The abundant cellular protein Cyclophilin A (CypA) was found to bind to HIV-1 capsid (CA) in 1993. Since that time, several complementary methods, including disruption of the binding interface by cyclosporine A, CA mutants, and CypA mutants, have been used to demonstrate that CypA acts within human target cells to promote HIV-1 infection. In contrast, in cells from non-human primates, CypA in target cells decreases HIV-1 infectivity, and it does so by promoting TRIM5α-mediated restriction. Using human cancer cell lines and the genetic methods available at the time, attempts to obtain evidence that CypA inhibits HIV-1 restriction by the human TRIM5α ortholog, let alone that human TRIM5α restricts HIV-1, were unsuccessful. Here we revisit the question of the mechanism by which CypA increases HIV-1 infectivity by exploiting lentiviral vectors optimized for primary human blood cells that serve as HIV-1 targets. Disruption of CA−CypA interaction is demonstrated to render HIV-1 vulnerable to endogenous human TRIM5α-mediated recognition and restriction, which occur prior to completion of reverse transcription. Identical findings were acquired with single-cycle vectors or with replication-competent viruses. Consistently, a previously identified, cyclosporine-resistant CA mutation A92E is also shown to confer resistance against restriction by human TRIM5α. Therefore, the results presented in this thesis reveal that HIV-1 exploits a host protein CypA bound to its CA to evade potent restriction by human TRIM5α. This finding not only answers a long-standing question regarding the role of CypA in HIV-1 infection, but also may reinvigorate the development of CypA inhibitors for treatment of HIV-1.

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Made available in DSpace on 2016-01-26T12:51:38Z (GMT). No. of bitstreams: 1 joaoricardoadossantos_tese.pdf: 8146308 bytes, checksum: b084a50364f9159086f5311dc3310a34 (MD5) Previous issue date: 2012-02-01 / Introduction: The main aim in the use of antiretroviral drugs is delaying the progression of immunodeficiency and restoring, as much as possible, an individual s immunity, increasing the length and quality of life of people living with HIV-1-AIDS. The various polymorphisms presented by HIV-1 may have implications for the pathogenesis, transmission, diagnosis, treatment and development of vaccines which enable an effective prophylaxis. Objective: Describing the resistance profile of HIV-1 to antiretroviral drugs in patients with treatment failure in a reference unit in the treatment of AIDS in the city of Catanduva, Northwestern Region of São Paulo State. Methods: Genotyping tests of 527 patients monitored by the Department of Infectious Diseases belonging to Emilio Carlos School Hospital, located in Catanduva-SP, requested between January 2000 and December 2010 were analyzed. All sequences of the viral genome (TR and PR segment of the pol gene) were analyzed in RENAGENO sites (MS-Brazil) and reanalyzed using Stanford University s algorithm, in order to assess the presence of HIV-1 resistance mutations through updated database. Results: Most analyzed patients were male (58.02%), aged between 40 and 50 years old and had already been subjected to ART. The main therapeutic regimen was 3 ARV, followed by 62.78% of patients. The 184V mutation was the most prevalent (52.7%) among all analyzed ones. There was a high prevalence for TAM: 215Y, 41L, 67N, 210W, 70R, whereas TAM 215F and 219Q were the least frequent ones. Among the multidrug resistance-related mutations, the presence of the 118i mutation may be highlighted in 23.5% of viral genomes. Among the NNRTI mutations, the high prevalence of 103N, found in 28.57% of cases, must be emphasized; 36I mutation was the most frequent among PR leading ones. Conclusion: Analysis of the genomic profile of the virus in the population studied showed that the presence of a specific point mutation does not necessarily increase the resistance of HIV-1 to a certain drug. Interactions among polymorphisms may cause not only resistance but also susceptibility to ART. / Introdução: O principal objetivo do uso dos antirretrovirais é retardar a progressão da imunodeficiência e restaurar, tanto quanto possível, a imunidade do indivíduo, aumentando o tempo e a qualidade de vida das pessoas que vivem com HIV-1-AIDS. Os diversos polimorfismos apresentados pelo HIV-1 podem ter implicações na patogênese, na transmissão, no diagnóstico, no tratamento e no desenvolvimento de vacinas que permitam uma profilaxia eficaz. Objetivo: Descrever o perfil de resistência do HIV-1 aos antirretrovirais em pacientes com falha terapêutica em uma unidade de referência no tratamento da AIDS no município de Catanduva, Noroeste Paulista. Métodos: Foram