Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS), characterized by lesions formed due to demyelination. MS is a complex disease thought to be triggered by environmental factors in genetically predisposed individuals. The strongest associated susceptibility allele is HLA-DRB1*1501. Environmental factors include smoking, latitude and previous infection of Epstein-Barr virus (EBV), a common herpes virus. There is no cure for MS, but several inhibitor and symptomatic drugs. Tysabri® (natalizumab) is the most effective drug, but it may lead to progressive multifocal leukoencephalopathy (PML), a rare but often fatal disease caused by reactivation of JC virus. The aim of this thesis was to replicate previous findings from a genome-wide association study and to find host genetic factors influencing JCV seropositivity and EBNA1 IgG titers in Swedish MS patients and healthy controls. Samples from the EIMS and IMSE studies were genotyped by TaqMan® OpenArray™ PCR, an end-point SNP genotyping analysis. 1143 cases and 556 healthy controls were genotyped. Due to poor call rates, genotype data from an Immunochip study was added. A total of 3408 samples (1664 cases and 1744 controls) were analyzed. EBNA1 IgG antibodies were previously measured as a detection of EBV infection and increased MS risk, and JCV IgG antibodies were measured to find patients potentially at risk for PML. One significant result was found, gene 105 (p = 0.01674, OR 0.68, CI 95% 0.49-0.93), with a protective effect in MS. More significant results might have been found with better loading of the plate, or with a different genotyping method.

Theory predicts that sexual reproduction confers an advantage over asexual reproduction due to the generation and maintenance of genetic variation afforded by the processes of recombination and segregation. However, this prediction has rarely been empirically tested. Oenothera is a flowering plant genus whose evolutionary history is punctuated with numerous transitions from sexual reproduction to a form of functionally asexual reproduction known as Permanent Translocation Heterozygosity (PTH). In Ch. 2, a greenhouse experiment examined patterns of phenotypic and genetic variation within and between populations across eight Oenothera species, representing four independent transitions to PTH. I found some evidence for a decrease in heritability and an increase in population differentiation in phenotypic traits associated with the loss of sex. Ch. 3 explored the possibility that rare outcrossing events represent a mechanism for the maintenance of variation in a PTH species. Analysis of microsatellite markers showed evidence for extremely low rates of outcrossing in natural populations (< 1%) of O. biennis, a PTH species.

Theory predicts that sexual reproduction confers an advantage over asexual reproduction due to the generation and maintenance of genetic variation afforded by the processes of recombination and segregation. However, this prediction has rarely been empirically tested. Oenothera is a flowering plant genus whose evolutionary history is punctuated with numerous transitions from sexual reproduction to a form of functionally asexual reproduction known as Permanent Translocation Heterozygosity (PTH). In Ch. 2, a greenhouse experiment examined patterns of phenotypic and genetic variation within and between populations across eight Oenothera species, representing four independent transitions to PTH. I found some evidence for a decrease in heritability and an increase in population differentiation in phenotypic traits associated with the loss of sex. Ch. 3 explored the possibility that rare outcrossing events represent a mechanism for the maintenance of variation in a PTH species. Analysis of microsatellite markers showed evidence for extremely low rates of outcrossing in natural populations (< 1%) of O. biennis, a PTH species.

No description available.

