The 35S rDNA gene clusters on the X and Y chromosomes of Drosophila melanogaster are repeats of approximately 150 to 225 copies. Each are transcribed as a single unit by RNA Polymerase I and modified into the 18S, 5.8S, 2S and 28S ribosomal rRNAs. Reduction in the array copy number results in a bobbed phenotype, characterized by truncated bristles and herniations of abdominal cuticle, due to a decrease in protein production. In some copies within the arrays, R1 and R2 retrotransposable elements are inserted in a conserved region of the 28S gene which represses the transcription of a functional rRNA. Inserted arrays are transcribed at very low levels, but it is not clear how they are identified for repression. Similarly, a subset of uninserted arrays are silenced, and the epigenetic mechanism controlling how this decision is made it is also unknown. The CCCTC binding factor (CTCF) is a boundary element binding protein and a transcriptional regulator found in the nucleolus of differentiated mammalian cells, whose localization requires poly (ADP-ribosyl)ation. We investigated whether CTCF might be involved in the regulation of rDNA expression in Drosophila. Our data show that CTCF is found at the nucleolus of both polytene and diploid nuclei, and we have identified binding sites in the 28S gene, R1 and R2 elements by a bioinformatic approach. ChIP data indicate that CTCF binds only to the site in the R1 retrotransposon. Reduction of CTCF or members of the poly(ADP-ribosyl)ation pathway by RNAi in S2 cells causes an increase in the amount of 35S rDNA gene, R1, and R2 transcripts. In flies, CTCF and PARG mutant alleles show disrupted nucleoli and increased rRNA transcripts. Mutant alleles of CTCF suppress variegation of a P-element inserted in a 35S rDNA array, but not of elements inserted elsewhere in the genome. Consistent with a role for CTCF in rRNA regulation, we found that during oogenesis CTCF is recruited to the nucleolus of nurse cells at early stages when the demand of ribosomes is low and it leaves this compartment in later stages when the cell increases rRNA production. We conclude from these studies that CTCF acts as a regulation of rDNA transcription by RNA polymerase I.

Um conjunto de quadros clínicos conhecidos genericamente por Leishmaniose, que representa um sério problema de Saúde Pública, tem como agentes etiológicos protozoários do gênero Leishmania. Em seu ciclo de vida, o parasita apresenta dois hospedeiros, um vertebrado e um invertebrado. O gênero Leishmania é dividido em dois subgêneros: Leishmania (Leishmania) e LeishmaniaViannia), de acordo com a posição ocupada pela forma promastigota no tubo digestivo do hospedeiro invertebrado. Genes que codificam RNA ribossômico são exclusivamente transcritos pela RNA polimerase I. A região promotora dessa polimerase é conhecida como espécie-específica. Estudos anteriores, baseados em ensaios de expressão transiente com construções nas quais a expressão do gene repórter CAT era dirigido por diferentes regiões do promotor mostraram que em Leishmania há um reconhecimento espécie-específico, mas que espécies filogeneticamente relacionadas reconhecem melhor o promotor do que a espécie homóloga. A caracterização estrutural da região promotora de RNA pol I de L. (V.) braziliensis possibilitou mapear o sítio de início de transcrição e definir a provável região promotora de RNA pol I desse organismo. Quando comparamos o 5´ ETS da região estudada, com a região correspondente das demais espécies do subgênero L. (Leishmania), notamos uma alta similaridade tanto no tamanho, quanto na seqüência de nucleotídeos. Já na região IGS os blocos de repetição apresentam tamanho similar, porém seqüências distintas, assim como a seqüência à montante do ETS. Não foi determinado o número de blocos de repetição presente em cada cístron de L.