In this paper, we propose an early retransmission scheme to improve TCP's performance in delivering time-sensitive media. Our extensive ns2 simulations show significant improvement. When integrated into a traditional TCP variant, namely TCP-SACK, the early retransmission scheme can substantially reduce the latency caused by retransmission timeout. As a result, it can help TCP-SACK achieve a considerably higher success rate in delivering real time media. Early Retransmission also enhances the performance of a delay-based TCP variant, namely PERT. Furthermore, we also explore the improvement brought by employing a fine-grained retransmission timer, and compare it with ER. We find out that ER outperforms the fine grained timer in a variety of conditions and the combination of the two can further improve performance.

African horse sickness virus (AHSV), a member of the Orbivirus genus within the Reoviridae family, has a 10-segment double-stranded (ds)RNA genome enclosed within a double capsid. In addition to seven structural proteins (VP1-VP7), four non-structural proteins (NS1, NS2 and NS3/NS3A) are synthesized in infected cells and are involved in virus morphogenesis. Due to the lack of a reverse genetic system for orbiviruses, analyses regarding AHSV gene function have been limited to the characterization of individual virus proteins following their expression in heterologous expression systems. The phenomenon of RNA interference (RNAi), has, however, revolutionized approaches to study the function of individual genes. RNAi is an evolutionary conserved mechanism by which RNA duplexes, known as short interfering RNA (siRNA), can reduce gene expression through enzymatic cleavage of complementary mRNA. In addition to synthetic siRNA, RNAi can also be induced in mammalian cells by plasmid and viral vector systems that express short hairpin RNAs (shRNAs) that are subsequently processed to siRNAs by the cellular machinery. Consequently, the aim of this investigation was to establish a plasmid DNA vector-based RNAi assay whereby the expression of the AHSV-9 NS2 gene could be suppressed in BHK-21 cells. Complementary oligonucleotides corresponding to selected AHSV-9 NS2 gene sequences were chemically synthesized, annealed and cloned into the pSUPER shRNA delivery vector, downstream of the RNA polymerase III H1 promoter. The vector-expressed shRNAs targeted regions within the NS2 gene corresponding to nucleotides 211 to 230 (shRNA-211), 377 to 396 (shRNA-377) and 958 to 977 (shRNA-958), respectively. To determine whether the NS2-directed shRNAs was capable of silencing NS2 protein expression, BHK-21 cells were co-transfected with the respective pSUPER shRNA delivery vectors and a NS2 reporter plasmid, pCMV-NS2-eGFP. Fluorescence microscopy indicated that NS2-eGFP expression was makerdly reduced in these cells compared to cells transfected with the reporter plasmid only, and fluorometry analysis indicated that the level of inhibition mediated by the shRNAs were in excess of 80%. The potential of the NS2-directed shRNAs to reduce the level of NS2 transcripts in AHSV-9 infected BHK-21 cells was also investigated by transfection of the BHK-21 cells with the respective pSUPER shRNA delivery vectors, followed by virus infection. Results obtained by means of semi-quantitative real-time reverse transcriptase-polymerase chain reactions indicated that shRNA-377 interfered the most efficiently with NS2 mRNA expression, and the greatest silencing effect was observed at 24 h post-infection. During the course of this investigation it was also attempted to establish a BHK-21 cell line that stably expressed the NS2-directed shRNA-377. For this purpose, a recombinant pSUPER.Retro.Puro retroviral vector was constructed and following transfection of BHK-21 cells, stable transfectants were selected by growth in the presence of puromycin. Results indicated that although the derived cell line suppressed AHSV-9 NS2 mRNA expression, the plasmid DNA was maintained extrachromosomally. Overall, the results of this investigation have provided evidence that AHSV-9 NS2 gene expression can be suppressed in mammalian cells by vector-derived shRNAs. / Dissertation (MSc)--University of Pretoria, 2010. / Microbiology and Plant Pathology / unrestricted

