37 results on '"Jacot D"'
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2. Articulatory rehearsal and phonological storage in working memory: A replication of Longoni et al. (1993)
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Couture, Camille, Veilleux, Charles, Chinhama, Susana, Jacot de Boinod, Olivia, Payment, Britanny, Husereau, Tracy, and Ouellette, Élodie
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phonological loop replication ,word length effect ,phonemic similarity ,working memory ,replicability predicament ,Psychology ,BF1-990 - Abstract
This study sought to replicate Longoni et al.'s (1993) investigation into the multiple subsystems within the phonological loop, originally proposed by Baddeley et al. (1984). To address the replicability crisis in scientific research, this replication maintains similar methodologies but also features a more diverse sample, characterized solely by advanced French proficiency and increased participant numbers. In addition, this study examined various characteristics of the phonological loop, including the phonemic similarity effect, word length effect, presentation conditions, articulatory suppression effect, and irrelevant sounds. However, the articulatory suppression effect, word length effect, presentation speed effect, and delay effect did not replicate. Notably, an interaction emerged between word length and phonemic similarity, indicating a multiplicative relationship rather than an additive one. The present study emphasizes the importance of further exploration into the factors that influence the non-replicated effects, including the discriminant validity of the variables. Future studies could leverage insights from the phonological loop's characteristics to enhance understanding of the working memory system.
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- 2024
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3. Clinical importance of reporting SARS-CoV-2 viral loads across the different stages of the COVID-19 pandemic
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Moraz, M., primary, Jacot, D., additional, Papadimitriou-Olivgeris, M., additional, Senn, L., additional, Greub, G., additional, Jaton, K., additional, and Opota, O., additional
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- 2020
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4. Statistiques machines SPS & LEP
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Cultrut, G, Desforges, B, and Jacot, D
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Accelerators and Storage Rings - Published
- 1992
5. UROPOT: study protocol for a randomized, double-blind phase I/II trial for metabolism-based potentiation of antimicrobial prophylaxis in the urological tract.
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Stritt K, Roth B, Masnada A, Hammann F, Jacot D, Domingos-Pereira S, Crettenand F, Bohner P, Sommer I, Bréat E, Sauser J, Derré L, Haschke M, Collins JJ, McKinney J, and Meylan S
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- Humans, Double-Blind Method, Clinical Trials, Phase II as Topic, Clinical Trials, Phase I as Topic, Mannitol adverse effects, Klebsiella pneumoniae drug effects, Switzerland, Urinary Tract Infections microbiology, Urinary Tract Infections prevention & control, Escherichia coli drug effects, Treatment Outcome, Amikacin adverse effects, Biofilms drug effects, Bacteriuria prevention & control, Anti-Bacterial Agents therapeutic use, Anti-Bacterial Agents adverse effects, Antibiotic Prophylaxis methods, Antibiotic Prophylaxis adverse effects, Randomized Controlled Trials as Topic
- Abstract
Background: Urinary tract catheters, including Double-J or ureteral stents, are prone to bacterial colonization forming biofilms and leading to asymptomatic bacteriuria. In the context of asymptomatic bacteriuria, endourological procedures causing mucosa-inducing lesions can lead to severe infections. Antibiotic prophylaxis is warranted, yet its efficacy is limited by biofilm formation on stents. Biofilms promote antibiotic tolerance, the capacity of genetically susceptible bacteria to survive a normally lethal dose of antimicrobial therapy. The UROPOT study evaluates the effectiveness of a first-in-type metabolism-based aminoglycoside potentiation for (i) preventing infectious complications of asymptomatic bacteriuria during mucosa lesion-inducing endourological procedures and (ii) assessing its anti-tolerance efficacy., Methods: The UROPOT trial is a phase I/II single-center (Lausanne University Hospital (CHUV), Switzerland) randomized double-blinded trial. Over 2 years, patients with asymptomatic Escherichia coli and/or Klebsiella pneumoniae bacteriuria, undergoing endourological procedures, will be randomly allocated to one of three treatment arms (1:1:1 randomization ratio, 30 patients per group) to evaluate the efficacy of mannitol-potentiated low-dose amikacin compared to established standard treatments (ceftriaxone or amikacin standard dose). Patients will be recruited at the CHUV Urology Outpatient Clinic. The primary outcome is the comparative incidence of postoperative urinary tract infections (assessed at 48 h) between the investigational amikacin/mannitol therapy and standard (ceftriaxone or amikacin) antibiotic prophylaxis, defined by specific systemic symptoms and/or positive blood and/or urine culture. Secondary outcomes include assessing microbiological eradication through anti-biofilm activity, sustained microbiological eradication, and mannitol and antibiotics pharmacokinetics in blood and urine. Safety outcomes will evaluate the incidence of adverse events following amikacin/mannitol therapy and postoperative surgical complications at postoperative day 14., Discussion: UROPOT tests a novel antimicrobial strategy based on "metabolic potentiation" for prophylaxis enabling aminoglycoside dose reduction and targeting biofilm activity. The anti-biofilm effect may prove beneficial, particularly in patients who have a permanent stent in situ needing recurrent endourological manipulations strategies in preventing infections and achieving sustained microbiological eradication in pre-stented patients., Trial Registration: The protocol is approved by the local ethics committee (CER-VD, 2023-01369, protocole 2.0) and the Swiss Agency for Therapeutic Products (Swissmedic, 701,676) and is registered on the NIH's ClinicalTrials.gov (trial registration number: NCT05761405). Registered on March 07, 2023., (© 2024. The Author(s).)
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- 2024
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6. Impact of mutations in the mtrR, rpdlVD and rrl genes on azithromycin resistance in Neisseria gonorrhoeae.
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Mauffrey F, Poncet F, Jacot D, Greub G, Nordmann P, and Blanc DS
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- Humans, Microbial Sensitivity Tests, Ribosomal Proteins genetics, Gonorrhea microbiology, Gonorrhea drug therapy, Male, Female, Azithromycin pharmacology, Neisseria gonorrhoeae genetics, Neisseria gonorrhoeae drug effects, Repressor Proteins genetics, Mutation, Drug Resistance, Bacterial genetics, Bacterial Proteins genetics, Anti-Bacterial Agents pharmacology
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Introduction: Bacterial sexually transmitted infections (STIs) pose a major public health problem. The emergence of antibiotic-resistant strains of Neisseria gonorrhoeae represents a serious threat to successful treatment and epidemiological control. The first extensively drug-resistant (XDR) strains (ceftriaxone-resistant and high-level azithromycin-resistant [HLR AZY]) have been reported., Aims: To identify molecular mechanisms implicated in azithromycin resistance in strains isolated from patients over a three-year period in a university hospital in Switzerland., Material and Methods: From January 2020 to December 2022, 34 isolates (one per patient) were recovered from samples analyzed at the University Hospital of Lausanne. Eight genes involved in azithromycin resistance were sequenced: mtrR repressor (mtrCDE operon repressor) and his promotor mtrR-pr, rplD gene (L4 ribosomal protein), rplV gene (L22 ribosomal protein) and the four alleles of the rrl gene (23S rRNA)., Results: With a cutoff value of 1 mg/L, 15 isolates were considered as being resistant to azithromycin, whereas the remaining 19 were susceptible. The C2597T mutation in 3 or 4 of the rrl allele confer a medium-level resistance to azithromycin (MIC = 16 mg/L, N = 2). The following mutations were significantly associated with MIC values ≥1 mg/L: the three mutations V125A, A147G, R157Q in the rplD gene (N = 10) and a substitution A->C in the mtrR promotor (N = 9). Specific mutations in the mtrR repressor and its promotor were observed in both susceptible and resistant isolates., Conclusions: Resistance to azithromycin was explained by the presence of mutations in many different copies of 23S RNA ribosomal genes and their regulatory genes. Other mutations, previously reported to be associated with azithromycin resistance, were documented in both susceptible and resistant isolates, suggesting they play little role, if any, in azithromycin resistance., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Mauffrey et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)
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- 2024
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7. The Impact of Laboratory Automation on the Time to Urine Microbiological Results: A Five-Year Retrospective Study.
