No description available.

Dans le contexte de la menace pandémique liée au virus influenza A(H5N1), un projet "GRIPPE AVIAIRE ET GRIPPE PANDÉMIQUE " a émergé au sein de LyonBioPôle avec comme objectif le développement d'outils de caractérisation des virus influenza pour la production de vaccins. Pour étudier le réassortiment génétique entre virus influenza, nous avons développé 3 systèmes de génétique inverse : virus humain A(H3N2) et aviaires A(H5N2) et A(H5N1) et produit des virus réassortants de composition déterminée. Leurs capacités réplicatives ont été évaluées par cinétiques de croissance virale sur MDCK avec quantification de la production virale par qRT-PCR temps réel. L'émergence du virus influenza A(H1N1)2009 pose deux questions sur l'acquisition par réassortiment génétique, d'une résistance à l'oseltamivir d'une part ou de facteurs de virulence d'autre part. Nous avons donc développé un protocole de co-infection virale de cellules MDCK pour étudier les constellations de gènes des réassortants entre différents virus: A(H1N1)2009-A(H1N1) H275Y et A(H1N1)2009-A(H5N1). Nous montrons par deux approches différentes, génétique inverse et co-infections virales, que le réassortiment génétique entre souches aviaires et humaines et surtout aviaires et porcines est possible, en privilégiant certaines constellations. Nous rapportons que le virus pandémique peut acquérir la NA H275Y des virus A(H1N1) Brisbane-like résistants à l'oseltamivir sans que ses capacités de réplication ne soient altérées. De même nous montrons que son réassortiment avec un virus hautement pathogène A(H5N1) est possible. Ces observations renforcent la nécessité de promouvoir la vaccination afin de limiter les risques de co-infection virale chez un même individu.

Submitted by Erica Netto (nettoeri@icict.fiocruz.br) on 2012-11-22T14:32:47Z No. of bitstreams: 1 PPGICS TANIA RN SILVA.pdf: 2814574 bytes, checksum: 84d13a44564941085cedc047c315cc19 (MD5) / Made available in DSpace on 2012-11-22T14:32:47Z (GMT). No. of bitstreams: 1 PPGICS TANIA RN SILVA.pdf: 2814574 bytes, checksum: 84d13a44564941085cedc047c315cc19 (MD5) / Esta pesquisa procura compreender o modo como se deu a produção de sentidos sobre a epidemia de influenza H1N1 na cobertura jornalística dos jornais O Globo, Extra e Expresso da Informação, do Rio de Janeiro, no período de 25 abril a 18 de agosto de 2009. A partir da delimitação de sete momentos considerados marcantes – a saber: o surgimento da doença, as primeiras suspeitas de contaminação, a confirmação dos primeiros casos, o anúncio de pandemia, a primeira morte no Brasil, a primeira morte no Rio de Janeiro e o início do declínio dos casos de contaminação – o trabalho consiste na análise da produção discursiva dos jornais em questão. Com base nos conceitos da Semiologia dos Discursos Sociais, de Milton José Pinto, e o adicional aporte teórico de Norman Fairclough (tridimensionalidade do discurso), Mikhail Bakhtin (dialogismo) e Eliseo Verón (contrato de leitura), busca-se compreender como as diversas vozes presentes no noticiário se articularam e quais estratégias enunciativas foram utilizadas pelos veículos para dar sentidos à epidemia naquele momento. Entre os principais achados, conclui-se que a estimulação do medo e a quantificação diária das vítimas foram os grandes norteadores das coberturas e pontos em comum dos três jornais. No campo das diferenças, O Globo se orientou por um intertexto político, o Extra adotou postura mais didática e o Expresso optou pela simplificação do noticiário sobre a H1N1. / This research seeks to understand how was made the production of meanings about the H1N1 influenza epidemic in the coverage of newspapers O Globo, Extra and Expresso da Informação, from Rio de Janeiro, between April 25th and August 18th, 2009. From delimitation of seven moments considered outstanding – namely: the emergence of the disease, the first suspicion of contamination, the confirmed first cases, the announcement of a pandemic, the first death in Brazil, the first death in Rio de Janeiro and the beginning decline of cases of contamination - the work proposes to examine the discursive production of the concerned newspapers. Based on the concepts of Semiology of Social Discourses, by Milton Jose Pinto, with additional theoretical contribution of Norman Fairclough (three-dimensionality of the discourse), Mikhail Bakhtin (dialogism) and Eliseo Verón (reading contract), we seek to understand how different voices in the news were articulated and what enunciative strategies were used by these vehicles to give meaning to the epidemic in that moment. Among the main findings, we conclude that stimulation of the fear and daily quantification of the victims were the major guide lines of the coverage and the commonality points of the three newspapers’ discourse. When it comes to the differences, O Globo was guided by a political intertext, Extra has adopted a more didactic approach and Expresso has opted for a simplification of the news about H1N1.

