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The population dynamics of mixed pathogen infectionsReade, Brian January 1998 (has links)
No description available.
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Avaliação da ocorrência do calicivírus felino e do herpesvírus felino tipo 1 em gatos com gengivite-estomatite crônicas naturalmente infectados pelo vírus da imunodeficiência felina / Occurrence of feline calicivirus and feline herpesvirus type 1 in cats with chronic gingivitis-stomatitis and naturally infected with feline immunodeficiency virusGeraldo Júnior, Carlos Alberto 26 July 2010 (has links)
As alterações inflamatórias que afetam a cavidade oral e a gengiva dos felinos são frequentemente observadas na rotina médica e constituem verdadeiro desafio diagnóstico e terapêutico ao clínico. Denomina-se complexo gengivite-estomatitefaringite felina (CGEF) como sendo uma síndrome onde a apresentação clínica comum é a inflamação grave da gengiva e mucosa oral. A etiopatogênese desta doença não está totalmente elucidada mas acredita-se que seja multifatorial. As viroses têm sido implicadas como agentes etiológicos na patogenia da gengivite-estomatite crônica felina, entretanto, o mecanismo pelo qual as infecções virais participam no desenvolvimento da doença gengival nos animais afetados permanece indeterminado. A hipótese do presente estudo é de que a depleção imunológica induzida pelo lentivírus felino (FIV) aumenta o risco de ocorrência do FCV e do FHV-1 e da estomatite-gengivite em gatos. Para tanto, foram realizados 2 experimentos: o primeiro (A) foi delineado para avaliar a ocorrência do FCV e do FHV-1 na cavidade oral de 58 gatos naturalmente infectados pelo FIV ou não, com e sem gengivite, por meio da reação de polimerização em cadeia (PCR), assim como correlacionar esses achados com as subpopulações de linfócitos T CD4+, CD8+ e da razão CD4+:CD8+ e o segundo (B) foi desenvolvido para avaliar a correlação do FCV e das subpopulações de linfócitos T CD4+ com os diferentes graus de estomatite-gengivite em 35 gatos naturalmente infectados pelo FIV ou não, divididos em 2 grupos. No experimento A, pôde-se determinar que apenas o FCV está relacionado à inflamação gengival, sendo detectado em 88,9% dos gatos com gengivite. Além disso, a infecção pelo FIV promoveu aumento significativo do número de linfócitos T CD8+ (p=0,004) e diminuição da razão CD4+:CD8+ (p<0,001). No experimento B, identificou-se que a infecção pelo FIV está associada à ocorrência da infecção pelo FCV (p=0,011), à presença de gengivite (p=0,022) e ao grau de gengivite (p<0,001), sendo que os gatos infectados pelo FIV foram os que apresentaram graus mais graves de gengivite. Portanto, no grupo dos animais infectados pelo FIV pôde-se observar maior ocorrência do FCV e presença de gengivite. Adicionalmente, o grau de gengivite está diretamente associado à infecção pelo FCV (p<0,001), onde os animais positivos para este vírus apresentaram graus mais graves de gengivite. Pelo presente estudo, pôde-se concluir que a ocorrência da infecção pelo FCV está diretamente associada ao CGEF em felinos e que a ocorrência do FCV foi significativa em animais que apresentaram graus mais graves de gengivite. Além disso, os gatos que apresentaram graus mais graves de gengivite, foram os que apresentaram menores valores de linfócitos T CD4+ e maior ocorrência de infecção pelo FCV. Contudo, não é possível saber se a co-infecção pelo FIV e FCV foi responsável pelo agravamento da gengivite e da condição imunológica dos gatos ou se a disfunção do sistema imune causada pelo FIV predispôs a infecção pelo FCV, levando a piora das lesões orais. / The inflammation that affects the oral cavity and the gingiva of felines are frequently observed in the medical practice and constitute a true diagnosis and therapy challenge to the physician. This condition is referred to as feline gingivitis-stomatitis-pharyngitis complex (FGSC) and it is a syndrome in which the common clinical profile is a severe gingival and oral mucosa inflammation. The etiopathogenesis of this disease is not completely elucidated but it is believed to be multifactorial. The viruses have been involved as etiologic agents in the feline chronic gingivitis-stomatitis pathogeny, however, the mechanism through which the viral infections participate in the development of the gingival disease of the infected animals remains undetermined. The present studys hypothesis is that the immunedepletion induced by the feline lentivirus (FIV) increases