analisados exames de genotipagem de 527 pacientes acompanhados pelo Departamento de Moléstias Infecciosas do Hospital Escola Emílio Carlos, localizado na cidade de Catanduva-SP, solicitados entre janeiro de 2000 e Dezembro de 2010. Todas as sequências do genoma viral (segmentos da TR e PR do gene Pol) foram analisadas nos sites da RENAGENO (MS-Brasil) e reanalizadas utilizando-se o algoritmo da Stanford University, a fim de avaliar a presença de mutações de resistência do HIV-1 através de banco de dados atualizado. Resultados: A maioria dos pacientes analisados pertence ao sexo masculino (58,02%) e à faixa etária entre 40 e 50 anos e já havia sido submetida à TARV. O principal esquema terapêutico utilizado foi composto por três antirretrovirais, sendo prescrito para 62,78% dos pacientes. A mutação 184V foi a mais prevalente (52,7%) entre todas as analisadas. Houve elevada prevalência para as TAM: 215Y, 41L, 67N, 210W, 70R, enquanto 215F e 219Q foram as TAM menos frequentes. Entre as mutações relacionadas à multirresistência, destacamos a presença da mutação 118I em 23,5% dos genomas virais. Dentre as mutações para ITRNN, ressalta-se a elevada prevalência da 103N, encontrada em 28,57% dos casos; a mutação 36I foi a mais frequente dentre as principais da PR. Conclusão: Análises do perfil genômico dos vírus presentes na população estudada mostraram que a presença pontual de uma determinada mutação não implica no aumento da resistência por parte do HIV-1 a determinada droga. Interações entre polimorfismos podem resultar não só em resistência, mas também em suscetibilidade à terapia antirretroviral.

Made available in DSpace on 2014-07-29T15:26:22Z (GMT). No. of bitstreams: 1 Tese Keila Correia de Alcantara.pdf: 2967378 bytes, checksum: abcf75d777805ea6de3323b7586a4654 (MD5) Previous issue date: 2010-10-31 / Introduction: The spread of the aids epidemic among young women and HIV-1 mother-tochild transmission (MTCT) represent important public health issues. In this context, prenatal care represents a unique opportunity for the early diagnosis of young women and for the implementation of full preventive strategies to HIV-1MTCT. Objectives: To study immunological, virological, clinical and epidemiological characteristics and to identify factors associated with HIV-1MTCT among HIV-1 pregnant women/infants recruited in Goias State. Material and methods: Cohort 1: 41 pregnant HIV/AIDS: infant pairs (April/2000-August/2001) were recruited and prospectively followed up at two regional reference centers-Mother-Infant Hospital (HMI/SUS) and Hospital Dr. Anuar Auad (HAA/HDT/SUS). Cohort 2: 172 HIV/AIDS pregnant women and 149 exposed children were recruited at the Institute of diagnosis and prevention (IDP/APAE) and prospectively followed up at HAA/HDT/SUS. The following tests were performed: maternal viral load, CD4+ T cell counts, HIV-1env/gag subtypes by heteroduplex mobility assay/HMA (cohort 1) and pol (protease and reverse transcriptase-PR/RT) sequencing for resistance profile, subtypes identification and phylogeography analysis for subtype C (cohort 2). Infants born to HIV-1/aids mothers were evaluated by plasma viral RNA and CD4+ T cell counts. Seroreversion of exposed- uninfected children was followed by sequential ELISA tests for IgG anti HIV-1. Results: Patients from cohorts 1 and 2 presented similar social-demographic and clinical profiles. The median age was 26 years; 15-41 years), lower educational level predominated and most were diagnosed during pregnancy (90%). Over 80% received ARV prophylaxis. One case of MTCT was observed in cohort 1 which was associated with short prophylaxis and long labor period. Exposed-uninfected infants born to symptomatic mothers seroreverted earlier. Cohort 2 included 80% of all HIV-1 infected pregnant women from Goias state in that period. The early prophylaxis and undetectable viral load predominated among previously diagnosed patients (p<0.05). One ARV naive patient presented transmitted drug resistance; 10 ARV experienced patients presented secondary drug resistance: 6 under MTCT prophylaxis, 4 under HAART. MTCT was observed in 3/149 (2.01%) cases and late diagnosis, vaginal delivery, brastfeeding and lack of oral ZDV were observed. Among MTCT cases resistance mutations were not detected. HMA env/gag (cohort 1) and pol sequencing (cohort 2) results showed mostly subtype B followed by subtypes F1, C and recombinants, mainly BF1. HIV-1 subtype C was identified only among pregnant women from cohort 2 which together with recombinants BC represented around 20% of the isolates. Subtype C and BC recombinants were isolated in interior municipalities of Goias state located close to the main highways that connect south/southern to north (BR153), northeast (BR020) and