Orientador: Paulo Eduardo Martins Ribolla / Resumo: A deficiência da enzima Glicose-6-Fosfato Desidrogenase (G6PD) é uma anormalidade genética de alta prevalência populacional que resulta em uma menor reatividade do sistema de óxido-redução eritrocitário, geralmente sem repercussões clínicas; estima-se que mais de 300 milhões de pessoas são portadoras dessa alteração. A enzima é expressa em todos os tecidos e catalisa a primeira etapa da Via das Pentoses. Nas hemácias, essa via é de fundamental importância na manutenção do equilíbrio de seu estado redox e a deficiência dessa enzima pode favorecer eventos hemolíticos agudos e crônicos; e em recém nascidos, pode contribuir para o agravamento da icterícia neonatal. O diagnóstico da deficiência baseia-se na atividade enzimática, identificada através de testes quantitativos e qualitativos. Os testes qualitativos limitam-se a agrupar indivíduos em “deficientes” e “não deficientes”, já os métodos quantitativos são mais precisos na inferência dessa atividade. Estas técnicas podem necessitar de repetições dos testes para confirmação de resultados incongruentes. Por outro lado, a variante genética responsável pela deficiência pode ser precisamente reconhecida através de testes de diagnóstico molecular. O presente projeto tem como objetivo desenvolver uma metodologia de identificação molecular da variante G202A, frequentemente encontrada na população brasileira, e realizar uma comparação do custo-benefício com a metodologia de sequenciamento de Sanger. Ao todo, foram analisadas 107 amost... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Glucose-6-phosphate dehydrogenase deficiency is a metabolic enzymatic defect affecting 300 million people worldwide. The enzyme is present in all tissues and catalyses the first reaction in the Pentose Phosphate pathway responsible for maintaining the redox equilibrium in red blood cell. Deficient enzyme may lead to acute and chronic haemolytic anaemia and neonatal jaundice. Diagnosis for G6PD deficiency is based on biochemical quantitative or qualitative tests. Qualitative tests only classifies subjects as “deficient” or “non-deficient”, while quantitative tests are more precise, however both biochemical approches need a confirmative assay to confirm ambiguous results. On the other hand molecular identification for the molecular variants are more accurate and precise. We developed a new molecular assay to identify the G202A molecular variant present at high frequency on Brazilian population and comparer it to Sanger sequencing. One hundred and seven peripheral blood sample were collected on filter paper. DNA extraction were performed followed by G6PD exon 4 amplification and sequencing. On-line tool “Primer1” generated allele-specific primers for TETRA-ARMS genotyping. Twenty two subjects were deficient homozygote, eighty four wild homozygote and one heterozygote. All subjects genotype were confirmed by Sanger sequencing. TETRA-ARMS costs per reaction is three times lower than Sanger sequencing. We conclude that TETRA-ARMS is a suitable protocol to detect G202A mutation on h... (Complete abstract click electronic access below) / Mestre

Made available in DSpace on 2015-07-22T20:49:45Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-07-29. Added 1 bitstream(s) on 2015-08-11T03:25:26Z : No. of bitstreams: 1 Publico-00231.pdf: 1784115 bytes, checksum: 4dcd9596246858abd2e260995c2c0ab4 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Introdução: Candida rugosa é um patógeno emergente que merece destaque pela sua maior ocorrência em países da América Latina. Esta levedura tem o potencial de colonizar e causar infecções de corrente sanguínea no homem, bem como de apresentar resistência a diversos antifúngicos, principalmente aos azólicos. Objetivos: comparar caracteres fenotípicos, como atributos de virulência e sensibilidade antifúngica, além de realizar identificação e tipagem molecular de isolados clínicos de C. rugosa obtidos de pacientes que desenvolveram candidemia, com cepas isoladas de pacientes que foram somente colonizados por esta espécie, sem desfecho de candidemia na internação. Também foi de nosso interesse avaliar tais diferenças entre as cepas provenientes de pacientes internados ao longo de dois períodos avaliados: 1995/96 e 2001/02. Material e Métodos: As cepas foram caracterizadas fenotipicamente quanto a fatores de virulência, incluindo a produção de enzimas extracelulares (proteinase, fosfolipase e lipase) e a formação de biofilme. Foram realizados teste de susceptibilidade a cinco antifúngicos pelo método de microdiluição em caldo, sendo eles: anfotericina B, fluconazol, voriconazol, caspofungina e anidulafungina. Para confirmação de espécie e avaliação de variabilidade genotípica, foram utilizadas as técnicas moleculares de RAPD, microssatélite e sequenciamento da região ITS (rRNA). Resultados: Observou-se grande variabilidade nos resultados referentes à produção de enzimas hidrolíticas. A população foi classificada, no geral, como baixa produtora de proteinase, não produtora de fosfolipase e baixa