the risk of development of FCV and FHV-1, and stomatitis-gingivitis in cats. In order to do so, two experiments were conducted: the first one (A) was designed to evaluate the occurrence of FCV and FHV-1 in the oral cavity of 58 cats naturally infected by FIV or not, with and without gingivitis, through polymerase chain reaction (PCR), and to correlate this findings with the subpopulations of lymphocytes T CD4+, CD8+ and the ratio of CD4+:CD8+; the second one (B) was developed to evaluate the correlation of the FCV and of the subpopulations of lymphocytes T CD4+ with the different degrees of stomatitis-gingivitis in 35 cats naturally infected by the FIV or not, divided into two groups. In the experiment A, it was possible to determine that only the FCV is related to gingivitis, being detected in 88.9% of the cats with gingivitis. Moreover, the FIV infection promoted a significant increase in the number of lymphocytes T CD8+ (p=0.004) and a decrease of the ratio CD4+:CD8+ (p<0.001). In the experiment B, the FIV infection is associated to the occurrence of gingivitis due to the FCV (p=0.011), to the presence of gingivitis (p=0.022), and to the degree of gingivitis (p<0.001), being that the FIV infected cats were the ones that presented the more severe degrees of gingivitis. Therefore, in the group of animals infected by the FIV it was possible to observe a greater occurrence of FCV and the presence of gingivitis. Additionally, the degree of gingivitis is directly related to the FCV infection (p<0.001), where the animals that tested positive for this virus presented more severe degree of gingivitis. From the present study, it was possible to conclude that the occurrence of infection due to the FCV is directly related to FGSC in felines and that the occurrence of FCV was significant in animals that presented more severe degrees of gingivitis. Moreover, the cats that presented more severe degrees of gingivitis were the ones that presented lower values of lymphocytes T CD4+ and greater occurrence of FCV infection. However, it is not possible to know whether the co-infection due to the FIV and the FCV was responsible for the worsening of the gingivitis and of the immune condition of the cats, or if the immune system dysfunction caused by the FIV predisposed the FCV infection, leading to the aggravation of the oral lesions.
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Avaliação da ocorrência do calicivírus felino e do herpesvírus felino tipo 1 em gatos com gengivite-estomatite crônicas naturalmente infectados pelo vírus da imunodeficiência felina / Occurrence of feline calicivirus and feline herpesvirus type 1 in cats with chronic gingivitis-stomatitis and naturally infected with feline immunodeficiency virusCarlos Alberto Geraldo Júnior 26 July 2010 (has links)
As alterações inflamatórias que afetam a cavidade oral e a gengiva dos felinos são frequentemente observadas na rotina médica e constituem verdadeiro desafio diagnóstico e terapêutico ao clínico. Denomina-se complexo gengivite-estomatitefaringite felina (CGEF) como sendo uma síndrome onde a apresentação clínica comum é a inflamação grave da gengiva e mucosa oral. A etiopatogênese desta doença não está totalmente elucidada mas acredita-se que seja multifatorial. As viroses têm sido implicadas como agentes etiológicos na patogenia da gengivite-estomatite crônica felina, entretanto, o mecanismo pelo qual as infecções virais participam no desenvolvimento da doença gengival nos animais afetados permanece indeterminado. A hipótese do presente estudo é de que a depleção imunológica induzida pelo lentivírus felino (FIV) aumenta o risco de ocorrência do FCV e do FHV-1 e da estomatite-gengivite em gatos. Para tanto, foram realizados 2 experimentos: o primeiro (A) foi delineado para avaliar a ocorrência do FCV e do FHV-1 na cavidade oral de 58 gatos naturalmente infectados pelo FIV ou não, com e sem gengivite, por meio da reação de polimerização em cadeia (PCR), assim como correlacionar esses achados com as subpopulações de linfócitos T CD4+, CD8+ e da razão CD4+:CD8+ e o segundo (B) foi desenvolvido para avaliar a correlação do FCV e das subpopulações de linfócitos T CD4+ com os diferentes graus de estomatite-gengivite em 35 gatos naturalmente infectados pelo FIV ou não, divididos em 2 grupos. No experimento A, pôde-se determinar que apenas o FCV está relacionado à inflamação gengival, sendo detectado em 88,9% dos gatos com gengivite. Além disso, a infecção pelo FIV promoveu aumento significativo do número de