Made available in DSpace on 2014-10-09T12:47:23Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:10:01Z (GMT). No. of bitstreams: 1 08344.pdf: 3520298 bytes, checksum: 2a5d00aa09a166d2736831c70798e5a4 (MD5) / Dissertacao (Mestrado Profissionalizante em Lasers em Odontologia) / IPEN/D-MPLO / Instituto de Pesquisas Energeticas e Nucleares, IPEN/CNEN-SP; Faculdade de Odontologia, Universidade de Sao Paulo

Made available in DSpace on 2015-04-20T12:31:54Z (GMT). No. of bitstreams: 1 Liliane Coelho da Rocha.pdf: 1977290 bytes, checksum: 135132c02bcd9e4dc7368e1a021d52b4 (MD5) Previous issue date: 2011-05-30 / Fundação de Amparo à Pesquisa do Estado do Amazonas / Variations in clinical manifestations of leishmaniasis suggest the existence of a differentiation species dependent in the ability of the Leishmania parasites cause lesions in the host. The search for factors that differentiate the species of this genus and its virulence and infectivity is needed to better understand the mechanisms by which these parasites cause damage to the reservoir hosts, thus enabling the discovery of new tools for immunological and therapeutic potential against leishmaniasis. Although many aspects of immune response to this parasite already known, there are several gaps in knowledge related to the characteristics of the parasite itself, that are related to infection. The in vitro and in vivo assays with axenic promastigotes of Leishmania (Leishmania) amazonensis in logarithmic phase, maintained for long periods in culture, macrophages incubated with strain and inoculated in susceptible mammals, were unable to infect macrophages and hamsters. The loss of infectivity and virulence of promastigotes grown continuously, probably due to selection in the sample initially stable, and infective to a population of non-infective promastigotes. The decoded genome of Leishmania (Leishmania) major and Leishmania (Leishmania) infantum and functional studies of many genes by different research groups, as well as other species of the genus, coupled with the simultaneous advance of proteomics, and accelerated favored significantly study the biology of the genus Leishmania. The use of proteomics technique for the study of proteins related to the infectivity of Leishmania, using 2-DE maps for the detection of protein expression profiles of infected and non infected forms of L. (L.) amazonensis coupled with mass spectrometry ESI-QTof (Electrospray Ionization) for identification of proteins were used in this study. Were detected 251 and 145 spots of proteins differents in promastigotes infective and non-infective, respectively. The two dimensional (2-DE) proteins of L. (L.) amazonensis promastigotes infective and non infective indicated differences in protein expression among the forms studied, revealing the absence of expression of some proteins in the non infective samples. Most of the proteins identified in this study is involved in metabolic processes related to the infectivity and virulence of Leishmania such as: heat shock - HSP83 and HSP70, enzymes - nucleoside diphosphate kinase, protein disulfide isomerase, enolase, trypanothione reductase, mitochondrial tryparedoxin peroxidase and ATPase, cytosolic tryparedoxin and the elongation factor-α. These data confirm the feasibility of doing a sweep of the protein profile of an organism related to its infectivity/virulence protein profiles based on 2-DE. Given the results presented in 2-DE maps and the identification of proteins present in the forms studied we can conclude that the infectivity and virulence of promastigotes of L. (L.) amazonensis is related to a number of factors and proteins whose expression has fundamental importance for the survival/multiplication of the parasite in the reservoir-host / Variações nos quadros clínicos da leishmaniose sugerem a existência de uma diferenciação, dependente da espécie e na capacidade de parasitos do gênero Leishmania causar lesões no hospedeiro. A busca por fatores que diferenciam as espécies deste gênero quanto a sua infectividade e virulência se faz necessária para uma melhor compreensão dos mecanismos pelos quais esses parasitos causam danos aos seus hospedeiros, possibilitando assim a descoberta de novas ferramentas de potencial imunológico e terapêutico contra a leishmaniose. Embora muitos aspectos, da resposta imune a esse parasito, já sejam conhecidos, existem diversas lacunas no