Rôle des leucocytes infectés du sperme dans la transmission muqueuse du VIH : modèle expérimental de l’infection par le SIVmac251 de Macaca fascicularis

Human Immunodeficiency Virus (HIV) infection mostly spreads by the mucosal route: sexual transmission is the dominant mode of transmission, responsible for between 85% and 90% of cases of infection worldwide. These epidemiological data indicate that semen is one of the major sources of HIV-1 transmission. Semen, like other bodily secretions involved in HIV sexual transmission, contains the virus as two forms: cell-free viral particles and cell-associated virus, mostly in infected leukocytes. Although cell-to-cell HIV transmission has been extensively described as more efficient, rapid and resistant to host immune responses, very few studies have investigated the role in vivo of infected leukocytes in virus mucosal transmission. One such study has been recently conducted in our lab, and demonstrated that SIV-infected splenocytes are able to transmit infection to female macaques after vaginal exposure. However, all these studies used immune cells from peripheral blood or lymphoid tissues, such as spleen, and none have investigated the capacity of infected leukocytes in semen to transmit the infection in vivo. Indeed, nature, phenotype and infectivity of HIV associated with semen leukocytes may be different from that of HIV from other sources.Therefore, the objectives of this work are, first, to study of semen leukocytes and their dynamics during SIVmac251 infection in detail, then to investigate seminal factors that may influence semen infectiousness, and finally to test semen leukocyte infectivity in vitro and in vivo, using a model of mucosal exposure in cynomolgus macaques.Macaque semen contains all the target cells for HIV/SIV: CD4+ T cells, macrophages and dendritic cells in lower proportions. Semen CD4+ T cells and macrophages display an activation, differenciation and expression of migration markers profile which is typical of mucosal leucocytes. SIV infection induces significant changes in their phenotype and dynamics. Both cell types can be productively infected and are found in the semen at all stages of infection. These observations suggest that semen CD4+ T cells and macrophages may be able to transmit infection after mucosal exposure.If the role of semen infected leukocytes in HIV/SIV mucosal transmission is confirmed in vivo, this mechanism will be important to consider for further preventive strategies design, like microbicides.Aujourd’hui, plus de 80% des nouvelles infections par le virus de l’immunodéficience humaine (VIH) se produisent au cours d’un rapport sexuel, avec une transmission du virus par voie muqueuse. Le sperme constitue donc une source majeure de virus à l’échelle mondiale. Le sperme d’hommes infectés par le VIH contient le virus sous deux formes : des particules virales libres et des cellules infectées, principalement des leucocytes.Plusieurs hypothèses ont été proposées afin d’expliquer le passage du virus à travers la barrière muqueuse, qu’il s’agisse d’une muqueuse génitale (cervico-vaginale, pénienne ou urétrale) ou intestinale (muqueuse anale ou rectale). Toutefois, une grande majorité des études qui ont été menées jusqu’à présent se sont concentrées sur le rôle des particules virales libres, et celui des cellules infectées demeure mal compris. Une étude menée dans notre laboratoire a montré que des leucocytes infectés par le virus de l’immunodéficience simienne (VIS) sont capables de transmettre l’infection après inoculation vaginale.Le projet de cette thèse est d’étudier le rôle des leucocytes infectés présents dans le sperme de macaque dans la transmission muqueuse du VIS/VIH. Ainsi, trois axes d’étude principaux ont été définis: 1) l’étude des leucocytes présents dans le sperme de macaque cynomolgus, et de l’influence que peut avoir l’infection par le VIS sur eux ; 2) l’identification des cellules immunitaires infectées présentes dans le sperme de macaque, et l’étude de leur dynamique au cours de l’infection par le VIS. ; 3) l’étude du pouvoir infectieux des deux principales cellules cibles pour le VIS/VIH : les lymphocytes CD4+ (LT CD4+) et les macrophages, in vitro et in vivo, après inoculation rectale et vaginale à des macaques cynomolgus.Le sperme de macaque contient toutes les cellules cibles du VIS/VIH : des lymphocytes T CD4+ (LTCD4+), des macrophages et des cellules dendritiques dans une moindre proportion). Les LTCD4+ et les macrophages du sperme présentent un phénotype d’activation, de différenciation et d’expression de marqueurs de migration typique des leucocytes résidant dans les tissus muqueux. L’infection par le VIS induit des changements significatifs dans leur phénotype et leur dynamique. Ces deux types cellulaires peuvent être infectés de façon productive et sont présents dans le sperme à tous les stades de l’infection. Ces données suggèrent que les LTCD4+ et les macrophages du sperme seraient capables de transmettre l’infection par voie muqueuse.Si le rôle des leucocytes infectés du sperme est confirmé in vivo, il sera important à l’avenir de prendre en compte ce mécanisme de transmission dans le développement de nouvelles stratégies préventives de l’infection par le VIH, notamment les microbicides