South/west (BR369/BR070). Phylogenetic/ phylogeographic analysis showed a subtype C clado, clusters (aLTR &#8805; 0.85) with sequences from Southern states and from Sao Paulo and evidences of multiple introductions. Conclusion: Our results indicate the importance of prenatal care for the early diagnosis/prevention of HIV-1 vertical transmission. However late diagnosis and missed opportunities to fully prevent transmission were associated with vertical transmission. Multiple introductions and the dissemination of HIV-1 subtype C by heterosexual contact in interior cities highlight the importance of monitoring the genetic diversity and the impact of subtype C dissemination in the interior of Brazil. Note: superscript + is where it appears and the program does not copy. / Introdução: O avanço da epidemia de aids em mulheres jovens e a transmissão materno-infantil do HIV-1 (TMI) representam importantes temas de saúde pública. Neste contexto, a assistência pré-natal representa uma oportunidade única para o diagnóstico da infecção pelo HIV-1 e implementação precoce de medidas profiláticas para TMI. Objetivos: Estudar as características imunológicas, virais, clínicas, epidemiológicas e identificar fatores associados à transmissão materno-infantil do HIV-1 entre gestantes infectadas pelo HIV-1/filhos recrutados no estado de Goiás. Material e métodos: Coorte 1: 41 pares mães HIV/aids-filhos (abril/2000-agosto/2001) recrutados e acompanhados prospectivamente em dois centros de referência regionais (Hospital Materno Infantil/HMI/SUS; Hospital Dr. Auar Auad/HAA/HDT/SUS). Coorte 2: 172 mães HIV/aids-149 filhos recrutados no Instituto de Diagnóstico e Prevenção/IDP/APAE e acompanhados prospectivamente no HAA/HDT/SUS. Foram avaliados viremia plasmática materna, contagem de células T CD4+, subtipos de HIV-1 nas regiões env/gag pelo ensaio da mobilidade de heteroduplex (HMA) para coorte 1 e sequenciamento gene pol (protease e transcriptase reversa-PR/RT) para identificar mutações de resistência aos antirretrovirais e subtipos do HIV-1 e análise filogeográfica das seqüências do subtipo C da coorte 2. As crianças filhas de mães HIV/aids foram submetidas a testes para quantificação do RNA HIV-1 plasmático e das células T CD4+. Nas crianças não infectadas a sororreversão foi acompanhada sequencialmente por ELISA para IgG anti HIV-1/2. Resultados: As pacientes da coorte 1 e 2 apresentaram características sócio-demográficas e clínicas semelhantes. A mediana de idade foi 26 anos (variação 15-41 anos), a maioria tinha baixa escolaridade e foi diagnosticada durante a gestação (90%). Mais de 80% recebeu profilaxia ARV para TMI. Na coorte 1 foi observado um caso de TMI associado a curta exposição à profilaxia e longo trabalho parto. Entre crianças expostas/nãoinfectadas a sororreversão foi mais rápida entre os nascidos de mães sintomáticas. A coorte 2 representou 80% do total de gestantes HIV-1+ do Estado de Goiás no período. A introdução precoce da profilaxia e viremia indetectável predominaram nas pacientes com diagnóstico anterior à gestação (p<0.05). Uma paciente virgem de tratamento apresentou resistência transmitida; 10 pacientes apresentaram resistência secundária: 6 sob profilaxia, 4 sob HAART. Entre os casos de TMI (3/149; 2.01%) observamos diagnóstico tardio, parto vaginal, amamentação e ausência do AZT oral e mutações de resistência não foram detectadas. Resultados do HMA (coorte 1) e do sequenciamento automatizado (coorte 2) em gestantes de Goiás mostraram a circulação dos subtipos B, F1 e recombinantes, principalmente BF1 nas regiões env/gag e pol do HIV-1. O subtipo C só foi detectado na coorte 2 e juntamente com os recombinantes BC representaram em torno de 20% dos isolados. HIV-1 subtipo C, originado do sul do país, foi detectado em gestantes de municípios do interior de Goiás por onde passam importantes vias de ligação sul-norte (BR153), sul-nordeste (BR020) e sulcentro-oeste/Mato Grosso (BR070/BR364). Análises filogenética/filogeográfica do subtipo C mostraram um clado monofilético formado por sequencias de Goias e da região Sul e de São Paulo e evidências de múltiplas introduções em Goiás. Conclusão: Nossos resultados indicam que o programa pré-natal de alta cobertura em Goiás representa uma importante oportunidade para diagnósttico e prevenção precoce de transmissão vertical do HIV-1. Entretanto os 3 casos de TMI observamos diagnóstico tardio e perda de oportunidade para a profilaxia completa da transmissão vertical do HIV-1. Múltiplas introduções e a disseminação do subtipo C por contato heterossexual no interior indicam a necessidade de monitoramento da diversidade genética e do impacto da disseminação do subtipo C no interior do Brasil. OBS: + está sobrescrita onde aparece e o programa não copia.