Wireless network analysis and simulations rely on accurate physical layer models. The increased interest in wireless network design and cross-layer design require an accurate and efficient physical layer model especially when a large number of nodes are to be studied and building the real network is not possible. For analysis of upper layer characteristics, a simplified physical layer model has to be chosen to model the physical layer. In this dissertation, the widely used two-state Markov model is examined and shown to be deficient for low to moderate signal-to-noise ratios. The physical layer statistics are investigated, and the run length distributions of the good and bad frames are demonstrated to be the key statistics for accurate physical layer modeling. A four-state Markov model is proposed for the flat Rayleigh fading channel by approximating the run length distributions with a mixture of exponential distributions. The transition probabilities in the four-state Markov model can be established analytically without having to run extensive physical layer simulations, which are required for the two-state Markov model. Physical layer good and bad run length distributions are compared and it is shown that the four-state Markov model reasonably approximates the run length distributions. Ns2 simulations are performed and the four-state Markov model provides a much more realistic approximation compared to the popular two-state Markov model. Achieving good results with the flat Rayleigh fading channel, the proposed four-state Markov model is applied to a few diversity channels. A coded orthogonal fre- quency division multiplexing (OFDM) system with a frequency selective channel and the Alamouti multiple-input multiple-output system are chosen to verify the accuracy of the four-state Markov model. The network simulation results show that the four-state Markov model approximates the physical layer with diversity channel well whereas the traditional two-state Markov model estimates the network throughput poorly. The success of adapting the four-state Markov model to the diversity channel also shows the flexibility of adapting the four-state Markov model to various channel conditions.

Made available in DSpace on 2016-08-29T15:33:14Z (GMT). No. of bitstreams: 1 tese_4161_.pdf: 2648809 bytes, checksum: 9d0d29882117ba5d84d7b1eb586817c2 (MD5) Previous issue date: 2011-08-04 / Sistemas Par-a-Par de Video Sob Demanda consolidaram sua importância nos últimos anos. Tal consolidação é decorrente dos elevados ganhos que se pode ter em termos de economia na banda de transmissão dos servidores. Neste trabalho, avalia-se como esta tecnologia pode potencializar os ganhos de transmissão de mídia contínua na Internet. Para atingir este objetivo, a metodologia adotada apoia-se em um ambiente de simulação a nível de pacotes que possui características que permitem capturar iferentes variáveis referentes a dinâmica da Internet, tais como: simulação completa da pilha TCP/IP, considerações sobre topologia de rede e inserção de tráfego de fundo. Na simulação foi implementado um algoritmo de difusão de vídeo P2P VoD e um algoritmo de pré-busca. As análises dos resultados apontam para uma potencial economia de upload no servidor de conteúdo de 43% em um cenário menos idealizado do que a proposta de base que atingiu 73%. Em termos da percepção da qualidade de vídeo dos clientes, o presente trabalho indica que sua experiência pode ser degradada de forma considerável usando UDP quando existe o tráfego de fundo, mesmo com a economia do servidor se mantendo constante. Ainda na percepção dos clientes, percebeu-se também que, embora o uso da pré-busca seja benéfico aos mesmos, o grande fator diferencial na melhor qualidade percebida foi a escolha da camada de transporte apropriada.