conhecimento relacionadas às características do próprio parasito que estejam envolvidas com a infecção. Ensaios in vitro e in vivo com promastigotas axênicas de fase logarítmica de Leishmania (Leishmania) amazonensis, mantidas por longos períodos em cultivo, incubados com macrófagos de linhagem e inoculados em mamíferos suscetíveis, mostraram-se incapazes de infectar macrófagos e hamsters. A perda da infectividade e virulência de formas promastigotas continuamente cultivadas provavelmente ocorreram devido à seleção na amostra inicialmente estável e infectiva para uma população de formas promastigotas não-infectivas. O genoma decifrado de Leishmania (Leishmania) major e Leishmania (Leishmania) infantum e os estudos funcionais de vários genes, por diferentes grupos de pesquisa, bem como de outras espécies do gênero, aliado ao avanço simultâneo da proteômica, acelerou e favoreceu de forma significativa o estudo da biologia do gênero Leishmania. O uso da técnica proteômica para o estudo de proteínas de Leishmania relacionadas à infectividade, através do uso de mapas 2-DE para a detecção dos perfis de expressão protéica das formas infectivas e não infectivas de L. (L.) amazonensis aliado a espectrometria de massas por ESI-QTof (Electrospray Ionization) para identificação das proteínas, foram utilizados nesse estudo. Foram detectados 251 e 145 spots protéicos diferentes nas formas promastigotas infectiva e não infectivas, respectivamente. A análise bidimensional (2-DE) de proteínas de promastigotas de L. (L.) amazonensis infectivas e não infectivas indicou diferenças na expressão protéica entre as formas estudadas, revelando a ausência de expressão de algumas proteínas nas amostras não infectivas. A maior parte das proteínas identificadas neste estudo está envolvida em processos metabólicos relacionados à infectividade e virulência de Leishmania como as: de choque térmico - HSP83 e HSP70, enzimas nucleosídeos difosfato quinase, dissulfeto isomerase, enolase, tripanotiona redutase, triparedoxina peroxidase mitocondrial e ATPase, a triparedoxina citosólica e os fatores de alongamento α. Esses dados confirmam a exequibilidade de se fazer uma varredura do perfil protéico de um organismo relacionado à sua infectividade/virulência baseada nos perfis protéicos em 2-DE. Em vista dos resultados apresentados nos mapas 2-DE e na identificação das proteínas presentes nas formas estudadas podemos concluir que a infectividade e virulência de promastigotas de L. (L.) amazonensis esta relacionada a um conjunto de fatores e proteínas cuja expressão é de fundamental importância para a sobrevivência/multiplicação do parasito no seu hospedeiro

Submitted by isabela.moljf@hotmail.com (isabela.moljf@hotmail.com) on 2017-07-26T13:40:04Z No. of bitstreams: 1 sandrahelenacarratotibirica.pdf: 2260939 bytes, checksum: e1f49dcf7848afde81dd604c28763e2d (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-08-08T18:45:05Z (GMT) No. of bitstreams: 1 sandrahelenacarratotibirica.pdf: 2260939 bytes, checksum: e1f49dcf7848afde81dd604c28763e2d (MD5) / Made available in DSpace on 2017-08-08T18:45:05Z (GMT). No. of bitstreams: 1 sandrahelenacarratotibirica.pdf: 2260939 bytes, checksum: e1f49dcf7848afde81dd604c28763e2d (MD5) Previous issue date: 2006-04-10 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O objetivo desse estudo foi avaliar a prevalência, infectividade, biometria, abundância e distribuição geográfica de espécies de Biomphalaria no município de Juiz de Fora, Minas Gerais, no ano de 2004. As coletas foram realizadas para atender a dois propósitos. O primeiro propósito visou identificar e avaliar a infectividade, abundância, biometria e distribuição geográfica das espécies encontradas. Desta forma, ocorreram coletas em 31 localidades sendo seis represas, onze açudes, sete hortas contendo valas de irrigação, cinco lagos, uma lagoa e uma cachoeira. As 124 visitas ao campo foram distribuídas nos quatro ciclos estacionais (cada ponto foi visitado quatro vezes) e 1770 moluscos foram capturados, com padronização do tempo de coleta. O segundo propósito, de alargar a amostra para se avaliar a infectividade, ocorreu no início da estação chuvosa do ano de 2004, e 3494 exemplares de Biomphalaria foram coletados sem padronização do tempo de captura. Os 5.264 espécimes, oriundos de dez localidades, sendo três açudes e sete hortas, predominaram nas regiões leste e norte da mancha urbana. Todas