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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Etude des variants résistants minoritaires aux antirétroviraux : impact sur la réponse virologique au traitement / Study of minority resistant variants to antiretroviral : impact on virologic response to treatment

Todesco, Eve 18 December 2015 (has links)
Les mutations de résistance pour une molécule sont produites avant que la molécule en question ne soit utilisée, et c’est sous « pression de sélection » que la souche résistante va être sélectionnée. Des données récentes montrent que des variants résistants minoritaires (VRMs) peuvent être une source d’échec virologique. Les nouvelles techniques de séquençage sont bien plus sensibles que les techniques classiques de séquençage et permettent la détection des VRMs. Afin d’évaluer l’intérêt de l’utilisation de ces techniques, nous avons étudié les prélèvements de patients en situation d’échec virologique après traitement par deux combinaisons antirétrovirales très utilisées (tenofovir/emtricitabine/efarirenz et tenofovir/emtricitabine/rilpivirine). De nombreux variants de résistance supplémentaires ont été détectés, touchant principalement la classe des Inhibiteurs Nucléosidiques de la Transcriptase Inverse (INTIs), avec un impact potentiel sur le choix du traitement de relais. Nous avons également étudié la prévalence des mutations de résistance transmise sur le gène de la protéase et de la transcriptase inverse chez des patients naïfs chroniquement infectés, chez deux groupes de transmission : des patients hommes ayant des rapports avec d’autres hommes (HSH), et des patients hétérosexuels. Nous avons retrouvé une prévalence plus élevée de mutations touchant les INTIs dans le groupe des patients hétérosexuels. Parmi les patients HSH, ceux infectés par un virus de sous-type B étaient plus fréquemment infectés par un virus résistant. Cette thèse met en avant la puissance des ces techniques, dont les conditions d'utilisation ne sont pas encore complètement définies. / Resistance mutations for a given molecule are produced before the molecule is used, and it is under "selection pressure" that the resistant strain will be selected. Recent data show that minority resistant variants (MRV) can be a source of virologic failure. New sequencing techniques are much more sensitive than conventional sequencing techniques and allow MRV detection. To assess the value of these new techniques, we studied samples from patients experiencing virologic failure after treatment with two antiretroviral combinations widely used (tenofovir/emtricitabine/efarirenz et tenofovir/emtricitabine/rilpivirine). Many additional resistance variants affecting the class of nucleoside reverse transcriptase inhibitors (NRTIs) were detected, with a potential impact on the choice of the subsequent regimen. We also studied the prevalence of transmitted resistance mutations in the protease and reverse transcriptase genes among naive patients chronically infected, among two groups of transmission: patients of men who have sex with men (MSM) and heterosexual patients. We found a higher prevalence of NRTI mutations among the heterosexual group. Among MSM patients, those infected with subtype B viruses were more frequently infected with a resistant virus. This thesis highlights the power of these techniques, the conditions of use are not yet fully defined.
2

Prevalência de mutações do HIV-1 e avaliação de subtipos virais em falha terapêutica no estado do Pará