(V.) braziliensis. Os estudos de ligação de fatores nucleares à região central do promotor mostraram que houve um reconhecimento diferencial dessa região entre a espécie homóloga L. (V.) braziliensis e as espécies heterólogas L. (V.) guyanensis, pertencente ao mesmo subgênero e L. (L.) amazonenis. Os complexos protéicos associados a essa região central apresentaram maior afinidade com a espécie heteróloga L. (V.) guyanensis. O fato de ser o ensaio de CAT trabalhoso e demorado levou à busca de outro repórter que evidenciasse a funcionalidade da região promotora ao mesmo tempo em que permitisse a quantificação dessa expressão, de modo a medir a força do promotor. Neste trabalho iniciamos a padronização para utilizar GFP como gene repórter no estudo da funcionalidade de promotores. Foi possível mostrar que a GFP é detectável em microscopia confocal e que as células que expressam GFP podem ser quantificadas em FACS, no entanto, essas detecções só foram possíveis em parasitas selecionados por uma marca de seleção, ou seja, numa transfecção estável. Assim, substituir o gene repórter CAT pelo gene GFP foi inadequado para os ensaios de transfecção transiente, impedindo que fosse medida a atividade da região promotora de L. (V.) braziliensis em diferentes espécies. / Leishmaniasis is the generic name of a serious public health problem that is caused by protozoa of the genus Leishmania. In its lifecycle, the parasite has two hosts, a vertebrate and an invertebrate. The genus Leishmania is divided into two subgenera: Leishmania (Leishmania) and Leishmania (Vianna), according to the position occupied by the promastigotes form at the gut of the invertebrate host. Genes that encode ribosomal RNA are exclusively transcribed by RNA polymerase I. The promoter region of the RNA polymerase I is known to present a species-specific recognition. Previous studies, based on transient expression assays with constructions in which the expression of the reporter gene CAT was directed by different regions of the promoter showed that RNA pol I promoter in Leishmania is species-specific, but in phylogenetically related species the expression of the reporter gene is higher than in the homologous species. The structural characterization of the promoter region of RNA pol I of L. (V.) braziliensis enabled to map the site of initiation of transcription and to define the promoter region of RNA pol I. The comparison of the determined 5\' region of the ETS region, with the corresponding region of other species of the subgenus L. (Leishmania), showed a high similarity both in size, as in the sequence of nucleotides. However, the IGS region and the repetitive blocks of nucleotides have similar size but different sequences. The studies of binding of nuclear factors to the central region of the promoter showed that there was a recognition between the species counterpart L. (V.) braziliensis and the heterologous species L. (V.) guyanensis, belonging to the same subgenus and L. (L.) amazonensis, that belongs to another subgenus. The complex protein associated with this central region showed greater affinity with the heterologous species L. (V.) guyanensis. The fact that to quantify the CAT expression represents a laborious and time consuming test lead us to search for another reporter that could identified the functionality of the promoter region and at the same time allowed the quantification of expression in order to measure the strength of the promoter. In the present work, we began the standardization for the use of GFP gene as reporter in the study of the functionality of promoters. It was possible to show that GFP is detectable in confocal microscope and the cells that express GFP can be quantified in FACS, however, these findings were made possible only in parasites selected by the mark, ie in a stable transfection. So, the replacement of CAT by GFP reporter showed to be inadequate for testing promoters in transient transfection. This prevented the measure of the activity of the promoter region of L. (V.) braziliensis in different species.

