No description available.

No description available.

No description available.

No description available.

No description available.

<p>The incidence and severity of infectious diseases increases in elderly people (>60 years of age). It is believe that the age-associated changes in the immune system, termed immunosenescence, lead to diminished effectiveness of the immune system leaving the aged susceptible to infectious pathogens and associated diseases. The limited efficacy of the currently available vaccines in elderly populations contribute immensely to the frequency of infectious diseases in the globally growing aging population. As such, the demographic shift warrants the development of effective prophylactic vaccines for the elderly.</p> <p>West Nile virus (WNV) became endemic in North America in 1999, and although it infects people of all ages, the incidence of severe neuroinvasive disease is more prevalent in the elderly. I hypothesized that the susceptibility of the elderly towards severe WNV disease is a consequence of aberrant immune function, and specifically lack of functional virus-specific CD8+ T cells. Contrary to my hypothesis, I found that the magnitude, breadth and functionality of WNV-specific CD8+ T cells were not different between the age cohorts. These results argue that advanced age does not limit the development of functional CD8+ T cell responses following primary infections with an acute virus. Furthermore, the aged members of our cohort maintained functional CD8+ T cells to cytomegalovirus (CMV) and Epstein-Barr virus (EBV), common persistent viruses.</p> <p>Collectively, my results demonstrate that development of vaccines designed to elicit CD8+ T cell immunity may be warranted for elderly individuals and perhaps live vectors should be considered for this population.</p> / Doctor of Philosophy (Medical Science)

WN virus has spread for over 60 years creating endemic and epidemic areas throughout Africa, Asia, and Europe, affecting human, bird, and equine populations. Its 1999 appearance in New York shows the ability of the virus to cross barriers and travel great distances, emerging into new territories previously free of infection. Spreading much faster than expected, WN virus has infected thousands of birds, equine, and humans throughout the conterminous United States (US). Case and serological studies performed in the Eastern hemisphere prior to 1999 offer detailed descriptions of endemic and epidemic locations in regards to geography, land cover, land use, population, climate, and weather patterns. Based on the severity of WN activity within each study area, the patterns associated with these environmental factors allow for the identification of values associated with different levels of risk. We can then model the landscape of the disease within the US and identify areas of high risk for infection. State and county public health officials can use this model as a decision-making tool to allocate funding for disease prevention and control. Dynamic factors associated with increased transmission, such as above average temperature and precipitation, can be closely monitored and measures of prevention can be implemented when necessary. In turn, detailed information from higher resolution analyses can be documented to an online GIS (Geographic Information System) that would contribute to a global collaboration on outbreaks and prevention of disease. / Master of Science

Field studies were conducted in southwestern Virginia to determine the bionomics and ovipositional preferences of Culex restuans Theobald and Culex pipiens Linnaeus using ovitraps and gravid traps. Both species have been implicated as enzootic and epizootic vectors of West Nile virus (WNV) and these studies provide information on the relative abundance of gravid mosquitoes. Ovitraps were used in the summers of 2002 and 2003 to measure the oviposition activity of Culex mosquitoes, mainly Cx. restuans and Cx. pipiens. In 2002, 1,345 egg rafts were collected from 5 traps set at different locations in the New River Valley (NRV). Cx. restuans constituted 93.2% of the catch; the remainder was Cx. pipiens (6.7%) and Cx. salinarius (<1%). In 2003, 4 ovitraps were placed at each of 6 locations in the NRV. Of 9,794 egg rafts collected, Cx. restuans comprised 92.8%, Cx. pipiens 6.5%, and Cx. salinarius <1%. Oviposition patterns were similar in both years. Cx. restuans oviposition was detected about mid-May, and raft numbers were highest in late June and the middle of July and then showed a steady decline throughout the remainder of each season. Cx. pipiens oviposition activity began later in the season and gradually increased, reaching its peak in August. Although the number of egg rafts of Cx. restuans decreased in August and September while the number of Cx. pipiens egg rafts increased, a crossover in the relative abundance of the two species never occurred. In 2003, the attractiveness of four infusions (cow manure, straw, grass, and rabbit chow) were compared in oviposition traps. For Cx. restuans, the manure infusions collected more egg rafts than the other three infusions for the first four weeks, with two of the weeks showing significance. During week 1, the manure infusions collected significantly more egg rafts than straw (P<0.01), grass (P<0.01), and rabbit (P<0.001). During week 2, manure collected more than grass (P<0.05) and rabbit (P<0.01). The straw and grass infusions yielded the most egg rafts after week 2, and only three weeks showed any significance. When traps began to collect Cx. pipiens, the majority were collected in the straw and grass infusions. During week 6, the hay infusions had significantly more egg rafts when compared to manure (P<0.001) and rabbit infusions (P<0.001) and the grass infusions had significantly more when compared to manure (P<0.05) and rabbit (P<0.01). Week 9 also showed significance when the hay infusions collected significantly more egg rafts than manure and rabbit (P<0.01 and P<0.01, respectively). The attractiveness of the cow manure and straw infusions were also compared in gravid traps. Because it is difficult to accurately discriminate between Cx. pipiens and Cx. restuans that have been collected as adults in gravid traps, these collections were combined into Culex. More Culex mosquitoes were collected in the manure infusions for the first two weeks (P<0.05). No significant differences were found between the numbers of mosquitoes captured in the traps baited with the different infusions after the second week. The shift observed in oviposition preference for both types of traps may have been due to cooler temperatures in the early part of the season. The straw infusions were aged outdoors for 3 days prior to use, and a sufficient incubation temperature to generate the bacteria producing the attractant chemicals may not have been attained. In addition, the manure lagoon had been drawn down and the consistency of the remaining manure became much drier by this time. No chemicals were ever added to the lagoon, but the draw down may have affected the attractiveness of the manure. / Master of Science