Lopes, Carmen Andréa Freitas January 2014 (has links)
Introdução: Resistência aos antirretrovirais pode limitar opções de tratamento, principalmente em pacientes com acúmulo de falhas terapêuticas, o que pode comprometer resultados clínicos. Objetivos: caracterizar o perfil de mutações na transcriptase reversa e protease do HIV-1 de pacientes em falha ao tratamento. Secundariamente, avaliar associação entre mutações e número de falhas terapêuticas, associação entre mutações e subtipos do HIV-1 e apresentar a evolução temporal da prevalência dos subtipos do HIV-1, no estado do Pará, ao Norte do Brasil. Método: Estudo transversal, no qual se avaliam genotipagens, entre janeiro de 2004 a dezembro de 2013, com dados obtidos de formulário de solicitação do exame padronizado pela RENAGENO e de impressos dos resultados, ambos arquivados em quatro serviços de atendimento especializados. Foram incluídos os testes realizados por laboratório da RENAGENO, em maiores de 18 anos, e o primeiro exame daqueles que o realizaram em mais de um momento, totalizando 377 amostras. As mutações são descritas de acordo com o banco de dados de resistência do HIV da Universidade de Stanford (http://hivdb.stanford.edu), estimam-se suas prevalências e avaliam-se mutações de resistência de acordo com o número de falhas no momento da genotipagem, bem como diferenças de mutações entre subtipos B e não-B do HIV-1. Resultados: A mutação M184V foi a mais prevalente (80,1%), seguida da K130N (40,6%) e TAM. Em pacientes multiexperimentados previamente à genotipagem, resistência a ZDV, d4T e TDF foi associada às mutações M41L, D67N, V118I, L210W, K219Q e T69D; bem como resistência a todos os IP/r associou-se às mutações principais M46I, V82A, L90M, I54V, I84V, M46L e L76V. O subtipo B é o predominante no Pará (90,7%) e diferenças de prevalência de mutações entre subtipos ocorreram entre as mutações L63P e A71T versus subtipo B, enquanto as mutações L76V, M36I, K20R, L10V, L89M e F53L associaram-se ao subtipo não-B. Conclusão: A seleção de mutações de resistência do HIV-1 relacionada aos antirretrovirais é similar ao descrito em literatura. O acúmulo de falhas ao tratamento favorece a emergência de mutações, o que reforça o monitoramento de falha virológica, seguida de genotipagem para minimizar o impacto de resistência. Estudos adicionais de epidemiologia molecular são necessários para avaliar melhor a questão da prevalência de subtipos de HIV-1 no estado e possíveis associações com mutações de resistência do HIV-1. / Introduction: Resistance to antiretroviral treatment can limit treatment options, especially in patients with accumulation of therapeutic failures, which may compromise clinical outcomes. Objectives: characterizing the profile of mutations in the protease and reverse transcriptase of HIV-1 patients in the treatment failure. Secondarily to evaluate the association between mutations and the number of treatment failures, association between mutations and subtypes of HIV-1 and present the temporal evolution of the prevalence of subtypes of HIV-1 in the state of Pará in northern Brazil. Method: cross-sectional study in which genotyping is evaluated between January, 2004 and December, 2013 with data obtained from the standardized application form for the examination RENAGENO and printed the results, both filed in four specialty care services. We included those by laboratory RENAGENO in 18 years and the first examination in those who underwent more than one time, totaling 377 samples. Mutations are described according to the database of HIV resistance at Stanford University (http://hivdb.stanford.edu), estimated their prevalence and resistance is evaluated according to the number of failures at the time of genotyping as well as differences between mutations and subtype B and non-B HIV-1. Results: The M184V mutation was the most prevalent (80.1%), followed by K130N (40.6%) and TAM. In patients who received at least three treatments prior to genotyping, resistance to ZDV, d4T and TDF was associated with mutations M41L, D67N, V118I, L210W, K219Q and T69D; well as resistance to all PI / r was associated with the major mutations M46I, V82A, L90M, I54V, I84V M46L and L76V. HIV-1 subtype B was the most prevalent (90.7%) and there were differences between subtypes B versus mutations: L63P and A71T were more frequent in the subtype B, whereas mutations L76V, K20R, L10V, L89M and F53L were in non-B subtypes. Conclusion: The selection of resistance mutations in HIV-1 related to antiretroviral is similar to that described in the literature. The accumulation of failures to treatment favors the emergence of mutations, reinforcing the monitoring and evaluation of virologic failure by genotyping to minimize the impact resistance. Additional molecular epidemiological studies are needed to better assess the issue of prevalence of subtypes of HIV-1 in the state and possible associations with resistance mutations in HIV-1.
3

Avaliação da epidemia do HIV-1 subtipo C no sul do Brasil / Evaluation of HIV-1 the subtype C epidemic in south Brazil

Souza, Ricardo da Silva de [UNIFESP] January 2008 (has links)
Submitted by Diogo Misoguti (diogo.misoguti@gmail.com) on 2016-06-28T17:57:16Z No. of bitstreams: 1 cp076202.pdf: 353215 bytes, checksum: 02f0b3e82f46b91b291d72431aa09667 (MD5) / Approved for entry into archive by Diogo Misoguti (diogo.misoguti@gmail.com) on 2016-06-28T17:57:53Z (GMT) No. of bitstreams: 1 cp076202.pdf: 353215 bytes, checksum: 02f0b3e82f46b91b291d72431aa09667 (MD5) / Made available in DSpace on 2016-06-28T17:57:53Z (GMT). No. of bitstreams: 1 cp076202.pdf: 353215 bytes, checksum: 02f0b3e82f46b91b291d72431aa09667 (MD5) Previous issue date: 2008
4

Prevalência de mutações do HIV-1 e avaliação de subtipos virais em falha terapêutica no estado do Pará

