No description available.

No description available.

No description available.

Ticks (Ixodes (Ceratixodes) uriae] were collected from two seabird colonies on the Isle of May in Scotland. Viruses were isolated from three tick pools, one from ticks collected during 1979 and two from ticks collected during 1981. The viruses replicated in suckling mouse brain, chick embryo fibroblasts, Vero and BHK-21 cells, but not in Xenopus cells. By virtue of their morphology in infected cells, physicochemical properties and reactions in complement fixation tests, they were identified as Kemerovo serogroup viruses belonging to the Great Island Complex (Orbivirus:Reoviridae). Ihe three isolates were distinguished from each other by plaque reduction neutralization tests. After three cycles of plaque purification, the replication of one isolate, Mill Door/79 virus, was examined in Vero and BHK-21 cells. The virus grew to maximum titres 8 to 9 hours post infection (p.i.); over 99% of the infectivity was cell-associated. Twelve virus-specified polypeptides, p141, p93, p69, p65, p53/51, p44, p37, p36, p30, p27, p21 and p20 were identified in infected Vero cell lysates by polyacrylamide gel electrophoresis (PAGE). Similar polypeptide profiles were observed in infected BHK-21 cell lysates. Attempts to purify the virus, by polyethylene glycol-6000 precipitation, resulted in the detection of p93, p69, p53/51, p37, p21 and p20 after PAGE, whereas only four, p93, p69, p53/51 and p37 were detected after attempts at purification using ether extractions. Results using pr~ase inhibitors and partial proteolysis indicated that three virus-specified polypeptides (p36, p30 and p27) may be cleavage products. All virus-specified polypeptides, with the exception of p30 and p20, were labelled in infected cell cultures with both [14c] mannose and [14c] glucosamine.

The aim of this study was to initiate a structural analysis of the capsid polypeptides from several serotypes of bluetongue virus in order to provide insight into the relatedness and possible origins of the different serotypes. Tryptic peptide mapping of ¹²⁵I-labelled group antigen by ion exchange chromatography was used to assess the structural relatedness of seven BTV serotypes from Southern Africa, North America and Australia. Each serotype had several tyrosine containing tryptic peptides which were unique, but approximately 35% of the peptides analyzed were found to be highly conserved between all 7 serotypes. BTV-20 appeared to be closely related to BTV-B and these two serotypes with BTV-4 and BTV-17 appeared to form a closely knit central cluster. / KMBT_363 / Adobe Acrobat 9.53 Paper Capture Plug-in