Rôle des leucocytes infectés du sperme dans la transmission muqueuse du VIH (Modèle expérimental de l infection par le SIVmac251 de Macaca fascicularis)

Aujourd hui, plus de 80% des nouvelles infections par le virus de l immunodéficience humaine (VIH) se produisent au cours d un rapport sexuel, avec une transmission du virus par voie muqueuse. Le sperme constitue donc une source majeure de virus à l échelle mondiale. Le sperme d hommes infectés par le VIH contient le virus sous deux formes : des particules virales libres et des cellules infectées, principalement des leucocytes.Plusieurs hypothèses ont été proposées afin d expliquer le passage du virus à travers la barrière muqueuse, qu il s agisse d une muqueuse génitale (cervico-vaginale, pénienne ou urétrale) ou intestinale (muqueuse anale ou rectale). Toutefois, une grande majorité des études qui ont été menées jusqu à présent se sont concentrées sur le rôle des particules virales libres, et celui des cellules infectées demeure mal compris. Une étude menée dans notre laboratoire a montré que des leucocytes infectés par le virus de l immunodéficience simienne (VIS) sont capables de transmettre l infection après inoculation vaginale.Le projet de cette thèse est d étudier le rôle des leucocytes infectés présents dans le sperme de macaque dans la transmission muqueuse du VIS/VIH. Ainsi, trois axes d étude principaux ont été définis: 1) l étude des leucocytes présents dans le sperme de macaque cynomolgus, et de l influence que peut avoir l infection par le VIS sur eux ; 2) l identification des cellules immunitaires infectées présentes dans le sperme de macaque, et l étude de leur dynamique au cours de l infection par le VIS. ; 3) l étude du pouvoir infectieux des deux principales cellules cibles pour le VIS/VIH : les lymphocytes CD4+ (LT CD4+) et les macrophages, in vitro et in vivo, après inoculation rectale et vaginale à des macaques cynomolgus.Le sperme de macaque contient toutes les cellules cibles du VIS/VIH : des lymphocytes T CD4+ (LTCD4+), des macrophages et des cellules dendritiques dans une moindre proportion). Les LTCD4+ et les macrophages du sperme présentent un phénotype d activation, de différenciation et d expression de marqueurs de migration typique des leucocytes résidant dans les tissus muqueux. L infection par le VIS induit des changements significatifs dans leur phénotype et leur dynamique. Ces deux types cellulaires peuvent être infectés de façon productive et sont présents dans le sperme à tous les stades de l infection. Ces données suggèrent que les LTCD4+ et les macrophages du sperme seraient capables de transmettre l infection par voie muqueuse.Si le rôle des leucocytes infectés du sperme est confirmé in vivo, il sera important à l avenir de prendre en compte ce mécanisme de transmission dans le développement de nouvelles stratégies préventives de l infection par le VIH, notamment les microbicides.Human Immunodeficiency Virus (HIV) infection mostly spreads by the mucosal route: sexual transmission is the dominant mode of transmission, responsible for between 85% and 90% of cases of infection worldwide. These epidemiological data indicate that semen is one of the major sources of HIV-1 transmission. Semen, like other bodily secretions involved in HIV sexual transmission, contains the virus as two forms: cell-free viral particles and cell-associated virus, mostly in infected leukocytes. Although cell-to-cell HIV transmission has been extensively described as more efficient, rapid and resistant to host immune responses, very few studies have investigated the role in vivo of infected leukocytes in virus mucosal transmission. One such study has been recently conducted in our lab, and demonstrated that SIV-infected splenocytes are able to transmit infection to female macaques after vaginal exposure. However, all these studies used immune cells from peripheral blood or lymphoid tissues, such as spleen, and none have investigated the capacity of infected leukocytes in semen to transmit the infection in vivo. Indeed, nature, phenotype and infectivity of HIV associated with semen leukocytes may be different from that of HIV from other sources.Therefore, the objectives of this work are, first, to study of semen leukocytes and their dynamics during SIVmac251 infection in detail, then to investigate seminal factors that may influence semen infectiousness, and finally to test semen leukocyte infectivity in vitro and in vivo, using a model of mucosal exposure in cynomolgus macaques.Macaque semen contains all the target cells for HIV/SIV: CD4+ T cells, macrophages and dendritic cells in lower proportions. Semen CD4+ T cells and macrophages display an activation, differenciation and expression of migration markers profile which is typical of mucosal leucocytes. SIV infection induces significant changes in their phenotype and dynamics. Both cell types can be productively infected and are found in the semen at all stages of infection. These observations suggest that semen CD4+ T cells and macrophages may be able to transmit infection after mucosal exposure.If the role of semen infected leukocytes in HIV/SIV mucosal transmission is confirmed in vivo, this mechanism will be important to consider for further preventive strategies design, like microbicides.PARIS11-SCD-Bib. électronique (914719901) / SudocSudocFranceF