Lopes, Carmen Andréa Freitas January 2014 (has links)
Introdução: Resistência aos antirretrovirais pode limitar opções de tratamento, principalmente em pacientes com acúmulo de falhas terapêuticas, o que pode comprometer resultados clínicos. Objetivos: caracterizar o perfil de mutações na transcriptase reversa e protease do HIV-1 de pacientes em falha ao tratamento. Secundariamente, avaliar associação entre mutações e número de falhas terapêuticas, associação entre mutações e subtipos do HIV-1 e apresentar a evolução temporal da prevalência dos subtipos do HIV-1, no estado do Pará, ao Norte do Brasil. Método: Estudo transversal, no qual se avaliam genotipagens, entre janeiro de 2004 a dezembro de 2013, com dados obtidos de formulário de solicitação do exame padronizado pela RENAGENO e de impressos dos resultados, ambos arquivados em quatro serviços de atendimento especializados. Foram incluídos os testes realizados por laboratório da RENAGENO, em maiores de 18 anos, e o primeiro exame daqueles que o realizaram em mais de um momento, totalizando 377 amostras. As mutações são descritas de acordo com o banco de dados de resistência do HIV da Universidade de Stanford (http://hivdb.stanford.edu), estimam-se suas prevalências e avaliam-se mutações de resistência de acordo com o número de falhas no momento da genotipagem, bem como diferenças de mutações entre subtipos B e não-B do HIV-1. Resultados: A mutação M184V foi a mais prevalente (80,1%), seguida da K130N (40,6%) e TAM. Em pacientes multiexperimentados previamente à genotipagem, resistência a ZDV, d4T e TDF foi associada às mutações M41L, D67N, V118I, L210W, K219Q e T69D; bem como resistência a todos os IP/r associou-se às mutações principais M46I, V82A, L90M, I54V, I84V, M46L e L76V. O subtipo B é o predominante no Pará (90,7%) e diferenças de prevalência de mutações entre subtipos ocorreram entre as mutações L63P e A71T versus subtipo B, enquanto as mutações L76V, M36I, K20R, L10V, L89M e F53L associaram-se ao subtipo não-B. Conclusão: A seleção de mutações de resistência do HIV-1 relacionada aos antirretrovirais é similar ao descrito em literatura. O acúmulo de falhas ao tratamento favorece a emergência de mutações, o que reforça o monitoramento de falha virológica, seguida de genotipagem para minimizar o impacto de resistência. Estudos adicionais de epidemiologia molecular são necessários para avaliar melhor a questão da prevalência de subtipos de HIV-1 no estado e possíveis associações com mutações de resistência do HIV-1. / Introduction: Resistance to antiretroviral treatment can limit treatment options, especially in patients with accumulation of therapeutic failures, which may compromise clinical outcomes. Objectives: characterizing the profile of mutations in the protease and reverse transcriptase of HIV-1 patients in the treatment failure. Secondarily to evaluate the association between mutations and the number of treatment failures, association between mutations and subtypes of HIV-1 and present the temporal evolution of the prevalence of subtypes of HIV-1 in the state of Pará in northern Brazil. Method: cross-sectional study in which genotyping is evaluated between January, 2004 and December, 2013 with data obtained from the standardized application form for the examination RENAGENO and printed the results, both filed in four specialty care services. We included those by laboratory RENAGENO in 18 years and the first examination in those who underwent more than one time, totaling 377 samples. Mutations are described according to the database of HIV resistance at Stanford University (http://hivdb.stanford.edu), estimated their prevalence and resistance is evaluated according to the number of failures at the time of genotyping as well as differences between mutations and subtype B and non-B HIV-1. Results: The M184V mutation was the most prevalent (80.1%), followed by K130N (40.6%) and TAM. In patients who received at least three treatments prior to genotyping, resistance to ZDV, d4T and TDF was associated with mutations M41L, D67N, V118I, L210W, K219Q and T69D; well as resistance to all PI / r was associated with the major mutations M46I, V82A, L90M, I54V, I84V M46L and L76V. HIV-1 subtype B was the most prevalent (90.7%) and there were differences between subtypes B versus mutations: L63P and A71T were more frequent in the subtype B, whereas mutations L76V, K20R, L10V, L89M and F53L were in non-B subtypes. Conclusion: The selection of resistance mutations in HIV-1 related to antiretroviral is similar to that described in the literature. The accumulation of failures to treatment favors the emergence of mutations, reinforcing the monitoring and evaluation of virologic failure by genotyping to minimize the impact resistance. Additional molecular epidemiological studies are needed to better assess the issue of prevalence of subtypes of HIV-1 in the state and possible associations with resistance mutations in HIV-1.
5