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Kritikos A, Prod'hom G, Jacot D, Croxatto A, and Greub G
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Total laboratory automation (TLA) is a valuable component of microbiology laboratories and a growing number of publications suggest the potential impact of automation in terms of analysis standardization, streaking quality, and the turnaround time (TAT). The aim of this project was to perform a detailed investigation of the impact of TLA on the workflow of commonly treated specimens such as urine. This is a retrospective observational study comparing two time periods (pre TLA versus post TLA) for urine specimen culture processing. A total of 35,864 urine specimens were plated during the pre-TLA period and 47,283 were plated during the post-TLA period. The median time from streaking to identification decreased from 22.3 h pre TLA to 21.4 h post TLA ( p < 0.001), and the median time from streaking to final validation of the report decreased from 24.3 h pre TLA to 23 h post TLA ( p < 0.001). Further analysis revealed that the observed differences in TAT were mainly driven by the contaminated and positive samples. Our findings demonstrate that TLA has the potential to decrease turnaround times of samples in a laboratory. Nevertheless, changes in laboratory workflow (such as extended opening hours for plate reading and antibiotic susceptibility testing or decreased incubation times) might further maximize the efficiency of TLA and optimize TATs.
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- 2024
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8. Predictors of mortality of Pseudomonas aeruginosa bacteraemia and the role of infectious diseases consultation and source control; a retrospective cohort study.
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Papadimitriou-Olivgeris M, Senn L, Jacot D, and Guery B
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Purpose: To determine predictors of mortality among patients with Pseudomonas aeruginosa bacteraemia., Methods: Retrospective study., Setting: This study conducted at the Lausanne University Hospital, Switzerland included adult patients with P. aeruginosa bacteraemia from 2015 to 2021., Results: During the study period, 278 episodes of P. aeruginosa bacteraemia were included. Twenty (7%) isolates were multidrug-resistant. The most common type of infection was low respiratory tract infection (58 episodes; 21%). Sepsis was present in the majority of episodes (152; 55%). Infectious diseases consultation within 48 h of bacteraemia onset was performed in 203 (73%) episodes. Appropriate antimicrobial treatment was administered within 48 h in 257 (92%) episodes. For most episodes (145; 52%), source control was considered necessary, with 93 (64%) of them undergoing such interventions within 48 h. The 14-day mortality was 15% (42 episodes). The Cox multivariable regression model showed that 14-day mortality was associated with sepsis (P 0.002; aHR 6.58, CI 1.95-22.16), and lower respiratory tract infection (P < 0.001; aHR 4.63, CI 1.78-12.06). Conversely, interventions performed within 48 h of bacteraemia onset, such as infectious diseases consultation (P 0.036; HR 0.51, CI 0.27-0.96), and source control (P 0.009; aHR 0.17, CI 0.47-0.64) were associated with improved outcome., Conclusion: Our findings underscore the pivotal role of early infectious diseases consultation in recommending source control interventions and guiding antimicrobial treatment for patients with P. aeruginosa bacteraemia., (© 2024. The Author(s).)
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- 2024
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9. Environmental and geographical factors influencing the spread of SARS-CoV-2 over 2 years: a fine-scale spatiotemporal analysis.
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De Ridder D, Ladoy A, Choi Y, Jacot D, Vuilleumier S, Guessous I, Joost S, and Greub G
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- Humans, Switzerland epidemiology, Air Pollution statistics & numerical data, Pandemics, Socioeconomic Factors, COVID-19 epidemiology, COVID-19 transmission, Spatio-Temporal Analysis, SARS-CoV-2
- Abstract
Introduction: Since its emergence in late 2019, the SARS-CoV-2 virus has led to a global health crisis, affecting millions and reshaping societies and economies worldwide. Investigating the determinants of SARS-CoV-2 diffusion and their spatiotemporal dynamics at high spatial resolution is critical for public health and policymaking., Methods: This study analyses 194,682 georeferenced SARS-CoV-2 RT-PCR tests from March 2020 and April 2022 in the canton of Vaud, Switzerland. We characterized five distinct pandemic periods using metrics of spatial and temporal clustering like inverse Shannon entropy, the Hoover index, Lloyd's index of mean crowding, and the modified space-time DBSCAN algorithm. We assessed the demographic, socioeconomic, and environmental factors contributing to cluster persistence during each period using eXtreme Gradient Boosting (XGBoost) and SHapley Additive exPlanations (SHAP), to consider non-linear and spatial effects., Results: Our findings reveal important variations in the spatial and temporal clustering of cases. Notably, areas with flatter epidemics had higher total attack rate. Air pollution emerged as a factor showing a consistent positive association with higher cluster persistence, substantiated by both immission models and, to a lesser extent, tropospheric NO
2 estimations. Factors including population density, testing rates, and geographical coordinates, also showed important positive associations with higher cluster persistence. The socioeconomic index showed no significant contribution to cluster persistence, suggesting its limited role in the observed dynamics, which warrants further research., Discussion: Overall, the determinants of cluster persistence remained across the study periods. These findings highlight the need for effective air quality management strategies to mitigate air pollution's adverse impacts on public health, particularly in the context of respiratory viral diseases like COVID-19., Competing Interests: GG reports a research agreement with Becton-Dickinson and Company, and was co-director of JeuPRO, a start-up distributing the card games Mykrobs and Krobs, which are two games on microbes. DR reports a relationship with Becton Dickinson and Company that includes speaking and lecture fees and travel reimbursement. These relationships with industry do not represent a direct conflict of interest on the present epidemiological work on SARS-CoV-2. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 De Ridder, Ladoy, Choi, Jacot, Vuilleumier, Guessous, Joost and Greub.)- Published
- 2024
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10. Development and evaluation of an artificial intelligence for bacterial growth monitoring in clinical bacteriology.