African horsesickness virus (AHSV) belongs to the Orbivirus genus within the family Reoviridae. AHSV is transmitted to vertebrates by Culicoides midges and causes an acute disease in horses with a high mortality rate. The virion consists of an outer layer composed of proteins VP2 and VP5, which surround an icosahedral core containing two major proteins, VP3 and VP7, three minor proteins, VP1, VP4 and VP6, and ten segments of double-stranded (ds)RNA. The VP7 protein is not only important in maintaining the structural integrity of the virus particles, but has been reported to play a key role in Culicoides cell entry. The phenomenon of RNA interference (RNAi), which can be used to selectively silence homologous genes post-transcriptionally, has revolutionized approaches to study gene function and it is also projected as a potential tool to inhibit virus replication. In mammalian cells, RNAi can be triggered by the direct introduction of 21-23 nucleotide duplexes of small interfering RNA (siRNA) that specifically and potently inhibits endogenous and heterogeneous gene expression. Consequently, the aims of the investigation were to develop RNAi assays whereby the expression of the AHSV-9 VP7 gene could be suppressed in Spodoptera frugiperda insect cells and in mammalian BHK-21 cell culture, as well as to determine whether gene-specific siRNAs may prevent AHSV-9 infection in cell culture. To investigate RNAi-mediated silencing of an enhanced green fluorescent protein (eGFP) in S.frugiperda cells, the bacmid expression system was used. Transfection of the insect cells with an eGFP-specific siRNA prior to infection with the recombinant bacmid, inhibited eGFP protein expression by 75%, as quantified by fluorometry. Although the results suggest that RNAi could potentially be used as tool to study the function of an expressed transgene in insect cells, the lack of complete inhibition, coupled with the highly cytolytic nature of the bacmid, may complicate interpretation of the gene interference results. To investigate whether siRNAs targeting the AHSV-9 VP7 mRNA is able to silence VP7 protein expression, two siRNAs were designed that targeted different regions on the VP7 mRNA. siVP7-336 and siVP7-441, directed at nucleotides 336-356 and 441-461 on the VP7 coding strand, respectively, were chemically synthesized. The effect of these siRNAs on VP7 protein expression was evaluated by cotransfection of BHK-21 cells with the respective siRNAs and the VP7 expression plasmid pCMVVP7- eGFP. The results indicated that siVP7-336 and siVP7-441 inhibited VP7-eGFP expression by 88% and 75%, respectively. BHK-21 cells were subsequently transfected with the respective siRNAs in separate experiments followed by viral infection. The VP7 mRNA quantities were measured by quantitative reverse transcription PCR and the effect of the siRNAs on viral replication was evaluated by plaque assays. Of the two siRNAs, siVP7-336 was found to be the most effective inhibitor of VP7 transcription and suppressed VP7 mRNA by 93%. The exposure of BHK-21 cells to the VP7 genespecific siRNA, siVP7-336, also led to a 84% reduction in progeny virions, as measured by a plaque assay. Taken together, the results demonstrate that siRNA-mediated gene silencing is an efficient approach for reducing the level of VP7 transcripts and proteins and for inhibiting virus propagation. / Dissertation (MSc (Microbiology))--University of Pretoria, 2008. / Microbiology and Plant Pathology / unrestricted

Les invasions biologiques constituent une source de préoccupation majeure du fait des conséquences écologiques, économiques et sanitaires dont elles sont responsables. Déterminer et comprendre les facteurs sous-jacents au succès invasif des espèces envahissantes permet de prédire de nouvelles invasions et de mettre en place des stratégies de contrôle. Culicoides imicola est un vecteur majeur d’Orbivirus d’intérêt vétérinaire incluant le virus de la fièvre catarrhale ovine (FCO). Suite à l’émergence de la FCO dans le bassin méditerranéen, les populations de C. imicola ont été découvertes dans des territoires où elles étaient considérées comme absentes, caractérisant alors cette présence comme la résultante d’une expansion récente de l’espèce. Cette thèse décrit un ensemble de travaux visant à comprendre l’histoire de la colonisation du bassin méditerranéen par C. imicola. L’utilisation d’une approche multi-marqueurs combinant des analyses de génétique de populations, des inférences basées sur la méthode Approximate Bayesian Computation (ABC) et la simulation mathématique de la dispersion atmosphérique de l’espèce, a permis (i) de déterminer l’origine des populations installées au Maghreb et au Moyen Orient et de décrire les routes de colonisation et la chronologie de ces évènements, (ii) de définir les caractéristiques démographiques, évolutives et temporelles de la colonisation du sud de l’Europe et (iii) de caractériser les principaux facteurs expliquant le succès d’expansion géographique des populations installées. Les principaux résultats de cette thèse permettent de proposer des hypothèses pour expliquer le succès de l’installation des populations de C. imicola dans le bassin méditerranéen / Biological invasions are of major concern because of their environmental, economic and health consequences. Determining and understanding the factors underlying the invasion success of species allow predicting potential other biological invasions, and developing vector control strategies. Culicoides imicola is a major vector species of Orbivirus, including the bluetongue virus (BTV) which affects domestic ruminants. Following BT emergence in the Mediterranean basin, C. imicola populations were recorded in territories where the species was considered to be absent, and consequently was described as expanding its range expansion on a short period. This Phd work describes a set of studies aiming at understanding the colonization history of the Mediterranean basin by C. imicola. The use of a multi-loci approach combining population genetics analyses, Approximate Bayesian Computation (ABC) methods and mathematical simulations of the atmospheric dispersion of the species enabled to (i) determine the origin of the established populations in the Maghreb and the Middle-East and describe the routes of colonization and the chronology of such events, (ii) define the demographic, evolutionary and temporal characteristics of south-western Europe colonization and (iii) characterize the main factors explaining the successful range expansion of the established populations. The main results of this thesis allow suggesting hypotheses to explain the successful establishment of C. imicola populations in the Mediterranean basin.