linfócitos T CD8+ (p=0,004) e diminuição da razão CD4+:CD8+ (p<0,001). No experimento B, identificou-se que a infecção pelo FIV está associada à ocorrência da infecção pelo FCV (p=0,011), à presença de gengivite (p=0,022) e ao grau de gengivite (p<0,001), sendo que os gatos infectados pelo FIV foram os que apresentaram graus mais graves de gengivite. Portanto, no grupo dos animais infectados pelo FIV pôde-se observar maior ocorrência do FCV e presença de gengivite. Adicionalmente, o grau de gengivite está diretamente associado à infecção pelo FCV (p<0,001), onde os animais positivos para este vírus apresentaram graus mais graves de gengivite. Pelo presente estudo, pôde-se concluir que a ocorrência da infecção pelo FCV está diretamente associada ao CGEF em felinos e que a ocorrência do FCV foi significativa em animais que apresentaram graus mais graves de gengivite. Além disso, os gatos que apresentaram graus mais graves de gengivite, foram os que apresentaram menores valores de linfócitos T CD4+ e maior ocorrência de infecção pelo FCV. Contudo, não é possível saber se a co-infecção pelo FIV e FCV foi responsável pelo agravamento da gengivite e da condição imunológica dos gatos ou se a disfunção do sistema imune causada pelo FIV predispôs a infecção pelo FCV, levando a piora das lesões orais. / The inflammation that affects the oral cavity and the gingiva of felines are frequently observed in the medical practice and constitute a true diagnosis and therapy challenge to the physician. This condition is referred to as feline gingivitis-stomatitis-pharyngitis complex (FGSC) and it is a syndrome in which the common clinical profile is a severe gingival and oral mucosa inflammation. The etiopathogenesis of this disease is not completely elucidated but it is believed to be multifactorial. The viruses have been involved as etiologic agents in the feline chronic gingivitis-stomatitis pathogeny, however, the mechanism through which the viral infections participate in the development of the gingival disease of the infected animals remains undetermined. The present studys hypothesis is that the immunedepletion induced by the feline lentivirus (FIV) increases the risk of development of FCV and FHV-1, and stomatitis-gingivitis in cats. In order to do so, two experiments were conducted: the first one (A) was designed to evaluate the occurrence of FCV and FHV-1 in the oral cavity of 58 cats naturally infected by FIV or not, with and without gingivitis, through polymerase chain reaction (PCR), and to correlate this findings with the subpopulations of lymphocytes T CD4+, CD8+ and the ratio of CD4+:CD8+; the second one (B) was developed to evaluate the correlation of the FCV and of the subpopulations of lymphocytes T CD4+ with the different degrees of stomatitis-gingivitis in 35 cats naturally infected by the FIV or not, divided into two groups. In the experiment A, it was possible to determine that only the FCV is related to gingivitis, being detected in 88.9% of the cats with gingivitis. Moreover, the FIV infection promoted a significant increase in the number of lymphocytes T CD8+ (p=0.004) and a decrease of the ratio CD4+:CD8+ (p<0.001). In the experiment B, the FIV infection is associated to the occurrence of gingivitis due to the FCV (p=0.011), to the presence of gingivitis (p=0.022), and to the degree of gingivitis (p<0.001), being that the FIV infected cats were the ones that presented the more severe degrees of gingivitis. Therefore, in the group of animals infected by the FIV it was possible to observe a greater occurrence of FCV and the presence of gingivitis. Additionally, the degree of gingivitis is directly related to the FCV infection (p<0.001), where the animals that tested positive for this virus presented more severe degree of gingivitis. From the present study, it was possible to conclude that the occurrence of infection due to the FCV is directly related to FGSC in felines and that the occurrence of FCV was significant in animals that presented more severe degrees of gingivitis. Moreover, the cats that presented more severe degrees of gingivitis were the ones that presented lower values of lymphocytes T CD4+ and greater occurrence of FCV infection. However, it is not possible to know whether the co-infection due to the FIV and the FCV was responsible for the worsening of the gingivitis and of the immune condition of the cats, or if the immune system dysfunction caused by the FIV predisposed the FCV infection, leading to the aggravation of the oral lesions.