Um conjunto de quadros clínicos conhecidos genericamente por Leishmaniose, que representa um sério problema de Saúde Pública, tem como agentes etiológicos protozoários do gênero Leishmania. Em seu ciclo de vida, o parasita apresenta dois hospedeiros, um vertebrado e um invertebrado. O gênero Leishmania é dividido em dois subgêneros: Leishmania (Leishmania) e LeishmaniaViannia), de acordo com a posição ocupada pela forma promastigota no tubo digestivo do hospedeiro invertebrado. Genes que codificam RNA ribossômico são exclusivamente transcritos pela RNA polimerase I. A região promotora dessa polimerase é conhecida como espécie-específica. Estudos anteriores, baseados em ensaios de expressão transiente com construções nas quais a expressão do gene repórter CAT era dirigido por diferentes regiões do promotor mostraram que em Leishmania há um reconhecimento espécie-específico, mas que espécies filogeneticamente relacionadas reconhecem melhor o promotor do que a espécie homóloga. A caracterização estrutural da região promotora de RNA pol I de L. (V.) braziliensis possibilitou mapear o sítio de início de transcrição e definir a provável região promotora de RNA pol I desse organismo. Quando comparamos o 5´ ETS da região estudada, com a região correspondente das demais espécies do subgênero L. (Leishmania), notamos uma alta similaridade tanto no tamanho, quanto na seqüência de nucleotídeos. Já na região IGS os blocos de repetição apresentam tamanho similar, porém seqüências distintas, assim como a seqüência à montante do ETS. Não foi determinado o número de blocos de repetição presente em cada cístron de L.(V.) braziliensis. Os estudos de ligação de fatores nucleares à região central do promotor mostraram que houve um reconhecimento diferencial dessa região entre a espécie homóloga L. (V.) braziliensis e as espécies heterólogas L. (V.) guyanensis, pertencente ao mesmo subgênero e L. (L.) amazonenis. Os complexos protéicos associados a essa região central apresentaram maior afinidade com a espécie heteróloga L. (V.) guyanensis. O fato de ser o ensaio de CAT trabalhoso e demorado levou à busca de outro repórter que evidenciasse a funcionalidade da região promotora ao mesmo tempo em que permitisse a quantificação dessa expressão, de modo a medir a força do promotor. Neste trabalho iniciamos a padronização para utilizar GFP como gene repórter no estudo da funcionalidade de promotores. Foi possível mostrar que a GFP é detectável em microscopia confocal e que as células que expressam GFP podem ser quantificadas em FACS, no entanto, essas detecções só foram possíveis em parasitas selecionados por uma marca de seleção, ou seja, numa transfecção estável. Assim, substituir o gene repórter CAT pelo gene GFP foi inadequado para os ensaios de transfecção transiente, impedindo que fosse medida a atividade da região promotora de L. (V.) braziliensis em diferentes espécies. / Leishmaniasis is the generic name of a serious public health problem that is caused by protozoa of the genus Leishmania. In its lifecycle, the parasite has two hosts, a vertebrate and an invertebrate. The genus Leishmania is divided into two subgenera: Leishmania (Leishmania) and Leishmania (Vianna), according to the position occupied by the promastigotes form at the gut of the invertebrate host. Genes that encode ribosomal RNA are exclusively transcribed by RNA polymerase I. The promoter region of the RNA polymerase I is known to present a species-specific recognition. Previous studies, based on transient expression assays with constructions in which the expression of the reporter gene CAT was directed by different regions of the promoter showed that RNA pol I promoter in Leishmania is species-specific, but in phylogenetically related species the expression of the reporter gene is higher than in the homologous species. The structural characterization of the promoter region of RNA pol I of L. (V.) braziliensis enabled to map the site of initiation of transcription and to define the promoter region of RNA pol I. The comparison of the determined 5\' region of the ETS region, with the corresponding region of other species of the subgenus L. (Leishmania), showed a high similarity both in size, as in the sequence of nucleotides. However, the IGS region and the repetitive blocks of nucleotides have similar size but different sequences. The studies of binding of nuclear factors to the central region of the promoter showed that there was a recognition between the species counterpart L. (V.) braziliensis and the heterologous species L. (V.) guyanensis, belonging to the same subgenus and L. (L.) amazonensis, that belongs to another subgenus. The complex protein associated with this central region showed greater affinity with the heterologous species L. (V.) guyanensis. The fact that to quantify the CAT expression represents a laborious and time consuming test lead us to search for another reporter that could identified the functionality of the promoter region and at the same time allowed the quantification of expression in order to measure the strength of the promoter. In the present work, we began the standardization for the use of GFP gene as reporter in the study of the functionality of promoters. It was possible to show that GFP is detectable in confocal microscope and the cells that express GFP can be quantified in FACS, however, these findings were made possible only in parasites selected by the mark, ie in a stable transfection. So, the replacement of CAT by GFP reporter showed to be inadequate for testing promoters in transient transfection. This prevented the measure of the activity of the promoter region of L. (V.) braziliensis in different species.