Prevalência de mutações do HIV-1 e avaliação de subtipos virais em falha terapêutica no estado do Pará

Lopes, Carmen Andréa Freitas January 2014 (has links)
Introdução: Resistência aos antirretrovirais pode limitar opções de tratamento, principalmente em pacientes com acúmulo de falhas terapêuticas, o que pode comprometer resultados clínicos. Objetivos: caracterizar o perfil de mutações na transcriptase reversa e protease do HIV-1 de pacientes em falha ao tratamento. Secundariamente, avaliar associação entre mutações e número de falhas terapêuticas, associação entre mutações e subtipos do HIV-1 e apresentar a evolução temporal da prevalência dos subtipos do HIV-1, no estado do Pará, ao Norte do Brasil. Método: Estudo transversal, no qual se avaliam genotipagens, entre janeiro de 2004 a dezembro de 2013, com dados obtidos de formulário de solicitação do exame padronizado pela RENAGENO e de impressos dos resultados, ambos arquivados em quatro serviços de atendimento especializados. Foram incluídos os testes realizados por laboratório da RENAGENO, em maiores de 18 anos, e o primeiro exame daqueles que o realizaram em mais de um momento, totalizando 377 amostras. As mutações são descritas de acordo com o banco de dados de resistência do HIV da Universidade de Stanford (http://hivdb.stanford.edu), estimam-se suas prevalências e avaliam-se mutações de resistência de acordo com o número de falhas no momento da genotipagem, bem como diferenças de mutações entre subtipos B e não-B do HIV-1. Resultados: A mutação M184V foi a mais prevalente (80,1%), seguida da K130N (40,6%) e TAM. Em pacientes multiexperimentados previamente à genotipagem, resistência a ZDV, d4T e TDF foi associada às mutações M41L, D67N, V118I, L210W, K219Q e T69D; bem como resistência a todos os IP/r associou-se às mutações principais M46I, V82A, L90M, I54V, I84V, M46L e L76V. O subtipo B é o predominante no Pará (90,7%) e diferenças de prevalência de mutações entre subtipos ocorreram entre as mutações L63P e A71T versus subtipo B, enquanto as mutações L76V, M36I, K20R, L10V, L89M e F53L associaram-se ao subtipo não-B. Conclusão: A seleção de mutações de resistência do HIV-1 relacionada aos antirretrovirais é similar ao descrito em literatura. O acúmulo de falhas ao tratamento favorece a emergência de mutações, o que reforça o monitoramento de falha virológica, seguida de genotipagem para minimizar o impacto de resistência. Estudos adicionais de epidemiologia molecular são necessários para avaliar melhor a questão da prevalência de subtipos de HIV-1 no estado e possíveis associações com mutações de resistência do HIV-1. / Introduction: Resistance to antiretroviral treatment can limit treatment options, especially in patients with accumulation of therapeutic failures, which may compromise clinical outcomes. Objectives: characterizing the profile of mutations in the protease and reverse transcriptase of HIV-1 patients in the treatment failure. Secondarily to evaluate the association between mutations and the number of treatment failures, association between mutations and subtypes of HIV-1 and present the temporal evolution of the prevalence of subtypes of HIV-1 in the state of Pará in northern Brazil. Method: cross-sectional study in which genotyping is evaluated between January, 2004 and December, 2013 with data obtained from the standardized application form for the examination RENAGENO and printed the results, both filed in four specialty care services. We included those by laboratory RENAGENO in 18 years and the first examination in those who underwent more than one time, totaling 377 samples. Mutations are described according to the database of HIV resistance at Stanford University (http://hivdb.stanford.edu), estimated their prevalence and resistance is evaluated according to the number of failures at the time of genotyping as well as differences between mutations and subtype B and non-B HIV-1. Results: The M184V mutation was the most prevalent (80.1%), followed by K130N (40.6%) and TAM. In patients who received at least three treatments prior to genotyping, resistance to ZDV, d4T and TDF was associated with mutations M41L, D67N, V118I, L210W, K219Q and T69D; well as resistance to all PI / r was associated with the major mutations M46I, V82A, L90M, I54V, I84V M46L and L76V. HIV-1 subtype B was the most prevalent (90.7%) and there were differences between subtypes B versus mutations: L63P and A71T were more frequent in the subtype B, whereas mutations L76V, K20R, L10V, L89M and F53L were in non-B subtypes. Conclusion: The selection of resistance mutations in HIV-1 related to antiretroviral is similar to that described in the literature. The accumulation of failures to treatment favors the emergence of mutations, reinforcing the monitoring and evaluation of virologic failure by genotyping to minimize the impact resistance. Additional molecular epidemiological studies are needed to better assess the issue of prevalence of subtypes of HIV-1 in the state and possible associations with resistance mutations in HIV-1.
6