Influenza virus belongs to the Orthomyxovirus family of viruses that causes respiratory infection in humans, leading to morbidity and mortality. The mature influenza A virion has an envelope that contains two major surface glycoproteins proteins – hemagglutinin (HA) and neuraminidase (NA). HA is a highly antigenic molecules and is responsible binding to host cell surface receptors (Sialic acid), and membrane fusion between the viral membrane and the host endosomal membrane. Most of the antibody response generated against influenza virus either by vaccination or by natural infection is directed against HA. Influenza virus has segmented negative–sense RNA genome which gives the virus the ability to evade the host immune response by incorporating mutations (antigenic drift) and/or by reassotment with other subtypes of influenza A viruses (antigenic shift). Currently licensed vaccines which include an inactivated vaccine, a live attenuated vaccine, and recombinant subunit vaccine are beneficial for providing protection against seasonal influenza viruses that are closely related to the vaccine strain but fail to provide protection against drifted strains. This limits their breadth of protection and thus requires annual revaccination with reformulated vaccines. Also, because selection of a vaccine strain for the next season is purely based on surveillance and prediction, sometimes mismatches do happen between the selected vaccine strains and circulating viruses, resulting in a drastic decrease in vaccine efficacy and thus high morbidity and mortality. Furthermore, the production of these seasonal vaccines takes 6-8 months on an average, and does not guarantee protection against infection with novel reassortant viruses which can cause pandemics. To overcome the draw-backs of seasonal influenza virus vaccines and to enhance our pandemic preparedness, there is an increasing need for game-changing influenza virus vaccines that can confer robust, long-lasting protection against a broad spectrum of influenza virus isolates. Influenza hemagglutinin (HA) is highly immunogenic and thus a major target for vaccine design. HA is synthesized as a precursor polypeptide (HA0), assembles into a trimer, matures by proteolytic cleavage along the secretory pathway and is transported to the cell surface. Mature HA has a globular head domain, primarily composed of the HA1 subunit, which mediates receptor binding, while the stem domain, predominantly comprises of the HA2 subunit, and houses the fusion peptide. At neutral pH, the HA stem is trapped in a metastable state but undergoes an extensive conformational rearrangement at low pH in the late endosome (host-cell endosome) to trigger the fusion of virus and host membranes. Clusters of ‘antigenic sites’ have been identified in the head domain of HA, indicating that it harbors an almost continuous carpet of epitopes that are targeted by antibodies. However, these immunodominant sites constantly accumulate mutations to escape immune pressure, and thereby narrow the breadth of head-directed neutralizing antibodies (nAbs). In contrast to the highly-variable head domain, the membrane-proximal HA stem subdomain has much less sequence variability and, thus, is a desirable target for influenza vaccine development. In the recent past, several broadly neutralizing antibodies (bnAbs) targeting this subdomain with neutralizing activity against diverse influenza A virus subtypes have been isolated from infected people, further proving that this subdomain of HA can be targeted as a vaccine candidate. Steering the immune response towards this conserved, subimmunodominant stem subdomain in the presence of the variable immunodominant head domain of HA has been quite challenging. Alternatively, mimicking the epitome of these stem-directed bnAbs in the native, pre-fusion conformation in a ‘headless’ stem immunogenic capable of eliciting a broadly protective immune response has been difficult because of the metastable nature of HA. Addressing the aforementioned challenges, here we describe the design, stabilization and characterization of novel stem derived immunogens from HA of influenza A viruses using a protein minimization approach. Chapter 1 gives an overview of the influenza virus life cycle, nomenclature and classification of influenza virus; outlines the structural organization and functional properties of