A Network Interface Card (NIC) is used for receiving the packets, processing the packets, passing the packets to the host processor, and sending the packets to other computers in a network. NIC uses the buffer management algorithm to distribute the buffer space among different applications. An application may use User Datagram Protocol (UDP) or Transmission Control Protocol (TCP), depending upon the type of application. Buffer Management Algorithm for UDP-based applications may be completely different from the one for TCP applications, since in UDP- based applications receiver do not send acknowledgement back to the sender. This thesis proposes two buffer management algorithms: 1) Fairly Shared Dynamic Algorithm (FSDA) for UDP-based applications; 2) Evenly Based Dynamic Algorithm (EBDA) for both UDP and TCP-based applications. FSDA utilizes full buffer memory and reduces the packet losses significantly. EBDA reduces packet losses by taking the packet size factor in summation rather than multiplication. This also helps in maintaining fairness among different applications. For the average network traffic load, the FSDA algorithm improves the packet loss ratio by 18.5 % over the dynamic algorithm and by 13.5% over the DADT, while EBDA improves by 16.7 % over the dynamic algorithm and by 11.8% over the DADT. For the heavy network traffic load, the FSDA algorithm improves the packet loss ratio by 16.8 % over the dynamic algorithm and by 12.5% over the DADT while EBDA improves the packet loss ratio by 16.8 % over the dynamic algorithm and by 12.6% over the DADT. For the actual traffic load, the improvement over DA and DADT is 13.6% and 7.5% for FSDA and 7.6% and 1.9% for EBDA.

L’émergence récente de nouvelles thérapies antivirales efficaces est une avancée considérable pour lutter contre l'infection chronique par le virus de l'hépatite C (VHC). Cependant, un pic de carcinomes hépatocellulaires, représentant l'atteinte hépatique ultime liée à l'infection, est attendu dans la prochaine décennie. Approfondir les connaissances des différentes étapes du cycle viral et de l’interférence du VHC avec l'hépatocyte hôte permet de mieux comprendre la pathogénèse associée à ce virus. Les travaux présentés dans cette thèse ont eu pour objectif d'identifier le réseau de partenaires cellulaires et viraux de la protéine non-structurale NS2 du VHC et de mieux comprendre les mécanismes d'action et de régulation de cette protéine transmembranaire multi-fonctionnelle, qui est un acteur clé du clivage protéolytique de la polyprotéine virale et de la morphogénèse des virions. Dans une première partie, nous avons analysé comparativement les mécanismes moléculaires de l’activité enzymatique des protéines NS2 du VHC et de plusieurs hepacivirus non-humains, qui infectent des primates du Nouveau Monde (GBV-B) ou qui ont été récemment identifiés chez plusieurs autres espèces animales (NPHV, RHV, BHV et GHV). Des analyses phylogénétiques, des modèles structuraux tridimensionnels et des Études dans un contexte d'expression transitoire de précurseurs polypeptidiques viraux ou dans des modèles d'infection ont montré que l’activité des protéases NS2 de divers hepacivirus (1) s'exerce à la jonction NS2/NS3 sous la forme d'homodimères formant deux triades catalytiques composites ; (2) est régulée dans le contexte de la polyprotéine virale par quelques résidus de surface du domaine N-terminal de NS3 (NS3N) nécessaires à son activation ; (3) est efficace en l'absence complète de NS3N, suggérant un rôle négatif ou régulateur, plutôt qu'activateur de NS3N, contrairement au dogme en vigueur actuellement. Ces travaux soulignent l'importance fonctionnelle des mécanismes protéolytiques de NS2 conservés parmi les différents hepacivirus. Dans une deuxième partie, nous avons identifié un réseau de facteurs cellulaires et viraux interagissant avec NS2 au cours du cycle infectieux par un crible interactomique reposant sur la purification par affinité et l'analyse par spectrométrie de masse des complexes protéiques isolés de cellules hépatocytaires infectées, ainsi que par un test de complémentation enzymatique fonctionnelle. Par une approche d'ARN interférence, nous avons ensuite montré qu'un nombre limité de facteurs cellulaires interagissant avec NS2 sont impliqués dans la production et la sécrétion de particules virales infectieuses, incluant des protéines du complexe de la peptidase signal (SPCS) au sein du réticulum endoplasmique, des protéines chaperonnes (DNAJB11, HSPA5) et une protéine impliquée dans le transport intracellulaire (SURF4). Notamment, nos Études suggèrent que plusieurs membres du SPCS forment un complexe multi-protéique avec NS2, impliquant Également la glycoprotéine virale E2, qui jouerait un rôle dans une Étape précoce de l'assemblage ou lors de l’enveloppement de la particule virale. En conclusion, mes travaux de thèse ont permis d'identifier