L'une des principales barrières à la prise en charge optimale des patients sous traitement antirétroviral est l'accès limité aux tests de charge virale (CV) et de génotypage particulièrement en milieu décentralisé. Ces tests ne sont généralement disponibles qu'au niveau des structures sanitaires centrales de grandes villes et le plasma en est l'échantillon de référence. Or, son transfert des régions périphériques vers les laboratoires de références est difficile, voire impossible. Pour rapprocher les patients du laboratoire, nous avons démontré la possibilité d'assurer un suivi virologique complet (CV et génotypage) à partir des DBS collectés et acheminés dans des conditions de terrain. Nous avons également pour la première fois, documenté la réponse virologique au traitement antirétroviral et la diversité génétique du VIH-1 chez des patients adultes suivis en milieux décentralisés au Sénégal, au Mali et en Guinée Conakry. Globalement, malgré les défauts d'observance au traitement souligné, les résultats de nos travaux ne montrent pas de différences significatives dans la survenue de l'échec virologique entre patients suivis dans les structures sanitaires centrales et périphériques, ceci quelque soit le pays considéré. Au Sénégal, chez les enfants nés de mères séropositives, la résistance vis à vis des INNTI était plus prépondérante, probablement du fait de l'utilisation systématique de la Névirapine durant la PTME. Par ailleurs, aucune mutation de résistance aux inhibiteurs d'intégrase n'a été observée malgré des taux de résistance élevés chez des patients en échec de première et deuxième ligne de traitement. Nos travaux confirment également une grande diversité génétique des sous-types viraux avec cependant la prédominance du CRF02_AG dans la sous région Ouest Africaine. Ces travaux de thèse mettent en évidence la faisabilité et la pertinence du DBS comme support pour le suivi virologique des patients en milieux décentralisés. Son utilisation a permis de montrer d'autre part des taux d'échecs virologiques élevés indiquant la nécessité de renforcer l'adhérence au traitement. Enfin, nos résultats soulignent l'utilité de prendre davantage en considération les profils de résistance pour initier un traitement de relais. / One of the major barriers to the optimal care of patients undergoing antiretroviral therapy is the limited access to viral load (VL) and genotyping tests, especially in remote areas. These technologies are usually available only at central health facilities in larger cities and plasma is the reference sample. However, plasma or whole blood samples shipment from remote areas to reference lab faces several constraints or even impossible. In order to bring closer patients to reference lab, we have demonstrated the ability of DBS (Dried Blood Spots) collected and shipped in field conditions to provide complete virological monitoring (VL and genotyping). We also documented for the first time, virological outcome of ART and HIV-1 genetic diversity in adult patients followed up in decentralized settings in Senegal, Mali and Guinea Conakry. Overall, despite the low treatment adherence noted sometimes, our findings show no significant differences in the occurrence of virological failure among patients followed up in the central and peripheral health facilities, whatever the country. In Senegal, no integrase inhibitors associated DRM has been found despite the high rate of resistance in patients failing first and second-line treatment. Furthermore, among children born to HIV infected mothers, NNRTI-associated drug resistant mutations (DRM) were more predominant, probably because of systematic use of Nevirapine in MTCT. Our studies also confirm the high genetic diversity of viral subtypes, with the dominance of CRF02_AG in West Africa. This work presented here highlights the feasibility and relevance of DBS as support for the virological monitoring of patients in decentralized settings in West Africa. Furthermore, its use showed high rate of virological failure indicating the need to reinforce adherence to treatment. Finally, our results highlight the utility to considering carefully drug resistance patterns before switching to another ART regimen.