as valas de irrigação investigadas estavam colonizadas por Biomphalaria. Através de técnicas de análise morfológica e molecular, identificaram-se três espécies: B. tenagophila, B. peregrina e B. straminea. Nas dez localidades em que se registrou a presença do molusco do gênero Biomphalaria a distribuição foi a seguinte: B. tenagophila foi prevalente em 60 % dos pontos, e B. peregrina em 20% dos pontos. Constatou-se, pela primeira vez no município, a espécie B. straminea que ocorreu em 20% dos pontos. Nenhum molusco foi encontrado infectado com Schistosoma mansoni, no entanto, exemplares de B. straminea capturados nas coordenadas 21º39’59’’S e 43°25’09’’W, quando submetidos ao teste de suscetibilidade ao S. mansoni apresentaram 25,4% de infectividade. Observou-se forte correlação inversa entre as variáveis abundância de Biomphalaria e pluviosidade local, em todas as espécies estudadas. A temperatura influenciou as populações de Biomphalaria estudadas na faixa das médias inferiores a 15,7°C. Estatisticamente, o estudo das variáveis tamanho e peso revelou que as menores médias biométricas ocorreram em B. peregrina, seguida de B. straminea, e as maiores dimensões corporais foram as de B. tenagophila. Verificou-se forte correlação positiva entre as variáveis peso (massa corpórea) e tamanho (diâmetro da concha), nos exemplares encontrados. Conclui-se que no município de Juiz de Fora ocorrem três espécies de Biomphalaria, sendo duas delas, B. straminea e B. tenagophila, de importância epidemiológica. A pluviosidade e a temperatura interferem na abundância dos espécimes locais. Todas as medidas de peso e tamanho das amostragens de Biomphalaria, em Juiz de Fora, estão abaixo das máximas dimensões referidas na literatura. / The objective of this study was to identify the species of Biomphalaria and evaluate their prevalence, infectivity, biometry, abundance and geographic distribution in the municipality of Juiz de Fora, Minas Gerais, Brazil, in 2004. The samples were collected for two purposes. The first was to identify the infectivity, abundance and geographic distribution of the species found. Therefore, samples were collected in 31 locations: 6 reservoirs, 11 rudimentary holding ponds, 7 irrigation ditches, 5 lakes, 1 ornamental pond and 1 waterfall. The 124 field visits were spaced throughout the four seasons (each point visited four times) and 1,770 snails were captured, with standardized collection intervals. The second purpose, to enlarge the sample to assess infectivity, occurred at the start of the wet season in 2004, and 3,494 exemplars of Biomphalaria were collected, without standardized collection intervals. These specimens were gathered from 10 locations – 3 rudimentary holding ponds and 7 irrigation ditches – predominantly in regions located to the east and north of the main urban sprawl. All told, then, 5,264 specimens were collected. All the irrigation ditches were colonized by Biomphalaria. Through morphological and molecular identification techniques, three species were identified: B. tenagophila, B. peregrina and B. straminea. B. tenagophila was prevalent in 60 % of the points and B. peregrina in 20% of them. This is the first report in the municipality of B. straminea, occurring in 20% of the points. No snails were found infected by Schistosoma mansoni, but snails of the species B. straminea captured at 21º39’59’’S and 43°25’09’’W, when submitted to the susceptibility test to S. mansoni, showed an infection rate of 25.4%. There was a strong inverse correlation between the abundance of Biomphalaria and the local rainfall, in all species studied. Temperature influenced the populations of Biomphalaria studied in the range below 15.7°C. Statistical study of the size and weight variables revealed that the smallest biometric averages occurred in B. peregrina, followed by B. straminea, and the largest body dimensions were those of B. tenagophlia. There was a strong positive correlation between weight (body mass) and size (shell diameter) in the exemplars found. The conclusion is that three species of Biomphalaria occur in the municipality of Juiz de Fora, two of them (B. straminea and B. tenagophila) of epidemiological importance. Rainfall and temperature interfered in the abundance of the local specimens. All the weight and size measures of the Biomphalaria specimens in Juiz de Fora are below the maximum figures referred to in the literature.

