotting analysis of the reaction of wildebeest, sheep and cattle sera with the structural antigens of alcelaphine herpesvirus-1 (malignant catarrhal fever virus)

Malignant catarrhal fever (MCF) is a disease of cattle and some other ruminants caused by alcelaphine herpesvirus-1 (AHV-1), a virus of wildebeest. The disease also occurs in the absence of wildebeest and is then thought to be caused by a viral agent harboured by the sheep. The structural proteins of AHV-1 have been used as antigens for the immunoblotting analysis of sera from wildebeest, sheep and cattle infected by either AHV-1 or the "sheep-associated" form of the disease. Wildebeest sera showed a uniform response reacting strongly with six polypeptides. Sheep sera also gave positive results but individual sera reacted with varying subsets of the antigens recognized by wildebeest. These results support the earlier suggestion that sheep harbour a herpesvirus related to AHV-1. A bovine serum from a case of MCF caused by AHV-1 also reacted only with a subset of the six wildebeest-reactive polypeptides. Sera from cattle affected with the "sheep-associated" form of the disease gave reactions in only two of the eight cases tested; both positive sera reacted to a few polypeptides only.     

Association between Burkholderia species and arbuscular mycorrhizal fungus spores in soil

Burkholderia pseudomallei, the bacterial cause of the potentially fatal infection known as melioidosis, has a facultative intracellular lifestyle. The intracellular presence of B. pseudomallei in various eukaryotes including arbuscular mycorrhizal fungus (AMF) spores can be demonstrated in vitro. AMF spores were isolated from soils in a melioidosis-endemic area. B. pseudomallei and other Burkholderia spp. DNA was detected in these AMF spore samples, confirming an AMF spore-Burkholderia spp. association in soils which did not yield Burkholderia spp. by culture. This association may explain the environmental persistence, difficulty of recovery and dispersal of Burkholderia spp. in specific environments.     

Expression of afibrobacter succinogenes 1,3-1,4-β-glucanase in Potato (Solanum tuberosum)

The potential development of potato (Solanum tuberosum) as a low-cost eukaryotic system for the production of a commercially valuable enzyme feed supplement was examined. AFibrobacter succinogenes 1,3-1,4-β-glucanase [1,3-1,4-β-D-glucan 4-glucanohydro-lase] gene under the control of the constitutive cauliflower mosaic virus 35S promoter was transferred into the potato cultivar, Desiree. The presence of the β-glucanase cDNA in the plant genome of independent transgenic potato lines was confirmed by PCR and Southern analysis. Northern analysis identified the presence of the β-glucanase mRNA in the leaf tissue of transgenic plants. Furthermore, western analysis showedF. succinogenes β-glucanase accumulations of 0.1% and 0.05% of total soluble protein in the leaves and tubers, respectively. Specific activities of the enzyme in leaves (1693 units mg^-1 β-glucanase) and tubers (2978 units mg^-1 β-glucanase) were comparable to that previously reported for the enzyme produced in bacteria. Lyophilization of leaves had no effect on the specific activity of the β-glucanase, and only marginally influenced the specific activity of the enzyme expressed in tubers. Relative to the control line (cv. Desiree), tuber yields were significantly reduced by 28%-72% in all lines expressing theF. succinogenes β-glucanase, and microscopy showed that expression of the β-glucanase caused changes in cell wall structure. Results of this study demonstrate that a 1,3-1,4-β-glucanase can be expressed in potato tissues, and that potato plants have the potential to be used for the commercial production of heterologous enzymes.     

A qualitative and quantitative assessment of the humoral antibody response of the sheep to orf virus infection

The serological response of naturally and experimentally infected lambs to orf virus infection was analysed using an enzyme-linked immunosorbent assay (ELISA) together with the Western blotting technique. The combination of these two methods permitted a qualitative and quantitative assessment of the response, which revealed considerable variation between animals. Despite this, all post-exposure sera reacted with a polypeptide (molecular weight 40 kilodaltons) which appears to be a component of the surface tubules that are characteristic of the virus.