Health and economic impact of seasonal influenza mass vaccination strategies in European settings: A mathematical modelling and cost-effectiveness analysis

Free PMC article: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8861572/Introduction: Despite seasonal influenza vaccination programmes in most countries targeting individuals aged ≥ 65 (or ≥ 55) years and high risk-groups, significant disease burden remains. We explored the impact and cost-effectiveness of 27 vaccination programmes targeting the elderly and/or children in eight European settings (n = 205.8 million). Methods: We used an age-structured dynamic-transmission model to infer age- and (sub-)type-specific seasonal influenza virus infections calibrated to England, France, Ireland, Navarra, The Netherlands, Portugal, Scotland, and Spain between 2010/11 and 2017/18. The base-case vaccination scenario consisted of non-adjuvanted, non-high dose trivalent vaccines (TV) and no universal paediatric vaccination. We explored i) moving the elderly to "improved" (i.e., adjuvanted or high-dose) trivalent vaccines (iTV) or non-adjuvanted non-high-dose quadrivalent vaccines (QV); ii) adopting mass paediatric vaccination with TV or QV; and iii) combining the elderly and paediatric strategies. We estimated setting-specific costs and quality-adjusted life years (QALYs) gained from the healthcare perspective, and discounted QALYs at 3.0%. Results: In the elderly, the estimated numbers of infection per 100,000 population are reduced by a median of 261.5 (range across settings: 154.4, 475.7) when moving the elderly to iTV and by 150.8 (77.6, 262.3) when moving them to QV. Through indirect protection, adopting mass paediatric programmes with 25% uptake achieves similar reductions in the elderly of 233.6 using TV (range: 58.9, 425.6) or 266.5 using QV (65.7, 477.9), with substantial health gains from averted infections across ages. At €35,000/QALY gained, moving the elderly to iTV plus adopting mass paediatric QV programmes provides the highest mean net benefits and probabilities of being cost-effective in all settings and paediatric coverage levels. Conclusion: Given the direct and indirect protection, and depending on the vaccine prices, model results support a combination of having moved the elderly to an improved vaccine and adopting universal paediatric vaccination programmes across the European settings.Highlights: Seasonal influenza vaccine programmes usually target at-risk and older individuals; We used an age-structured dynamic-transmission model for eight European settings; Older people benefit from adjuvanted or high-dose trivalent or quadrivalent vaccines; Adopting mass paediatric influenza vaccination is also likely to be cost-effective; Results rest on vaccine costs, willingness to vaccinate and unknown long-term effects.I-MOVE+ (Integrated Monitoring of Vaccines in Europe) project, received a grant from the European Commission Horizon 2020 research and innovation programme (grant agreement No 634446).info:eu-repo/semantics/publishedVersio

Semen CD4+ T cells and macrophages are productively infected at all stages of SIV infection in macaques.

International audienceThe mucosal events of HIV transmission have been extensively studied, but the role of infected cells present in the genital and rectal secretions, and in the semen, in particular, remains a matter of debate. As a prerequisite to a thorough in vivo investigation of the early transmission events through infected cells, we characterized in detail by multi-parameter flow cytometry the changes in macaque seminal leukocytes during SIVmac251 infection, focusing on T cells, macrophages and dendritic cells. Using immunocytofluorescence targeting SIV proteins and real-time quantitative PCR targeting SIV DNA, we investigated the nature of the infected cells on sorted semen leukocytes from macaques at different stages of infection. Finally, we cocultured semen CD4(+) T cells and macrophages with a cell line permissive to SIV infection to assess their infectivity in vitro. We found that primary infection induced strong local inflammation, which was associated with an increase in the number of leukocytes in semen, both factors having the potential to favor cell-associated virus transmission. Semen CD4(+) T cells and macrophages were productively infected at all stages of infection and were infectious in vitro. Lymphocytes had a mucosal phenotype and expressed activation (CD69 & HLA-DR) and migration (CCR5, CXCR4, LFA-1) markers. CD69 expression was increased in semen T cells by SIV infection, at all stages of infection. Macrophages predominated at all stages and expressed CD4, CCR5, MAC-1 and LFA-1. Altogether, we demonstrated that semen contains the two major SIV-target cells (CD4+ T cells and macrophages). Both cell types can be productively infected at all stages of SIV infection and are endowed with markers that may facilitate transmission of infection during sexual exposure