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Jacot D, Gizha S, Orny C, Fernandes M, Tricoli C, Marcelpoil R, Prod'hom G, Volle J-M, Greub G, and Croxatto A
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- Humans, Algorithms, Bacteriological Techniques methods, Image Processing, Computer-Assisted methods, Bacterial Infections diagnosis, Bacterial Infections microbiology, Bacteriology, Automation, Laboratory methods, Culture Media chemistry, Bacteria growth & development, Bacteria isolation & purification, Bacteria classification, Artificial Intelligence, Sensitivity and Specificity
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In clinical bacteriology laboratories, reading and processing of sterile plates remain a significant part of the routine workload (30%-40% of the plates). Here, an algorithm was developed for bacterial growth detection starting with any type of specimens and using the most common media in bacteriology. The growth prediction performance of the algorithm for automatic processing of sterile plates was evaluated not only at 18-24 h and 48 h but also at earlier timepoints toward the development of an early growth monitoring system. A total of 3,844 plates inoculated with representative clinical specimens were used. The plates were imaged 15 times, and two different microbiologists read the images randomly and independently, creating 99,944 human ground truths. The algorithm was able, at 48 h, to discriminate growth from no growth with a sensitivity of 99.80% (five false-negative [FN] plates out of 3,844) and a specificity of 91.97%. At 24 h, sensitivity and specificity reached 99.08% and 93.37%, respectively. Interestingly, during human truth reading, growth was reported as early as 4 h, while at 6 h, half of the positive plates were already showing some growth. In this context, automated early growth monitoring in case of normally sterile samples is envisioned to provide added value to the microbiologists, enabling them to prioritize reading and to communicate early detection of bacterial growth to the clinicians., Competing Interests: Becton-Dickinson supported this study by funding the data acquisition and plate reviews by two microbiologists. BD developed the software. CHUV independently reviewed all the data and algorithm performances and reports no patent-licensing arrangements. Five co-authors, Cedrick Orny, Mathieu Fernandes, Carmelo Tricoli, Raphael Marcelpoil, and Jean-Marc Volle, are/were employed by Becton-Dickinson.The authors declare no other conflict of interest.
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- 2024
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11. Clinical significance of concomitant bacteriuria in patients with Staphylococcus aureus bacteraemia.
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Papadimitriou-Olivgeris M, Jacot D, Senn L, and Guery B
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- Humans, Staphylococcus aureus, Retrospective Studies, Clinical Relevance, Bacteriuria complications, Bacteriuria microbiology, Bacteremia complications, Bacteremia microbiology, Staphylococcal Infections complications, Staphylococcal Infections microbiology
- Abstract
This retrospective study, conducted at Lausanne University Hospital (2015-2021), compared Staphylococcus aureus bacteraemia (SABA) patients with or without concomitant bacteriuria (SABU). Among 448 included bacteraemic patients, 62 (13.8%) had S. aureus concurrently isolated from urine. In multivariate analysis, there was a significant difference in the odds of community-onset bacteraemia (P 0.030), malignancy (P 0.002), > 1 pair of positive blood cultures (P 0.037), and persistent bacteraemia for at least 48 h (P 0.045) in patients with concurrent SABU. No difference concerning mortality was found. On the other hand, SABU was associated with higher rates of SABA recurrence after antibiotic cessation., (© 2023. The Author(s).)
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- 2023
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12. Swiss public health measures associated with reduced SARS-CoV-2 transmission using genome data.
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Nadeau SA, Vaughan TG, Beckmann C, Topolsky I, Chen C, Hodcroft E, Schär T, Nissen I, Santacroce N, Burcklen E, Ferreira P, Jablonski KP, Posada-Céspedes S, Capece V, Seidel S, Santamaria de Souza N, Martinez-Gomez JM, Cheng P, Bosshard PP, Levesque MP, Kufner V, Schmutz S, Zaheri M, Huber M, Trkola A, Cordey S, Laubscher F, Gonçalves AR, Aeby S, Pillonel T, Jacot D, Bertelli C, Greub G, Leuzinger K, Stange M, Mari A, Roloff T, Seth-Smith H, Hirsch HH, Egli A, Redondo M, Kobel O, Noppen C, du Plessis L, Beerenwinkel N, Neher RA, Beisel C, and Stadler T
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- Humans, Public Health, Switzerland epidemiology, Communicable Disease Control, Genome, Viral genetics, Phylogeny, SARS-CoV-2 genetics, COVID-19 genetics
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Genome sequences from evolving infectious pathogens allow quantification of case introductions and local transmission dynamics. We sequenced 11,357 severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) genomes from Switzerland in 2020-the sixth largest effort globally. Using a representative subset of these data, we estimated viral introductions to Switzerland and their persistence over the course of 2020. We contrasted these estimates with simple null models representing the absence of certain public health measures. We show that Switzerland's border closures decoupled case introductions from incidence in neighboring countries. Under a simple model, we estimate an 86 to 98% reduction in introductions during Switzerland's strictest border closures. Furthermore, the Swiss 2020 partial lockdown roughly halved the time for sampled introductions to die out. Last, we quantified local transmission dynamics once introductions into Switzerland occurred using a phylodynamic model. We found that transmission slowed 35 to 63% upon outbreak detection in summer 2020 but not in fall. This finding may indicate successful contact tracing over summer before overburdening in fall. The study highlights the added value of genome sequencing data for understanding transmission dynamics.
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- 2023
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13. SARS-CoV-2 neutralizing antibody response in vaccinated and non-vaccinated hospital healthcare workers with or without history of infection.
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Jacot D, von Rotz U, Pellaton C, Blondet F, Aebischer O, Perreau M, De Rham M, Pantaleo G, Marchetti O, and Greub G
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- Humans, Reinfection, Health Personnel, Hospitals, Vaccination, Antibodies, Neutralizing, Antibodies, Viral, SARS-CoV-2, COVID-19 prevention & control
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Between March 2021 and February 2022, SARS-CoV-2 neutralizing antibodies dynamics was investigated in a prospective observational study in 903 healthcare workers of a hospital in Switzerland. A surrogate neutralization assay measuring the competitive inhibition of the angiotensin converting enzyme 2 (ACE2) binding to the spike protein (S) of the SARS-CoV-2 wild type virus and to five variants of concern (Alpha, Beta, Gamma, Delta, Omicron) was used. We observed a broad distribution of neutralization activity among participants and substantial differences in neutralizing titers against variants. Participants were grouped based on combinations of vaccination status (1, 2 or 3 doses) and/or prior or subsequent SARS-CoV-2 infection/reinfection. Triple vaccination resulted in the highest neutralization response, as did double vaccination with prior or subsequent infection. Double vaccination without infection showed an intermediate neutralization response while SARS-CoV-2 infection in non-vaccinated participants resulted in poor neutralization response. After triple vaccination or double vaccination plus infection, additional vaccination and/or reinfection had no impact on neutralizing antibody titers over the observed period. These results strongly support the booster dose strategy, while additional booster doses within short time intervals might not improve immunization. However, dynamics of neutralizing antibodies titers needs to be monitored individually, over time and include newly emerging variants., Competing Interests: Declaration of competing interest G. Greub is medical advisor of Resistell, a startup active in the development of a new instrument to faster antibiotic susceptibility results. G. Greub has a research agreement with Becton Dickinson (USA) and Resistell (Switzerland), both unrelated to the present work. The rest of the authors have no conflict of interest to declare., (Copyright © 2022 The Author(s). Published by Elsevier Masson SAS.. All rights reserved.)
- Published
- 2023
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14. Detection of SARS-CoV-2 infection clusters: The useful combination of spatiotemporal clustering and genomic analyses.