Thesis (MSc (Medical Virology )--University of Stellenbosch, 2004. / 150 leaves printed on single pages, preliminary pages i-vii and numberd pages 1-143. Includes bibliography and figures digitized at 300 dpi grayscale and 300 dpi 24-bit Color to pdf format (OCR), using a Hp Scanjet 8250 Scanner and digitized at 600 dpi grayscale to pdf format (OCR), using a Bizhub 250 Konica Minolta Scanner. / ENGLISH ABSTRACT: The first episode of HIV-1 in South Africa was documented in 1982. Homosexual transmission of the virus was the predominate mode of transmission in an epidemic of mainly HIV-1 subtype Band D infections. To date, no full-length sequences of Subtype D strains from South Africa has been reported. Here we describe the characterization and some of the unique features of the Tygerberg HIV-1 subtype D strains. A near full-length 9 kb fragment was obtained through a one step PCR using high molecular weight DNA. Cloning was done successfully with the pCR-XLTapa cloning kit. Large quantities of plasmid DNA was grown and sequenced on both strands of the DNA. ORF determination and subtyping was followed by standard phylogenetic methods to construct evolutionary phylogenetic trees. Subtyping and similarity plots revealed that the sequences from Tygerberg are pure subtype D. All the Tygerberg strains had intact genes with no premature stop codons. At the tip of the V3 loop, the Tygerberg strains have the GOGO motif. R214 has a more variable vpu gene than the rest of the Tygerberg strains, but is still subtype D in this region. No premature stop codons have been observed in the tat gene and the glycosilation of the strains are less than the subtype D consensus. We are the first to report full-length sequences of HIV-1 subtype D strains from South Africa. The sequences represent non-mosaic genomes of subtype D. Our results confirm that the subtype D sequences from the beginning of the HIV-1 epidemic differ from the Subtype D sequences from recent isolates. / AFRIKAANSE OPSOMMING: Die eerste episode van HIV-1 infeksie in Suid Afrika is in 1982 gedokumenteer. Die epidemie het hoofsaaklik uit subtipe B en D bestaan en was deur homoseksuele kontak oorgedra. Geen vollengte subtipe D DNS volgordes van Suid-Afrika is tans beskryf nie. Hier beskryf ons die karakterisering van vollengte subtipe D stamme asook sommige van die unieke eienskappe van die virusse. Die vollengte 9 kb genoom volgorde was verkry deur 'n eenstap PKR reaksie met hoë molekulêre gewig DNS uit te voer. Die 9 kb fragment was suksesvol gekloneer met behulp van die peR-Xl-TOPO klonerings toetsstel. Groot hoeveelhede plasmied DNS was opgegroei en die nukleotied volgorde bepaal op beide stringe van die genoom. Die stamme was gesubtipeer en filogenetiese analise was uitgevoer met standaard metodes. Die volledige DNS volgordes was bepaal en subtipering het daarop gedui dat die stamme van Tygerberg suiwer subtipe D is. Geen premature stop kodons is in die nukleotied volgordes van die Tygerberg stamme gevind nie. By die draai van die varieerbare deel (V3) het al die Tygerberg stamme die GQGQ motief gehad. R214 het 'n meer varieerbare vpu geen, maar behoort steeds tot die subtipe D groep in die gedeelte. Daar was geen premature stop kodons in die tat geen gevind nie en die glikosilasie van die stamme is minder as die van die konsensus subtipe D stam. Ons is die eerste groep om vollengte subtipe D stamme van Suid-Afrika te karakteriseer. Die DNS volgordes verteenwoordig suiwer subtipe D genome. Ons resultate bevestig die van ander dat die nukleotied volgordes van die ouer subtipe D stamme verskil van die nuwer stamme.