Modifications histologiques et répartition de la PrPres dans le tube digestif de Macaque rhésus infectés par l'agent infectieux de la variante de la maladie de Creutzfeldt-Jakob et de l'encéphalopathie spongiforme bovine

LYON1-BU Santé (693882101) / SudocTOULOUSE-EN Vétérinaire (315552301) / SudocSudocFranceF

Ancestral capture of syncytin-Car1, a fusogenic endogenous retroviral envelope gene involved in placentation and conserved in Carnivora

Syncytins are envelope protein genes of retroviral origin that have been captured for a function in placentation. Two such genes have already been identified in simians, two distinct, unrelated genes have been identified in Muridae, and a fifth gene has been identified in the rabbit. Here, we searched for similar genes in the Laurasiatheria clade, which diverged from Euarchontoglires--primates, rodents, and lagomorphs--shortly after mammalian radiation (100 Mya). In silico search for envelope protein genes with full-coding capacity within the dog and cat genomes identified several candidate genes, with one common to both species that displayed placenta-specific expression, which was revealed by RT-PCR analysis of a large panel of tissues. This gene belongs to a degenerate endogenous retroviral element, with precise proviral integration at a site common to dog and cat. Cloning of the gene for an ex vivo pseudotype assay showed fusogenicity on both dog and cat cells. In situ hybridization on placenta sections from both species showed specific expression at the level of the invasive fetal villi within the placental junctional zone, where trophoblast cells fuse into a syncytiotrophoblast layer to form the maternofetal interface. Finally, we show that the gene is conserved among a series of 26 Carnivora representatives, with evidence for purifying selection and conservation of fusogenic activity. The gene is not found in the Pholidota order and, therefore, it was captured before Carnivora radiation, between 60 and 85 Mya. This gene is the oldest syncytin gene identified to date, and it is the first in a new major clade of eutherian mammals

Impact of the lockdown on the burden of COVID-19 in outpatient care in France, spring 2020

International audienceBackground: To limit the spread of SARS-CoV-2 several countries implemented measures to reduce the number of contacts such as a national lockdown. We estimated the impact of the first lockdown on the burden of COVID-19 in the community in France.Methods: Physicians participating in the French Sentinelles network reported the number of patients with an acute respiratory infection (ARI) seen in consultation and performed nasopharyngeal swabs in a sample of these patients (first patient of the week). The swabs were tested by RT-PCR for the presence of SARS-CoV-2. Clinical and virological data were combined to estimate ARI incidence attributable to SARS-CoV-2 from 17 March to 10 May 2020.Results: The incidence of ARI attributable to COVID-19 decreased after the second week of the lockdown period from 142 (95%CI [101; 183]) to 41 (95%CI [21; 60]) per 100,000 population. A decrease was observed in all areas in metropolitan France. The youngest age groups (<15-years-old) were least affected with a cumulated incidence estimated to 14 per 100,000 population during the study period.Conclusions: The data collected in primary care suggests that the first lockdown implemented in France during spring 2020 significantly reduced the incidence of acute respiratory infections including COVID-19 in France and limited the geographic spread of SARS-CoV-2

Innate and Adaptive Anti-SIV Responses in Macaque Semen: Implications for Infectivity and Risk of Transmission

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Captured retroviral envelope syncytin gene associated with the unique placental structure of higher ruminants

International audienceSyncytins are envelope genes of retroviral origin that have been co-opted for a role in placentation and likely contribute to the remarkable diversity of placental structures. Independent capture events have been identified in primates, rodents, lagomorphs, and carni-vores, where they are involved in the formation of a syncytium layer at the fetomaternal interface via trophoblast cell-cell fusion. We searched for similar genes within the suborder Ruminantia where the placenta lacks an extended syncytium layer but displays a heter-ologous cell-fusion process unique among eutherian mammals. An in silico search for intact envelope genes within the Bos taurus ge-nome identified 18 candidates belonging to five endogenous retro-virus families, with one gene displaying both placenta-specific expression, as assessed by quantitative RT-PCR analyses of a large panel of tissues, and conservation in the Ovis aries genome. Both the bovine and ovine orthologs displayed fusogenic activity by conferring infectivity on retroviral pseudotypes and triggering cell-cell fusion. In situ hybridization of placenta sections revealed specific expression in the trophoblast binucleate cells, consistent with a role in the formation-by heterologous cell fusion with uterine cells-of the trinucleate cells of the cow and the syncytial plaques of the ewe. Finally, we show that this gene, which we named "Syncytin-Rum1," is conserved among 16 representatives of higher ruminants, with evidence for purifying selection and conservation of its fusogenic properties, over 30 millions years of evolution. These data argue for syncytins being a major driving force in the emergence and diversity of the placenta. synepitheliochorial | placental evolution | phylogeny | placentome | ER