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Choi Y, Ladoy A, De Ridder D, Jacot D, Vuilleumier S, Bertelli C, Guessous I, Pillonel T, Joost S, and Greub G
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- Humans, SARS-CoV-2 genetics, Pandemics, Communicable Disease Control, Genomics, Cluster Analysis, COVID-19
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Background: The need for effective public health surveillance systems to track virus spread for targeted interventions was highlighted during the COVID-19 pandemic. It spurred an interest in the use of spatiotemporal clustering and genomic analyses to identify high-risk areas and track the spread of the SARS-CoV-2 virus. However, these two approaches are rarely combined in surveillance systems to complement each one's limitations; spatiotemporal clustering approaches usually consider only one source of virus transmission (i.e., the residential setting) to detect case clusters, while genomic studies require significant resources and processing time that can delay decision-making. Here, we clarify the differences and possible synergies of these two approaches in the context of infectious disease surveillance systems by investigating to what extent geographically-defined clusters are confirmed as transmission clusters based on genome sequences, and how genomic-based analyses can improve the epidemiological investigations associated with spatiotemporal cluster detection., Methods: For this purpose, we sequenced the SARS-CoV-2 genomes of 172 cases that were part of a collection of spatiotemporal clusters found in a Swiss state (Vaud) during the first epidemic wave. We subsequently examined intra-cluster genetic similarities and spatiotemporal distributions across virus genotypes., Results: Our results suggest that the congruence between the two approaches might depend on geographic features of the area (rural/urban) and epidemic context (e.g., lockdown). We also identified two potential superspreading events that started from cases in the main urban area of the state, leading to smaller spreading events in neighboring regions, as well as a large spreading in a geographically-isolated area. These superspreading events were characterized by specific mutations assumed to originate from Mulhouse and Milan, respectively. Our analyses propose synergistic benefits of using two complementary approaches in public health surveillance, saving resources and improving surveillance efficiency., Competing Interests: GG has a research agreement with Becton-Dickinson on automation using the BD-Kiestra automated system as well as a research agreement with Resistell on nanotechnology to determine the antibiotic susceptibility of bacteria. In addition, Gilbert Greub is co-director of JeuPRO, a start-up distributing the card games Mykrobs and Krobs, which are two games on microbes. All these relationships with industry does not represent a direct conflict of interest on the present epidemiological work on SARS-CoV-2. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Choi, Ladoy, De Ridder, Jacot, Vuilleumier, Bertelli, Guessous, Pillonel, Joost and Greub.)
- Published
- 2022
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15. SARS-CoV-2 seroprevalence in hospital healthcare workers in Western Switzerland at the end of the second pandemic wave.
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Jacot D, von Rotz U, Blondet F, Aebischer O, Matthieu P, De Rham M, Pantaleo G, Marchetti O, and Greub G
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- Antibodies, Viral, Health Personnel, Hospitals, Humans, Personnel, Hospital, SARS-CoV-2, Seroepidemiologic Studies, Switzerland epidemiology, COVID-19 epidemiology, Pandemics
- Abstract
Introduction. In early January 2020, the pandemic of COVID-19 (coronavirus disease 2019) rapidly spread from China and caused a worldwide pandemic. Hypothesis. Healthcare workers represent a high-risk group for acquiring COVID-19 and for nosocomial transmission of severe acute respiratory coronavirus 2 (SARS-CoV-2). Aim. We aimed to investigate over a 1 year period, across two pandemic waves, the SARS-CoV-2 seroprevalence in employees at a Western Switzerland public hospital. Methodology. A prospective observational SARS-CoV-2 seroprevalence study was proposed to all hospital employees who enrolled on a voluntary basis. Results. Out of 594 participants recruited on a voluntary basis, 269 volunteers (45.3 %) had anti-SARS-CoV-2 antibodies: this seroprevalence was twice higher than that reported in the local community. Healthcare workers with prolonged exposure to patients with COVID-19 showed a significantly higher odds ratio (OR) of having a positive SARS-CoV-2 serology [OR 3.19, 95 % confidence interval (CI) 2.16-4.74]. Symptoms showing the highest association with a positive serology were anosmia (OR 11.9, 95 % CI 5.58-30.9) and ageusia (OR 10.3, 95 % CI 4.8-26.3). A total of 17.1 % (95 % CI 12.2-21.1 %) of SARS-CoV-2 seropositive volunteers did not report a suspicion of COVID-19 in their personal history. Conclusion. Overall, we observed that the impact of the second SARS-CoV-2 pandemic wave was considerable and significantly affected healthcare workers with prolonged exposure to patients with COVID-19.
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- 2022
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16. How to Manage Pseudomonas aeruginosa Infections.
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Papadimitriou-Olivgeris M, Jacot D, and Guery B
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- Humans, Colistin therapeutic use, Tazobactam pharmacology, Tazobactam therapeutic use, Anti-Bacterial Agents pharmacology, Pseudomonas aeruginosa, Carbapenems pharmacology, Drug Combinations, Microbial Sensitivity Tests, Drug Resistance, Multiple, Bacterial, Pseudomonas Infections drug therapy, Pseudomonas Infections chemically induced, Fosfomycin therapeutic use
- Abstract
Pseudomonas aeruginosa is a pathogen frequently encountered in healthcare-associated infections and immunocompromised patients. In bacteremia, this pathogen is associated with higher mortality than other Gram-negative pathogens. This increase in mortality was also found globally for multi-resistant compared to susceptible strains. Several factors have been associated with the development of resistance: previous ICU stay, use of carbapenems, and comorbidities were identified in multivariate analysis. In the therapeutic choice, previous antibiotic treatment remains the strongest driver suggesting a potential resistant strain. These risk factors will decide whether multi-resistant strains must be considered in the empiric coverage. For susceptible strains, a single agent can be used, β-lactams are usually the first choice. Associations do not provide any advantage on mortality. Optimization of pharmacokinetic/pharmacodynamic parameters, such as prolonged infusion (for time-dependent antibiotics), increased dosage (for concentration-dependent antibiotics), and therapeutic drug monitoring, also influences the outcome. The increasing number of resistant strains led the clinician to use either recently approved new molecules but also associations. For multi-resistant strains, new molecules such as ceftolozane-tazobactam, ceftazidime-avibactam, and cefiderocol have shown an adequate activity against P. aeruginosa. Older molecules like colistin and fosfomycin are also used in this indication. The complexity of the resistance and consequences on a larger scale of antibiotic prescription will probably lead to more individualized prescriptions., (© 2022. The Author(s), under exclusive license to Springer Nature Switzerland AG.)
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- 2022
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17. Assessment of SARS-CoV-2 Genome Sequencing: Quality Criteria and Low-Frequency Variants.