No description available.

Submitted by Socorro Pontes (socorrop@ufersa.edu.br) on 2018-03-19T13:18:49Z No. of bitstreams: 1 VanderlanWSS_TESE.pdf: 2092778 bytes, checksum: 98b36c85f8cc1fcfb1471b0f0ed96da2 (MD5) / Approved for entry into archive by Vanessa Christiane (referencia@ufersa.edu.br) on 2018-06-18T17:01:50Z (GMT) No. of bitstreams: 1 VanderlanWSS_TESE.pdf: 2092778 bytes, checksum: 98b36c85f8cc1fcfb1471b0f0ed96da2 (MD5) / Approved for entry into archive by Vanessa Christiane (referencia@ufersa.edu.br) on 2018-06-18T17:01:57Z (GMT) No. of bitstreams: 1 VanderlanWSS_TESE.pdf: 2092778 bytes, checksum: 98b36c85f8cc1fcfb1471b0f0ed96da2 (MD5) / Made available in DSpace on 2018-06-18T17:02:11Z (GMT). No. of bitstreams: 1 VanderlanWSS_TESE.pdf: 2092778 bytes, checksum: 98b36c85f8cc1fcfb1471b0f0ed96da2 (MD5) Previous issue date: 2018-10-17 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The objective of this work was to determine the epidemiological situation of Bluetongue virus (VLA) infection in sheep herds and to characterize the technological and sanitary aspects in the states of Alagoas (AL), Ceara (CE), Maranhao (MA) , Paraiba (PB), Piaui (PI), Rio Grande do Norte (RN) and Sergipe (SE). For this purpose, 226 farms visited and applied a questionnaire where blood of 2.692 apparently healthy sheep collected. In the present study, a mean prevalence in the northeast of 60,62% (137/226) of positive animal properties and 26,52% (714/2.692) of seropositive sheep. A mean VLA seroprevalence of 33,06% (162/490) in sheep and 82,93% (34/41) in the herds, with at least one positive animal observed in the state of CE. In AL, a seroprevalence of 2,55% was observed (7/275) from the animals and 21.74% (5/23) on farms. In the MA State, 64,13% (177/276) of the animals and 100% (23/23) of the herds were positive. Regarding the RN State, of the 33 properties surveyed, 12 (36,36%) had seroreagents and 16 of the animals studied (4,04%) were positive. In PB State, 2,82% (8/284) of the sheep were seroreagent and of the 24 farms analyzed, 2 (8,33%) presented a positive animal. In the PI, 76,98% (291/378) of the animals and all the properties (32/32) were seroreagent. In SE State, 894% (53/593) of the sheep were positive and 58,0% (29/50) in the sampled herds showed positivity. There was a significant association (p <0,05) regarding the sex, age and degree of kinship of the animals. The acquisition of animals for replacement of the herds (p <0,05) (odds ratio = 5,87, 95% CI = 2,06-16,76, p = 0,001) was identified as a risk factor for BTV in the evaluated states. In this study, the technological and sanitary aspects verified that the breeding system most adopted in the Northeast was the extensive (84,07%), with the activity directed mainly to meat (84,07%). It was verified that the animals were handled in sheepfolds on 68,14% of the properties. The predominance of joint rearing with goats and cattle was too observed. It was verified that 81,42% of the properties had some kind of technical assistance and that only 31,86% of the owners invest in their professional qualification of the employees. The most adopted practices on farms were cleaning the facilities (67,70%) and disposal of animals (80,09%). It was observed that 60,18% of the farms apply some type of vaccine. It was also observed that worm was the biggest problem faced in sheep farms (97,80%), and 96,02% of the producers used vermifugation as the control method. Other health problems frequently reported by the interviewees were Myiasis (93,83%), Caseous Lymphadenitis (89,87%), Pododermatitis (87,67%) and Bronchopneumonia (81,94%). The results obtained in this work indicate that the BTV is present in the sheep herds of the states analyzed and that the exploitation of these in the Northeast has low technological level. It was also verified that the control of the diseases of these states is deficient, which explains, in part, the low productivity of the herds / O escopo deste trabalho foi determinar a situação epidemiológica da infecção pelo vírus da Língua Azul (VLA) e caracterizar os aspectos tecnológicos e sanitários nos rebanhos ovinos dos estados de Alagoas (AL), Ceará (CE), Maranhão (MA), Paraíba (PB), Piauí (PI), Rio Grande do Norte (RN) e Sergipe (SE). Para tanto, foram visitadas e aplicados questionários em 226 propriedades, onde coletou-se o soro de 2.692 ovinos, aparentemente saudáveis. Observou-se uma prevalência média no nordeste de 60,62% (137/226) de propriedades com animais positivos e 26,52% (714/2692) de ovinos soropositivos. No CE houve uma soroprevalência média do VLA de 33,06% (162/490) nos ovinos, e de 82,93% (34/41) nas propriedades com pelo menos um animal positivo. Em AL, foi verificada uma soroprevalência de 2,55% (7/275) nos animais, e de 21,74% (5/23) nos criatórios. Já no MA, 64,13% (177/276) dos animais e 100% (23/23) dos rebanhos foram positivos. Em relação ao RN, das 33 propriedades pesquisadas, 12 (36,36%) tiveram sororreagentes e dos 396 animais estudados, 16 (4,04%) foram positivos. Na PB, 2,82% (8/284) dos ovinos foram sororreagentes e dos 24 rebanhos analisados, 2 (8,33%) apresentaram animal positivo. No PI, 76,98% (291/378) dos animais e todas as propriedades (32/32) foram sororeagentes. Em SE, 8,94% (53/593) dos ovinos foram positivos e nos rebanhos amostrados, 58% (29/50) apresentaram positividade. Houve associação significativa (p<0,05) quanto ao sexo, idade e grau de sangue dos animais. A aquisição (compra) de animais para reposição do plantel (p<0,05) (odds ratio = 5,87; IC 95% = 2,06-16,76; p=0,001) foi identificada como fator de risco para Língua Azul nos estados avaliados. No estudo dos aspectos tecnológicos e sanitários verificou-se que o sistema de criação mais adotado no Nordeste foi o extensivo (84,07%), com a atividade voltada majoritariamente para corte (84,07%), sendo verificado que os animais eram manejados em apriscos em 68,14% das propriedades. Foi observada a predominância de criação conjunta com caprinos e com bovinos. Verificou-se que 81,42% das propriedades possuíam algum tipo de assistência técnica e que apenas 31,86% dos proprietários investiam na qualificação profissional de seus funcionários. As práticas mais adotadas nas fazendas foram a limpeza das instalações (67,70%) e o descarte de animais (80,09%). Quanto à vacinação dos rebanhos, foi observado que 60,18% dos criatórios aplica algum tipo de vacina. Observou-se, também, que a verminose foi o maior problema enfrentado nos criatórios de ovinos (97,80%), sendo que 96,02% dos produtores utilizam como método de controle a vermifugação. Outros problemas sanitários frequentemente relatados pelos entrevistados foram a Miíase (93,83%), Linfadenite Caseosa (89,87%), Pododermatite (87,67%) e Broncopneumonia (81,94%). Os resultados obtidos neste trabalho indicam que o VLA encontra-se presente nos ovinos dos estados analisados e que a exploração destes no Nordeste possui baixo nível tecnológico. Verificou-se, também, que o controle das enfermidades destes estados é deficiente, o que explica, em parte, a baixa produtividade dos rebanhos / 2018-03-19

No description available.