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Untersuchungen zur Tenazität des Norovirus-Surrogates Felines Calicivirus unter dem Einfluss von D/L-Milchsäure, Natriumchlorid und Natriumnitrit sowie zum Verhalten in RohwürstenHeinze, Janin 25 June 2010 (has links) (PDF)
Noroviren gelten neben Rotaviren, Salmonellen und Campylobacter spp. derzeit als Hauptursache infektiöser meldepflichtiger Gastroenteritiden des Menschen in Deutschland. Im Jahr 2008 wurden 212.692 Fälle norovirusbedingter Erkrankungen gemeldet (RKI 2009b). Dabei spielen lebensmittelassozierte Infektionen eine bedeutende Rolle. Besonders rohe und unerhitzt verzehrte Produkte bergen ein Risikopotential. Neben Muscheln, Salaten und Früchten konnten die Erreger auch aus Rohwurstprodukten isoliert werden. Aus mikrobiologischer Sicht sind Rohwürste bereits als Risikoprodukte bekannt. Bisher existieren jedoch nur unzureichende wissenschaftliche Ergebnisse über die Infektionsgefahr durch Viren in Lebensmitteln.
In der vorliegenden Arbeit wurde die Tenazität und Inaktivierungskinetik von Noroviren anhand des Norovirus-Surrogates Felines Calicivirus untersucht. Zunächst wurde in Suspensionsversuchen der Einfluss verschiedener Konzentrationen von D/L-Milchsäure (0,1; 0,15; 0,2; 0,3 und 0,4 %), Natriumchlorid (2; 6; 12 und 20 %) und Natriumnitrit (100; 150 und 200 ppm) über einen Zeitraum von 7 Tagen bei 4 und 20 °C auf das Virus geprüft. Anschließend wurden Versuchsreihen mit artifiziell kontaminierten Rohwürsten durchgeführt.
Der Infektiositätsnachweis erfolgte im Crandell-Reese-Feline-Kidney-Zellkultursystem.
In den Suspensionsversuchen zeigte sich eine konzentrations-, zeit- und temperaturabhängige Wirkung der geprüften Parameter. Signifikante Infektiositätsreduktionen ergaben sich bei 20 °C- Lagerung für D/L-Milchsäure-Konzentrationen ab 0,15 % und bei 4 °C -Lagerung ab 0,3 %. Natriumchlorid bewirkte signifikante Titerreduktionen bei 20 °C-Lagerung ab einer NaCl-Konzentration von 2 %, jedoch nicht unter Kühlbedingungen. Die Reduktion der Virusinfektiosität nahm mit steigender Natriumchlorid- bzw. D/L-Milchsäurekonzentration zu. Für praxisübliche Konzentrationen von Natriumnitrit konnte keine zusätzliche Reduktion der Infektiosität nachgewiesen werden.
In den Versuchsreihen mit kurz- und langgereiften Rohwürsten erwies sich FCV als sehr stabil. In beiden Produkten konnte bis zum Ende des Versuchszeitraumes nach 21 bzw. 56 Tagen infektiöses Virus nachgewiesen werden. Somit könnten Rohwurstprodukte bei einer möglichen Kontamination mit Noroviren zum Zeitpunkt des Verzehrs ein Gesundheitsrisiko für den Verbraucher darstellen. Jedoch zeigten sich auch deutliche temperatur- und zeitabhängige Wirkungen. Ein positiver Einfluss auf die Inaktivierung ist durch die Anwendung von Reife- und Lagerungstemperaturen um 22 °C zu erwarten. Es kam zu einer kontinuierlichen Virustiterreduktion von insgesamt 1,6 log10 TCID50 / g (für kurzgereifte Produkte) bzw. 3,1 log10 TCID50 / g (für langgereifte Produkte). Eine Beeinflussung der Tenazität des Norovirus-Surrogates FCV durch spezifische Herstellungs- und Lagerungsbedingungen ist somit möglich. Insbesondere die gezielte Kombination einzelner Faktoren miteinander, wie NaCl- und Milchsäuregehalt der Rohwurst, in Verbindung mit spezifischer Lagerungstemperatur und –dauer führt zu effektiver Infektiositätsminderung potentiell enthaltener Viren. Die so erzielte Risikominimierung durch Kombination ausgewählter Parameter bedeutet für die Rohwurstproduktion eine sowohl effiziente, als auch praktikable Möglichkeit, die Lebensmittelsicherheit in Bezug auf virale Infektionserreger deutlich zu erhöhen.