e média produtora de biofilme. A produção de lipase foi o único fator de virulência expresso de maneira considerável pelos isolados clínicos, destacando-se a alta produção desta enzima por cepas isoladas de sangue, sugerindo a importância da mesma no estabelecimento de infecção por C. rugosa. Com relação à sensibilidade aos antifúngicos, os isolados mostraram-se sensíveis a todas as drogas, exceto ao fluconazol. A avaliação dos resultados obtidos por 3 diferentes métodos moleculares demonstrou alto relacionamento filogenético entre os isolados clínicos, exceto pela cepa de referência a qual foi sempre posicionada em diferente cluster. A análise genotípica revelou similaridade de 90,5% entre todos os isolados, e de 87% para a cepa de referência ATCC1051 pela técnica de RAPD, e uma similaridade de 92% entre os isolados clínicos e de 86,5% para a cepa controle pelo método de microssatélite. O seqüenciamento da região ITS identificou todos os isolados como sendo C. rugosa, apresentando uma identidade que variou de 89% a 93% para os isolados clínicos, e 99% para a cepa de referência ATCC10571. Conclusões: Não foi possível estabelecer uma correlação direta entre a expressão de todos os fatores fenotípicos avaliados e o desfecho clínico dos pacientes, embora haja evidências importantes da atividade de lipase influenciando candidemia por C. rugosa. Sugere-se que houve uma disseminação clonal dos isolados de C. rugosa no ambiente hospitalar avaliado ao longo de vários anos. Adicionalmente, as diferenças genéticas encontradas entre os isolados clínicos e a cepa de referência ATCC10571, juntamente com algumas diferenças fenotípicas observadas exclusivamente nesta cepa, tais como alta produção de biofilme, macromorfologia acentuadamente rugosa e baixa atividade de lipase, indicam a possibilidade de heterogeneidade do táxon C. rugosa. / Introduction: Candida rugosa is an emergent pathogen recognized by its higher occurrence in Latin American countries. This yeast has the ability to colonize and cause human bloodstream infections as well as to show resistance to several antifungal drugs, specifically to azoles. Objectives: To compare phenotypic properties such as virulence attributes and antifungal susceptibility, as well as to perform molecular identification and typing of C. rugosa clinical isolates obtained from patients who were either colonized or developed candidemia due to this species during the hospitalization period. We were also interested in evaluating such differences among strains isolated across two different periods: 1995/96 and 2001/02. Material and Methods: The strains were phenotypically characterized according to virulence factors, including the production of extra cellular enzymes (protease, phospholipase and lipase) and biofilm formation. We performed susceptibility testing to 5 antifungal drugs by using broth microdilution: amphotericin B, fluconazole, voriconazole, caspofungin and anidulafungin. To confirm identification to the species level and evaluate genetic variability, we have employed RAPD, microsatelite and rDNA ITS region sequencing. Results: Phenotypic properties varied considerably among the isolates, specifically regarding to hydrolytic enzymes production. Most of the isolates were low proteinase producers. The strains were phospholipase negative and showed a not very expressive biofilm formation in general. Nevertheless, lipase production was the only virulence factor considerably expressed by the clinical isolates, specifically by blood strains, suggesting the importance of this attribute in C. rugosa infection. The strains were sensitive to all the antifungal drugs tested, except fluconazole. The clinical isolates were highly related as determined by 3 different methods. However the control strain ATCC10571 was considered genotipically very different Our isolates were 90.5% similar among them and 87% similar to C. rugosa control strain as determined by RAPD, and 92% similar among them and 86,5% similar to ATCC10571, as determined by microsatelite. All the isolates were identified as C. rugosa by ITS region sequencing. The percentage of similarity ranged from 89% to 93% for the clinical isolates, and 99% to C. rugosa ATCC10571. Conclusions: It was not possible to establish a direct relationship between the expression of all virulence properties and patients clinical outcomes. However there is mounting evidence that lipase activity influences candidemia due to C. rugosa. It is possible that clonal dissemination in the hospital environment have occurred throughout several years. In addition, the genetic differences found between our isolates C. rugosa control strain ATCC10571, together with the phenotypic differences observed, such as higher biofilm formation and rough colony morphology, as well as low lipase activity for this control strain, suggest the genetic heterogeneity among the taxon C. rugosa. / TEDE / BV UNIFESP: Teses e dissertações

