Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-12-15T13:04:14Z No. of bitstreams: 1 marinamarquespardini.pdf: 1130678 bytes, checksum: 6b0cced1c7d41de2488ba773203968cd (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-12-15T14:16:47Z (GMT) No. of bitstreams: 1 marinamarquespardini.pdf: 1130678 bytes, checksum: 6b0cced1c7d41de2488ba773203968cd (MD5) / Made available in DSpace on 2016-12-15T14:16:47Z (GMT). No. of bitstreams: 1 marinamarquespardini.pdf: 1130678 bytes, checksum: 6b0cced1c7d41de2488ba773203968cd (MD5) Previous issue date: 2008-06-05 / As infestações por carrapatos em bovinos reduzem a produtividade do gado de corte e leiteiro causando grandes perdas econômicas à pecuária. Os prejuízos acarretam desde debilidade física e transmissão de doenças ao rebanho, como anaplasmose e babesiose, até a morte dos indivíduos mais vulneráveis. Os carrapatos permanecem por longos períodos fixados em seus hospedeiros sendo expostos ao sistema de defesa do bovino, o que provoca inflamação e ativa elementos da resposta imune humoral e celular do hospedeiro. Em contrapartida, componentes imunogênicos da glândula salivar do carrapato modulam a resposta bovina para perfis de citocinas favoráveis à hematofagia. Existem poucos estudos sobre mecanismos imunes que guiam a interação parasito-hospedeiro e determinam o sucesso ou não do parasitismo. Trabalhos recentes apontam para importância de fatores genéticos relacionados à resistência ao carrapato em determinadas raças bovinas, além de estudos que mostram o papel crítico das citocinas na prevenção e progressão de quadros patológicos. O objetivo desse trabalho foi avaliar a resposta imunológica de bovinos infestados artificialmente pelo carrapato Boophilus microplus através de ensaios de proliferação celular e detecção de óxido nítrico (NO) e interferon-gama (IFN-) em células mononucleares do sangue periférico a fim de verificar diferentes níveis de resistência bovina. Seis bovinos mais resistentes e seis mais susceptíveis de uma população F2 de 332 animais, originária do cruzamento de F1 (½ Holandês : ½ Gir), foram selecionados com base na contagem de carrapatos e valor genético. Amostras de sangue foram coletadas nos pontos 0, 5º e 12º dias pós-infestação para cultura de células e estimulação in vitro com antígenos do B. microplus. A proliferação celular e os níveis de NO e IFN- foram avaliados respectivamente pelos métodos de MTT, Griess e ELISA. As células dos animais resistentes (R) tenderam ao aumento de proliferação no 5º dia quando estimuladas com antígenos do carrapato retornando aos níveis iniciais no 12° dia. Já nos animais susceptíveis (S), a estimulação pareceu inibir a proliferação das células no dia 0 e não alterou os índices do 5° e 12° dia. Apesar disso, não houve diferença significativa na proliferação celular entre os grupos R e S. Quando as células obtidas no dia 0 foram cultivadas na ausência de estímulo, os níveis de NO dos animais R tenderam a ser mais altos que dos animais S. A estimulação com antígenos de carrapato pareceu inibir a produção de NO no 5º dia por células de animais R. Também não houve diferença significativa nas produções de NO e de IFN- entre os grupos R e S. Os resultados sugerem que o NO possa ter um papel no início da resposta imune que delineia o mecanismo de resistência ao carrapato, uma vez que as alterações mais importantes foram detectadas até o 5º dia após a infestação. É possível que o mecanismo de resistência esteja associado à regulação negativa da resposta imune a fim de não incitar a modulação desta pelo carrapato, porém sendo eficaz o suficiente para eliminá-lo. A avaliação da resposta imunológica nos primeiros momentos após a fixação do carrapato no couro bovino, bem como um acompanhamento mais detalhado dos pontos temporais da infestação poderia fornecer dados mais conclusivos. / Tick infestations in cattle reduce its beef and dairy productivity causing great economic losses to livestock. The potential damages are physical weakness, transmission of diseases to the herd, as anaplasmosis and babesiosis, and even vulnerable animals deaths. Thus, the tick control has been considered priority in tropical regions worldwide. The ticks remain fixed to their hosts for long periods being exposed to the cattle defense system; it causes inflammation and activates the host’s humoral and cellular immune response. Nevertheless, immunogenic components