The main goal of thesis is to explore the changing global epidemiological situation depending on climate changes and to map trends of changes in epidemiological situation. A sub-objective is to find out if there are differences in the geographical distribution of the incidence of West Nile Virus (WNV) in the period 2004-2014 next to map surveillance, to propose options for improving prevention in a changing geographical distribution, to describe cases of the diseases reported in the Czech Republic, to determine whether in the Pilsen and Budweis medical facilities are routinely investigating also on detection of WNV infection and finally to chart the WNV infection rate and its causes in horse breeding. Influence of climate change on distribution of WNV can be very well observed. This change is mainly due to settlement of new countries by the originator and also reservoirs which are moving further to the north or south becouse of climate. Distribution of WNV to the new countries is also supported by the changing of landscape, mainly due to the changing climate. The changes of migration routes of migratory birds which are also affected by climate changes have also the effect on changing geographic distribution. The globalization of the world is also mostly responsible for change of distribution. The change of epidemiological situation is given by that the virus attacks organisms that did not meet with virus until now. Therefore, there is a change in the clinical picture and more serious forms of the disease appear in the greater degree than before. Official statistics numbers of diseases in the EU in 2008-2012 published by the ECDC revealed that number of illnesses depends on the global climate changes and also on the climate in a current year. Data for year 2010 clearly reveal how big influence extreme temperatures have on the number of reported illnesses. With regard to prevention in the Czech Republic, as a main step was to designed the informing of tourists. The substantial part of the repressive measures against WNV disease is to stop transmission of WNV blood transfusions. This deals with in annex 3of Decree no. 143/2008 Coll.. Currently the draft of methodological instruction which sets out the procedure for assessing the risk of WNV infection and the procedure to reduce the risk of transmission of the virus through blood transfusions is in the comment procedure. By the survey of health facilities was found out that it is according the legislation, specifically Decree 233/2011 Coll.. Private microbiology and serology laboratories in Pilsen and Budweis do not test on positivity of WNV. Targeted surveillance of horse WNV in Czech Republic is doing from 2011. In 2011 2013 it was 4 5 WNV positive horses, in 2014 it was already 13 horses from a total of 783 horses tested positive WNV. Various geographic distribution of horses and high specific antibody titers according to veterinarians indicate increasing activity of the virus in the Czech Republic and the possible expansion of WNV into new areas. The thesis also analyzes three cases of WNV disease that have been imported to the Czech Republic from the USA, Tanzania and from Cyprus. In thesis is also described the first autochthonous case of WNV infection in the Czech Republic in 2013 which demonstrates the changing epidemiological situation in the country. Based on the obtained data is appreciable that the virus will be with regard to a changing climate and increased globalization spread to new areas in which will be probably cause diseases with serious clinical course. Whereas the virus has a tends to mutation it is expected also a gradual change of the clinical picture. To stop the spread of the virus should be carried out surveillance at all levels. Insomuch as is not in current time human vaccine available to curb the spread of the The essential elements od prevention includes informing tourists traveling to high-risk countries and countries potentially risky.