Abstract Chronic Chlamydia pneumoniae infections have been associated with cardiovascular diseases (CVD), but the treatment is difficult. Some drugs used for CVD have been found to have an inhibitory effect on the C. trachomatis infection, which is not considered to be associated with CVD. The purpose of this study was to investigate the effects of heparan sulfate-like glycosaminoglycans, COX inhibitors and rapamycin on the C. pneumoniae infection with cell culture methods. Almost any conceivable factors may affect the results of cell cultures. This study showed the complex interaction between temperature, time and medium during the pre-treatment before inoculation. The influences of these factors on the results overlapped and interlaced. The simple washing procedure could enhance the infectivity of C. pneumoniae although it is generally considered to cause the loss of chlamydial EBs and sequentially decrease the chlamydial infectivity. Although the detailed mechanisms were not studied, the results of this study showed that selective COX inhibitors and rapamycin can inhibit the infectivity of C. pneumoniae by inhibiting the growth and maturation, whereas heparan sulfate-like glycosaminoglycans perhaps inhibit the attachment of C. pneumoniae EBs onto the host cells. Recovery and repassage results showed that the growth can be only delayed by selective COX inhibitors, and it can recover to normal level once the drugs were removed. However, rapamycin inhibited the maturation of chlamydial EBs and therefore the infectivity fell down further even when the rapamycin was removed. This study also presented the variations of pathogenicity between different C. pneumoniae strains in vitro. This study is based on in vitro experiments with an acute infection model. Thus, any definite conclusions on the possible antichlamydial effects of the drugs tested in the treatment of cardiovascular diseases which are associated with chronic C. pneumoniae infections cannot be drawn on the basis of this study.

Infectious diseases among preeschool children are in 70–80% of the cases caused by virus. The most common illnesses the children suffer are otitis, respiratory tract infections (common colds) and gastroenteritis. To reduce the risk of infectivity it’s recommended to wash hands regularly and to use gloves and disposable sheets during diaper change. To be able to ensure environmental qualities and health qualities in the preeshool, the hygiene routines for handwashing and diaper change, among others, must be documented in writing. Research show that if the teachers gets educated in infectivity and infection prevention, their attitudes and the implementation of the hygiene routines can be improved. In my study I wanted to show what the routines for handwashing, diaper change and the acceptance of ill childen look like. I also wanted to look into what knowledge the teachers confides in, when it comes to infection prevention, and also what perceptions there are about working with infection prevention in these preeshools. To answer my questions surveys have been sent out to all preeschools in the municipality and one preeschool director has been interviewd. The results show the lack off documented hygiene routines in 10% of the participants workplaces, which makes it hard to assure the health qualities in these preeshools. In a few other preeschools it turns out that all of the teachers lack eduaction in infectivity and infection prevention. My results implies that education in infectivity and infection prevention as well as documented hygiene routines, may affect if infection prevention routines are discussed at the workplace or not. Further studies in this subject are recommended before any conclusions can be made about this. / Infektionssjukdomar hos förskolebarn är i 70–80 procent av fallen orsakade av virus. De sjukdomar som barnen i största utsträckning drabbas av är öroninflammationer, luftvägsinfektioner (förkylningar) och mag- och tarmåkommor. För att minska risken för smittspridning rekommenderas regelbunden handtvätt och användning av handskar och engångsunderlägg vid blöjbyte. För att kunna säkerställa miljö- och hälsokvaliteten, i förskolan, måste det finnas skriftligt dokumenterade rutiner på bland annat handtvätt och blöjbyte. Forskning visar att om pedagogerna fått utbildning inom smittspridning och smittskydd, kan attityden och genomförandet av hygienrutinen förbättras. I min undersökning ville jag synliggöra hur rutinerna kring handtvätt, blöjbyte och mottagandet av sjuka barn ser ut. Jag ville också undersöka vilken kunskap pedagogerna förlitar sig på rörande smittskydd, samt vilka attityder som finns om smittskyddsarbetet i verksamheten. För att få svar på mina frågor har enkäter skickats ut till samtliga avdelningar i kommunen och en förskolechef har intervjuats. Resultaten visar att det saknas skriftliga hygienrutiner hos 10% av deltagarna vilket leder till att det blir svårt att säkerställa hälsokvaliteten i dessa verksamheter. I ett fåtal andra verksamheter visar det sig att samtliga pedagoger saknar utbildning inom smittspridning och smittskydd. Mina resultat antyder att utbildning inom smittspridning och smittskydd liksom dokumenterade hygienrutiner, kan påverka ifall smittskyddsrutiner diskuteras i arbetslagen eller inte. Vidare forskning inom ämnet rekommenderas innan några slutsatser kan dras om detta.