Submitted by DONICER EDUARDO MONTES VERGARA null (donicer.montes@unisucre.edu.co) on 2016-04-11T17:24:33Z No. of bitstreams: 1 H.Tese-Donicer- Defensa Definitivo -08-04-2016.pdf: 1794206 bytes, checksum: a97a3f4dcd0f3e1489260272006d51af (MD5) / Approved for entry into archive by Juliano Benedito Ferreira (julianoferreira@reitoria.unesp.br) on 2016-04-12T14:43:11Z (GMT) No. of bitstreams: 1 montesvergara_de_dr_jabo.pdf: 1794206 bytes, checksum: a97a3f4dcd0f3e1489260272006d51af (MD5) / Made available in DSpace on 2016-04-12T14:43:11Z (GMT). No. of bitstreams: 1 montesvergara_de_dr_jabo.pdf: 1794206 bytes, checksum: a97a3f4dcd0f3e1489260272006d51af (MD5) Previous issue date: 2016-03-24 / Características reprodutivas, como a ocorrência de prenhez precoce, são mais importantes economicamente ao comparar-se com as características de crescimento. Desta forma, o aumento da taxa de fertilidade e emprego de animais geneticamente superiores é determinante no progresso da produtividade nas fazendas comerciais de produção de carne bovina. A seleção modifica as frequências alélicas de uma população ao transmitir as variantes gênicas mais interessantes. Considerando o desequilíbrio de ligação, alguns locos adjacentes às mutações favoráveis são transmitidos ao longo das gerações. Estes são conhecidos como assinaturas de seleção e podem ser identificados com o uso de “chips” de SNP e metodologias estatísticas adequadas. Com o objetivo de identificar assinaturas de seleção recentes em QTL previamente mapeados para características reprodutivas de fêmeas bovinas ligadas à precocidade sexual, foram genotipadas 2.035 fêmeas da raça Nelore (Bos taurus indicus) com o chip “Illumina BovineHD BeadChip”. Posteriormente foi inferida a fase de ligação dos SNPs e a reconstrução dos haplótipos. A detecção de assinaturas de seleção foi realizada por meio da aplicação da metodologia “Relative Extended Haplotype Homozygosity” (REHH). A identificação de genes que contribuem para a importância da característica nestas regiões foi feita com a ferramenta Map Viewer do “National Center for Biotechnology Information”- NCBI e GBrowse carregada com o genoma bovino versão UMD 3.1. Foram detectadas 2.756 regiões núcleo, com tamanho médio 27,6 ± 29,1 Kb, abrangendo 70,1 Mb dos 25 cromossomos estudados. Dos SNPs utilizados, 17.312 participaram da formação das regiões núcleo, com o mínimo de 10 no BTA27 e o máximo de 20 SNPs nos cromossomos 1, 3-7, 9-15,18-21, e 23-24. Foram identificadas 40 assinaturas de seleção recentes com diferentes níveis de significância e 56 genes A maioria dos genes localizados nas regiões de assinaturas de seleção tem relação com os processos biológicos de metabolismo mitocondrial, desenvolvimento pós-embrionário, regulação da taxa de ovulação e fertilidade, resposta imune, metabolismo de triglicerídeo, proliferação celular e neurônios receptores olfativos. A investigação de mecanismos regulatórios da expressão dos genes associados aos processos biológicos descritos pode oferecer conhecimentos sobre os mecanismos moleculares que afetam a característica ocorrências de prenhez precoce, na raça Nelore. / Some reproductive traits such as early pregnancy are more profitable than those related to growth. Increasing fertility rate and using genetically superior animals are crucial in productivity of meat commercial farms. Artificial selection modifies allele frequencies of a cattle population by transmitting the most significant gene variants. Considering linkage disequilibrium, some loci adjacent to favorable mutations are transmitted across generations. Known as signatures of selection, such locations can be identified by the SNP chips, and appropriate statistical methods. To determine recent selection signature in quantitative trait loci (QTL) previously mapped for reproductive cow features linked to sexual precocity, 2,035 Nelore (Bos taurus indicus) females were genotyped by Illumina Bovine chip. After, inferring the connection phase of SNPs allowed haplotype reconstruction. Selection signatures were detected by Relative Extended Haplotype Homozygosity (REHH) method. Genes supposedly important were recognized by Map Viewer from the National Center for Biotechnology Information (NCBI), and also through a loaded GBrowse with bovine genome UMD, version 3.1. A total of 2,756 core regions were detected, with an average size of 27.6 ± 29.1 Kb, covering 70.1 Mb of 25 chromosomes. 17,312 SNPs are involved in the formation of core regions with at least 10 on BTA27, and a maximum of 20 SNPs on 1, 3-7, 9-15, 18-21, and 23-24 chromosomes. We identify 40 possible recent selection signatures, with different levels of significance, and 56 positional candidate genes. Most of genes located in selection signature regions are related to biological processes of mitochondrial metabolism, post-embryonic development, ovulation rate regulation and fertility, immune response, triglyceride metabolism, cell proliferation, and olfactory receptor neurons. The investigation of regulatory mechanisms of gene expression associated with biological processes described can provide knowledge on the molecular mechanisms affecting characteristic of early pregnancy occurrences in Nellore.

