Hepatitis C virus-specific cellular immune responses in individuals with no evidence of infection

The detection of hepatitis C virus (HCV)-specific T cell responses in HCV-uninfected, presumably unexposed, subjects could be due to an underestimation of the frequency of spontaneously resolving infections, as most acute HCV infections are clinically silent. To address this hypothesis, HCV-specific cellular immune responses were characterized, in individuals negative for an HCV PCR assay and humoral response, with (n = 32) or without (n = 33) risk of exposure to HCV. Uninfected volunteers (n = 20) with a chronically HCV-infected partner were included as positive controls for potential exposure to HCV and HCV infection, respectively. HCV-specific T cell responses in freshly isolated peripheral blood mononuclear cells were studied ex vivo by ELISPOT and CFSE-based proliferation assays using panels of HCV Core and NS3-derived peptides. A pool of unrelated peptides was used as a negative control, and a peptide mix of human cytomegalovirus, Epstein-Bar virus and Influenza virus as a positive control. Overall, 20% of presumably HCV-uninfected subject tested had detectable T-cell responses to the virus, a rate much higher than previous estimates of HCV prevalence in developed countries. This result would be consistent with unapparent primary HCV infections that either cleared spontaneously or remained undetected by conventional serological assays

Prévention santé : pratiques et représentations les enseignants d'éducation physique et sportive et de sciences de la vie et de la terre

International audienceThis paper presents the results of two research studies concerning teachers and their professional practices in the field of health educa¬ tion. The aim of education for health is brought to light in the official texts for physical education teachers and biology teachers. As regards biology teachers, we have more particularly focused our attention on AIDS prevention and sex education, as regards physical education, we have focused on the new objective: managing one's physical life. The hypothesis common to these two studies defines the teachers' representations which influence their behaviours, under the circumstances, their didactic, teaching and relational practices as regards the two presented objectives.The two groups of teachers concerned by our research are faced with changes in direction of the official instructions which have conse¬ quences on their teaching. We have tried to measure the extent of these changes and the impact of the representations: the latter concern the role teachers find legitimate for themselves and for their subject matter.Nous présentons ici les résultats de deux recherches concernant les enseignants et leurs pratiques professionnelles dans le champ de l'éducation à la santé. La finalité d'une éducation à la santé est mise en lumière dans les textes officiels pour les enseignants d'éducation physique et sportive et de sciences de la vie et de la terre. Pour les enseignants de biologie, nous nous sommes intéressées au domaine de la prévention du sida et de l'éducation sexuelle; pour l'éducation physique et sportive, nous nous sommes intéressées au nouvel objectif : gérer sa vie physique. L'hypothèse commune à ces deux recherches définit les représentations des enseignants à la source de leurs comportements, ici leurs pratiques didactiques, pédagogiques et rela¬ tionnelles relatives aux deux objectifs présentés. Les deux groupes d'enseignants concernés par nos recherches sont confrontés à des changements d'orientation des directives officielles ayant des conséquences dans leur enseignement. Nous avons cher¬ ché à situer l'ampleur de ces changements; l'impact des représentations : celles-ci concernent le rôle que l'enseignant pense légitime pour lui-même et sa discipline

The core-specific precursor T cell response is directed to the N-terminal and central parts of the protein and positively correlates to the viral load in chronically HCV-infected patients.

International audienceThe cellular immune response to hepatitis C virus (HCV) plays a critical role in determining the clearance or persistence of HCV. Moreover, in chronic HCV infection, these responses that are insufficient to eradicate virus completely may cause liver injury. In this study, the memory T cells responses specific to the core protein were measured by interferon-gamma Elispot assay after in vitro stimulation of peripheral blood mononuclear lymphocytes from chronically infected subjects. Ten out of the 22 patients studied (45%) present a core-specific response with a preferential recognition of the N-terminal and central parts. There was no relationship between T cell responses and the parameters of disease evolution as determined by ALT (serum alanine transaminase levels), and histologic hepatic damage (Metavir score A and F), but there was a positive relationship between the presence of a core-specific T cell responses and the viraemia

Kinetics of Lymphocyte Proliferation during Primary Immune Response in Macaques Infected with Pathogenic Simian Immunodeficiency Virus SIVmac251: Preliminary Report of the Effect of Early Antiviral Therapy