Development of selective real-time PCR (SPCR) asays for the detection of K103N resistance mutation in minor HIV-1 populations

Seleka, Mpho Maria 12 1900 (has links)
Thesis (MScMedSc)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: Background: The conventional sequence analysis is the most common method used for the detection of drug-resistant mutants. Due to its sensitivity limitations, it is unable to detect these mutants when comprising less than 20% (minor populations) of the total virus population in a sample. However, real-time PCR-based assays offer a rapid, sensitive, specific and easy detection and quantification of such mutants. The HIV-1 variants harbouring the K103N mutation are associated with resistance to nevirapine (NVP) and efavirenz (EFV). The persisting drug-resistant mutants decay slowly to low levels, and therefore they are called minor drug-resistant mutants. Consequently, they affect subsequent treatment with the drugs of the relevant class. Objectives: The objective of this study was to design two TaqMan real-time PCR-based assays called selective-polymerase chain reaction (SPCR), namely the total viral copy SPCR assay and the K103N-SPCR assay. The former detects HIV-1 of subtype C reverse transcriptase sequences, whereas the latter detects K103N drug-resistant variants in these sequences. Design and Methods: In developing the SPCR assays, sets of appropriate primers and probes for the HIV-1 subtype C reverse transcriptase (RT) were developed to use in the K103N-specific reaction and the total copy reaction. Twelve DNA plasmid standards with sequence diversity were constructed for the assay from two HIV-1subtype C samples known to harbour the K103N mutation (AAC or AAT) in our Department‟s Resistance Databank. Their RT regions were amplified, cloned and verified with sequencing. Site-directed mutagenesis was used to induce mutations at 103 amino acid position in some of these clones to generate more standards with either one of the three codons (AAA, AAC and AAT). The two assays were optimized and validated, and a standard curve was generated for each assay using 10-fold serial dilution (5x107-5x100 DNA copy/μL) of a K103N-mutant plasmid standard. The optimized and validated SPCR assays were used to screen 40 nested PCR products of previously genotyped patient samples for minor K103N variants. Results: Two sensitive and reproducible selective real-time PCR (SPCR) assays, with cut-offs of 8.23 and 10.33 and a detection limit of 0.01% for the K103N resistance variants, were successfully developed. The assays detected a prevalence of 25.64-46.15% for the K103N resistance mutation in 39 patient samples. The genotyping (population sequencing) missed 40-53.85% of these variants. Conclusion: In conclusion, sensitive and reliable selective real-time PCR assays to detect and quantify minor K103N variants of HIV-1 in nested PCR products were successfully developed. The assay had a lower detection limit of 0.01%. / AFRIKAANSE OPSOMMING: Agtergrond: Konvensionele volgorde bepaling analise is die mees algemeenste metode wat gebruik word vir die opsporing van middel-weerstandige mutasies, maar weens beperkte sensitiwiteit is dit nie moontlik om hierdie mutante op te spoor wanneer dit minder as 20% (minderheids populasie) van die totale viruspopulasie in `n monster uitmaak nie. Nietemin, kwalitatiewe PKR-gebaseerd toetse bied vinnige, sensitiewe, spesifieke en makliker opsporings en kwantifisering van sulke mutante aan. MIV-1 variante wat die K103N mutasie bevat word geassosieer met weerstand teen nevirapine (NVP) and efavirenz (EFV). Volhoudende middel-weerstandige mutasies vergaan stadig na laer vlakke en word daarom na minderheids middel weerstandige mutasies verwys. Gevolglik affekteer dit opvolgende behandeling met die middel van die relevante klas. Doelwitte: Die doel van die studie was om twee TaqMan kwantifiserende PKR gebaseerde selektiewe polymerase ketting reaksies (SPKR), naamlik totale virale kopie SPKR en K103N-SPKR te ontwikkel. Die voormalige toets het die MIV-1 subtipe C omgekeerde transkriptase volgorde bepaal, waar K103N die middel-weerstand variante in hierdie volgorde opspoor. Ontwerp en Metodes: `n Geskikte stel inleiers en peiler was ontwikkel vir die MIV-1 subtipe C omgekeerde transkriptase (OT) vir gebruik in die K103N-spesifieke en die totaal kopie reaksie. Twaalf DNS plasmied standaarde met volgorde diversiteit was saamgestel vir die toets vanaf twee MIV-1 subtipe C monsters wat volgens ons Departement se weerstand databasis geklassifeer is vir die besit van die K103N mutasie (AAC of AAT). Die OT streke was geamplifiseer, gekloneer en geverifieer deur volgorde bepaling. Punt-gerigte mutagenese is gebruik om `n mutasie by die amino suur posisie 103 van sekere klone te induseer om meer standaarde te genereer wat een van die drie kodons (AAA, AAC en AAT) bevat. Die twee toetse is geoptimiseer en gevalideer en `n standard kurwe is genereer vir elk van die toetse deur die gebruik van tienvoud serie verdunnings (107-1 DNS kopie/μL) van `n algemene K103N-mutante plasmied standard. Die geoptimiseerde en gevalideerde SPKR toets was gebruik om vir die minderheids K103N variante in 40 “nested” PKR produkte van voorheen gegenotipeerde pasiënt te soek. Resultate: Twee sensitiewe en herproduseerbare selektiewe kwantitiewe PKR toetse met `n ΔCt afsnypunt van 8.23 en `n deteksie limiet van 0.006% was ontwikkel vir die K103N weerstand variant. Die toets het `n voorkomsyfer van 25.6 % vir die K103N weerstand mutasie in 40 pasiënt monsters bepaal, waar genotipering (populasie volgorde ) 40% van hierdie variante nie opgespoor het nie. Gevolgtrekking: `n Sensitiewe en betroubare selektiewe kwantitatiewe PKR toets vir die opspoor en kwantifisering van die minderheids K103N variante van MIV-1 in PKR produkte was ontwikkel. Hierdie toets het `n laer opsporings limiet van 0.01%. / Poliomyelitis Research Foundation (PRF) / National Research Fund (NRF) / National Health Laboratory Service Research Trust (NHLS RT)
7