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Jacot D, Pillonel T, Greub G, and Bertelli C
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- Genome, Viral, Humans, RNA, Viral, Retrospective Studies, COVID-19, SARS-CoV-2
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Although many laboratories worldwide have developed their sequencing capacities in response to the need for SARS-CoV-2 genome-based surveillance of variants, only a few reported some quality criteria to ensure sequence quality before lineage assignment and submission to public databases. Hence, we aimed here to provide simple quality control criteria for SARS-CoV-2 sequencing to prevent erroneous interpretation of low-quality or contaminated data. We retrospectively investigated 647 SARS-CoV-2 genomes obtained over 10 tiled amplicons sequencing runs. We extracted 26 potentially relevant metrics covering the entire workflow from sample selection to bioinformatics analysis. Based on data distribution, critical values were established for 11 selected metrics to prompt further quality investigations for problematic samples, in particular those with a low viral RNA quantity. Low-frequency variants (<70% of supporting reads) can result from PCR amplification errors, sample cross contaminations, or presence of distinct SARS-CoV2 genomes in the sample sequenced. The number and the prevalence of low-frequency variants can be used as a robust quality criterion to identify possible sequencing errors or contaminations. Overall, we propose 11 metrics with fixed cutoff values as a simple tool to evaluate the quality of SARS-CoV-2 genomes, among which are cycle thresholds, mean depth, proportion of genome covered at least 10×, and the number of low-frequency variants combined with mutation prevalence data.
- Published
- 2021
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18. Evaluation of sixteen ELISA SARS-CoV-2 serological tests.
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Jacot D, Moraz M, Coste AT, Aubry C, Sacks JA, Greub G, and Croxatto A
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- Antibodies, Viral, Enzyme-Linked Immunosorbent Assay, Humans, Immunoglobulin G, Immunoglobulin M, Pandemics, Sensitivity and Specificity, Serologic Tests, COVID-19, SARS-CoV-2
- Abstract
Background: In response to the current COVID-19 pandemic, multiple companies marketed serological tests. Rigorous, independent and comparative performances of these assays on defined clinical specimens are needed., Methods: In a first preliminary phase, we investigated 16 IgG, IgM, IgA and pan Ig serological ELISA using a panel of 180 sera, comprising 97 sera from patients with a positive RT-PCR, and 83 negative sera sampled before November 1, 2019. In a second phase and to complete the evaluation on the full panel (100 positive and 300 negative), tests that passed pre-defined exclusion criteria of 90% sensitivity and 97% specificity were further evaluated on 220 additional sera chosen to assess possible cross-reactivity with other human viral infections., Results: Among the 16 tests evaluated in the preliminary phase, two were excluded due to insufficient sensitivity at 15 days post-symptom onset and one was excluded due to poor specificity. Of the 13 tests evaluated using the full panel comprised of a diverse pool of sera including those reactive against known respiratory viruses, no systematic cross-reactivity was observed. However, heterogeneities across tests were found. Consistent with kinetics of antibody expression, maximal sensitivity was found two weeks post-symptom onset., Conclusion: In this independent evaluation, we compared the performance of 16 SARS-CoV-2 serological tests using well-characterized sera and found 13 tests with more than 90% sensitivity at 15 days post-symptom onset and 97% specificity across a diverse range of negative samples., (Copyright © 2021. Published by Elsevier B.V.)
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- 2021
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19. Performance evaluation of the Becton Dickinson Kiestra™ IdentifA/SusceptA.
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Jacot D, Sarton-Lohéac G, Coste AT, Bertelli C, Greub G, Prod'hom G, and Croxatto A
- Subjects
- Anti-Bacterial Agents pharmacology, Automation, Laboratory, Enterococcus drug effects, Staphylococcus drug effects, Streptococcus drug effects, Yeasts drug effects, Gram-Negative Bacteria drug effects, Microbial Sensitivity Tests methods
- Abstract
Objectives: New automated modules are required to provide fully automated solutions in diagnostic microbiology laboratories. We evaluated the performance of a Becton Dickinson Kiestra™ IdentifA/SusceptA prototype for MALDI-TOF identification (ID) and Phoenix™ antibiotic susceptibility testing (AST)., Methods: The performance of the IdentifA/SusceptA coupled prototype was compared with manual processing for MALDI-TOF ID on 1302 clinical microbial isolates or ATCC strains and for Phoenix™ M50 AST on 484 strains, representing 61 species., Results: Overall, the IdentifA exhibited similar ID performances than manual spotting. Higher performances were observed for Gram-negative bacteria with an ID at the species level (score >2) of 96.5% (369/382) and 86.9% (334/384), respectively. A significantly better performance was observed with the IdentifA (95.2%, 81/85) compared with manual spotting (75.2%, 64/85) from colonies on MacConkey agar. Contrariwise, the IdentifA exhibited lower ID performances at the species level than manual processing for streptococci (76.1%, 96/126 compared with 92%, 115/125), coagulase-negative staphylococci (73.3%, 44/60 compared with 90%, 54/60) and yeasts (41.3%, 19/46 compared with 78.2%, 36/46). Staphylococcus aureus and enterococci were similarly identified by the two approaches, with ID rates of 92% (65/70) for the IdentifA and 92.7%, (64/69) for manual processing and 94.8%, (55/58) for the IdentifA and 98.2%, (57/58) for manual processing, respectively. The SusceptA exhibited an AST overall essential agreement of 98.82% (6863/6945), a category agreement of 98.86% (6866/6945), 1.05% (6/570) very major errors, 0.16% (10/6290) major errors, and 0.91% (63/6945) minor errors compared to the reference AST., Conclusions: Overall, the automated IdentifA/SusceptA exhibited high ID and AST performances., (Copyright © 2020 The Author(s). Published by Elsevier Ltd.. All rights reserved.)
- Published
- 2021
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20. Viral load of SARS-CoV-2 across patients and compared to other respiratory viruses.
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Jacot D, Greub G, Jaton K, and Opota O
- Subjects
- Adolescent, Adult, Aged, Aged, 80 and over, COVID-19 diagnosis, COVID-19 Nucleic Acid Testing, Child, Child, Preschool, Coronavirus Infections diagnosis, Disease Progression, Female, Humans, Infant, Infant, Newborn, Influenza B virus isolation & purification, Influenza, Human virology, Male, Middle Aged, Pandemics, Respiratory Syncytial Virus Infections virology, Respiratory Syncytial Viruses isolation & purification, Serologic Tests methods, Switzerland epidemiology, COVID-19 virology, Coronavirus Infections virology, SARS-CoV-2 isolation & purification, Viral Load statistics & numerical data
- Abstract
RT-PCRs to detect SARS-CoV-2 RNA is key to manage the COVID-19 pandemic. We analyzed SARS-CoV-2 viral loads from 22'323 RT-PCR results according to samples types, gender, age, and health units. Viral load did not show any difference across age and appears to be a poor predictor of disease outcome. SARS-CoV-2 viral load showed similar high viral loads than the one observed for RSV and influenza B. The importance of viral load to predict contagiousness and to assess disease progression is discussed., Competing Interests: Declaration of Competing Interest The authors declare to have no conflict of interest., (Copyright © 2020. Published by Elsevier Masson SAS.)
- Published
- 2020
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21. C -Mannosylation of Toxoplasma gondii proteins promotes attachment to host cells and parasite virulence.