Polymorphism in the Human Leucocyte Antigen (HLA) region of chromosome is the major source of host genetic variability in outcome of HIV-1 infection. However, there is limited understanding of the mechanisms underlying the beneficial effect of protective class I alleles such as HLA-B57, B27 and B51. Taking advantage of a unique cohort (SM cohort) infected with clade B’ HIV-1 through contaminated blood, in which many variables, such as the length of infection, the infecting viral strain and host genetic background are controlled, we performed a comprehensive study in order to understand HLA-B51 associated HIV-1 control. We first focused on the T cell responses against three dominant HLA-B51 restricted epitopes: GagNI9 (NANPDCKTI), Pol TV8 (TAFTIPSV) and Pol LI9 (LPPVVAKEI), and HLA-B51 associated escape mutations in these three epitopes. A sequential selection of epitope mutations (i.e., epitope Pol LI9, Pol TV8 and Gag NI9) was observed. Good control of viral load and higher CD4+ counts were significantly associated with at least one detectable T cell response to un-mutated epitopes. HLA-B51 restricted CD8+ T-cell clones, generated from the patients, could effectively inhibit HIV-1 replication when wild type epitopes are properly processed and presented. We then assessed the evolution of escape mutations under the selecting pressure of HLA-B51 CTLs in vitro by co-culturing HLA-B51 CTL clones with HIV-1 infected target cells (Virus Evolution Assay). Our data showed that three dominant HLA-B51 restricted CTL responses have driven the sequential escape mutations within the epitopes, leading to the loss of viral control, which confirmed our in vivo findings. Furthermore, applying Virus Evolution Assay, we assessed the impact of antigen sensitivity and TCR usage as well as founder virus effect on HIV-1 evolution and control. Our data suggested that antigen sensitivity plays an important role in anti-viral efficacy of CTLs; the TCR usage of CTLs has stronger effect on virus evolution. More importantly, our study highlighted the major impact of the founder virus sequence on viral control. It has been shown that HIV-1 has adapted to the T-cell responses to epitope Pol TI8 in other HLA-B51+ patient cohorts. However, in our cohort, T-cell responses targeting this epitope, with Valine at position 8 (Pol TV8), provide the hosts with a long-term protection against HIV-1 infection, because of a fine balance of efficient viral control, lower level of immune pressure and the slower rate of development of escape mutations. In addition, we assessed the ex vivo phenotypic characteristics of HLA-B51 restricted dominant T cell responses and our preliminary data indicated that the early differentiated and less senescence phenotype of CD8+ T cell responses in HIV-1 chronic infection is likely to be a result of low viral antigen exposure due to T cell driven escape. In conclusion, immune-dominant T-cell responses targeting three HLA-B51 restricted epitopes (Pol LI9, Pol TV8 and Gag NI9) could be advantageous for the host. In particular, the responses against epitope Gag NI9 with slow development of escape mutations or epitope Pol TV8 with a fine balance of moderate immune pressure and delayed escape mutations, are beneficial for long-term control of HIV-1 infection.

During last three decades, a great effort was invested to the development of polymer conjugates of low molecular drugs with the aim to improve the specific targeting of drugs to diseased tissues, cells and organs. The main reason for this effort was the fact that high molecular weight copolymers have a favourite distribution profile in tissues and organisms. A linker between a polymer backbone and drug has very important role: it is possible to synthesize a biodegradable linker, which can be enzymatically hydrolyzed. Conversely, there is a possibility to synthesize an inert linker, resistant to the hydrolysis. Proper choice of the suitable precursor- polymer is also essential, hence it has to accomplish all of the stringent demands for biocompatibility. Macromolecular polymer-drug conjugates tend to accumulate in solid tumors because of the so called enhanced permeability and retention (EPR) effect. There is a whole range of possible applications of high molecular polymer-drug conjugates. In the introduction part of this thesis, I summarize potential use of drugs based on poly(N-(2-hydroxypropyl)methacrylamide) (HPMA) copolymers. Moreover, I introduce some therapeutically important proteins used in experimental drug discovery. In our laboratory, we have developed a concept of HPMA copolymers...

