Étude du rôle des régions variables 4 et 5 dans les changements de conformation de la gp120 du VIH-1

Le VIH infecte les cellules par fusion de sa membrane avec la membrane de la cellule cible. Cette fusion est effectuée par les glycoprotéines de l'enveloppe (Env) qui sont synthétisées en tant que précurseur, gp160, qui est ensuite clivé en gp120 et gp41. La protéine gp41 est la partie transmembranaire du complexe de l'enveloppe et l’ancre à la particule virale alors que la gp120 assure la liaison au récepteur cellulaire CD4 et corécepteur CCR5 ou CXCR4. Ces interactions successives induisent des changements de conformation d’Env qui alimentent le processus d'entrée du virus conduisant finalement à l'insertion du peptide de fusion de la gp41 dans la membrane de la cellule cible. La sous-unité extérieure gp120 contient cinq régions variables (V1 à V5), dont trois (V1, V2 et V3) étant capables d’empêcher l’adoption spontanée de la conformation liée à CD4. Cependant, le rôle de régions variables V4 et V5 vis-à-vis de ces changements de conformation reste inconnu. Pour étudier leur effet, des mutants de l'isolat primaire de clade B YU2, comprenant une délétion de la V5 ou une mutation au niveau de tous les sites potentiels de N-glycosylation de la V4 (PNGS), ont été générés. L'effet des mutations sur la conformation des glycoprotéines d'enveloppe a été analysé par immunoprécipitation et résonance de plasmon de surface avec des anticorps dont la liaison dépend de la conformation adopté par la gp120. Ni le retrait des PNGS de la V4 ni la délétion de V5 n’a affecté les changements conformationnels d’Env tels que mesurés par ces techniques, ce qui suggère que les régions variables V1, V2 et V3 sont les principaux acteurs dans la prévention de l’adoption de la conformation lié de CD4 d’Env.HIV infects cells by fusing its membrane with the membrane of the target cell. This fusion is performed by the envelope glycoproteins (Env) which are synthesized as a precursor, gp160, which is later cleaved into gp120 and gp41. The transmembrane protein gp41 anchors the envelope complex to the viral particle whereas the gp120 ensures the binding to the cell receptor CD4 and coreceptor CCR5 or CXCR4. These sequential interactions trigger conformational changes on Env that fuel the viral entry process ultimately leading to the insertion of the gp41-derived-fusion peptide into the target cell membrane. The exterior subunit gp120 contains five variable regions (V1 to V5), of which three (V1, V2 and V3) have been shown to restrain the spontaneous sampling of the CD4-bound conformation by gp120. However, the role of variable regions V4 and V5 in these conformational changes remains unknown. To investigate their effect, mutants of the clade B YU2 primary isolate, comprising a deletion of the V5 or mutating all V4 potential N-linked glycosylation sites (PNGS), have been generated. The effect of mutations on the conformation of the envelope glycoproteins was analyzed by immunoprecipitation with conformation-dependent antibodies and surface plasmon resonance. Neither the removal of the V4 PNGS nor the removal of V5 affected Env conformational changes as measured by these techniques. Thus, suggesting that variable regions V1, V2 and V3 are the major players in preventing Env from spontaneously snapping into the CD4-bound conformation

Lineage-specific differences in the gp120 Inner Domain Layer 3 of Human and Simian Immunodeficiency Viruses