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Albuquerque-Wendt A, Jacot D, Dos Santos Pacheco N, Seegers C, Zarnovican P, Buettner FFR, Bakker H, Soldati-Favre D, and Routier FH
- Subjects
- Animals, Cell Adhesion, Cell Movement, Computer Simulation, Female, Gene Deletion, Glycosylation, Humans, Male, Mice, Parasites cytology, Parasites immunology, Proteolysis, Toxoplasma cytology, Toxoplasma immunology, Virulence, Host-Parasite Interactions immunology, Mannose metabolism, Parasites pathogenicity, Protozoan Proteins metabolism, Toxoplasma pathogenicity
- Abstract
C- Mannosylation is a common modification of thrombospondin type 1 repeats present in metazoans and recently identified also in apicomplexan parasites. This glycosylation is mediated by enzymes of the DPY19 family that transfer α-mannoses to tryptophan residues in the sequence W X
2 W X2 C, which is part of the structurally essential tryptophan ladder. Here, deletion of the dpy19 gene in the parasite Toxoplasma gondii abolished C -mannosyltransferase activity and reduced levels of the micronemal protein MIC2. The loss of C -mannosyltransferase activity was associated with weakened parasite adhesion to host cells and with reduced parasite motility, host cell invasion, and parasite egress. Interestingly, the C -mannosyltransferase-deficient Δ dpy19 parasites were strongly attenuated in virulence and induced protective immunity in mice. This parasite attenuation could not simply be explained by the decreased MIC2 level and strongly suggests that absence of C- mannosyltransferase activity leads to an insufficient level of additional proteins. In summary, our results indicate that T. gondii C -mannosyltransferase DPY19 is not essential for parasite survival, but is important for adhesion, motility, and virulence., (© 2020 Albuquerque-Wendt et al.)- Published
- 2020
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22. CRISPR/Cas9-Mediated Generation of Tetracycline Repressor-Based Inducible Knockdown in Toxoplasma gondii.
- Author
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Jacot D and Soldati-Favre D
- Subjects
- Animals, Clustered Regularly Interspaced Short Palindromic Repeats genetics, Cryptosporidium genetics, Cryptosporidium pathogenicity, Gene Knockout Techniques, Genome, Protozoan genetics, Mutagenesis, Site-Directed, Protein Stability, Temperature, Toxoplasma genetics, CRISPR-Cas Systems genetics, Toxoplasma pathogenicity
- Abstract
The phylum Apicomplexa groups numerous pathogenic protozoan parasites including Plasmodium, the causative agent of malaria, Cryptosporidium which can cause severe gastrointestinal infections, as well as Babesia, Eimeria, and Theileria that account for considerable economic burdens to poultry and cattle industry. Toxoplasma gondii is the most ubiquitous and opportunistic member of this phylum able to infect all warm-blooded animals and responsible for severe disease in immunocompromised individuals and unborn fetuses.Due to its ease of cultivation and genetic tractability T. gondii has served as recipient for the transfer and adaptation of multiple genetic tools developed to control gene expression. In these parasites, a collection of tight conditional systems exists to control gene expression at the levels of transcription, RNA degradation or protein stability. The recent implementation of the CRISPR/Cas9 technology considerably reduces time and effort to generate transgenic parasites and at the same time increases to an ultimate level of precision the editing of the parasite genome. Here, we provide a step-by-step protocol for CRISPR/Cas9-mediated generation of tetracycline repressor-based inducible knockdown in T. gondii.
- Published
- 2020
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23. The lectin-specific activity of Toxoplasma gondii microneme proteins 1 and 4 binds Toll-like receptor 2 and 4 N-glycans to regulate innate immune priming.
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Sardinha-Silva A, Mendonça-Natividade FC, Pinzan CF, Lopes CD, Costa DL, Jacot D, Fernandes FF, Zorzetto-Fernandes ALV, Gay NJ, Sher A, Jankovic D, Soldati-Favre D, Grigg ME, and Roque-Barreira MC
- Subjects
- Animals, Interleukin-12 immunology, Mice, Mice, Knockout, Toll-Like Receptor 2 genetics, Toll-Like Receptor 4 genetics, Toxoplasmosis, Animal genetics, Cell Adhesion Molecules immunology, Dendritic Cells immunology, Immunity, Innate, Macrophages immunology, Protozoan Proteins immunology, Sialic Acids immunology, Toll-Like Receptor 2 immunology, Toll-Like Receptor 4 immunology, Toxoplasma immunology, Toxoplasmosis, Animal immunology
- Abstract
Infection of host cells by Toxoplasma gondii is an active process, which is regulated by secretion of microneme (MICs) and rhoptry proteins (ROPs and RONs) from specialized organelles in the apical pole of the parasite. MIC1, MIC4 and MIC6 assemble into an adhesin complex secreted on the parasite surface that functions to promote infection competency. MIC1 and MIC4 are known to bind terminal sialic acid residues and galactose residues, respectively and to induce IL-12 production from splenocytes. Here we show that rMIC1- and rMIC4-stimulated dendritic cells and macrophages produce proinflammatory cytokines, and they do so by engaging TLR2 and TLR4. This process depends on sugar recognition, since point mutations in the carbohydrate-recognition domains (CRD) of rMIC1 and rMIC4 inhibit innate immune cells activation. HEK cells transfected with TLR2 glycomutants were selectively unresponsive to MICs. Following in vitro infection, parasites lacking MIC1 or MIC4, as well as expressing MIC proteins with point mutations in their CRD, failed to induce wild-type (WT) levels of IL-12 secretion by innate immune cells. However, only MIC1 was shown to impact systemic levels of IL-12 and IFN-γ in vivo. Together, our data show that MIC1 and MIC4 interact physically with TLR2 and TLR4 N-glycans to trigger IL-12 responses, and MIC1 is playing a significant role in vivo by altering T. gondii infection competency and murine pathogenesis., Competing Interests: The authors have declared that no competing interests exist.
- Published
- 2019
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24. Three F-actin assembly centers regulate organelle inheritance, cell-cell communication and motility in Toxoplasma gondii .
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Tosetti N, Dos Santos Pacheco N, Soldati-Favre D, and Jacot D
- Subjects
- Actins genetics, Formins genetics, Gene Deletion, Gene Knockout Techniques, Actins metabolism, Cell Communication, Formins metabolism, Locomotion, Organelles metabolism, Protein Multimerization, Toxoplasma physiology
- Abstract
Toxoplasma gondii possesses a limited set of actin-regulatory proteins and relies on only three formins (FRMs) to nucleate and polymerize actin. We combined filamentous actin (F-actin) chromobodies with gene disruption to assign specific populations of actin filaments to individual formins. FRM2 localizes to the apical juxtanuclear region and participates in apicoplast inheritance. Restricted to the residual body, FRM3 maintains the intravacuolar cell-cell communication. Conoidal FRM1 initiates a flux of F-actin crucial for motility, invasion and egress. This flux depends on myosins A and H and is controlled by phosphorylation via PKG (protein kinase G) and CDPK1 (calcium-dependent protein kinase 1) and by methylation via AKMT (apical lysine methyltransferase). This flux is independent of microneme secretion and persists in the absence of the glideosome-associated connector (GAC). This study offers a coherent model of the key players controlling actin polymerization, stressing the importance of well-timed post-translational modifications to power parasite motility., Competing Interests: NT, ND, DJ No competing interests declared, DS Reviewing editor, eLife, (© 2019, Tosetti et al.)
- Published
- 2019
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25. Crosstalk between PKA and PKG controls pH-dependent host cell egress of Toxoplasma gondii .
