Resistance of sheep to laboratory infestations of the tick, Ixodes ricinus

The development of tick resistance was studied in three one-year-old female Galway cross ewes which received up to three staggered infestations of 100 adult pairs of Ixodes ricinus. Sheep acquired resistance after the first infestation and the ticks showed suppressed feeding and oviposition success. The histology of tick-bite lesions revealed a cellular infiltrate consisting predominantly of neutrophils and this was followed by the infiltration and degranulation of basophils. Mononuclear cells accompanied basophil infiltration and then dominated the cellular infiltrate. Eosinophils infiltrated tick-bite lesions in considerable numbers especially in the tertiary infestation, in which degranulation of mast cells and basophils was also most rapid.     

Response of Trypanosoma congolense in goats to single and double treatment with diminazene aceturate.

Diminazene aceturate is one of a limited number of compounds currently marketed for treatment of trypanosomiasis in cattle, sheep and goats. The pharmacokinetics of the compound in goats suggest that double treatment with diminazene aceturate might enhance the compound's therapeutic activity. A study was therefore conducted in goats using two clones of Trypanosoma congolense, IL 3274 and IL 1180, which were previously shown to be resistant and sensitive, respectively, to single treatment with diminazene aceturate. The results indicated that, as compared to single treatment, double treatment with diminazene aceturate at a dose of 7.2 mg kg-1 bodyweight, at either eight or 24 hour intervals, did not greatly enhance the therapeutic activity of the drug. Furthermore, treatment with the same drug dose eliminated infections with T congolense IL 3274 when treatment was administered 24 hours after infected Glossina morsitans centralis had fed, but failed to do so if treatment was delayed until after goats were detected to be parasitaemic. This suggests that failure of T congolense IL 3274 to respond to treatment with diminazene may not be due to drug resistance per se.     

Cloning and expression of the cDNA for bovine granulocyte-macrophage colony-stimulating factor

A sequence encoding bovine granulocyte-macrophage colony-stimulating factor (GM-CSF) has been identified from a concanavalin A-stimulated bovine lymphocyte cDNA library. This sequence was isolated by hybridization with synthetic oligonucleotide probes based upon the human GM-CSF sequence. This bovine cDNA was engineered for expression and secretion of activity into the periplasmic space of E. coli. Periplasmic extracts contain a 14,500-dalton protein and stimulate colony formation of bovine bone marrow progenitor cells. The predicted protein is 70% homologous with human GM-CSF and 55% homologous with murine GM-CSF. Numerous structural features are conserved among these three proteins, such as location of cysteine residues, glycosylation sites, and overall change. The biological activity of bovine GM-CSF is species specific, since recombinant preparations do not cause proliferation of human or murine bone marrow cells. Similarly, murine GM-CSF does not exhibit activity on cells of bovine or human origin. However, human GM-CSF does stimulate colony formation of bovine bone marrow cells, although the specific activity appears reduced when compared to assays on human cells.     

Barriers as boundaries for metapopulations and demes of Peromyscus leucopus in farm landscapes

Effects of potential barriers (roads and cultivated fields) on both demographic and genetic features of subpopulations of white-footed mice were studied near Ottawa, Canada. Live trapping, colored bait and track registry were used to study animal movements across roads on four 1.44 ha areas each within a small forest bisected by a narrow gravel road. The genetic study was done in 11 other forest fragments separated from each other by cultivated fields. Frequencies of three electrophoretic variants of salivary amylases were established for mice caught in each patch of wood and genetic similarity of subpopulations was calculated. Movements of mice across the roads were very infrequent (quantitative barrier), although movements adjacent to roads were frequent and long enough to cross the roads. Salivary amylase data showed that studied subpopulations were genetically very similar although the sample was intentionally biased toward demographic isolation. Results are discussed in terms of possible hierarchical relationships of metapopulations and genetic demes in the context of landscape ecology, management and conservation practice.     