different viral proteins. An introduction to the kind of immune responses generated during vaccination or natural infection with the virus is discussed. The conventional vaccines that are currently used and their limitations, recent progress in the field of novel vaccine developmental approaches targeting the conserved epitopes on HA, is also described in this chapter. This chapter also gives a broad overview of bnAbs that have been isolated in the recent past, which target the novel antigenic signatures on HA. The design of a stem domain construct from an H3N2 virus (A/HK/68) is described in Chapter 2. In order to ensure that HA2 folds into the neutral pH conformation, regions of HA1 interacting with it were included in the design. Additionally, two Asp mutations were introduced in the B loop of HA2 to destabilize the low pH conformation and stabilize the desired native, neutral pH conformation. Studies using small peptides (57-98 of HA2) indicated that Asp mutations at positions 63 and 73 destabilized the low pH conformation. Studies on mutants with additional pairs of introduced Cys residues showed that the designed protein H3HA6 was folded into the neutral pH form. Immunization studies using mice showed that the protein was highly immunogenic and provided complete protection against a lethal dose of a homologous virus. Two constructs H3HA6a and H3HA6b, designed from the stem region of drifted H3N2 viruses (A/Phil/2/82 and A/Bris/10/07) were tested for protection against HK/68 to determine the extent of cross-strain protection provided by HA6. While HA6a (from A/Phil/2/82) provided near complete protection against HK/68, HA6b could protect against challenge only partially, possibly because of lower titers of antibodies elicited by this antigen. Studies using FcRγ chain knockout mice indicated that majority of the protection mediated by anti-HA6 antibodies was because of antibody mediated effectors functions, although neutralization as a mechanism of protection was also likely to contribute. In all the 18 subtypes of HA, the B loop contains residues that form the hydrophobic core of the extended coiled coil of the low pH form. As in the case of H3HA6, we suggest that these residues could be mutated to Asp to destabilize the low pH conformation. Two circularly permuted stem domain constructs from an H1N1 virus (A/PR/8/34) and an H5N1 virus (A/Viet/1203/04) were made. The design and characterization of these proteins is described in Chapter 3. H1HA6, H1HA0HA6 and H5HA6 were purified from inclusion bodies and refolded. The proteins H1HA6 and H1HA0HA6 were highly immunogenic and provided protection against a lethal challenge with homologous PR/8/34 virus. Anti-H1HA6 sera had higher titres of antibodies against heterogonous HAs as compared to convalescent sera. Stem derived immunogens from drifted H1N1 viruses (A/NC/20/99 and A/Cal/7/09) have been made and tested for cross-protection with PR/8/34 challenge. While H5HA6 also elicited high titers of antibodies, it could only protect partially against PR/8/34 challenge probably because high enough titers of cross-reactive protective antibodies were not elicited by this protein. These stem immunogens conferred robust subtype specific and modest heterosubtypic protection in vivo against lethal virus challenge. However, the immunogens, especially H1HA6, a stem immunogen from group 1 (PR8) virus is aggregation prone when expressed in E.coli. The strategy used to improve the biophysical and biochemical properties and thus the immunogenicity of these stem derived immunogens is discussed in Chapter 4. A random mutagenesis library of H1HA6 was constructed by error prone PCR using modified nucleotide analogues. The library was displayed on the yeast cell surface to isolate mutants showing better surface expression and improvement in binding to the broadly neutralizing antibody CR6261 compared to the wild-type protein. We isolated few clones, of which one mutant (H1HA6P2) dominated the enriched population. The other mutants differed slightly from H1HA6P2. This mutant differs from the wild-type by two mutations K314E and M317T (H1 numbering) which are close to the CR6261 binding site but outside the antibody foot-print (epitope). This mutant showed improved binding to CR6261 and exhibited significant improvement in surface expression. Improvement was also observed in binding of this mutant