Ce travail avait pour objectif : 1) évaluer le portage de gamétocytes et leur génotype avant et après le traitement d’une part, et d’étudier leur infectivité ; 2) exprimer le domaine catalytique (PfMCA1-cd-Sc) de la métacaspase de Plasmodium falciparum (PfMCA1) chez la levure et 3) tester in vitro l’activité antiplasmodiale de nouvelles molécules synthétiques dérivées des pyrano et ferro-quinoléines sur des clones de laboratoire 3D7 et Dd2. Pour cela, le test in vivo de 28 jours de l’OMS, les marqueurs moléculaires de résistance et le « direct feeding » ont été utilisés pour le premier objectif. La culture des levures, l’expression des protéines de la métacaspase 1 de Plasmodium falciparum, le western blot, le test de prolifération et de survie, et les marqueurs de mort cellulaire ont servi pour le second objectif et enfin, la culture parasitaire et tests in vitro par la méthode de fluorimétrie au Sybr Green I ont permis l’évaluation de l’activité antiplasmodiale de nouvelles molécules. Nous avons démontré que les gamétocytes post-traitement étaient porteurs de mutations ponctuelles et plus infectants dans le groupe chloroquine ; que l’expression hétérologue du domaine catalytique de la métacaspase de Plasmodium falciparum (PfMCA1) dans la levure Saccharomyces cerevisiae entraînait une mort clonale de type apoptotique et un retard de croissance dépendant de l’activité VAD-Protéase et enfin, que les substitues aromatiques à base de pyrimidine ou de benzylméthylamine ferrocène révèlent une activité satisfaisante par rapport à la méthoxyéthylidene sur les clones 3D7 et Dd2. / Plasmodium species use programmed cell death for the survival of their offspring as some prokaryotic parasites. This study was designed to - assess the gametocytes carrier and their genotypes before/ after treatment and studying their infectivity; - express the catalytic domain (PfMCA1-cd-Sc) of Plasmodium falciparum metacaspase (PfMCA1) in yeast; - Test the “in vitro” anti-plasmodial activity of pyrano and ferro- quinolines derived new synthetic molecules on 3D7 and Dd2 Chloroquine laboratory clones. The 28-day “in vivo” WHO test, molecular markers of resistance and direct feeding; yeast culture, protein expression of P. falciparum metacaspase 1, Western blot, proliferation and survival test, and cell death markers were used to achieve the first two objectives while parasite culture and in vitro tests by the method of fluorimetry in SYBR Green I was used to evaluate the anti-plasmodial activity of new molecules. Results show that post-treatment gametocytes were carriers of point mutations and the most infective in the Chloroquine group. The heterologous expression of PfMCA1 catalytic domain in Saccharomyces cerevisiae resulted in apoptotic clonal death and growth retardation activity-dependent Protease-VAD, showing the involvement of PfMCA1 in the process of cell death. The aromatic substitutes with pyrimidine or benzyldimethylamine ferrocene residues showed satisfactory activity against the methoxyethylidene on 3D7 and Dd2. The data suggest that the structural optimization of these compounds based on pyrimidine and ferrocene is more interesting from the standpoint anti-plasmodial activity for candidate molecules in the near future.