Avaliação de mutações de resistência ao tratamento com análogos de nucleos(t)ídeos e de escape vacinal do vírus da hepatite B (VHB) em pacientes com hepatite crônica.

Pacheco, Sidelcina Rugieri January 2016 (has links)
Submitted by Ana Maria Fiscina Sampaio (fiscina@bahia.fiocruz.br) on 2016-07-13T12:04:07Z No. of bitstreams: 1 Sidelcina Rugieri Pacheco Avaliação...2016.pdf: 1183745 bytes, checksum: cafa75f83141a4f66d07bae037fb741b (MD5) / Approved for entry into archive by Ana Maria Fiscina Sampaio (fiscina@bahia.fiocruz.br) on 2016-07-13T12:11:45Z (GMT) No. of bitstreams: 1 Sidelcina Rugieri Pacheco Avaliação...2016.pdf: 1183745 bytes, checksum: cafa75f83141a4f66d07bae037fb741b (MD5) / Made available in DSpace on 2016-07-13T12:11:45Z (GMT). No. of bitstreams: 1 Sidelcina Rugieri Pacheco Avaliação...2016.pdf: 1183745 bytes, checksum: cafa75f83141a4f66d07bae037fb741b (MD5) Previous issue date: 2016 / CAPES / CNPq / Fundação Gonçalo Moniz. Centro de Pesquisas Gonçalo Moniz. Salvador, BA, Brasil / INTRODUÇÃO: A hepatite B (VHB) é uma infecção dinâmica crônica, que apesar de existir programas de imunização e tratamento antiviral disponível, existe o risco de emergência de mutações de resistência aos análogos de núcleos(t)ídeos (AN) que devem ser rastreadas, devido as suas implicações clínicas. O Brasil disponibiliza pelo SUS cinco drogas para o tratamento antiviral: IFN, LAM, ADF, ETV e TDF e um guia de conduta clínica para orientar o tratamento no território nacional, o Protocolo de Diretrizes Terapêuticas para Hepatite B e co-infecções. OBJETIVO: O objetivo do presente estudo foi avaliar as mutações de resistência aos AN, mutações de escape vacinal e genótipos circulantes em pacientes com hepatite B crônica em dois centros de referencia em Hepatites, na Bahia (região Nordeste) e no Acre (região Norte) do Brasil. MATERIAL E MÉTODOS: Foi utilizadas ferramentas de biologia molecular e bioinformática, através de nested PCR e sequenciamento direto das amostras, para rastrear as mutações de resistência, a região alvo foi a transcriptase reversa (RT) do gene P e as mutações de escape vacinal foi a região do gene S do VHB, como também os genótipos e subgenotipos do VHB. RESULTADOS: Foram incluídos 527 pacientes durante o período de 2011-2015, sendo 320 pacientes do HUPES/BA e 207 do FUNDHACRE/AC. Os pacientes que representam a região Nordeste foram 59,3 % do sexo masculino e uma média de idade de 44,75±12,4 DP, os pacientes da região Norte 42% foram do sexo masculino e a média de idade foi de 40,36±13,9 DP. Todos os pacientes incluídos apresentaram AgHBs persistente por mais de seis meses e 86,1% apresentaram AgHBe negativo. Foram sequenciadas 296 amostras dos pacientes com VHB crônica. Foram encontradas mutações de resistência aos AN na Região Norte 1,2% (2), Região Nordeste 7,4%(8) e no global 3,8%(20). Os padrões de mutações de resistência primária encontrados foram: rtA194T, (3) rtL180M+M204V, rtL180M+M204I, rtS202I, rtM204I, rtA181S, rtA181E e rtA184S. Em relação ao escape vacinal a frequencia para a Região Norte foi de 7,1% (11), Região Nordeste 8,4% (9) e no global 7,6% (20). Nos pacientes virgens de tratamento (n=189), a frequência de mutações de resistência foi de 6%, somente nas amostras