Made available in DSpace on 2014-06-11T19:31:29Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-02-26Bitstream added on 2014-06-13T20:41:51Z : No. of bitstreams: 1 almeida_ramb_dr_botfm.pdf: 853261 bytes, checksum: 866edf2277c1ac0e74ea9c48e8cb31a9 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Universidade Estadual Paulista (UNESP) / Iniciativas como a “WHO/UNAIDS ‘3 by 5’ permitiram que se atingisse, no ano de 2007, a marca de 3 milhões de pessoas com acesso à terapia antiretroviral (TARV) em países de baixa e média renda. O aumento da cobertura nestes países demanda custos importantes com anti-retrovirais, porém também levanta outro problema, que é o monitoramento da terapia em localidades de poucos recursos. Há consenso no fato de que devem ser pesquisados marcadores de eficácia da TARV mais acessíveis. Considerando o comportamento da β-2 microglobulina sérica e das citocinas séricas TNF-α, IFN-γ, IL-2, IL-4 e IL-10 com relação à atividade inflamatória induzida pela replicação do HIV-1, o objetivo deste estudo foi o de verificar o comportamento destas substâncias como indicadores da presença, ou não, de falha terapêutica à HAART. Entre agosto de 2004 e novembro de 2005, 89 indivíduos infectados pelo HIV-1, atendidos pela Área de Doenças Tropicais da Faculdade de Medicina de Botucatu-UNESP, e 20 indivíduos normais, doadores de sangue do Hemocentro de Botucatu [43 mulheres e 66 homens; idade média = 39,7 anos (22 - 66 anos)] foram divididos em 4 grupos: G1- 15 indivíduos infectados pelo HIV-1, virgens de tratamento ou sem HAART há pelo menos seis meses e com contagens de linfócitos T CD4 + menores que 350 células/mm3; G2- 31 indivíduos infectados pelo HIV-1, em uso de HAART e sem falha terapêutica virológica (FT); G3- formado por 43 indivíduos infectados pelo HIV-1, em uso de HAART e com FT, e GC- formado por 20 indivíduos normais, não infectados pelo HIV-1, que serviram de controles para as citocinas séricas. Foram revisados os dados demográficos, clínicos e de HAART e realizados os exames β-2 microglobulina sérica, citocinas séricas (TNF-α, IFN-γ, IL-2, IL-4 e IL-10), genotipagem do HIV-1, carga viral plasmática (CV) e linfócitos T CD4 + e T CD8 +. Para... / Initiatives such as WHO/UNAIDS ‘3 by 5’ made it possible to achieve the figure of 3 million people with access to antiretroviral therapy (ART) in middle- and low-income countries in 2007. The increase in these countries’ coverage leads to important expenditure on antiretroviral drugs; however, it also raises another problem, which is therapy monitoring in low-income locations. There is agreement on the fact that more accessible ART efficacy markers must be studied. By considering the behavior of serum β-2 microglobulin and serum cytokines TNF-α, IFN-γ, IL-2, IL-4 and IL-10 in relation to inflammatory activity induced by HIV-1 replication, the objective of this study was to assess the behavior of such substances as indicators of the presence, or not, of antiretroviral therapeutic failure (TF). From August 2004 to November 2005, 89 HIV-1-infected individuals assisted by the Tropical Diseases Sector of the Botucatu School of Medicine – UNESP and 20 normal blood donors at the Blood Transfusion Center of Botucatu [43 female and 66 male; mean age = 39.7 years (22 - 66 years)] were divided into 4 groups: G1- 15 HIV-1-infected individuals, previously untreated or without HAART for at least six months and CD4 + < 350 cells/mm3; G2- 31 HIV-1-infected individuals undergoing HAART without virological therapeutic failure (TF), G3- 43 HIV-1-infected individuals undergoing HAART with TF, and CG- 20 normal individuals who served as controls for serum cytokines. Demographic, clinical and HAART data were reviewed, and serum β-2 microglobulin, serum cytokines (TNFα, IFN-γ, IL-2, IL-4 and IL-10), HIV-1 genotyping, plasma viral load (VL) and T CD4 + and T CD8 + lymphocytes tests were performed. The Mann-Whitney test for independent samples was used for between-group comparison in the case of numeric variables, and Fisher’s exact test was applied for category variables. Statistical difference... (Complete abstract click electronic access below)

Doctor of Philosophy / Department of Agronomy / Guihua Bai / Guorong Zhang / Fusarium head blight (FHB) is a devastating fungal disease in wheat, reducing not only grain yield but also quality. The pathogen produces the mycotoxin deoxynivalenol (DON) that induces severe toxicological problems in human and animals. Using host resistance has been the most efficient way to control the disease. To identify quantitative trait loci (QTLs) for FHB resistance in Chinese landrace Haiyanzhong (HYZ), a recombinant inbred lines (RILs) population derived from a cross between HYZ and Wheaton was developed. The RILs were evaluated for percentage of symptomatic spikelets (PSS) in three greenhouse experiments, and genotyped using simple sequence repeats (SSRs) and single nucleotide polymorphism (SNPs) developed from genotyping-by-sequencing (GBS). Eight QTLs were identified for type II (PSS) resistance on chromosomes 5A, 6B, 7D, 2B (2), 3B, 4B, and 4D, with 5A as the major QTL. Ten SNPs closely linked to 5A, 6B, and 2B QTLs were successfully converted to Kompetitave allelic specific PCR (KASP) assays. To identify common QTLs across different populations, we constructed high-density GBS-SNP maps in an additional four RIL populations derived from the Chinese landraces, Wangshuibai (WSB), Baishanyuehuang (BSYH), Huangfangzhu (HFZ), and Huangchandou (HCD) and conducted meta-analysis of the QTLs for FHB resistance using a consensus map developed from the five populations. We identified six MQTLs on chromosomes 3BS (2), 3A, 3D, 2D, and 4D and 23 tightly linked GBS-SNPs to the MQTLs. These GBS-SNPs were successfully converted to KASPs. The KASPs linked to MQTLs can be used for pyramiding these QTL in breeding programs. To quickly reduce FHB damage in U.S. hard winter wheat (HWW), we transferred Fhb1, a major QTL with stable effects on FHB resistance, from Ning7840 into three adapted HWW cultivars Overland, Jagger, and Overley, by marker-assisted backcross (MAB), and assessed the effect of Fhb1 on FHB resistance in these different backgrounds. The results showed that Fhb1 can significantly lower FHB severity, Fusarium-damaged kernel (FDK), and DON accumulation in the all the three HWW backgrounds. Some of the selected lines showed high levels of FHB resistance, but agronomically similar traits as recurrent parents, can be used as resistant parents to improve HWW FHB resistance.