to F16v3-ScFv (another broadly neutralizing antibody). Two cysteine mutations were also introduced to further stabilize the trimeric form of the protein. Chapter 5 describes the biophysical and biochemical characterization of the high affinity isolated mutant at the protein level. We expressed this affinity matured mutant gene in E.coli and purified the protein from inclusion bodies. The stabilized mutant protein showed remarkable improvement in biophysical and biochemical properties and was recognized by stem directed conformation sensitive broadly neutralizing antibodies CR6261, F10 and F16v3 with affinity comparable to the full-length HA ectodomain. These results clearly suggest that this mutant protein is properly folded in its native pre-fusion conformation and thus can be an excellent candidate for eliciting stem directed broadly neutralizing antibodies. All these stabilized versions of stem derived immunogens will be tested for immunogenicity and cross-protection with different viral challenges. Chapter 6 describes the development of a method for mapping antibody epitopes (especially conformational epitopes) down to the residue level. Using a panel of single cysteine mutants, displayed on the yeast cell surface, this bypasses the need for laborious and time consuming protein purifications steps used in conventional methods for epitope mapping. We made a panel of single cysteine mutants, covering the entire surface of the antigen (CcdB, a bacterial toxin protein), displayed each mutant individually as well as in a pool, representing all mutants together on the yeast cell surface, and covalently labeled the cysteine with biotin-PEG2-maleimide to mask the area. The effect on antibody binding was monitored to identify the residues and relative positions important for antibody interactions with the displayed antigen by flow cytometry. By using this method we were able to map the conformational as well as linear epitopes of a panel of monoclonal antibodies down to the residue level with ease, and also identify the regions on the antigen which contribute to the antigen city during immunization in different animals. Since, this method is quite easy, rapid and gives in-depth information about antigenic epitopes, it can be useful in rational design of epitomes specific vaccines and other antibody therapeutics. It can easily be extended to other display systems and is a general approach to probe macromolecular interfaces.

No description available.

The recent experience with the 2009 H1N1 pandemic has drawn attention to the need to better understand the public’s response to emergently released vaccines (ERV). This study applied a mixed methods approach to examine the causal pathways underlying the vaccination behaviour during a public health emergency. The integrated evidence from empirical and theoretical-based findings highlights a number of factors to consider in interventions to improve vaccination rates with an ERV. These factors include: 1) providing clear risk messages around the disease and the ERV, 2) improving accessibility to the vaccine, 3) encouraging primary healthcare providers to provide recommendations for vaccination, 4) implementing strategies to increase seasonal influenza vaccination prior to the next public health emergency, 5) developing strategies to target sub-populations more reluctant to accept an ERV. Developing theory-based interventions that are behaviour-specific may be more likely to result in behaviour change within the public in future emergency vaccination campaigns.

The spread of pandemic influenza A (2009 H1N1 influenza) virus resulted in a global influenza pandemic in 2009. During the early stages of the pandemic, population surveillance was crucial. However, officials around the world realized that many of our surveillance and reporting systems were not prepared to respond in a coordinated, integrated way, which made informed public health decision-making very difficult. More accurate estimates of the total number of hospitalized 2009 H1N1 influenza cases were required to calculate population-based 2009 H1N1 influenza-associated mortality, morbidity and hospitalization rates. For instance, how many people were hospitalized with 2009 H1N1 influenza in Massachusetts? Of these, how many were admitted to the ICU and how many died? Compared to seasonal influenza, were some race/ethnic