Les virus respiratoires induisent de nombreuses et fréquentes pathologies en pédiatrie avec une morbidité importante. Ces virus sont bien connus car étudiés depuis longtemps mais ils sont en évolution constante. L’apparition des antibiotiques, des antiviraux, des soins intensifs, de la vaccination, les connaissances sur l’hygiène ont transformé l’impact de ces virus sur les populations humaines. Nos modes de vie principalement citadins favorisent la diffusion virale locale par le regroupement de presque tous les enfants dans des crèches ou des écoles. De même l’explosion récente des moyens de transport en particulier aérien qui ont reliés physiquement tous les pays du monde entre eux et qui accentuent la diffusion virale mondiale. Faut-il appliquer les mêmes raisonnements dans tous les pays du monde pour lutter contre ces infections ? Cette thèse apporte de nouvelles connaissances sur ce sujet en se focalisant sur les virus influenza et le virus respiratoire syncytial :1) Pendant la pandémie H1N1 au Canada, la mise en évidence de l’augmentation des hospitalisations des enfants asthmatiques, paradoxalement moins souvent ventilés durant leurs séjours en réanimation pédiatrique.2) L’intérêt de la vaccination contre le virus pandémique H1N1 pour diminuer le recours à la ventilation assistée chez les enfants hospitalisés en réanimation pédiatrique.3) Le Canada n’a pas connu de 3ème vague pandémique en raison d’une campagne vaccinale massive qui bien que tardive, a été efficace même 1 an plus tard.(4) La saisonnalité de la bronchiolite dans les régions tropicales est très différente de celle retrouvée dans les pays tempérés et nécessite de réajuster les recommandations de prise en charge à l’aune des données localesEn décrivant la cinétique et l’impact de la pandémie grippale de 2009 sur les enfants hospitalisés en soins intensifs pédiatriques au Canada d’Octobre 2009 à Mars 2011, en comparant cette cohorte à une cohorte similaire en France Hexagonale, et en décrivant 2 épidémies de VRS en Martinique en 2007 et 2008 pour confronter ces données avec celles décrites dans les pays tempérés, ce travail illustre combien nos connaissances doivent toujours être remises en question du fait de l’évolution du climat, de l’évolution de la société et de l’évolution des connaissances médicales / Respiratory viruses are responsible for much pediatric pathology with significant morbidity. These viruses are well known for a long time but are subject to constant changes. The development of antibiotics, antivirals, intensive care, vaccination, knowledge on hygiene has modified the impact of these viruses on human populations. Our predominantly urban lifestyles support local viral spread by bringing almost all children together in nurseries or schools. In the same way, the large use of modern transport facilities especially air transport (which connect all continents between them) facilitate the world viral spread. In this new environment, should we apply the same medical reasoning all over the world to fight against these infections? This thesis brings new knowledge on this topic, focusing on influenza virus and syncytial respiratory virus:1) During Influenza A(H1N1)pdm09, hospitalizations of children with asthma increase, but they were least often to be ventilated during their pediatric intensive care stay.2) The value of vaccination against the pandemic virus to reduce the use of assisted ventilation in children hospitalized in Pediatric Intensive Care Unit.3) Canada did not experience a third pandemic wave in 2010 because of a massive vaccination campaign that, even late, was effective one year later.4) The bronchiolitis season in the tropics is different from what we know in temperate countries. It is mandatory to adjust management recommendations in the light of regional data.By describing the kinetics and impact of the 2009 influenza pandemic on children in pediatric intensive care in Canada from October 2009 to March 2011, comparing this cohort to a similar cohort in France, and comparing 2 epidemics of VRS in Martinique (French West Indies) in 2007 and 2008 with those that have been carried out in temperate countries, this thesis is an example why we have to constantly question our knowledge because of climate change, change in society and medical knowledge evolution.