Binding of HIV-1 and SIV gp120 exterior envelope glycoprotein to CD4 triggers conformational changes in gp120 that promote its interaction with one of the chemokine receptors, usually CCR5, ultimately leading to gp41-mediated virus-cell membrane fusion and entry. We previously described that topological Layers (Layer 1, Layer 2 and Layer 3) in the gp120 inner domain contribute to gp120-trimer association in the unliganded state but also help secure CD4 binding. Relative to Layer 1 of HIV-1 gp120, the SIVmac239 gp120 Layer 1 plays a more prominent role in maintaining gp120-trimer association but is minimally involved in promoting CD4 binding, which could be explained by the existence of a well-conserved Tryptophan 375 (Trp 375) in HIV-2/SIVsmm. Here we investigated the role of SIV Layer 3 on viral entry, cell-to-cell fusion and CD4 binding. We observed that a network of interactions involving some residues of the β8-α5 region in SIVmac239 Layer 3 may contribute to CD4 binding by helping shape the nearby Phe 43 cavity which directly contacts CD4. In summary, our results suggest that SIV Layer 3 has a greater impact on CD4 binding than in HIV-1. This work defines lineage-specific differences in Layer 3 from HIV-1 and SIV

Lineage-specific differences in the gp120 Inner Domain Layer 3 of Human and Simian Immunodeficiency Viruses

Binding of HIV-1 and SIV gp120 exterior envelope glycoprotein to CD4 triggers conformational changes in gp120 that promote its interaction with one of the chemokine receptors, usually CCR5, ultimately leading to gp41-mediated virus-cell membrane fusion and entry. We previously described that topological Layers (Layer 1, Layer 2 and Layer 3) in the gp120 inner domain contribute to gp120-trimer association in the unliganded state but also help secure CD4 binding. Relative to Layer 1 of HIV-1 gp120, the SIVmac239 gp120 Layer 1 plays a more prominent role in maintaining gp120-trimer association but is minimally involved in promoting CD4 binding, which could be explained by the existence of a well-conserved Tryptophan 375 (Trp 375) in HIV-2/SIVsmm. Here we investigated the role of SIV Layer 3 on viral entry, cell-to-cell fusion and CD4 binding. We observed that a network of interactions involving some residues of the β8-α5 region in SIVmac239 Layer 3 may contribute to CD4 binding by helping shape the nearby Phe 43 cavity which directly contacts CD4. In summary, our results suggest that SIV Layer 3 has a greater impact on CD4 binding than in HIV-1. This work defines lineage-specific differences in Layer 3 from HIV-1 and SIV

Identifying useful actions to improve team resilience in information systems projects

Due to today's business environment demands organizations need to create teams to perform work in projects, with quality, within time and budget. Therefore, teams play a very important role in the organizational development, by creating conditions that enable to overcome difficulties and to promote the improvement of the organizational overall performance. Hence the relevance of studying the project teams resilience, identifying the actions that can influence the project development and its final outcomes. The resilience of a team can be defined as the team's ability to deal with problems, overcome obstacles, or resist the pressure of adverse situations, without entering into rupture. This research, focused on team resilience, firstly involved a literature review, followed by brainstorming sessions, resulting in a preliminary list of useful actions to improve project team resilience. Then, a survey was administered in order to identify the most useful actions perceived from the identified list. Completed questionnaires were received from 115 team members of information technologies/information systems projects being developed in an academic setting. By identifying the most useful actions perceived, as those having the highest potential for increasing project team resilience, practitioners and organizations can set their priorities towards improving team resilience. The results showed that the top ten list of useful actions identified is composed by very well-known and recognized actions, such as the promotion of collaboration and solidarity among project team members, and the recognition, appreciation and use of the talents and competencies of each team member.info:eu-repo/semantics/publishedVersio

A Highly-Conserved Residue of the HIV-1-gp120 Inner Domain is Important for ADCC Responses Mediated by Anti-Cluster A Antibodies

Previous studies have shown that sera from HIV-1-infected individuals contain antibodies able to mediate antibody-dependent cellular cytotoxicity (ADCC). These antibodies preferentially recognize envelope glycoprotein (Env) epitopes induced upon CD4 binding. Here, we show that a highly conserved tryptophan at position 69 of the gp120 inner domain is important for ADCC mediated by anti-cluster A antibodies and sera from HIV-1-infected individuals

Cross-validation of ELISA and a portable surface plasmon resonance instrument for IgG antibody serology with SARS-CoV-2 positive individuals.