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ATIVIDADE ANTIVIRAL DE ÓLEOS ESSENCIAIS E MONOTERPENOS CONTRA VÍRUS DE BOVINOS E FELINOS COMO POTENCIAIS MODELOS PARA VÍRUS HUMANOS / ANTIVIRAL ACTIVITY OF THE ESSENTIAL OILS AND MONOTERPENS AGAINST BOVINE AND FELINE VIRUSES AS POTENTIAL MODELS TO HUMAN VIRUSESKubiça, Thaís Felli 16 March 2012 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The essential oils obtained from plants used as condiments are an important source of compounds with pharmacologic activity. In the present study, the antiviral activity of the essential oil of Ocimum basilicum L. (basil) and from the monoterpens camphor, 1,8-cineol and timol was tested against the bovine viral diarrhea virus (BVDV), while the essential oil of Rosmarinus officinalis L. (rosemary), Lippia graveolens HBK. (mexican oregano) and Thymus vulgaris L. (thyme) were tested against the feline calicivirus (FCV). The colorimetric test MTT ([3- (4.5-dimetilazol-2-il)-2.5-brometo of difeniltetrazolium]) was applied for the measurement of cytotoxicity, and the antiviral tests were performed by the plaque reduction assay. Three different protocols were applied: a) the virus was incubated with the essential oils or compounds before the inoculation into cells (virucidal assay); b) the cells were treated with the essential oils or compounds prior to virus inoculation; or, c) essential oils and compounds were added to the cells after virus inoculation and maintained for 72 hours. The results were expressed as CC50 (cytotoxic concentration to 50% of the cell culture), IC50 (inhibitory concentration to 50%) and SI (selectivity index = CC50/IC50). The best results were evidenced for the monoterpens camphor (SI=13.88) and the 1,8-cineol (IS=9.05) against BVDV. These results were obtained from the virucidal protocol and these compounds showed also the lower toxicicity towards the bovine kidney cells culture (Madin-Darby bovine kidney cells = MDBK) (CC50 = 4420.12 μg/mL and 2996.10 μg/mL, respectively). Regarding to the tests with FCV, the thyme essential oil showed the best results with SI=8.57 for c treatment. The basil essential oil had a moderate action in the a protocol (SI=6.54) and also for the c protocol (SI=6.86). In addition, the basil essential oil exhibited low levels of cytotoxicity towards the Crandel-Reese feline kidney cells (CRFK), with CC50 of 1300.21 μg/mL. In conclusion, the essential oils and monoterpens examined showed different levels of inhibitory activity on diverse moments of the viral infection. The antiviral activity demonstrated by the essential oils and compounds on BVDV and FCV may suggest a possible action on the hepatitis C virus (HCV) and norovirus (NoVs), respectively; since BVDV ande FCV shows several structural and replicative similarities to HCV and NoVs. / Óleos essenciais obtidos de plantas utilizadas como condimentos constituem uma fonte de compostos com promissoras atividades farmacológicas. No presente estudo, a atividade antiviral do óleo essencial de Ocimum basilicum L. (manjericão) e dos monoterpenos cânfora, 1,8-cineol e timol foi testada frente ao vírus da diarréia viral bovina (BVDV), enquanto que os óleos essenciais de Rosmarinus officinalis L. (alecrim), Lippia graveolens HBK. (orégano mexicano) e Thymus vulgaris L. (tomilho) foram testados frente ao calicivírus felino (FCV). O teste colorimétrico com MTT ([3- (4,5-dimetilazol-2-il)-2,5-brometo de difeniltetrazolium]) foi aplicado para a detecção de citotoxicidade, já os testes de atividade antiviral foram realizados através da metodologia de ensaio de redução de placas. Para este, três diferentes protocolos foram aplicados: o vírus foi incubado com os óleos essenciais ou compostos antes da infecção viral (ensaio virucida); as células foram pré tratadas com os óleos essenciais ou compostos antes da inoculação do vírus; ou as células infectadas foram incubadas com esses após as 2 horas de adsorção viral. Os resultados foram expressos como CC50 (concentração citotóxica para 50% do cultivo celular), CI50 (concentração inibitória para 50%) e IS (índice de seletividade = CC50/CI50). Os resultados de atividade frente ao BVDV evidenciaram, no geral, uma boa ação antiviral exercida pelos monoterpenos, sendo que a cânfora (IS=13,88) seguida do 1,8-cineol (IS=9,05) foram os compostos que apresentaram os mais elevados índices de seletividade obtidos no ensaio virucida, bem como a menor toxicidade frente às células de linhagem de rim bovino (Madin-Darby bovine kidney cells = MDBK) (CC50 = 4420,12 μg/ml e 2996,10 μg/ml, respectivamente). Em relação aos testes com FCV, o óleo essencial de tomilho mostrou os melhores resultados, com índice de 8,57 para o tratamento no qual os óleos essenciais foram adicionados às células antes da inoculação viral. Já o óleo essencial de alecrim, além de apresentar uma moderada ação nos ensaios virucida (IS=6,54) e de pós-tratamento (IS=6,86), exibiu baixos níveis de toxicidade em relação às células de linhagem de rim felino (Crandell-Reese feline kidney = CRFK), com CC50 de 1300,21 μg/ml. Dessa forma, conclui-se que os óleos essenciais e monoterpenos em estudo apresentaram algum nível de atividade inibitória em diferentes momentos da infecção viral.