<div> <div> <div> <p>Flaviviruses is a genus within the family Flaviviridae. The genus consists of more than 70 viruses, including important threatening human pathogens such as dengue virus (DENV), West Nile virus (WNV), and Zika virus (ZIKV). These viruses are causative agents for a range of mild to lethal diseases and there are currently no US- licensed therapeutic treatments for infection. The virus genome is a positive-sense, single-stranded RNA, encoding ten viral proteins. Of the ten flavivirus proteins, Non- Structural protein 1 (NS1) remains the most elusive in terms of its functions. To date NS1 has been linked to disease pathology and progression and plays roles in virus replication and assembly. However, little is understood how NS1 orchestrates these functions and how NS1 from different viruses function distinctively from one another. Moreover, flavivirus NS1 has a peculiar ability to associate with lipid membranes. During the life cycle of NS1, the protein travels through the classical secretory path- way, similar to infectious virus particles, and is secreted into the extracellular space as mostly hexameric oligomers containing a lipid core. How the protein binds to lipids and whether such lipid binding is important for NS1 functions and overall flavivirus pathology remain unknown. Using structure-based mutagenesis, we found a group of mutants on WNV NS1, which particularly altered the viral specific infectivity but maintained wild-type level of virus replication. Purified mutated virus particles revealed that the specific infectivity alteration was not because of the particle but interaction of the virus particles and NS1 mutated proteins. Here we demonstrated that specific residues on NS1 were responsible for distinctly roles in NS1 functions and the virus specific infectivity was regulated by NS1 protein. In other structure-base study, we focused on the membrane association ability of NS1. All structure-predicted regions on NS1 were examined for its contribution for the membrane/lipid binding function. This interaction was required for NS1 biology activities including intracel- lular trafficking, oligomerization, and endocytosis. The lipidomes from deletion of each membrane association region revealed differences in lipid classes binding to each region and the composition flexiblity of the lipid cargo of NS1 hexamer. </p> </div> </div> </div>

No / To investigate whether there are differences between members of the Burkholderia cepacia complex in their ability to invade human respiratory epithelial cells, 11 strains belonging to genomovars I-V were studied in an antibiotic protection assay using the A549 cell line. Strains belonging to genomovars II and III were more invasive than those of genomovars I, IV and V. There was also intra-genomovar variation in invasiveness. No correlation between invasiveness and other putative virulence factors of importance in B. cepacia infection in individuals with cystic fibrosis, cable pilus and B. cepacia epidemic strain marker was identified.

Many bacteria, viruses and other parasites cause severe morbidity or mortality in their host populations, creating strong selection for physiological or behavioural mechanisms to avoid disease. Likewise, changes in host susceptibility and contact patterns can dramatically influence the spread of infectious diseases, and hence selection for traits such as virulence and infectivity range in parasites. Understanding how ecological and evolutionary changes in one population affect selection in another represents a key challenge for theoreticians and empiricists alike, and is essential for gaining further insights into host-parasite relationships. This thesis contains theoretical models that explore how genetic and environmental factors shape the evolutionary and coevolutionary dynamics of hosts and parasites. In particular, the roles of genetic specificity (i.e. genotype-by-genotype interactions) and population mixing patterns are investigated, using both mathematical models and computer simulations. A broad range of scenarios are covered, including the coevolution of broad resistance and infectivity ranges (generalism), the persistence of coevolutionary cycling and the maintenance of sex, the effects of mating behaviour on disease prevalence and evolution, and the evolution of sexual and social behaviour. The models presented herein develop our understanding of host-parasite relationships and highlight the importance of genetic interactions and ecological feedbacks.