We report on the development of surface plasmon resonance (SPR) sensors and matching ELISAs for the detection of nucleocapsid and spike antibodies specific to the novel coronavirus 2019 (SARS-CoV-2) in human serum, plasma and dried blood spots (DBS)

Patient Safety in the Cardiac Operating Room: Human Factors and Teamwork: A Scientific Study from the American Heart Association

The cardiac surgical operating room (OR) is a complex environment in which highly trained subspecialists interact with each other using sophisticated equipment to care for patients with severe cardiac disease and significant comorbidities. Thousands of patient lives have been saved or significantly improved with the advent of modern cardiac surgery. Indeed, both mortality and morbidity for coronary artery bypass surgery have decreased during the past decade. Nonetheless, the highly skilled and dedicated personnel in cardiac ORs are human and will make errors. Refined techniques, advanced technologies, and enhanced coordination of care have led to significant improvements in cardiac surgery outcomes

The Changing Landscape for Stroke\ua0Prevention in AF: Findings From the GLORIA-AF Registry Phase 2

Background GLORIA-AF (Global Registry on Long-Term Oral Antithrombotic Treatment in Patients with Atrial Fibrillation) is a prospective, global registry program describing antithrombotic treatment patterns in patients with newly diagnosed nonvalvular atrial fibrillation at risk of stroke. Phase 2 began when dabigatran, the first non\u2013vitamin K antagonist oral anticoagulant (NOAC), became available. Objectives This study sought to describe phase 2 baseline data and compare these with the pre-NOAC era collected during phase 1. Methods During phase 2, 15,641 consenting patients were enrolled (November 2011 to December 2014); 15,092 were eligible. This pre-specified cross-sectional analysis describes eligible patients\u2019 baseline characteristics. Atrial fibrillation disease characteristics, medical outcomes, and concomitant diseases and medications were collected. Data were analyzed using descriptive statistics. Results Of the total patients, 45.5% were female; median age was 71 (interquartile range: 64, 78) years. Patients were from Europe (47.1%), North America (22.5%), Asia (20.3%), Latin America (6.0%), and the Middle East/Africa (4.0%). Most had high stroke risk (CHA2DS2-VASc [Congestive heart failure, Hypertension, Age  6575 years, Diabetes mellitus, previous Stroke, Vascular disease, Age 65 to 74 years, Sex category] score  652; 86.1%); 13.9% had moderate risk (CHA2DS2-VASc = 1). Overall, 79.9% received oral anticoagulants, of whom 47.6% received NOAC and 32.3% vitamin K antagonists (VKA); 12.1% received antiplatelet agents; 7.8% received no antithrombotic treatment. For comparison, the proportion of phase 1 patients (of N = 1,063 all eligible) prescribed VKA was 32.8%, acetylsalicylic acid 41.7%, and no therapy 20.2%. In Europe in phase 2, treatment with NOAC was more common than VKA (52.3% and 37.8%, respectively); 6.0% of patients received antiplatelet treatment; and 3.8% received no antithrombotic treatment. In North America, 52.1%, 26.2%, and 14.0% of patients received NOAC, VKA, and antiplatelet drugs, respectively; 7.5% received no antithrombotic treatment. NOAC use was less common in Asia (27.7%), where 27.5% of patients received VKA, 25.0% antiplatelet drugs, and 19.8% no antithrombotic treatment. Conclusions The baseline data from GLORIA-AF phase 2 demonstrate that in newly diagnosed nonvalvular atrial fibrillation patients, NOAC have been highly adopted into practice, becoming more frequently prescribed than VKA in Europe and North America. Worldwide, however, a large proportion of patients remain undertreated, particularly in Asia and North America. (Global Registry on Long-Term Oral Antithrombotic Treatment in Patients With Atrial Fibrillation [GLORIA-AF]; NCT01468701