pour la première fois une série limitée de facteurs hépatocytaires interagissant spécifiquement avec la protéine NS2 du VHC au cours de l'infection et de déterminer parmi ceux-ci les facteurs essentiels la morphogenèse virale. Par ailleurs, nos résultats ont permis d’enrichir les connaissances naissantes des hepacivirus non-humains récemment identifiés et de montrer que ceux-ci partageaient avec le VHC des mécanismes clés mis en jeu au cours du cycle viral, ce qui contribue consolider leur intérêt comme modèles animaux de substitution. / The recent emergence of a panel of direct acting antivirals will certainly help combat chronic hepatitis C in the future. However, in the current context worldwide, a peak of hepatitis C virus (HCV)-induced hepatocellular carcinoma is expected in the next decade. Deepening our understanding of HCV life cycle and HCV interference with host cells may help monitor HCV-associated pathogenesis. The aim of my PhD work was to identify the network of host and viral interactors of HCV nonstructural protein 2 and to unravel the mechanisms of action and regulation of this multifunctional, transmembrane protein, which is key both for the viral polyprotein cleavage and virion morphogenesis.In the first part of the work, we comparatively characterized molecular mechanisms underlying the enzymatic activity of NS2 proteins from HCV and from various non-human hepaciviruses that infect small New World primates (GBV-B) or that were recently identified in the wild in several mammalian species (NPHV, RHV, BHV, GHV). A combination of phylogenetic analyses, tridimensional structural models, and studies relying on the transient expression of viral polypeptide precursors or on infection models showed that NS2 proteases of the various hepaciviruses (1) act as dimers with two composite active sites to ensure NS2/NS3 junction cleavage, (2) are regulated in the polyprotein backbone via a hydrophobic patch at the surface of NS3 N-terminal domain (NS3N) that is essential to activate NS2 protease, and (3) are efficient in the complete absence of NS3N, which is unprecedented and suggests that NS3N has rather a negative or regulating role on NS2 activity. These data underline the functional importance of NS2 proteolytic mechanisms that are conserved across hepaciviruses.In the second part, we identified a network of cellular factors and viral proteins that interact with NS2 in the course of HCV infection using an interactomic screen based on affinity purification and mass spectrometry analysis of protein complexes retrieved form HCV infected hepatoma cells, as well as a split-luciferase complementation assay. Next, using a gene silencing approach, we found that a limited set of NS2 interactors among these host factors were involved in HCV particle assembly and/or secretion. This includes members of the endoplasmic reticulum signal peptidase complex (SPCS), chaperone proteins (DNAJB11, HSPA5) and a factor involved in intracellular transport (SURF4). Notably, our data are in favor of the existence of a multiprotein complex involving NS2, several members of the SPCS, and the viral E2 glycoprotein, which likely plays a role in an early step of HCV particle assembly or during particle envelopment. Altogether, my PhD work allowed us to identify a limited set of hepatocyte factors interacting with HCV NS2 during infection and to pinpoint those that are essential for HCV morphogenesis. Additionally, our results contributed to the molecular characterization of the recently identified non-human hepaciviruses and revealed that these hepaciviruses share with HCV key mechanisms in the course of their infectious life cycles. This highlights the value of non-human hepaciviruses as surrogate animal models of HCV infection.

No infrastructure, no centralized administration and self-configuration are the main characteristics of MANETs. The primary motivation of MANET deployment is to increase portability, mobility and flexibility. However, this mobility causes an unpredictable change in topology and makes routing more difficult. Many routing algorithms have been proposed and tested over the last few years in order to provide an efficient routing in Ad Hoc networks. In this report we will show our conducted study with AODV (reactive), DSDV (proactive) and ZRP (hybrid) routing protocols. The performance of routing protocols have been evaluated carefully by analyzing the affects of changing network parameters such as, number of nodes, velocity, pause time, workload and flows on three performance metrics: packet delivery ratio, routing cost and average end- to- end delay. All the simulation work has been conducted in NS2. Our simulation results show that AODV gives better performance in all designed simulation models in terms of packets delivery ratio. DSDV shows the second best performance. Performance of ZRP is found average.