O tratamento de indivíduos infectados pelo HIV-1 com terapia anti-retroviral (ARV) pode reduzir a viremia plasmática abaixo dos limites de detecção dos ensaios atuais em muitos pacientes, porém difícil de ser alcançada em crianças na vida real. Falha em alcançar ou manter a supressão da replicação viral está geralmente associada com o desenvolvimento de vírus resistentes a drogas. Nós investigamos o perfil de resistência genotípica em crianças com supressão viral prolongada (< 400 cópias/mL de RNA viral plasmático) em vigência de tratamento anti-retroviral. Nós obtivemos 32 amostras de células mononucleares do sangue periférico (do inglês PBMC) de 16 crianças do CEADIPe - UNIFESP quem tinham tido carga viral indetectável por 12 meses ou mais, em dois momentos: a primeira amostra na inclusão e a segunda após mínimo de 9 meses de acompanhamento. A análise das seqüências foi realizada em vírus isolado de PBMC pelo \"ABI PRISM 377 sequencer\" (Applied Biosystems, USA). Dentre as principais características da população do estudo encontramos: mediana da idade na inclusão de 11 (6-15 anos); esquemas terapêuticos com 2 inibidores da transcriptase reversa análogos nucleosídeo (ITRN) + 1 inibidor da protease (IP) ou 2 ITRN + 1 inibidor da transcriptase reversa não-nucleosídeo (ITRNN) ou 2 ITRN + 2 IP + 1 ITRNN ou 2 ITRN + 2 IP ou 2 ITRN; mediana de células CD4 (cél/mm 3 ) de 1016 (347- 2588) e 938 (440-3038) no primeiro e segundo momentos, respectivamente; classificação clínica (CDC 1994): N = 1, A = 3, B = 6; e classificação imune (CI): CI 1 = 4, CI 2 = 6, CI 3 = 6. O tempo médio de seguimento foi 15 (9 - 27) meses a partir da inclusão. Seis (37,5%) e 7 (43,75%) dos 16 pacientes mostraram no mínimo uma mutação associada aos ITRN, na primeira e na segunda amostra, respectivamente. Dois dos dezesseis (12,5%) apresentaram mutações associadas aos ITRNN na primeira amostra e 3/16 (18,75%) na segunda. Além disso, 14/16 (87,5%) mostraram pelo menos uma mutação associada aos IP nos dois momentos. A despeito do tratamento com drogas anti-retrovirais potentes e supressão do RNA do HIV-1 no plasma a níveis indetectáveis por vários meses, resistência parcial à terapia pode ter resultado primariamente de arquivos de vírus ou refletir precocemente condições sub-ótimas de tratamento. / Treatment of HIV1-infected individuals with antiretroviral therapy (ARV) can reduce plasma viremia to below the limits of detection of current assays in many patients, although it is difficult to happen to children in real life. Failure to achieve or maintain suppression of viral replication is often associated with the development of drug-resistant virus. We investigated genetic resistance profiles of low-level plasma HIV-1 in children with prolonged viral suppression (<400copies/mL of plasma HIV-1 RNA) while receiving ARV. We obtained 32 samples of peripheral-blood mononuclear cells (PBMC) from 16 children from CEADIPe - UNIFESP who had had undetectable viral load for 12 months or more, at two moments: first sample at the inclusion and second after a minimum 9-months follow-up time. Sequence analysis was performed on virus isolated from PBMC by \"ABI PRISM 377 sequencer\" (Applied Biosystems, USA). The main characteristics of the study population were: median age baseline = 11 (6-15 years); drug combinations = 2 nucleoside reverse transcriptase inhibitor (NRTI) + 1 protease inhibitor (PI) or 2 NRTI + 1 non-nucleoside reverse transcriptase (NNRTI) or 2 NRTI + 2 PI + 1 NNRTI or 2 NRTI + 2 PI or 2 NRTI; median CD4 cell count (cells/mm 3 ) = 1016 (347-2588) and 938 (440-3038) at first and second time points, respectively; clinic classification (CDC 1994): N = 1, A = 3, B = 6; and immune classification (IC): IC 1 = 4, IC 2 = 6, IC 3 = 6. The median follow-up time was 15 (9 - 27) months starting from the inclusion. Six (37,5%) and 7 (43,75%) of the 16 patients showed at least one NRTI-associated mutation, in the first and second samples, respectively. Two out of sixteen (12,5%) presented NNRTI-associated mutation at the first moment and 3/16 (18,75%) at the second. In addition, 14/16 (87,5%) showed at least one PI-associated mutation at both moments. Despite treatment with potent antiretroviral drugs and plasma HIV-1 RNA suppression to undetectable levels for several months, partial resistance to therapy may result primarily from archival or contemplate earlier sub optimal treatment conditions.