Nous montrons dans cette étude que dans les cellules déplétées pour la nucléoline, une plus faible accumulation de pré-ARNr est associée à une augmentation de marques d’hétérochromatine (H3K9me2) et une diminution de marques d’euchromatine (H4K12ac et H3K4me3) sur la chromatine des gènes ribosomiques. Des expériences de ChIP-seq montrent que la nucléoline est enrichie dans la région codante et promotrice de l’ADNr et est préférentiellement associée avec les gènes non méthylés des ARNr. La déplétion de la nucléoline entraîne une accumulation de l’ARN Pol I au début de l’ADNr et une diminution de UBF sur la région codante et promotrice. La nucléoline interfère avec la liaison de TTF-1 sur le promoteur-proximal T0, inhibant ainsi le recrutement de TIP5 du complexe NoRC, et établissant un état d’hétérochromatine répressive. Ces résultats révèlent l’importance de la nucléoline dans le maintien d’un état euchromatinien des ADNr et dans l’élongation de la transcription. Nous montrons aussi dans cette thèse que l’acétylation est une nouvelle modification post-traductionnelle de la nucléoline. Des études d’immunofluorescence utilisant l’anticorps anti nucléoline acétylée montrent que la nucléoline acétylée est exclue des nucléoles. De plus, par ChIP-seq nous n’avons jamais pu détecter d’association significative de la nucléoline acétylée sur la chromatine des ADNr. Aussi, nous n’avons détecté aucune activation de la transcription de Pol II sur des matrices de chromatine avec la nucléoline acétylée. Nous trouvons une distribution de la nucléoline acétylée majoritairement dans le nucléoplasme où elle co-localise parfaitement avec le facteur d’épissage SC35, et partiellement avec les structures marquées avec un anticorps dirigé contre Y12, mais ne co-localise pas avec des structures contenant la coïline, ce qui suggère que cette fraction de la nucléoline pourrait être impliquée dans la synthèse ou le métabolisme des pré-ARNm. / Here we have shown that, in nucleolin depleted cells, lower accumulation of pre-rRNA is associated with the increase in heterochromatin marks (H3K9me2) and decrease of the euchromatin histone marks (H4K12Ac and H3K4me3) in rDNA chromatin. ChIP-seq experiments show that nucleolin is enriched in the coding and promoter region of the rDNA and is preferentially associated with the unmethylated rRNA genes. Nucleolin knockdown results in the accumulation of RNAPI at the beginning of the rDNA and a decrease of UBF in the coding and promoter regions. Nucleolin is able to interfere with the binding of TTF-1 on the promoter-proximal terminator T0 thus inhibiting the recruitment of the NoRC subunit TIP5 and HDAC1 and establishing a repressive heterochromatin state. These results reveal the importance of nucleolin in the maintenance of the euchromatin state of rDNA and transcription elongation.In this thesis we have also shown that acetylation is a novel post-translational modification of nucleolin. Immuno-fluorescence studies using anti-acetylated nucleolin antibody illustrated that acetylated nucleolin is excluded from nucleoli and interestingly, neither could we detect any significant binding of ac-nucleolin on rDNA chromatin by doing ChIP-Seq, nor did we detect any activation of Pol II transcription with ac-nucleolin from DNA and chromatin templates. Moreover, we found acetylated nucleolin had a predominant nucleoplasmic distribution where it associates with the splicing factor SC35 and partially with the structures labeled with Y12 antibody, but not with coilin containing structures.