and age groups affected more than others, and what types of characteristics led to more severe manifestations of 2009 H1N1 influenza among these groups in Massachusetts? To address the above questions, I proposed a retrospective cohort study using data from the Hospital Discharge Database (HDD), which contains data for all inpatients discharged from 76 acute care hospitals in Massachusetts, as well as Census information to provide a measure of socioeconomic status (SES). My specific aims are as follows: 1. Develop methods to identify influenza cases precisely and describe characteristics of those hospitalized with ILI in MA between April 26-Sept 30, 2009; 2. Conduct analyses to identify race/ethnicity-related trends in reference to 2009 H1N1 influenza-related hospitalizations; 3. Conduct analyses to identify age-related trends in reference to 2009 H1N1 influenza-related hospitalizations. First, I established influenza case selection criteria using hospital discharge data. I addressed limitations in the published methods on defining cases of influenza using administrative databases, and evaluated ICD-9 codes that correspond with common and relatively serious respiratory infections and influenza using a ‘maximum’ and ‘minimum’ approach. Results confirmed that 2009 H1N1 influenza affected a younger population, and disproportionately affected racial minorities in Massachusetts. There were also higher rates of ICU admission compared to seasonal influenza. I then presented epidemiological data indicating race/ethnic disparity among 2009 H1N1 influenza cases in Massachusetts. I found that Hispanics had significantly lower odds of 2009 H1N1 influenza-related ICU stay. SES gradients calculated using five-digit zip code information did not account for these differences. Within race/ethnic strata, Hispanics Finally, I presented epidemiological data indicating differences among 2009 H1N1 influenza cases by age group in Massachusetts. I calculated measures of Diagnostic Cost Group (DxCG) comorbidity for the study population to provide a comorbidity measure at baseline. Main results indicate that although comorbidity scores were similar between the 2009 H1N1 influenza and seasonal influenza groups, 2009 H1N1 influenza caused more severe disease in younger age groups. This is the first study to report population-based statewide outcomes in all acute care centers in MA. In this dissertation I address challenges surrounding influenza surveillance to create case selection criteria within an administrative database. Using my case selection criteria, I then provide data related to fatality and severity of 2009 H1N1 influenza in Massachusetts in reference to sociodemographic variables such as racial/ethnicity and age groups, and provide evidence for patient-level interventions to those hardest hit by influenza. These findings provide valuable information about using large administrative databases to describe pandemic influenza cases and guide resource allocation to reduce disparities in relation to pandemic influenza preparedness.

我們身處於一個充滿風險的社會。金融海嘯、核能危機、全球暖化、食品問題等，在說明社會步向現代化的後遺症，正如何為人類帶來更難預測的風險，並無孔不入般影響我們的日常生活(Beck, 1992)。在這理論基礎上，本文將探究新聞製作於建構風險的角色，並提出一個名為「客觀化」(objectification) 的過程---新聞媒體如何在科學專家的意見眾說紛紜、對風險難有最終定案之下，把有關社會風險的新聞論述詮釋為客觀的社會事實。我尤其探討風險範例的建構---一些有關風險的新聞事件其後演變為重要範例，並影響日後類似事件的新聞論述。 / 為求以實證方法探究風險「合理化」的過程，我將以香港(中華人民共和國的特別行政區) 的新聞論述如何回應2009年全球豬流感危機作為案例。豬流感是香港經歷2003年非典型肺炎危機(又稱「沙士」) 的重創後，首次面對的全球疫症危機。香港新聞如何呈現豬流感疫情，亦深受「沙士」時的歷史回憶、經驗及後遺所影響。故此，這案例有助我研究風險範例於風險「合理化」時的作用。我從香港報章隨機抽樣出有關豬流感的新聞論述的樣本，並透過內容分析和文本分析，研究香港新聞如何敍述豬流感危機，以及相關敍述所包含的意識形態。我亦走訪了當年採訪豬流感新聞的新聞工作者、有份向傳媒提供專家意見的醫學專家、以及負責制定香港政府防控豬流感政策的官員，以了解建構豬流感風險背後的社會互動。 / 本文的研究顯示，香港有關豬流感危機的新聞論述，是如何奠基於「沙士」這風險範例而建構。豬流感起來襲初時，新聞論述廣泛地藉「沙士」的經驗去詮釋豬流感可能帶給香港的後果。新聞工作者於「沙士」時的採訪經歷，亦成為他們報道豬流感新聞時尋找醫學專家意見的參照經驗，尤其是當醫學專家意見紛紜、新聞工作者要判斷誰人的意見較有權威去界定健康風險之時。本文主要闡述新聞的建構於社會回應風險時所起的關鍵作用，從而帶出這於風險社會理論、以及當我們探究新聞媒體及傳播於現代風險社會的角色時，仍未受足夠重視的重要層面。 / We are witnessing the formation of a risk society, with financial instability, nuclear catastrophes, global warming, and food crises, and just to give a few examples, becoming parts of our everyday life in an age of risk characterized by uncertainties stemming from system failure of modernization (Beck, 1992). In the light of this theoretical concern, in this study I shall scrutinize how news making plays its role in the construction of risk. This, I suggest, is a process of risk objectification ---how news media justifies its discourse of social risk by making social facts upon uncertainties and inconclusive scientific opinions. Specifically, I shall focus on the creation of risk exemplar. That is, some news events become critical exemplar that would shape the news construction of subsequent crises of similar sources. / To look into the process of risk objectification empirically, I shall examine what were the main features of the news discourse in Hong Kong, a Special Administrative Region of China, in reaction to the global health crisis of Swine Flu in 2009. Swine Flu was the first pandemic crisis encountered by Hong Kong after its devastating suffering from the epidemic of Severe Acute Respiratory Syndrome (SARS) in 2003. The news representation of Swine Flu was influenced by the historical memory, experience and legacies of SARS and this helps illustrate how risk exemplar contributes to risk legitimization. I carried out content and textual analysis respectively on a random sample of Hong Kong’s newspapers for the purpose of analyzing the key narrations of Swine Flu and the underlying ideological packages of such narrations. I also conducted in-depth interviews with journalists, medical experts and public officials who were deeply involved in the news making of Swine Flu so as to uncover the social dynamics in the process of risk construction. / Key findings of this thesis highlight how the health crisis of Swine Flu was staged by the risk exemplar of SARS. Experience of SARS was widely drawn upon for making sense of the potential impacts of Swine Flu when it first broke out. It was also the key reference for journalists when seeking expert advices, particularly when identifying those who are more authoritative among different opinions in defining the nature of the risk. It is my argument that news making plays a critical role in the shaping of the social reactions to a risk. My analysis thus adds an important, but somehow unduly neglected, dimension to theory of risk society and our understanding of the role of news media and communication in contemporary risk society. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Chan, Chi Kit. / Thesis (Ph.D.) Chinese University of Hong Kong, 2014. / Includes bibliographical references (leaves 240-250). / Abstracts also in Chinese. / Chan, Chi Kit.

Chong, Ka Chun. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 125-141). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Introdução: As infecções respiratórias causam elevadas morbidade e mortalidade, sendo os vírus os principais agentes destas doenças. O monitoramento e vigilância de vírus respiratórios, desde os mais conhecidos até os emergentes, são importantes para a gestão em saúde, orientando tempo de profilaxia e minimizando o impacto de epidemias nas comunidades. Objetivos: Estudar a epidemiologia molecular do vírus sincicial respiratório (VSR) e descrever a epidemiologia dos seguintes vírus: influenza (IF), influenza A (H1N1), adenovírus (AdV) e parainfluenza (PIV) no Hospital de Clínicas de Porto Alegre. Para isso foram conduzidos três estudos: (1) caracterização das infecções respiratórias causadas por VSR, IF, AdV e PIV em crianças; (2) validação de uma técnica de reação em cadeia da polimerase em tempo real (RT-PCR) para detecção de VSR A/B e IF A/B e (3) caracterização de genótipos do VRS em crianças com infecções comunitárias e hospitalares. Métodos: No primeiro estudo foram levantadas as seguintes variáveis: casos de infecções respiratórias por VSR, AdV, PIV ou IF e H1N1; internações em enfermarias hospitalares e internações em unidades de terapia intensiva (UTI); infecções hospitalares e taxas de letalidade. As variáveis foram coletadas durante o atendimento de crianças (idade 0-12 anos) no HCPA entre 2007 e 2010. No segundo estudo, os alvos do ensaio de RT-PCR foram: o gene da proteína da matriz de IFA, o gene da hemaglutinina do IFB e o gene da nucleoproteína de RSVA/B. A especificidade do ensaio e seu limite de detecção foram determinados. Uma comparação entre RT-PCR e imunofluorescência indireta foi realizada. No terceiro estudo, 63 isolados de VSR (21 de origem nosocomial e 42 adquiridos na comunidade) foram sequenciados para estabelecer uma análise filogenética deste vírus. Resultados: Cada um dos vírus estudados apresentou um comportamento diferente. O VSR demonstrou ser o