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Des concepts et méthodes associés à la co-circulation des virus dans les populations naturelles d’hôtes à la nécessité d’interdisciplinarité : l’exemple du chat et de ses virus / From concepts and methods associated with viruses’ co-circulation in natural populations to the need for interdisciplinarity : the example of the cat and its virusesHellard, Éléonore 06 April 2012 (has links)
De nombreux parasites circulent dans les populations naturelles. Au sein d’un hôte, souvent pluri-infecté, ils peuvent interagir, augmentant ou réduisant le risque d’infection et les symptômes d’autres pathogènes. L’étude de ces interactions commence seulement dans les populations naturelles. Les enjeux sont cruciaux : détecter les interactions d’intérêt, estimer la probabilité de coinfection, comprendre la cocirculation des parasites. La détection des interactions sur le terrain est compliquée par la nature des données (e.g., présence-absence) et les facteurs confondants créant des associations statistiques (fausses interactions). Ce travail visait à mener une réflexion transversale sur ces interactions et le multiparasitisme, avec des applications à des données sérologiques pour 4 virus félins suivis dans des populations rurales de chats domestiques. De nouvelles méthodes de modélisation dynamique et statistique ont été développées pour prendre en compte les facteurs générant de fausses interactions (effet cumulatif de l’âge, facteurs de risque communs) et évaluer le biais des méthodes classiques. Des synergies entre 3 couples de virus félins ont été révélées. On a aussi identifié des caractéristiques comportementales et physiologiques (modes de vie, niveau de testostérone), qui, en modulant l’exposition et la sensibilité aux pathogènes, génèrent une forte hétérogénéité entre les hôtes. Enfin, une vision intégrative des systèmes hôte-parasites est indispensable pour appréhender la complexité des communautés et évaluer l’impact de la multitude d’hôtes, de parasites et d’interactions sur la coévolution, la conservation des espèces et la gestion des maladies infectieuses / Numerous parasites circulate within natural host populations. Within a host, often pluri-infected, parasites can interact, increasing or decreasing the infection risk and/or symptoms’ severity of other pathogens. Studies of such interactions only start in natural populations. Their stakes are high: detecting interactions of interest, estimating coinfection probabilities and understanding the cocirculation of parasites. The detection of interactions in the field is however complicated by the nature of data (often presence-absence) and the existence of confounding factors that can create statistical associations (false interactions). This work aimed at having a cross-cutting reflection on those interactions and on multiparasitism, with applications on a rich dataset of four feline viruses followed in rural populations of domestic cats. New dynamical and statistical modeling methods were developed to take into account factors generating false interactions (cumulative effect of age, shared risk factors) and evaluate the biases of classical methods. Synergies between three pairs of feline viruses were revealed. In addition, we identified behavioral and physiological factors (e.g., way of life, testosterone levels) that, by modulating exposition and/or susceptibility to pathogens, generate strong heterogeneity between hosts. Finally, a more integrative approach to host-parasites systems is proposed. It now appears necessary if one wants to deal with communities’ complexity and further evaluate the impact of multiple hosts, multiple parasites and their interactions on their coevolution, species conservation and infectious diseases management
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Untersuchungen zur Tenazität des Norovirus-Surrogates Felines Calicivirus unter dem Einfluss von D/L-Milchsäure, Natriumchlorid und Natriumnitrit sowie zum Verhalten in Rohwürsten: Untersuchungen zur Tenazität des Norovirus-Surrogates Felines Calicivirus unter dem Einfluss von D/L-Milchsäure, Natriumchlorid und Natriumnitrit sowie zum Verhalten in RohwürstenHeinze, Janin 16 March 2010 (has links)
Noroviren gelten neben Rotaviren, Salmonellen und Campylobacter spp. derzeit als Hauptursache infektiöser meldepflichtiger Gastroenteritiden des Menschen in Deutschland. Im Jahr 2008 wurden 212.692 Fälle norovirusbedingter Erkrankungen gemeldet (RKI 2009b). Dabei spielen lebensmittelassozierte Infektionen eine bedeutende Rolle. Besonders rohe und unerhitzt verzehrte Produkte bergen ein Risikopotential. Neben Muscheln, Salaten und Früchten konnten die Erreger auch aus Rohwurstprodukten isoliert werden. Aus mikrobiologischer Sicht sind Rohwürste bereits als Risikoprodukte bekannt. Bisher existieren jedoch nur unzureichende wissenschaftliche Ergebnisse über die Infektionsgefahr durch Viren in Lebensmitteln.