Les Flavivirus transmis par les moustiques comme le virus du Nil occidental, le virus de la dengue, le virus de la fièvre jaune, le virus de l’encéphalite japonaise et le virus Zika constituent des préoccupations croissantes de santé publique. Ils se sont répandus dans le monde au cours des dernières décennies, et les épidémies sont devenues plus fréquentes et plus sévères. Chaque année, des millions de personnes sont infectées et environ 50 000 patients décèdent d’infections à Flavivirus. Malgré les nombreux efforts de recherche, il n’y a actuellement aucun médicament antiviral spécifique disponible, et des nouvelles stratégies antivirales sont indispensables. Comprendre comment les Flavivirus fonctionnent au niveau moléculaire aidera à découvrir des nouvelles cibles pour l'intervention thérapeutique. Les Flavivirus ont un génome d'ARN simple brin de polarité positive qui code pour trois protéines structurales et huit protéines non structurales. Seules deux des huit protéines non structurales ont des activités enzymatiques. NS3 possède un domaine protéase et un domaine hélicase, et NS5 a un domaine méthyl- et guanylyltransférase et un domaine ARN polymérase ARN-dépendante. Ensemble, ils répliquent le génome viral. Ici, nous caractérisons l'interaction entre NS3 et NS5 dans le complexe de réplication du virus du Nil occidental pendant la synthèse d’ARN de polarité positive. Un modèle d'interaction comprenant NS3, NS5 et l’ARN viral a été développé basé sur des structures cristallines connues ainsi que des activités enzymatiques des deux protéines individuelles, et ce modèle a été soumis à des simulations de dynamique moléculaire. Les interactions potentielles entre les protéines NS3 et NS5 ont été identifiées. Les résidus impliqués dans ces interactions ont été mutés dans un réplicon du virus du Nil occidental et les effets de ces mutations sur la réplication virale ont été évalués. Une région particulière à la surface de la protéine NS3 a été identifiée comme étant cruciale pour la réplication virale, très probablement parce qu'elle interagit avec NS5. Cette région pourrait être une cible attrayante pour la recherche de composés qui pourraient interférer avec l'interaction entre NS3 et NS5 et donc posséder un potentiel antiviral intéressant. / Abstract : Mosquito-borne Flaviviruses like West Nile virus, Dengue virus, Yellow Fever virus, Japanese encephalitis virus, and Zika virus are increasing public health concerns. They have spread globally during the past decades, and outbreaks have recently become more frequent and more severe. Every year, millions of people are infected, and approximately 50,000 patients die from Flavivirus infections. Despite extensive research efforts, there are currently no specific antiviral drugs available, and new antiviral strategies are greatly needed. Understanding how Flaviviruses work on a molecular level will help in uncovering new points for therapeutic intervention. Flaviviruses have a single-stranded RNA genome of positive polarity that encodes three structural and eight non-structural proteins. Only two of the eight non-structural proteins have enzymatic activities. NS3 has an N-terminal protease domain and a C-terminal helicase domain, and NS5 has an N-terminal capping enzyme domain and a C-terminal RNA-dependent RNA polymerase domain. Together, they replicate the viral genome. Here we characterize the NS3:NS5 interaction within the West Nile virus RNA replicase complex during positive strand synthesis. An interaction model including NS3, NS5 and viral RNA was developed based on the known crystal structures as well as enzymatic activities of the two individual proteins, and this model was subjected to molecular dynamics simulations. Potential interactions between the NS3 and NS5 proteins were identified. Residues involved in these interactions were mutated in a West Nile virus replicon, and the effects of these mutations on viral replication were evaluated. One particular region on the surface of the NS3 protein was identified to be crucial for viral replication, most likely because it mediates the interaction with NS5. This region might be an attractive target for the search of compounds that could interfere with the NS3:NS5 interaction and therefore possess an interesting antiviral potential.