Respiratory syncytial virus (RSV) causes a common infection that is associated with a range of respiratory illnesses from common cold-like symptoms to serious lower respiratory tract illnesses such as pneumonia and bronchiolitis. RSV is the single most important cause of serious lower respiratory tract illness in children < 1 year of age. Host innate and acquired immune responses activated following RSV infection have been suspected as contributing to RSV disease. Toll-like receptors (TLRs) activate innate and acquired immunity and are candidates for playing key roles in the host immune response to RSV. Leukocytes express TLRs including TLR2, TLR6, TLR3, TLR4, and TLR7 that can potentially interact with RSV and promote immune responses following infection. Using knockout mice, we have demonstrated that TLR2 and TLR6 signaling in leukocytes can activate innate immunity against RSV by promoting TNF-α, IL-6, CCL2 (MCP-1), and CCL5 (RANTES) production. As previously noted, TLR4 also contributed to cytokine activation (71, 90). Furthermore, we demonstrated that signals generated following TLR2 and TLR6 activation were important for controlling viral replication in vivo. Additionally, TLR2 interactions with RSV promoted neutrophil migration and dendritic cell activation within the lung. Collectively, these studies indicate that TLR2 is involved in RSV recognition and subsequent innate immune activation and may play a role in modulating acquired immune responses through DCs. Despite the fact that RSV is the single most important cause of infant upper respiratory tract disease, there are no licensed vaccines available to prevent RSV disease. We have developed a virus-like particle (VLP) vaccine candidate for RSV. The VLP is composed of the NP and M proteins of Newcastle disease virus (NDV) and a chimera protein containing the cytoplasmic and transmembrane domains of the NDV HN protein and the ectodomain of the human RSV G protein (H/G). BALB/c mice immunized with 10 or 40 μg total VLP-H/G protein by intraperitoneal or intramuscular inoculation stimulated antibody responses to G protein as good as or better than comparable amounts of UV-inactivated RSV. Furthermore, VLP-H/G induced robust CTL responses in vaccinated animals. Immunization with two or even a single dose of these particles resulted in the complete protection of BALB/c mice from RSV replication in the lungs. Upon RSV challenge of VLP-H/G immunized mice, no enhanced pathology in the lungs was observed, although lungs of mice immunized in parallel with formalin-inactivated RSV (FI-RSV) showed the significant pathology that has been previously observed with FI-RSV vaccination. Thus, the VLP-H/G candidate vaccine was immunogenic in BALB/c mice and prevented replication of RSV in murine lungs with no evidence of immunopathology. These data support further development of virus-like particle vaccine candidates for RSV.

Made available in DSpace on 2016-01-26T12:51:26Z (GMT). No. of bitstreams: 1 joaobatistasalomaojunior_tese.pdf: 726701 bytes, checksum: be09a3fcaa3d491c8ac2601eb72d7961 (MD5) Previous issue date: 2008-02-08 / Acute lower respiratory tract disease (ALRTD) accounts for high infantile mortality and morbidity rate worldwidely. Respiratory syncytial virus (RSV) is frequently found among pathogens. Objectives: The objectives were: 1) to evaluate the RSV frequency in children from 0 to 6 years hospitalized due to acute lower respiratory disease in São José do Rio Preto, SP; 2) to characterize the virus seasoning in this city and 3) to verify possible association among epidemiologic, clinical and diagnostic data with this viral agent. Casuistic and Method: From May 2004 to September 2005, 278 children aged from 0 to 6 years with ALRTD were studied. They have contracted the disease in the community, hospitalized in the children s ward, emergency room and Pediatric Intensive Care Unit of Hospital de Base, São José do Rio Preto. They were asymptomatic in a 7-day period before the beginning of the disease. Questionnaires were used for the children's characterization and their clinical presentation. Samples of nasopharyngeal secretion were collected to identify RSV, using reverse transcription polymerase chain reaction (RT-PCR). Results: The