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Jia Y, Marq JB, Bisio H, Jacot D, Mueller C, Yu L, Choudhary J, Brochet M, and Soldati-Favre D
- Subjects
- 3',5'-Cyclic-GMP Phosphodiesterases metabolism, Acylation, Cell Line, Transformed, Cyclic AMP metabolism, Cyclic AMP-Dependent Protein Kinase Catalytic Subunits metabolism, Cyclic AMP-Dependent Protein Kinase RIalpha Subunit metabolism, Cyclic GMP metabolism, Cyclic GMP-Dependent Protein Kinases metabolism, Fibroblasts parasitology, Gene Expression Regulation, Humans, Hydrogen-Ion Concentration, Life Cycle Stages genetics, Phosphoproteins genetics, Phosphoproteins metabolism, Phosphorylation, Protozoan Proteins metabolism, Signal Transduction, Toxoplasma growth & development, Toxoplasma metabolism, 3',5'-Cyclic-GMP Phosphodiesterases genetics, Cyclic AMP-Dependent Protein Kinase Catalytic Subunits genetics, Cyclic AMP-Dependent Protein Kinase RIalpha Subunit genetics, Cyclic GMP-Dependent Protein Kinases genetics, Host-Parasite Interactions, Protozoan Proteins genetics, Toxoplasma genetics
- Abstract
Toxoplasma gondii encodes three protein kinase A catalytic (PKAc1-3) and one regulatory (PKAr) subunits to integrate cAMP-dependent signals. Here, we show that inactive PKAc1 is maintained at the parasite pellicle by interacting with acylated PKAr. Either a conditional knockdown of PKAr or the overexpression of PKAc1 blocks parasite division. Conversely, down-regulation of PKAc1 or stabilisation of a dominant-negative PKAr isoform that does not bind cAMP triggers premature parasite egress from infected cells followed by serial invasion attempts leading to host cell lysis. This untimely egress depends on host cell acidification. A phosphoproteome analysis suggested the interplay between cAMP and cGMP signalling as PKAc1 inactivation changes the phosphorylation profile of a putative cGMP-phosphodiesterase. Concordantly, inhibition of the cGMP-dependent protein kinase G (PKG) blocks egress induced by PKAc1 inactivation or environmental acidification, while a cGMP-phosphodiesterase inhibitor circumvents egress repression by PKAc1 or pH neutralisation. This indicates that pH and PKAc1 act as balancing regulators of cGMP metabolism to control egress. These results reveal a crosstalk between PKA and PKG pathways to govern egress in T. gondii ., (© 2017 The Authors.)
- Published
- 2017
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26. Efficient invasion by Toxoplasma depends on the subversion of host protein networks.
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Guérin A, Corrales RM, Parker ML, Lamarque MH, Jacot D, El Hajj H, Soldati-Favre D, Boulanger MJ, and Lebrun M
- Subjects
- Adaptor Proteins, Signal Transducing genetics, Adaptor Proteins, Signal Transducing metabolism, Animals, Calcium-Binding Proteins metabolism, Cell Cycle Proteins metabolism, Cells, Cultured, Cytoskeletal Proteins metabolism, DNA-Binding Proteins metabolism, Disease Models, Animal, Endosomal Sorting Complexes Required for Transport metabolism, Female, Gene Expression, Genetic Vectors, HeLa Cells, Humans, Mice, Mice, Inbred BALB C, Organisms, Genetically Modified, Point Mutation, Protozoan Proteins genetics, Recombinant Proteins, Sf9 Cells, Toxoplasma genetics, Transcription Factors metabolism, Host-Parasite Interactions physiology, Protozoan Proteins metabolism, Toxoplasma metabolism, Toxoplasma pathogenicity, Toxoplasmosis metabolism
- Abstract
Apicomplexan parasites are important pathogens of humans and domestic animals, including Plasmodium species (the agents of malaria) and Toxoplasma gondii, which is responsible for toxoplasmosis. They replicate within the cells of their animal hosts, to which they gain access using a unique parasite-driven invasion process. At the core of the invasion machine is a structure at the interface between the invading parasite and host cell called the moving junction (MJ)
1 . The MJ serves as both a molecular doorway to the host cell and an anchor point enabling the parasite to engage its motility machinery to drive the penetration of the host cell2 , ultimately yielding a protective vacuole3 . The MJ is established through self-assembly of parasite proteins at the parasite-host interface4 . However, it is unknown whether host proteins are subverted for MJ formation. Here, we show that Toxoplasma parasite rhoptry neck proteins (RON2, RON4 and RON5) cooperate to actively recruit the host CIN85, CD2AP and the ESCRT-I components ALIX and TSG101 to the MJ during invasion. We map the interactions in detail and demonstrate that the parasite mimics and subverts conserved binding interfaces with remarkable specificity. Parasite mutants unable to recruit these host proteins show inefficient host cell invasion in culture and attenuated virulence in mice. This study reveals molecular mechanisms by which parasites subvert widely conserved host machinery to force highly efficient host cell access.- Published
- 2017
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27. A druggable secretory protein maturase of Toxoplasma essential for invasion and egress.
- Author
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Dogga SK, Mukherjee B, Jacot D, Kockmann T, Molino L, Hammoudi PM, Hartkoorn RC, Hehl AB, and Soldati-Favre D
- Subjects
- Antibodies, Antimalarials pharmacology, Aspartic Acid Proteases genetics, Aspartic Acid Proteases immunology, Cell Adhesion Molecules genetics, Cell Line, DNA, Protozoan, Escherichia coli genetics, Fibroblasts, Gene Knockdown Techniques, Genes, Protozoan, Humans, Protozoan Proteins genetics, Recombinant Proteins, Toxoplasma genetics, Aspartic Acid Proteases pharmacology, Organelles metabolism, Protozoan Proteins pharmacology, Toxoplasma enzymology, Toxoplasma metabolism
- Abstract
Micronemes and rhoptries are specialized secretory organelles that deploy their contents at the apical tip of apicomplexan parasites in a regulated manner. The secretory proteins participate in motility, invasion, and egress and are subjected to proteolytic maturation prior to organellar storage and discharge. Here we establish that Toxoplasma gondii aspartyl protease 3 (ASP3) resides in the endosomal-like compartment and is crucially associated to rhoptry discharge during invasion and to host cell plasma membrane lysis during egress. A comparison of the N-terminome, by terminal amine isotopic labelling of substrates between wild type and ASP3 depleted parasites identified microneme and rhoptry proteins as repertoire of ASP3 substrates. The role of ASP3 as a maturase for previously described and newly identified secretory proteins is confirmed in vivo and in vitro . An antimalarial compound based on a hydroxyethylamine scaffold interrupts the lytic cycle of T. gondii at submicromolar concentration by targeting ASP3.
- Published
- 2017
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28. Myosin-dependent cell-cell communication controls synchronicity of division in acute and chronic stages of Toxoplasma gondii.