of the salivary gland of cattle tick modulate the response to profiles of cytokines that promote the blood-feeding. There are few studies approaching immune mechanisms that lead to host-parasite interaction and determine the success or unsuccessful of parasitism. Recent works suggest the importance of genetic factors related to the resistance to ticks in Bos taurus and Bos indicus breeds. In addition, studies show the critical role of cytokines in the prevention and progression of diseases. The aimed of this work was to evaluate the immune response in cattle artificially infested by Boophilus microplus through cell proliferation assays and detection of nitric oxide (NO) and interferon-gamma (IFN-) in peripheral blood mononuclear cells, in order to establish different resistance levels in Girolando breed. Six tick-resistant and six tick-susceptible animals from a F2 population of 332 animals originated from crossing cattle F1 (½ Holstein : ½ Gir) were selected based on the ticks counting and breeding value. Blood samples were collected for cell culture and stimulation in vitro with antigens of B. microplus in the points 0, 5 and 12 days after infestation. The cell proliferation and the NO and IFN- levels were evaluated by MTT, Griess and ELISA, respectively. There was a tendency of increasing proliferation of resistant animals (R) cells in the 5th day when they were stimulated with the tick antigens, returning to initial levels at 12th day. In the other hand, for the susceptible animals (S) the stimulation seemed to inhibit proliferation of cells in day 0, and did not altered the rates of 5th and 12th day. There was no significant difference between the cell proliferation of the groups R and S. When the cells obtained in the day 0 were cultured in the absence of stimulation, the levels of NO of animals R tended to be higher than that of the animals S. The stimulation with tick antigens inhibited the NO production by cells of animals R in the 5th day. In addition, there was no significant difference in NO and IFN- production between the groups R and S. The results suggest that NO may play a role in the early immune response that outlines the mechanism of resistance to ticks, since the most important changes were detected until the 5th day after the infestation. It is possible that the resistance mechanism is associated to the downregulation of immune response in order not to encourage the modulation by the ticks, although being effective enough to eliminate it. An evaluation of the immune response in the first moments after the tick fixation to cattle leather, as well as a more detailed monitoring of the temporal points of the infestation, could provide more conclusive data.

Made available in DSpace on 2014-08-20T14:38:04Z (GMT). No. of bitstreams: 1 dissertacao_alvaro_carlos_menezes_arteche.pdf: 1268541 bytes, checksum: 48cb8939395a534c09b30fdb0ec17ef9 (MD5) Previous issue date: 2011-11-21 / This study analyzed, by reaction to indirect immunofluorescence and individual weighting, the levels of protection and weight-gain in beef calves from birth to the age of eight month, which received two doses of vaccine against tick fever and were maintained free from ticks, compared to naturally infested calves in extensive management conditions with continuous grazing in a rural property situated in the municipality of Santana do Livramento Espinilho / RS. Two groups were randomly gathered, n=30, from which Group I (test) was kept free from ticks from birth to weaning and received two doses of the attenuated, trivalent, refrigerated vaccine against tick fever. Groupe II (control) followed the property s traditional management, which reflects the one used in the region, allowing the tick infestation by the animals. Weight control was accomplished in the first day (d0) and in the last day of the experiment (d180). The serology revealed that 100% of the vaccinated animals presented titles equal to 1:5120 for the three parasites Anaplasma marginale, Babesia bovis e Babesia bigemina (p≤0,025), whereas in the control group the highest titles were 1:2560 in four animals for A. marginale, 1:1280 in four animals for B. bovis and 1:1280 in two animals for B. bigemina (p≤ 0,025). Group I got a mean weight-gain of 30,5 kg more than the control group at the end of the experiment (p≤0,025). The results obtained show that keeping animals free from tick, from birth to