results showed that in the 290 hospitalizations of ALRTD, RSV was positive in 29.3%. ALRTD was more frequent in infants (average = 13.5 months) and male (57.6%). RSV was more frequent in bronchiolitis cases (64%). RSV+ infections were more frequent in the first year of life (35%). In RSV + infections, pneumonia frequency varied from 19.5 to 26.2% in the studied age groups; acute wheezing was observed in 31.8% of children aged over 2 years; bronchiolitis was registered in 62.5% of the children younger than 1 year; pneumonia with pleural effusion was noticed in 18.7% of the children aged over 2 years. Conclusions: The frequency of RSV in children from 0 to 6 years hospitalized due to ALRTD was 29.3% in São José do Rio Preto, SP. The ALRTD were more frequent between June and November 2004. In 2005, the hospitalizations occurred mainly starting from March decreasing in September. There was RSV prevalence in children younger than 2 years, male and with bronchiolitis. The RSV frequency in the hospitalizations was higher in 2004 than in 2005. In the RSV+ infections, the cases of pneumonia had similar occurrence in the studied age groups. There was reduction of the RSV frequency as age increases in the cases of pneumonia with pleural effusion and increase in the cases of acute wheezing; in bronchiolitis most of the RSV+ cases occurred in children younger than1 year. The clinical and radiological data obtained did not allow the proper identification of the infection by RSV. Laboratory examination by means of RT-PCR was necessary to identify it. / As doenças agudas do aparelho respiratório inferior (DARI) são responsáveis por altos índices de mortalidade e morbidade infantil em todo mundo. Dentre os patógenos predominantes encontra-se o vírus sincicial respiratório (VSR). Objetivos: Os objetivos foram: 1) avaliar a freqüência do VSR em crianças de 0 a 6 anos hospitalizadas por DARI em São José do Rio Preto, SP; 2) caracterizar a sazonalidade do vírus nessa cidade e 3) evidenciar possível associação de dados epidemiológicos, clínicos e diagnósticos e este agente viral. Casuística e Método: No período de maio de 2004 a setembro de 2005 foram estudadas 278 crianças de 0 a 6 anos com DARI adquirida na comunidade, internadas na enfermaria, emergência e Unidade de Terapia Intensiva Pediátrica do Hospital de Base de São José do Rio Preto, que estavam assintomáticas por um período de 7 dias antes do início da doença. Foram utilizados questionários para caracterização das crianças e do quadro clínico. Para identificação do VSR foram coletadas amostras de secreção de nasofaringe, utilizando-se a técnica de Reverse Transcription Polymerase Chain Reaction (RT-PCR). Resultados: Os resultados mostraram que nas 290 internações por DARI, o VSR foi positivo em 29,3%. DARI foi mais freqüente em lactentes (mediana = 13,5 meses) e do gênero masculino (57,6%). O VSR foi mais freqüente nos casos de bronquiolite (64%). As infecções VSR+ foram mais freqüentes no primeiro ano de vida (35%). Nas infecções VSR+, a freqüência de pneumonia variou de 19,5 a 26,2% nas faixas etárias estudadas; em 31,8% das crianças maiores de 2 anos observou-se sibilância aguda; bronquiolite foi registrada em 62,5% das crianças menores de 1 ano; pneumonia com derrame pleural foi notada em 18,7% das crianças maiores de 2 anos. Conclusões: A freqüência do VSR em crianças de 0 a 6 anos hospitalizadas por DARI em São José do Rio Preto, SP, foi 29,3%. As DARI foram mais freqüentes entre junho e novembro de 2004. Em 2005, as internações ocorreram principalmente a partir de março, com queda em setembro. Houve predomínio do VSR em crianças de 0 a 2 anos, do gênero masculino e com bronquiolite. A freqüência do VSR nas internações foi maior em 2004 que em 2005. Nas infecções VSR+ os casos de pneumonia tiveram ocorrência semelhante nas faixas etárias estudadas. Houve redução da freqüência do VSR com aumento da idade nos casos de pneumonia com derrame pleural e aumento nos casos de sibilância aguda; na bronquiolite a maioria dos casos VSR+ ocorreu em crianças menores de 1 ano. Os dados clínicos e radiológicos encontrados não permitiram a identificação correta da infecção pelo VSR, havendo necessidade do exame laboratorial pela técnica RT-PCR para sua identificação.