In der vorliegenden Arbeit wurde die Tenazität und Inaktivierungskinetik von Noroviren anhand des Norovirus-Surrogates Felines Calicivirus untersucht. Zunächst wurde in Suspensionsversuchen der Einfluss verschiedener Konzentrationen von D/L-Milchsäure (0,1; 0,15; 0,2; 0,3 und 0,4 %), Natriumchlorid (2; 6; 12 und 20 %) und Natriumnitrit (100; 150 und 200 ppm) über einen Zeitraum von 7 Tagen bei 4 und 20 °C auf das Virus geprüft. Anschließend wurden Versuchsreihen mit artifiziell kontaminierten Rohwürsten durchgeführt.
Der Infektiositätsnachweis erfolgte im Crandell-Reese-Feline-Kidney-Zellkultursystem.
In den Suspensionsversuchen zeigte sich eine konzentrations-, zeit- und temperaturabhängige Wirkung der geprüften Parameter. Signifikante Infektiositätsreduktionen ergaben sich bei 20 °C- Lagerung für D/L-Milchsäure-Konzentrationen ab 0,15 % und bei 4 °C -Lagerung ab 0,3 %. Natriumchlorid bewirkte signifikante Titerreduktionen bei 20 °C-Lagerung ab einer NaCl-Konzentration von 2 %, jedoch nicht unter Kühlbedingungen. Die Reduktion der Virusinfektiosität nahm mit steigender Natriumchlorid- bzw. D/L-Milchsäurekonzentration zu. Für praxisübliche Konzentrationen von Natriumnitrit konnte keine zusätzliche Reduktion der Infektiosität nachgewiesen werden.
In den Versuchsreihen mit kurz- und langgereiften Rohwürsten erwies sich FCV als sehr stabil. In beiden Produkten konnte bis zum Ende des Versuchszeitraumes nach 21 bzw. 56 Tagen infektiöses Virus nachgewiesen werden. Somit könnten Rohwurstprodukte bei einer möglichen Kontamination mit Noroviren zum Zeitpunkt des Verzehrs ein Gesundheitsrisiko für den Verbraucher darstellen. Jedoch zeigten sich auch deutliche temperatur- und zeitabhängige Wirkungen. Ein positiver Einfluss auf die Inaktivierung ist durch die Anwendung von Reife- und Lagerungstemperaturen um 22 °C zu erwarten. Es kam zu einer kontinuierlichen Virustiterreduktion von insgesamt 1,6 log10 TCID50 / g (für kurzgereifte Produkte) bzw. 3,1 log10 TCID50 / g (für langgereifte Produkte). Eine Beeinflussung der Tenazität des Norovirus-Surrogates FCV durch spezifische Herstellungs- und Lagerungsbedingungen ist somit möglich. Insbesondere die gezielte Kombination einzelner Faktoren miteinander, wie NaCl- und Milchsäuregehalt der Rohwurst, in Verbindung mit spezifischer Lagerungstemperatur und –dauer führt zu effektiver Infektiositätsminderung potentiell enthaltener Viren. Die so erzielte Risikominimierung durch Kombination ausgewählter Parameter bedeutet für die Rohwurstproduktion eine sowohl effiziente, als auch praktikable Möglichkeit, die Lebensmittelsicherheit in Bezug auf virale Infektionserreger deutlich zu erhöhen.
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