The aim of this study was to evaluate the kinetics of lymphocyte proliferation during primary infection of macaques with pathogenic simian immunodeficiency virus (SIV) and to study the impact of short-term postexposure highly active antiretroviral therapy (HAART) prophylaxis. Twelve macaques were infected by intravenous route with SIVmac251 and given treatment for 28 days starting 4 h postexposure. Group 1 received a placebo, and groups 2 and 3 received combinations of zidovudine (AZT), lamivudine (3TC), and indinavir. Macaques in group 2 received AZT (4.5 mg/kg of body weight), 3TC (2.5 mg/kg), and indinavir (20 mg/kg) twice per day by the oral route whereas macaques in group 3 were given AZT (4.5 mg/kg) and 3TC (2.5 mg/kg) subcutaneously twice per day, to improve the pharmacokinetic action of these drugs, and a higher dose of indinavir (60 mg/kg). The kinetics of lymphocyte proliferation were analyzed by monitoring 5-bromo-2′-deoxyuridine (BrdU) uptake ex vivo and by fluorescence-activated cell sorting analysis. HAART did not protect against SIV infection but did strongly impact on virus loads: viremia was delayed and lowered during antiviral therapy in group 2, with better control after treatment was stopped, and in group 3, viremia was maintained at lower levels during treatment, with virus even undetectable in the blood of some macaques, but there was no evidence of improved control of the virus after treatment. We provide direct evidence that dividing NK cells are detected earlier than dividing T cells in the blood (mostly in CD45RA(−) T cells), mirroring plasma viremia. Dividing CD8(+) T cells were detected earlier than dividing CD4(+) T cells, and the highest percentages of proliferating T cells coincided with the first evidence of partial control of peak viremia and with an increase in the percentage of circulating gamma interferon-positive CD8(+) T cells. The level of cell proliferation in the blood during SIV primary infection was clearly associated with viral replication levels because the inhibition of viral replication by postexposure HAART strongly reduced lymphocyte proliferation. The results and conclusions in this study are based on experiments in a small numbers of animals and are thus preliminary

Inhibition of Pyrimidine Biosynthesis Pathway Suppresses Viral Growth through Innate Immunity

author Gwénaëlle André-Leroux : Current address: INRA, Unité Mathématiques, Informetique et Génome, Jouy en Josas, FranceInternational audienceSearching for stimulators of the innate antiviral response is an appealing approach to develop novel therapeutics against viral infections. Here, we established a cell-based reporter assay to identify compounds stimulating expression of interferon-inducible antiviral genes. DD264 was selected out of 41,353 compounds for both its immuno-stimulatory and antiviral properties. While searching for its mode of action, we identified DD264 as an inhibitor of pyrimidine biosynthesis pathway. This metabolic pathway was recently identified as a prime target of broad-spectrum antiviral molecules, but our data unraveled a yet unsuspected link with innate immunity. Indeed, we showed that DD264 or brequinar, a well-known inhibitor of pyrimidine biosynthesis pathway, both enhanced the expression of antiviral genes in human cells. Furthermore, antiviral activity of DD264 or brequinar was found strictly dependent on cellular gene transcription, nuclear export machinery, and required IRF1 transcription factor. In conclusion, the antiviral property of pyrimidine biosynthesis inhibitors is not a direct consequence of pyrimidine deprivation on the virus machinery, but rather involves the induction of cellular immune response

Synthesis and evaluation of original bioisosteres of bacterial type IIA topoisomerases inhibitors

International audienceA recently discovered series of inhibitors of the ATPase function of bacterial type IIA topoisomerases featuring a carboxypyrrole component led us to attempt to replace this group with a potentially bioisosteric carboxypyrazole. Accordingly, synthetic pathways to 2-(4-(1H-pyrazole-5-carboxamido)piperidin-1-yl)thiazole-5-carboxylic acids or 2-(4-(N-methyl-1H-pyrazole- 5-carboxamido)piperidin-1-yl)thiazole-5-carboxylic acids featuring an array of substituents on the pyrazole ring were explored. Unfortunately, none of the analogues made were effective on the ATPase function of Mycobacterium tuberculosis gyrase as well on the DNA supercoiling activity of the whole gyrase of M. tuberculosis and Escherichia coli. However, this work is still providing original insights in chemistry as well as in the structure–activity relationships of this series of inhibitorsUne série récente d’inhibiteurs de la fonction ATP-asique des topoisomérases bactériennes de type IIA comportant un noyau carboxypyrrole nous a conduits à tenter de remplacer celui-ci par un noyau carboxypyrazole bioisostère. Ainsi, des accès aux dérivés d’acide 2-(4-(1H-pyrazole-5-carboxamido)piperidin-1-yl)thiazole-5-carboxylique, comportant une gamme de substituants, ont été explorés. Malheureusement, aucun des analogues préparés n’a eu d’effet, que ce soit sur la fonction ATP-asique de la gyrase de Mycobacterium tuberculosis ou sur l’activité de surenroulement des gyrases de M. tuberculosis ou d’Escherichia coli. Toutefois, ce travail représente une contribution originale en ce qui concerne la chimie ou les relations structure–activité de cette série d’inhibiteurs

Synthesis and evaluation of original bioisosteres of bacterial type IIA topoisomerases inhibitors

A recently discovered series of inhibitors of the ATPase function of bacterial type IIA topoisomerases featuring a carboxypyrrole component led us to attempt to replace this group with a potentially bioisosteric carboxypyrazole. Accordingly, synthetic pathways to 2-(4-(1H-pyrazole-5-carboxamido)piperidin-1-yl)thiazole-5-carboxylic acids or 2-(4-(N-methyl-1H-pyrazole-5-carboxamido)piperidin-1-yl)thiazole-5-carboxylic acids featuring an array of substituents on the pyrazole ring were explored. Unfortunately, none of the analogues made were effective on the ATPase function of Mycobacterium tuberculosis gyrase, as well on the DNA supercoiling activity of the whole gyrase of M. tuberculosis and Escherichia coli. However, this work is still providing original insights in chemistry as well as in the structure-activity relationships of this series of inhibitors.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author