Industrial Development Centre (IUC) in Olofström inc. has constructed a measurement value logger which can sample values from eight channels, buffer them and then send them wireless with the Bluetooth technology to e.g. a computer.</p> In this thesis the data transfer rate, i.e. the number of values per second has been studied for different logger settings and when there are interferences in the Bluetooth traffic. How Bluetooth is affected by interferences has been studied with a number of experiments performed at IUC's RF-damped Faraday's cage. The thesis provides a model for this Bluetooth logger. The model extends the existing simulation system NS2-UCBT with a 'logger protocol'. NS2-UCBT was also extended to better support modeling of losses (due to Bluetooth channel impairments) and for the model of these losses to be based on experiments. The resulting simulation program allows developers to construct and evaluate a measurement system utilizing such a Bluetooth logger. Using the simulation model, the data rate measured in samples per second was examined for the logger. The simulations shows that optimizing the logger's configuration will improve that data rate considerable. This report contains: a summary of the problem and earlier research, an explanation of the simulation system and the simulation program, comparisons between simulations and experiments, some conclusions, and proposes future work in this area. / Industriellt Utvecklings Centrum (IUC) i Olofström AB har tagit fram en mätvärdeslogger som kan sampla värden från åtta kanaler, mellanlagra dem och skicka dem till exv. en dator trådlöst med Bluetooth teknologin. I det här examensarbetet har överföringshastigheten, dvs antal mätvärden per sekund studerats för olika inställningar på loggern och då det förekommer störningar i Bluetooth trafiken. Hur Bluetooth påverkas av störningar har undersökts genom en rad experiment i IUC's RF-dämpade skärmlabb. Arbetet har lett fram till en modell för mätvärdesloggern och ett simuleringsprogram som gör det möjligt för utvecklare att konstruera och utvärdera sina mätsystem med mätvärdes logger. Modellen använder det befintliga NS2-UCBT simuleringssystemet utvidgat med ett 'logger protokoll', mer utvecklad förlusthantering än NS2-UCBT i grundutförandet erbjuder och flexibel förlusthantering baserad på experiment. Med simuleringsmodellen undersöktes loggerns datahastighet i sampel per sekund. Simuleringarna visa att genom att förbättra loggerns konfiguration kan avsevärt högre datahastighet nås. Den här rapporten innehåller: en sammanfattning av problemställningen och tidigare forskning, en beskrivning av simulationssystemet och simulationsprogrammet, jämförelser mellan simuleringar och experiment, en del slutsatser, och förslag på framtida arbete i området.