Some virus diseases of domestic animals in the Sultanate of Oman

Summary Little is known of the occurrence of animal virus diseases in the Sultanate of Oman. This paper reports the results of a countrywide survey carried out in 1978 to establish the prevalence of some important viral pathogens of domestic animals with the dual purpose of providing baselines for future investigations and guidelines for those entrusted with disease control.Foot-and-mouth disease virus type O, previously identified in Oman in 1976, was isolated from clinically affected animals. In addition, virus types A and Asia 1 were isolated from unaffected animals. Serological studies indicated that infection with all 3 types had been widespread. The presence of infectious bovine rhinotracheitis was confirmed by virus isolations and sheep and goat pox, long recognised in Oman, was confirmed by the demonstration of pox particles in dried lesion material.In serological studies antibodies were found to the viruses of peste des petits ruminants, bovine herpes mammillitis, bovine virus diarrhoea, parainfluenza 3 and African horse sickness. There were no significant antibody levels to rinderpest in unvaccinated animals and no antibody to equine infectious anaemia or vesicular stomatitis viruses.

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Algunas Enfermedades Virales En El Sultanato De Oman

Resumen Se conoce muy poco de la ocurrencia de enfermedades virales en el Sultanato de Omán. Este trabajo describe los resultados de un estudio a nivel nacional realizado en 1978, con el fin de establecer la prevalencia de algunos patógenos virales importantes en animales domésticos. Consecuentemen te se establecieron las bases para futuras investigaciones y también los parámetros para investigaciones relacionados con el control de enfermedados.El virus de la fiebre aftosa tipo O, el cual había sido identificado en Omán en 1976, se aisló de animales afectados clínicamente. También el virus tipo A y Asia l se aislaron de animales aparentemente sanos. Los estudios serológicos mostraron sin lugar a dudas, que los 3 virus aftosos tenían amplia distribución. Se confirmó también la presencia del virus de rinotraque itis infecciosa bovina y del virus de la viruela ovina y caprina.En estudios serológicos se encontraton anticuerpos contra los virus de la peste de pequeños rumiantes, mamilitis herpética bovina, diarrea viral bovina, parainfluenza 3 y enfermedad africana de los caballos.No se encontraron niveles significativos de anticuerpos contra el virus de rinderpest, en animales sin vacunar y tampoco contra los virus de la ane mia equina infecciosa y estomatitis vesicular.

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Quelques Maladies A Virus Des Animaux Domestiques Dans Le Sultanat D'Oman

Résumé A l'heure actuelle les connaissances intéressant les maladies animales virales dans le Sultanat d'Oman sont réduites.Ce travail est l'exposé des résultats acquis à l'occasion d'une enquête régionale faite en 1978 pour situer l'existence possible de quelques unes des plus importantes affections virales animales dans le double but d'établir les bases d'un programme de recherches futures et de servir de guide dans l'établissement de mesures de contrôle pour lutter contre elles.Le virus—de type O—de la fièvre aphteuse, déjà identifié en Oman en 1976, a été isolé d'animaux cliniquement malades. En outre, le virus de type A et le virus de type ASIA I ont été également isolés à partir d'animaux apparemment sains. L'étude sérologique a montré que l'infection par ces trois virus est largement répandue. L'existence de la rhinotrachéite bovine a été confirmée par isolement du virus, la cl velée et la variole de la chèvre, déjà connue en Oman depuis longtemps ont été confirmées par l'isolement due virus claveleux à partir de prélèvements de lésions sèches.Au cours d'études sérologiques, des anticorps concernant la peste des petits ruminants, l'herpès mammaire et le virus de la diarrhée hémorragique des bovins, le virus parainfluenza 3 et celui de la peste équine, ont pu être décelés. Il n'a pas été mis en évidence de façon significative, d'anticorps contre le virus de la peste bovine chez les animaux non vaccinés, ni aucun anticorps contre celui de l'anémie infectieuse du cheval pas plus que la stomatite vésiculeuse contagieuse.

     

VI. Animal Transmission Studies

The Cyprus strain of bluetongue virus was successfully transmitted through six passages and the Station strain through one passage in calves. Although the animals developed no visible evidence of infection, viremia as shown by both passage and fluorescent antibody examination of infected foetal bovine kidney culture, and by serological conversion was nevertheless demonstrated. No enhancement of virulence for calves or sheep was shown following bovine passage. A ewe inoculated in late pregnancy with blood drawn from a calf 59 days after its infection, gave birth to a lamb from whose blood the virus was isolated. Significant complement-fixation titres persisted for at least 200 days.