La réparation par excision de nucléotides (NER) garantit l'intégrité du génome lors de l'exposition aux rayons UV. Après irradiation aux UV, un des premiers problèmes rencontrés par la cellule est l'arrêt général de la transcription dû au blocage de l'ARN polymérase II (ARNP2) au niveau des lésions UV. Pour régler ce problème, le NER possède une voie de réparation spécifiquement couplée à la transcription (TCR). Les connaissances concernant le NER ont été obtenu via des études sur la transcription par l'ARNP2. Cependant, dans les cellules à fort métabolisme, plus de 60% de la transcription correspond à la transcription, dans le nucléole, de l'ADN ribosomique (ADNr) par l'ARN polymérase I (ARNP1). De nombreuses protéines sont absence du nucléole, c'est pourquoi certains processus nucléaires ne peuvent avoir lieu dans cette structure. Afin d ‘être répliqué et réparé, l'ADNr se déplace à la périphérie du nucléole. Malgré l'importance de la transcription par l'ARNP1, la réparation de l'ADNr a été peu étudiée chez l'homme. De plus, à notre connaissance, aucune étude ne s'est penchée sur le mécanisme moléculaire du déplacement de l'ADNr à la périphérie du nucléole. Notre étude démontre l'implication de la TCR dans la réparation de l'ADNr après lésions UV induites. De plus, nos recherches ont démontré que l'ARNP1 reste accrochée à l'ADNr et sont tous les deux délocalisés à la périphérie du nucléole après irradiation aux UV. Enfin, nous avons identifié l'actin et la moysine I nucléaires comme facteurs protéiques nécessaire à cette délocalisation / Nucleotide excision repair (NER) guarantees genome integrity and proper cellular functions against UV-induced DNA damage. After UV irradiation, one of the first burden cells have to cope with is a general transcriptional block caused by the stalling of RNA polymerase II (RNAP2) onto distorting UV lesions. To insure UV lesions repair specifically on transcribed genes, NER is coupled with transcription in an extremely organized pathway known as Transcription-Coupled Repair (TCR). Most of the knowledge about TCR has been gathered from RNAP2 transcription. However, in highly metabolic cells, more than 60% of total cellular transcription results from ribosomal DNA (rDNA) transcription, by the RNA polymerase I (RNAP1), which takes place in the nucleolus. Many nuclear proteins are excluded from the nucleolus and because of this some nucleolar processes cannot occur inside this structure. In order to be replicated and repaired rDNAs need to be displaced at the nucleolar periphery. Despite the importance of RNAP1 transcription, repair of the mammalian transcribed rDNA has been scarcely studied. Moreover, to the best of our knowledge no molecular mechanism has been proposed for rDNA displacement. Our study clearly demonstrated that the full TCR machinery is needed to repair UV-damaged rDNA and restart RNAP1 transcription. Our results show that UV lesions block RNAP1 transcription and that RNAP1 is firmly stalled onto rDNAs without being degraded. Our study also describes the displacement of the RNAP1/rDNA complex to the nucleolar periphery after UV irradiation and identifies both nuclear ß-actin and nuclear myosin I as factors required for this displacement

La nucléoline, une des protéines non-ribosomique les plus abondantes du nucléole, semble être impliquée dans de nombreux aspects du métabolisme de l'ADN en plus de son rôle dans la régulation de la transcription par l'ARN polymérase I, la maturation du pré-ARNr et l’assemblage des ribosomes. L'objectif de cette thèse est d'étudier l'interaction de la nucléoline avec la chromatine, et de déchiffrer la fonction de la nucléoline dans la régulation de l’expression génique. Il a été rapporté que la nucléoline est nécessaire pour la transcription des gènes codant pour l'ADN ribosomal in vivo, mais le mécanisme par lequel la nucléoline module la transcription d’ARN polymérase I (Pol I) est inconnue. Dans cette thèse, je montre que l’inhibition de l’expression de la nucléoline par siRNAconduit dans les gènes de l’ADNr à une augmentation de la marque hétérochromatine et une diminution des marques caractéristiques de l’euchromatine. La nucléoline est associée à des gènes ADNr non méthylés et ChIP-seq montrent un fort enrichissement de la nucléoline dans le promoteur et la région codante de l'ADNr. La nucléoline est capable d'interférer avec la liaison de TTF-1 sur le terminateur T0 proches du promoteur inhibant ainsi le recrutement du