da região Nordeste. Não houve diferença estatisticamente significante entre o grupo com ou sem mutação dos pacientes virgens de tratamento. Não foram encontradas mutações de resistência nas amostras da região Norte. Os genótipos circulantes nas duas regiões foram A, D e F, e a região Nordeste foi encontrada o genótipo C (C2). CONCLUSÃO: Os resultados demonstram a importância de rastrear e monitorar as mutações de resistência aos AN e de escape vacinal devido a importância epidemiológica e clínica na conduta terapêutica. / INTRODUTION: Hepatitis B virus (HBV) is a chronic dynamic infection, which although there immunization programs and antiviral therapy available, there is a risk of emergence of resistance mutations cores analogs (t) ide to be screened, because of their implications clinics. The Brazil offers the SUS five drugs for antiviral treatment: IFN, LAM, ADF, ETV and TDF and clinical guide of conduct to guide treatment in the country, the Therapeutic Guidelines Protocol for Hepatitis B and co-infections. AIM: The aim of this study was to evaluate the resistance mutations core analogues (t) ide, vaccine escape mutations and circulating genotypes in patients with chronic hepatitis B in two reference centers in Hepatitis, Bahia (Northeast) and Acre (Northern region) of Brazil. MATERIAL AND METHODS: Was used tools of molecular biology and bioinformatics by nested PCR and direct sequencing of samples to track resistance changes, the target region is the reverse transcriptase (RT) P gene and vaccine escape mutations was region of the gene S of HBV, as well as the HBV genotypes and subgenotipos. RESULTS: 527 patients were included during the period 2011-2015, with 320 patients HUPES / BA and 207 FUNDHACRE / AC. Patients representing the Northeast were 59.3% male and an average age of 44.75 ± 12.4 PD patients in the northern region 42% were male and the average age was 40, 36 ± 13.9 DP. All patients had persistent HBsAg for more than six months and 86.1% were HBeAg negative. We were sequenced 296 samples from patients with chronic HBV. the cores of similar resistance mutations were found (t) ide in the North 1.2% (2), Northeast 7.4% (8) and 3.8% overall (20). The patterns of primary resistance mutations were: rtA194T (3) rtL180M + M204V, M204I + rtL180M, rtS202I, rtM204I, rtA181S, and rtA181E rtA184S. Regarding vaccine escape the frequency for the Northern Region was 7.1% (11), Northeast 8.4% (9) and the global 7.6% (20). In treatment-naïve patients (n = 189), the frequency of resistance mutations was 6%, only the samples in the Northeast. There was no statistically significant difference between the groups with or without mutation of naive patients. There were no resistance mutations in samples from the North. Circulating genotypes in the two regions A, D and F, and the Northeast found the C genotype (C2). CONCLUSION: The results demonstrate the importance of tracking and monitoring the resistance mutations similar cores (t) ide and vaccine escape due to epidemiological and clinical importance in the therapeutic approach.
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An integrative approach to understanding the fitness cost of rifampicin resistance in Pseudomonas aeruginosa