principal agente envolvido em infecções nosocomiais. Já os pacientes com AdV, bem como o VSR, apresentaram altas taxas de admissão em UTI em 2007 e 2010. O AdV e o H1N1 tiveram as maiores taxas de letalidade. O ensaio de RT-PCR mostrou-se específico e foi mais sensível do que a imunofluorescência, sendo capaz de detectar co-infecções. Os seguintes limites de detecção foram obtidos: 1 cópia/mL para a IFA, 10 cópias/mL para IFB, 5 cópias/mL para RSVA e 250 cópias/mL para RSVB. A investigação dos genótipos de VSR revelou que todos os isolados VSRA circulantes eram do mesmo grupo filogenético, o genótipo NA1 de origem japonesa. Por outro lado, os isolados VSRB foram distribuídos em grupos diferentes: BA4, POA1, POA2, POA3 e POA4. Este estudo foi o primeiro que descreveu a circulação do genótipo NA1 no Brasil, bem como quatro novos genótipos (POA1, POA2, POA3 e POA4). Conclusão: Os resultados obtidos no primeiro estudo demonstram o impacto das epidemias sazonais de vírus respiratórios. O segundo estudo corroborou relatos da literatura que técnicas moleculares, como RT-PCR, são adequadas para a detecção de vírus respiratórios. O terceiro estudo relatou genótipos emergentes de VSR. Estudos de vigilância como os descritos acima deveriam ser conduzidos periodicamente para acompanhar o padrão de comportamento dos vírus na população alvo. / Background: Respiratory tract infections of viral origin are a major cause of morbidity and mortality worldwide. Surveillance of well-known viruses and emerging threats is important for management, prophylaxis and to minimize impact on the community. Objective: To study the molecular epidemiology of respiratory syncytial virus (RSV) and describe the epidemiology of viruses: influenza (IF), influenza A (H1N1), adenovirus (AdV) and parainfluenza (PIV) at Hospital de Clinicas de Porto Alegre. Three studies were performed: (1) characterization of respiratory infections caused by RSV, IF, AdV and PIV in children, (2) validation of a technique of polymerase chain reaction in real-time (RT-PCR) to detect RSVA/B and IFA/B and (3) detection of genotypes of RSV in children with communityand hospital-acquired infection. Methods: In the first study, variables such as number of cases of viral (RSV, AdV, PIV or IF and H1N1) infection, hospitalizations in general wards and intensive care units (ICUs), nosocomial infections and lethality rates were collected. These variables obtained from each children (age 0-12 years) between 2007 and 2010. In the second study the assay RT-PCR was used to target the matrix gene of IFA, the hemagglutinin gene of IFB and the nucleoprotein gene of RSVA/B. The specificity of the assay and its limit of detection were determined. A comparison of RT-PCR and indirect immunofluorescence was performed. In the third study, 63 RSV isolates (21 nosocomial and 42 community-acquired) were submitted to sequencing to establish a phylogenetic analysis of this virus. Results: The different viruses presented a diversity of behaviors according to hospitalization, nosocomial outbreaks or lethality in children. RSV accounted for most nosocomial infections. Rates of ICU admission for AdV and RSV infection were highest in 2007 and 2010. During 2008–2009, H1N1 and AdV had the highest ICU admission rates. AdV and H1N1 had the highest lethality rates. The RT-PCR assay was more sensitive than immunofluorescence and it was able to detect viral co-infections. Futhermore, the limits of detection were 1 copy/μL for IFA, 10 copies/μL for IFB, 5 copies/μL for RSVA, and 250 copies/μL for RSVB. The genotyping study showed that hospital- and community-acquired RSVA isolates were from the same phylogenetic group (the same group of the NA1 Japanese isolates). Conversely, RSVB isolates were distributed across different groups: BA4, POA1, POA2, POA3 and POA4. This was the first study to describe circulation of the NA1 genotype in Brazil, as well as four RSVB genotypes: POA1, POA2, POA3 and POA4. Conclusion: The results obtained in the first study demonstrate the impact of seasonal epidemics of respiratory viruses. The second study confirmed that molecular techniques such as RT-PCR, are suitable for the detection of respiratory viruses. The third study reported emerging genotypes of RSV. Surveillance studies such as this should be performed periodically to monitor the behavior pattern of the virus in the target population.