sous-unité NoRC TIP5 et HDAC1 et la création d'un état répressif hétérochromatine. Cette invasion de macroH2A1 dans le nucléole joue un rôle majeur dans l'inhibition de la transcription par la RNA Polymérase I en l'absence de la nucléoline. Ces résultats révèlent l'importance de la nucléoline pour le maintien de l'état euchromatien de l'ADNr et le rôle de macroH2A1 dans la régulation de la transcription de l'ADNr. / Besides the well-known role of the nucleolus in ribosome biogenesis, nucleoli play important roles in the regulation of many fundamental cellular processes, including cell cycle regulation, apoptosis, telomerase production, RNA processing and therefore it is not surprising that many nucleolar proteins appear to be multifunctional proteins. Nucleolin, one of the most abundant non-ribosomal proteins of the nucleolus, has been the focus of many studies since it was first described 35 years ago. It seems to be involved in many aspects of DNA metabolism, chromatin regulation and appeared to be a good pharmacological target for drug development in addition to its role in RNA polymerase I transcription and pre-ribosomal processing and assembly in pre-ribosomes. In eukaryotic cells, DNA is packed into nucleosomes to form chromatin in the nucleus. The cells develop a variety of strategies to overcome the nucleosomal barriers. These strategies include DNA methylation, histone post-translational modifications, incorporation of histone variants and ATP dependent chromatin remodeling. The aim of this thesis is to study the interaction of nucleolin with chromatin, and to decipher the mechanism of nucleolin in gene regulation. It was reported that nucleolin possesses a histone chaperone activity, helps the transcription through nucleosomes, and it is required for ribosomal DNA gene (rDNA) transcription in vivo, but the mechanism by which nucleolin modulates RNA polymerase I (Pol I) transcription is unknown. In the thesis it is shown that nucleolin knockdown results in an increase of the heterochromatin mark H3K9me2 and a decrease of H4K12Ac and H3K4me3 euchromatin histone marks in rDNA genes. Nucleolin is associated with unmethylated rDNA genes and ChIP-seq experiments identified a strong enrichment of nucleolin in the promoter and coding regions of rDNA. Nucleolin is able to interfere with the binding of TTF-1 on the promoter-proximal terminator T0 thus inhibiting the recruitment of the nucleolar remodeling complex (NoRC) subunit TIP5 and HDAC1 and the establishment of a repressive heterochromatin state. In addition, in absence of nucleolin or after inhibition of Pol I by actinomycin D, a strong relocalization of the histone variant macroH2A1 to the nucleolus and on the rDNA genes was observed. This invasion of macroH2A1 in the nucleolus plays a major role in the inhibition of Pol I transcription in absence of nucleolin, as knockdown of macroH2A1 eliminates the repressive effect of nucleolin depletion. These results reveal the importance of nucleolin for the maintenance of the euchromatin state of rDNA required for an efficient production of ribosomal RNAs and the role of macroH2A1 in rDNA transcription.

- 1 - ABSTRACT Nucleoli are formed on the basis of genes of ribosomal DNA (rDNA) clusters called Nucleolus Organizer Regions (NORs). The essential structural components of the nucleoli, Fibrillar Centers (FC) and Dense Fibrillar Components (DFC), together compose FC/DFC units. These units are centers of rDNA transcription by RNA polymerase I (pol I), as well as the early processing events, in which an essential role belongs to fibrillarin. Each FC/DFC unit probably corresponds to a single transcriptionally active gene. In our work we study changes of FC/DFC units in the course of cell cycle. Correlative light and electron microscopy analysis showed that the pol I and fibrillarin positive nucleolar beads correspond to individual FC/DFC units. In vivo observations showed that at early S phase, when transcriptionally active ribosomal genes were replicated, the number of the units in each cell increased by 60 to 80 %. During that period the units transiently lost pol I, but not fibrillarin. Then, until the end of interphase, number of the units did not change, and their duplication was completed only after the cell division, by mid G1 phase. This peculiar mode of reproduction suggests that a considerable subset of ribosomal genes remain transcriptionally silent from mid S phase to mitosis but become again active...