Made available in DSpace on 2014-12-17T14:55:18Z (GMT). No. of bitstreams: 1 ViniciusSVS_TESE.pdf: 2375594 bytes, checksum: e3d85d405a408eb605711ffd55dbe760 (MD5) Previous issue date: 2014-03-17 / The monitoring of patients performed in hospitals is usually done either in a manual or semiautomated way, where the members of the healthcare team must constantly visit the patients to ascertain the health condition in which they are. The adoption of this procedure, however, compromises the quality of the monitoring conducted since the shortage of physical and human resources in hospitals tends to overwhelm members of the healthcare team, preventing them from moving to patients with adequate frequency. Given this, many existing works in the literature specify alternatives aimed at improving this monitoring through the use of wireless networks. In these works, the network is only intended for data traffic generated by medical sensors and there is no possibility of it being allocated for the transmission of data from applications present in existing user stations in the hospital. However, in the case of hospital automation environments, this aspect is a negative point, considering that the data generated in such applications can be directly related to the patient monitoring conducted. Thus, this thesis defines Wi-Bio as a communication protocol aimed at the establishment of IEEE 802.11 networks for patient monitoring, capable of enabling the harmonious coexistence among the traffic generated by medical sensors and user stations. The formal specification and verification of Wi-Bio were made through the design and analysis of Petri net models. Its validation was performed through simulations with the Network Simulator 2 (NS2) tool. The simulations of NS2 were designed to portray a real patient monitoring environment corresponding to a floor of the nursing wards sector of the University Hospital Onofre Lopes (HUOL), located at Natal, Rio Grande do Norte. Moreover, in order to verify the feasibility of Wi-Bio in terms of wireless networks standards prevailing in the market, the testing scenario was also simulated under a perspective in which the network elements used the HCCA access mechanism described in the IEEE 802.11e amendment. The results confirmed the validity of the designed Petri nets and showed that Wi-Bio, in addition to presenting a superior performance compared to HCCA on most items analyzed, was also able to promote efficient integration between the data generated by medical sensors and user applications on the same wireless network / O monitoramento de pacientes realizado nos hospitais normalmente ? feito de forma manual ou semi-automatizada, em que os membros da equipe de sa?de precisam constantemente se deslocar at? os pacientes para verificarem o estado de sa?de em que eles se encontram. A ado??o desse procedimento, todavia, compromete a qualidade do monitoramento realizado, uma vez que a escassez de recursos f?sicos e humanos nos hospitais tende a sobrecarregar os membros da equipe de sa?de e assim impedir que os mesmos se desloquem aos pacientes com a freq??ncia adequada. Diante disso, diversos trabalhos existentes na literatura especificam alternativas voltadas ? melhoria desse monitoramento mediante o uso de redes sem fio. Nesses trabalhos, a rede ? destinada apenas ao tr?fego de dados gerados por sensores m?dicos e n?o existe a possibilidade da mesma ser alocada para o envio de informa??es oriundas de aplica??es presentes nas esta??es de usu?rio existentes no hospital. Todavia, em se tratando de ambientes de automa??o hospitalar, esse aspecto constitui-se em um ponto negativo, haja vista que os dados gerados nessas aplica??es podem estar diretamente relacionados ao monitoramento de pacientes realizado. Desse modo, esta tese define o Wi-Bio como sendo um protocolo de comunica??o voltado ao estabelecimento de redes de monitoramento de pacientes IEEE 802.11 capazes de permitir a conviv?ncia harmoniosa entre os tr?fegos gerados por sensores m?dicos e esta??es de usu?rio. A especifica??o e verifica??o formal do Wi-Bio foram feitas mediante o projeto e an?lise de modelos em redes de Petri e sua valida??o foi realizada atrav?s simula??es efetuadas na ferramenta Network Simulator 2 (NS2). As simula??es realizadas no NS2 foram projetadas para retratarem um ambiente real de monitoramento de pacientes correspondente a um andar do setor de enfermarias do Hospital Universit?rio Onofre Lopes (HUOL), localizado na cidade de Natal/RN. Al?m disso, no intuito de verificar a viabilidade do Wi-Bio quanto aos padr?es de redes sem fio vigentes no mercado, o cen?rio de testes tamb?m foi simulado sob uma perspectiva em que os elementos da rede utilizavam o mecanismo de acesso HCCA descrito na emenda IEEE 802.11e. Os resultados obtidos atestaram a validade das redes de Petri projetadas e mostraram que o Wi-Bio, al?m de apresentar um desempenho superior ao do HCCA na maioria dos quesitos analisados, tamb?m se mostrou capaz de promover uma integra??o eficiente entre os dados gerados por sensores m?dicos e aplica??es de usu?rio sob a mesma rede sem fio