Submitted by Mario BC (mario@bc.ufrpe.br) on 2016-06-15T16:11:55Z No. of bitstreams: 1 Renata Pimentel Bandeira de Melo.pdf: 793664 bytes, checksum: 79341c83c86e5ba3b6f51a28991d5e93 (MD5) / Made available in DSpace on 2016-06-15T16:11:55Z (GMT). No. of bitstreams: 1 Renata Pimentel Bandeira de Melo.pdf: 793664 bytes, checksum: 79341c83c86e5ba3b6f51a28991d5e93 (MD5) Previous issue date: 2016-02-18 / Toxoplasma gondii is an obligate intracellular coccidian, tissue cyst forming, which causes toxoplasmosis, zoonotic disease of great impact in public health. T. gondii is able to infect most of warm-blooded animals, including humans. Felids are recognized as the only definitive hosts and are important in toxoplasmosis epidemiology, shedding oocysts in feces, contaminating environment. The purpose of this study was to isolate and genotyping T. gondii in feral cats (Felis catus) from the Fernando de Noronha Archipelago, Pernambuco state, Brazil. During one year sick feral cats were caught by Archipelago Animal Vigilance Center. After chemical restraint (ketamine 10% and xylazine 1%) blood samples of 31 feral cats from different locations on the island were collected. These weak animals posteriorly died and fragments of brain, heart, lung, diaphragm, and liver were collected. Blood samples were intended to serology by Indirect Immunofluorescence Assay (IFA) for IgG antibody detection and tissue fragments were submitted to mouse bioassay for T. gondii isolation. Anti-T.gondii antibodies were detected in 18/31 (58%) felines. Tissues from seven animals were submitted to bioassay, obtaining two T. gondii isolates non-pathogenic for mouse. Genotyping was performed by PCR-RFLP using 10 molecular markers (SAG1, SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1 e Apico), identifying an atypical strain of T. gondii (ToxoDB #146). This is the first report of this genotype in feral cats worldwide. The results obtained contribute to molecular epidemiology studies of this pathogen and show/demonstrate T. gondii infection in feline population of the Archipelago. Control measures based on health education should be reinforced to prevent the cat infection and to reduce infection sources for definitive and intermediate hosts, especially to human population of this island. / Toxoplasma gondii é um coccídeo intracelular obrigatório formador de cistos teciduais, responsável pela toxoplasmose, zoonose de grande impacto na saúde pública. É capaz de infectar a maioria dos animais homeotérmicos, incluindo humanos. Os felídeos são os únicos hospedeiros definitivos, apresentando grande importância na epidemiologia da toxoplasmose pela capacidade de eliminar oocistos nas fezes, contaminando o ambiente. Este estudo teve como objetivo isolar e genotipar T. gondii em gatos ferais (Felis catus) do Arquipélago de Fernando de Noronha, Estado de Pernambuco, Brasil. Durante o período de um ano, gatos ferais fracos foram capturados pelo Centro de Vigilância Animal do Arquipélago. Após contenção química (quetamina 10% e xilazina 1%) foram coletadas amostras de sangue de 31 felinos ferais de diferentes localidades da Ilha. Esses animais doentes, posteriormente, vieram a óbito e fragmentos de encéfalo, coração, pulmão, diafragma e fígado foram coletados. As amostras de sangue foram destinadas à sorologia por meio da Reação de Imunofluorescência Indireta (RIFI) para pesquisa de anticorpos (IgG) anti-T.gondii e os fragmentos de tecido deos felinos positivos na RIFI foram submetidos ao bioensaio em camundongos para isolamento do protozoário. Anticorpos anti-Toxoplasma gondii foram detectados em 18/31 (58%) felinos. Sete animais tiveram seus tecidos submetidos ao bioensaio, obtendo-se dois isolados de T. gondii não patogênicos para camundongos. A genotipagem foi realizada por meio da PCR-RFLP multilocus, utilizando 10 marcadores genéticos (SAG1, SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1 e Apico). Uma cepa atípica de T. gondii (ToxoDB #146) foi identificada, sendo este o primeiro relato deste genótipo em gatos ferais no mundo. Os resultados obtidos neste trabalho contribuem para o estudo da epidemiologia molecular deste agente e permitem concluir que a infecção por T. gondii ocorre na população de felinos do Arquipélago. Medidas de controle baseadas na educação sanitária devem ser reforçadas para prevenir a infecção dos felinos e reduzir as fontes de infecção para outros hospedeiros intermediários, sobretudo para a população humana desta Ilha.