CONTEXTE La syphilis est une maladie ré-émergente depuis 2000. Son traitement est simple, mais son diagnostic est complexe. La technique d’amplification génique de Treponema pallidum (Tp-PCR) existe depuis 1990 mais le CDC l’a incluse dans sa définition de cas en janvier 2014. OBJECTIFS 1) Evaluer la performance diagnostique de la Tp-PCR à différents stades cliniques et milieux biologiques. 2) Mesurer la sensibilité, spécificité et les valeurs prédictives de la Tp-PCR en fonction de 3 groupes de référence dans des ulcères récents. 3) Comparer les performances des 2 principales cibles de Tp-PCR.MATÉRIEL ET MÉTHODES Premièrement, une revue systématique et méta-analyse des études publiées depuis 1990 ont été menées. Ensuite une étude multicentrique prospective a été conduite dans 5 villes européennes pendant 2 ans chez des patients avec un ulcère oro-génital. Tous ont reçu le test de référence local et 2 Tp-PCRs dans l’ulcère (gène tpp47 vs. polA). Les valeurs de sensibilité, spécificité et valeurs prédictives de la Tp-PCR ont été calculées comparativement au fond noir (FN), à la sérologie et à un gold standard amélioré. La concordance des 2 cibles a été évaluée par un coefficient kappa.RÉSULTATS PRINCIPAUX La méta-analyse conclut que la Tp-PCR a une meilleure performance dans les ulcères récents. L’étude clinique montre que la Tp-PCR décrit une meilleure performance comparativement au gold standard amélioré et a même une meilleure sensibilité que le FN. Les 2 cibles ont la même valeur diagnostique et une concordance quasi parfaite. CONCLUSIONS La Tp-PCR ciblant tpp47 ou polA est cliniquement utile pour diagnostiquer une syphilis primaire et pourrait même remplacer le FN sous certaines conditions. / BACKGROUND Syphilis has re-emerged in at-risk populations since 2000. Although the treatment of syphilis is simple, its diagnosis remains challenging. Treponema pallidum Polymerase Chain Reaction (Tp-PCR) has been used in the diagnosis of syphilis since 1990 but it is included in the case definition of the CDC since January 2014. OBJECTIVES 1) To assess the accuracy of Tp-PCR in various biological specimens and syphilis stages. 2) To measure its diagnostic performance (sensitivity, specificity and predictive values) in ulcers from early syphilis compared to three groups of reference. 3) To compare the accuracy of the two most currently used targets: tpp47 and polA genes.METHODS We conducted a systematic review and meta-analysis of all studies published from 1990. We implemented a multicentre, prospective, observational study in 5 European cities between 09/2011 and 09/2013 among patients with an oral or genital ulcer suggestive of syphilis. All patients were tested with traditional reference tests plus 2 Tp-PCRs (tpp47 and polA). We estimated the sensitivity, specificity and predictive values of Tp-PCR compared to darkfield microscopy (DFM), serology and an enhanced gold standard. We used the kappa coefficient to assess the agreement between the 2 targets.MAIN RESULTST p-PCR had the best accuracy in ulcers from early syphilis. Tp-PCR performed better when compared to the enhanced gold standard and had a higher sensitivity than DFM. The 2 Tp-PCRs had a similar accuracy and an almost perfect agreement.CONCLUSIONS Tp-PCR targeting either tpp47 or polA is clinically useful to confirm an early syphilis in smears and could even replace DFM under specific conditions.