Le virus respiratoire syncytial (RSV) est un virus à ARN de polarité négative. Les études démontrent que toute la population sera infectée par ce virus au moins deux fois avant l’âge de 3 ans. Le RSV peut provoquer plusieurs pathologies respiratoires telles que la bronchiolite aiguë et la pneumonie. Les infections sévères corrèlent avec le développement de l’asthme. Lors d’une infection virale, les particules du RSV sont détectées par le senseur RIG-I qui induit l’activation des facteurs de transcription NF-κB et IRF-3. Respectivement, les facteurs de transcription activeront les réponses inflammatoire et antivirale. Au coeur des pathologies induites par le RSV se trouve une réponse immunitaire mal adaptée. Plus précisément, par l’entremise de NF-κB, le RSV provoque une production exagérée de cytokines et chimiokines qui induisent une réponse inflammatoire démesurée provoquant du dommage tissulaire. Paradoxalement, le RSV est capable d’échapper à la réponse antivirale. Ces deux phénomènes sont contrôlés par l’entremise des protéines non structurales NS1 et NS2. Le mécanisme délimitant le mode d’action de NS1 et NS2 sur la réponse antivirale reste à être déterminé. Avec pour objectif d’élucider comment NS1 et NS2 inhibent la réponse antivirale, nous avons investigué le mécanisme de reconnaissance de l’hôte vis-à-vis de RSV. Nous démontrerons, pour la première fois, que le senseur cytosolique MDA5 est impliqué dans la réponse antivirale contre le RSV. Nous présenterons des résultats préliminaires qui suggèrent que le rôle de MDA5 est non redondant à RIG-I. À l’aide d’ARN interférant dirigé contre RIG-I et de transfection de MDA5, nous démontrerons que MDA5 ne contribue pas à la phosphorylation d’IRF-3, mais plutôt qu’elle régit la stabilité du facteur de transcription. Nous démontrerons aussi que, contrairement à l’hypothèse actuelle sur le fonctionnement de NS1 et NS2, l’inhibition de ces derniers ne provoque pas une augmentation de la cytokine antivirale IFN−β. Cependant, l’expression ectopique de NS1 et NS2 réduit l’activité du promoteur de l’IFN-β et de la protéine cytoplasmic antivirale ISG56 lorsqu’elle est mesurée par essai luciférase. / Respiratory Syncytial Virus (RSV) is a RNA virus with negative polarity. RSV infections are the most common cause of hospitalization among infants. Among populations at risk, infection of RSV can be quite severe. RSV infections can cause bronchiolitis, pneumonia, while severe infections are linked to the development of asthma. Early in the infectious cycle of RSV, the cytosolic sensor RIG-I captures viral particles, and activates the immune response by engaging the transcription factors IRF-3 and NF-κB. At the heart of RSV mediated pathologies is a skewed immune response. More precisely, RSV over stimulates the release of proinflammatory chemokines and cytokines. Intriguingly, while RSV is able to stimulate the production of proinflammatory cytokines and chemokines, RSV under stimulates the antiviral response. The ability of RSV to evade the antiviral response is thought to be mediated by its non-structural proteins: NS1 and NS2. However, the mechanism by which NS1 and NS2 enable RSV to evade the antiviral response remains to be determined. In this memoir we investigated, how RSV is recognized by the innate immune response in airway epithelial cells. With this information we hope to improve our understanding of how NS1 and NS2 allow RSV to circumvent the antiviral response. We show for the first time that cytosolic sensor MDA5 plays a role in the recognition of RSV particles. Using a combination of interfering RNA directed against RIG-I, and transfection of MDA5, we show that MDA5 does not contribute to the phosphorylation of IRF-3. According to the data presented, we suggest that MDA5’s role in the immune response is to prevent the degradation of IRF-3. Contrary to previous research, we show that the inhibition of the nonstructural protein does not increase the production of the antiviral cytokine IFN-β. However, the ectopic expression of NS1 and NS2 does lead to a reduction of the promoter activity of IFN-β and the antiviral protein ISG56 when measured by luciferase assay. This research highlights the importance of MDA5 as a potential therapeutic target in the development of a cure for RSV.