weaning, and maintaining them vaccinated against tick fever is safer, more efficient and economically and technically more advantageous than the traditional management system carrapateamento (natural tick infestation). / Avaliaram-se, pela reação de imunofluorescência indireta (RIFI) e de pesagens individuais, os níveis de proteção e ganho de peso de terneiros de corte do nascimento ao desmame com oito meses de idade que receberam duas doses de vacina contra tristeza bovina e foram mantidos livres de carrapatos em comparação a terneiros naturalmente infestados em condições de manejo extensivo com pastoreio contínuo em propriedade rural localizada no município de Santana do Livramento-Espinilho/RS. Formaram-se dois grupos aleatóriamente, n=30, sendo o GRUPO I (teste) mantido livre de carrapatos desde o nascimento até o desmame e com duas doses da vacina atenuada, trivalente e refrigerada contra tristeza bovina. O GRUPO II, controle, seguiu o manejo tradicional da propriedade, que reflete o da região, permitindo que os animais fossem infestados por carrapatos. As pesagens foram realizadas no primeiro dia do experimento (d0) e no último dia do experimento (d180). A sorologia revelou que 100% dos animais vacinados apresentaram títulos maiores ou iguais a 1:5120 para os três parasitos Anaplasma marginale, Babesia bovis e Babesia bigemina (p≤0,025) enquanto que no grupo controle os títulos máximos foram 1:2560 em quatro animais para A. marginale, 1:1280 em quatro animais para B. bovis e 1:1280 em dois animais para B. bigemina. Houve diferença significativa entre os dois grupos (p≤0,025). O grupo I obteve 30,5 Kg a mais de ganho médio de peso que o grupo controle no final do experimento (p≤0,025). Com os resultados obtidos, conclui-se que é mais eficiente, seguro e vantajoso econômica e tecnicamente manter os animais livres de carrapatos, desde o nascimento até o desmame, e vacinados contra tristeza bovina, do que com o manejo tradicional carrapateamento .

Little is understood about off-host behavior and ecology of immature Amblyomma maculatum Koch (Gulf Coast tick). A more complete understanding of this tick is essential to protect human and animal health. My research focused on seasonality and distribution of immatures in Mississippi, potential suitability of some insect and human hosts to larvae, and aspects of nymphal questing behavior. A single larva was collected (third off-host collection reported) when sampling A. maculatum habitat using a novel device. Collection of this larva in November expands the stage’s known seasonality and confirmed a prediction concerning seasonality of larval A. maculatum. Low frequency of immatures (8.3%) confirmed that they’re incredibly difficult to collect off-host. Nymphal collections peaked in March, and known seasonality was extended for both nymphs and adults. I examined known records, elucidating seasonality and distribution of A. maculatum in Mississippi. Either multiple generations per year or diapause are responsible for observed bi-modal distribution of immature collections. Additionally, I compiled the most extensive host record of immature A. maculatum in Mississippi and investigated seasonality patterns using USDA plant hardiness zones. I compiled the most complete record of ticks found on arthropods. Amblyomma americanum and A. maculatum were both confirmed to crawl onto arthropods, giving support to occasional, unintentional dispersal by phoresy. There was no conclusive evidence that larval A. maculatum feed on arthropods, however data supported feeding by larval A. americanum. These results have interesting implications regarding evolution of pathogens/endosymbionts. I provided the first evidence that larval A. maculatum can attach to humans. Rickettsia parkeri, a human pathogen transmitted by this species has recently been shown to be capable of transovarial transmission. Therefore, larval A. maculatum may provide another avenue of transmission. I have demonstrated that A. maculatum are difficult to collect off-host in part because they prefer to quest low to the ground. In choice studies, 5-cm-tall stems were most likely to be occupied by nymphs released into an array of stems. Low vapor pressure deficit encouraged questing, while higher VPD and warmer temperature increased questing height. These results may have implications in understanding host-seeking behavior in other tick species as well.