La protéine Nef des virus de l’immunodéficience humaine (VIH-1 et VIH-2) joue un rôle essentiel dans la physiopathologie de l’infection et induction du SIDA. La capacité de Nef à perturber le trafic intracellulaire de protéines membranaires, et notamment du récepteur CD4, circulant entre les compartiments de la voie d’endocytose pourrait rendre compte de son importance comme facteur de virulence au cours de l’infection naturelle. Les mécanismes responsables des perturbations de la voie d’endocytose induites par Nef au cours de l’infection ne sont pas totalement élucidés, mais il est admis qu’elles résultent d’interactions avec les complexes adaptateurs (AP) associés à la clathrine et participant au transport vésiculaire entre les différents compartiments de la voie d’endocytose. Notre objectif était de déterminer les mécanismes par lesquels Nef influe positivement sur le pouvoir infectieux du VIH-1 en interagissant avec la machinerie cellulaire de la voie d’endocytose. Notre programme s’est organisé autour de deux axes principaux: le premier a consisté à étudier l’implication respective des différents types de complexes AP (AP-1, -2 et -3) sur les perturbations du fonctionnement de la voie d’endocytose induites par Nef en analysant son impact sur le niveau d’expression de surface de CD4; le deuxième axe a consisté à évaluer l’impact de l’interaction de Nef avec les complexes AP sur les capacités infectieuses des particules virales. Le rôle respectif des différents complexes AP dans ces fonctions de Nef a donc été étudié après déplétion de l’expression des complexes AP-1, AP-2 et AP-3 par une approche d’ARN interférence. Les résultats obtenus montrent que contrairement à certaines données de la littérature, la déplétion des complexes AP de la voie d’endocytose ne semble pas avoir un impact majeur sur la capacité de Nef à moduler l’expression de surface de CD4, même si une légère diminution de l’activité de Nef a pu être révélée dans notre étude réalisée sur des cellules HeLa-CD4 transduites par les shRNA ciblant les complexes AP-2. Inversement, nos résultats confirment que la déplétion des complexes AP-1, AP-2 et AP-3 dans les cellules productrices des particules virales se traduit par une diminution importante des propriétés infectieuses de ces particules sur lesquelles l’impact positif de Nef n’est plus alors capable de se manifester. En conclusion, ce travail a donc permis de montrer que les complexes AP de la voie d’endocytose sont indispensables pour que Nef puisse exercer son rôle positif sur le pouvoir infectieux du VIH-1. Il est maintenant important de confirmer ces résultats en analysant le rôle fonctionnel des complexes AP sur les activités de Nef dans les cibles cellulaires naturelles du VIH-1, lymphocytes et macrophages. / Nef protein of human immunodeficiency virus (HIV-1 and HIV-2) plays an essential role in the pathophysiology of infection and induction of AIDS. The ability of Nef to disrupt intracellular trafficking of membrane proteins, including the CD4 receptor, moving between the compartments of the endocytic pathway could account for its importance as a virulence factor during natural infection. The mechanisms responsible for disruption of the endocytic pathway induced by Nef during infection are not fully understood, but it is accepted that they arise from interactions with adaptor complexes (AP) associated with clathrin and participant in vesicular transport between the different compartments of the endocytic pathway. Our objective was to determine the mechanisms by which Nef positively affects the infectivity of HIV-1 by interacting with the cellular machinery of the endocytic pathway. Our program has been organized around two main axes: the first was to investigate the respective involvement of different types of complexes (AP-1, -2 and -3) on the Nef induced disruption of the endocytic pathway by analyzing its impact on the level of surface expression of CD4; the second axis was to evaluate the impact of the interaction of Nef with AP complexes on the infectious capacity of the viral particles. The respective roles of the different AP complexes in these functions of Nef has been studied after depletion of the expression of complex AP-1, AP-2 and AP-3 by RNA interference approach. The results show that, contrary to some literature data, depletion of AP complex endocytic pathway does not appear to have a major impact on the ability of Nef to modulate the surface expression of CD4, although a slight decreased activity of Nef could be revealed in our study on HeLa-CD4 cells transduced with the shRNA targeting complex AP-2. Conversely, our results confirm that the depletion of complex AP-1, AP-2 and AP-3 in the cells producing viral particles resulted in a significant decrease in infectious properties of these particles on which the positive impact of Nef is no longer able to manifest. In conclusion, this work has shown that complex AP of endocytic pathway are essential for Nef to exercise its positive role in the infectivity of HIV-1. It is now important to confirm these findings by analyzing the functional role of AP complexes on the activities of Nef in the natural cellular targets of HIV-1, lymphocytes and macrophages.