Qi, Qin January 2014 (has links)
Antibiotic resistance in bacteria is acquired through spontaneous chromosomal mutations or horizontal gene transfer. In the absence of antibiotics, resistant mutants generally show reduced fitness due to compromised growth rate, competitive ability and virulence compared to their antibiotic-sensitive ancestors. The focus of my research is to dissect the molecular underpinnings of the variations in the fitness cost of chromosomal antibiotic resistance using a systems-level approach. From an evolutionary perspective, my research aims are to understand how the fitness cost influences adaptation in resistant populations in an antibiotic-free environment. Using rifampicin resistance in Pseudomonas aeruginosa as a model, my work shows that most of the variation in the fitness cost of rifampicin resistance can be attributed to the direct effect of rifampicin resistance mutations on transcriptional efficiency. Through RNA-Seq transcriptome profiling, I demonstrate that global changes in gene expression levels associated with resistance mutations are surprisingly subtle, suggesting that the transcriptional regulatory network of P. aeruginosa is robust against compromised transcriptional efficiency. Using experimental evolution and whole-genome sequencing, my work reveals a systematic difference in the genetic basis of adaptation in mutants that were propagated in the absence of antibiotics. During compensatory adaptation, resistant mutants can recover the fitness cost of resistance by fixing second-site mutations that directly offset the deleterious effects of resistance mutations. Amongst resistant mutant populations with low fitness costs, general adaptation limits compensatory adaptation, which is most likely to be due to the rarity of compensatory mutations and clonal interference. Far from being the most ubiquitous mechanism in the evolution of resistance, compensatory adaptation is the exception that is more likely to be observed in resistant mutants with high fitness costs. In addition, I applied key elements of the integrative experimental approach developed in this work to dissect the molecular basis of the fitness cost associated with carriage of the pNUK73 small plasmid in P. aeruginosa, which carries the rep gene encoding a plasmid replication protein. My results confirmed that rep expression generates a significant fitness cost in P. aeruginosa and demonstrate how the molecular origins of the fitness cost of resistance can be dissected in a different biological context.
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Drug resistance genotyping and phylogenetic analysis of HIV in chronically infected antiretroviral naive patients

Baloyi, Tlangelani 18 May 2019 (has links)
MSc (Microbiology) / Department of Microbiology / Background: Antiretroviral treatment (ART) has grown to be one of the most effective tool in the fight to control HIV/AIDS morbidity and mortality worldwide. However, due to the emergence of drug resistant HIV, ART efficacy can be jeopardized. Drug resistant HIV strain has a potential of becoming a major public threat, as its limit treatment options on people living with HIV. With several findings worldwide reporting drug resistant HIV to be currently being transmitted to ART-naïve persons, measures have been taken to genotype drug resistant HIV prior to treatment initiation. However, in resource limited countries such measures are not executed especially in public sectors due to the costs associated with the required assays for genotyping. Objective: The objectives of the study was to establish a deep sequencing protocol (Next Generation Sequencing-NGS) using an Illumina MiniSeq Platform and subsequently apply it to genotype HIV in chronically infected drug naïve persons for resistance mutations and viral genotypes Methods: HIV positive Individuals without any exposure to ART (Treatment-naive) were recruited. Partial pol fragment (complete protease and ~1104bp reverse transcriptase) were amplified and purified. Libraries were prepared using Nextera XT library preparation kit, fragmented, tagmented, pooled and denatured then sequenced with Illumina MiniSeq instrument. Consensus sequences were derived, aligned and phylogenetically analysed. The Stanford HIV Drug Resistance Algorithm was used to infer the presence of drug resistant mutants, at the viral minority and majority population levels. Results and discussion: An NGS protocol to generate nucleotide sequences for drug resistance inference was established. No major drug resistance mutations were detected against protease, reverse transcriptase inhibitors in the study subjects investigated. Nevertheless, V179D change was observed in one patient (8.3%). V179D has been shown to impact a low-level resistance to NNRTI. On the other hand, several secondary and unusual mutations at known drug sites were detected even at minority threshold level of <20%. Conclusion: No major drug resistance mutations was detected in the drug naïve study population. This finding suggests that there is no risk of treatment failure to the investigated subjects, however it is important to assess the potential phenotypic v | P a g e significance of the identified secondary resistance mutations in the context of HIV-1 subtype C. The established NGS protocol should be applied in subsequent HIV drug resistance studies. / NRF

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