- Author
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Frénal K, Jacot D, Hammoudi PM, Graindorge A, Maco B, and Soldati-Favre D
- Subjects
- Animals, Apicoplasts metabolism, Brain metabolism, Cell Communication, Cell Differentiation, Cell Division, Cell Movement, Female, Gene Deletion, Gene Silencing, Image Processing, Computer-Assisted, Imaging, Three-Dimensional, Macrophages metabolism, Mice, Mice, Inbred CBA, Microscopy, Electron, Transmission, Molecular Chaperones metabolism, Phenotype, Myosins metabolism, Protozoan Proteins metabolism, Toxoplasma metabolism, Toxoplasmosis parasitology, Trimethoprim, Sulfamethoxazole Drug Combination metabolism
- Abstract
The obligate intracellular parasite Toxoplasma gondii possesses a repertoire of 11 myosins. Three class XIV motors participate in motility, invasion and egress, whereas the class XXII myosin F is implicated in organelle positioning and inheritance of the apicoplast. Here we provide evidence that TgUNC acts as a chaperone dedicated to the folding, assembly and function of all Toxoplasma myosins. The conditional ablation of TgUNC recapitulates the phenome of the known myosins and uncovers two functions in parasite basal complex constriction and synchronized division within the parasitophorous vacuole. We identify myosin J and centrin 2 as essential for the constriction. We demonstrate the existence of an intravacuolar cell-cell communication ensuring synchronized division, a process dependent on myosin I. This connectivity contributes to the delayed death phenotype resulting from loss of the apicoplast. Cell-cell communication is lost in activated macrophages and during bradyzoite differentiation resulting in asynchronized, slow division in the cysts.
- Published
- 2017
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29. An Apicomplexan Actin-Binding Protein Serves as a Connector and Lipid Sensor to Coordinate Motility and Invasion.
- Author
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Jacot D, Tosetti N, Pires I, Stock J, Graindorge A, Hung YF, Han H, Tewari R, Kursula I, and Soldati-Favre D
- Subjects
- Actin Cytoskeleton physiology, Actins physiology, Animals, Apicomplexa metabolism, Cell Adhesion Molecules physiology, Cell Movement, Exocytosis physiology, Membrane Proteins metabolism, Membrane Proteins physiology, Methyltransferases metabolism, Microfilament Proteins metabolism, Models, Molecular, Organelles, Phosphatidic Acids metabolism, Plasmodium berghei metabolism, Plasmodium berghei physiology, Protein Conformation, Protozoan Infections parasitology, Protozoan Proteins metabolism, Rabbits, Toxoplasma cytology, Toxoplasma metabolism, Toxoplasma physiology, Toxoplasmosis parasitology, Apicomplexa cytology, Apicomplexa physiology, Lipids, Microfilament Proteins physiology, Molecular Motor Proteins physiology, Protozoan Proteins physiology
- Abstract
Apicomplexa exhibit a unique form of substrate-dependent gliding motility central for host cell invasion and parasite dissemination. Gliding is powered by rearward translocation of apically secreted transmembrane adhesins via their interaction with the parasite actomyosin system. We report a conserved armadillo and pleckstrin homology (PH) domain-containing protein, termed glideosome-associated connector (GAC), that mediates apicomplexan gliding motility, invasion, and egress by connecting the micronemal adhesins with the actomyosin system. TgGAC binds to and stabilizes filamentous actin and specifically associates with the transmembrane adhesin TgMIC2. GAC localizes to the apical pole in invasive stages of Toxoplasma gondii and Plasmodium berghei, and apical positioning of TgGAC depends on an apical lysine methyltransferase, TgAKMT. GAC PH domain also binds to phosphatidic acid, a lipid mediator associated with microneme exocytosis. Collectively, these findings indicate a central role for GAC in spatially and temporally coordinating gliding motility and invasion., (Copyright © 2016 Elsevier Inc. All rights reserved.)
- Published
- 2016
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30. The Conoid Associated Motor MyoH Is Indispensable for Toxoplasma gondii Entry and Exit from Host Cells.
- Author
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Graindorge A, Frénal K, Jacot D, Salamun J, Marq JB, and Soldati-Favre D
- Subjects
- Animals, Blotting, Western, Chlorocebus aethiops, Fluorescent Antibody Technique, Indirect, Gene Knockout Techniques, Humans, Immunoprecipitation, Microscopy, Confocal, Microscopy, Electron, Transmission, Organelles, Toxoplasma cytology, Transfection, Vero Cells, Host-Parasite Interactions physiology, Myosin Heavy Chains metabolism, Protozoan Proteins metabolism, Toxoplasma pathogenicity, Toxoplasmosis metabolism
- Abstract
Many members of the phylum of Apicomplexa have adopted an obligate intracellular life style and critically depend on active invasion and egress from the infected cells to complete their lytic cycle. Toxoplasma gondii belongs to the coccidian subgroup of the Apicomplexa, and as such, the invasive tachyzoite contains an organelle termed the conoid at its extreme apex. This motile organelle consists of a unique polymer of tubulin fibres and protrudes in both gliding and invading parasites. The class XIV myosin A, which is conserved across the Apicomplexa phylum, is known to critically contribute to motility, invasion and egress from infected cells. The MyoA-glideosome is anchored to the inner membrane complex (IMC) and is assumed to translocate the components of the circular junction secreted by the micronemes and rhoptries, to the rear of the parasite. Here we comprehensively characterise the class XIV myosin H (MyoH) and its associated light chains. We show that the 3 alpha-tubulin suppressor domains, located in MyoH tail, are necessary to anchor this motor to the conoid. Despite the presence of an intact MyoA-glideosome, conditional disruption of TgMyoH severely compromises parasite motility, invasion and egress from infected cells. We demonstrate that MyoH is necessary for the translocation of the circular junction from the tip of the parasite, where secretory organelles exocytosis occurs, to the apical position where the IMC starts. This study attributes for the first time a direct function of the conoid in motility and invasion, and establishes the indispensable role of MyoH in initiating the first step of motility along this unique organelle, which is subsequently relayed by MyoA to enact effective gliding and invasion.
- Published
- 2016
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31. Apicomplexan Energy Metabolism: Carbon Source Promiscuity and the Quiescence Hyperbole.
- Author
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Jacot D, Waller RF, Soldati-Favre D, MacPherson DA, and MacRae JI
- Subjects
- Apicomplexa enzymology, Carbon metabolism, Citric Acid Cycle physiology, Life Cycle Stages, Malaria therapy, Plasmodium enzymology, Plasmodium metabolism, Apicomplexa metabolism, Malaria parasitology
- Abstract
The nature of energy metabolism in apicomplexan parasites has been closely investigated in the recent years. Studies in Plasmodium spp. and Toxoplasma gondii in particular have revealed that these parasites are able to employ enzymes in non-traditional ways, while utilizing multiple anaplerotic routes into a canonical tricarboxylic acid (TCA) cycle to satisfy their energy requirements. Importantly, some life stages of these parasites previously considered to be metabolically quiescent are, in fact, active and able to adapt their carbon source utilization to survive. We compare energy metabolism across the life cycle of malaria parasites and consider how this varies in other apicomplexans and related organisms, while discussing how this can be exploited for therapeutic intervention in these diseases., (Copyright © 2015 Elsevier Ltd. All rights reserved.)
- Published
- 2016
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32. Fundamental Roles of the Golgi-Associated Toxoplasma Aspartyl Protease, ASP5, at the Host-Parasite Interface.
- Author
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Hammoudi PM, Jacot D, Mueller C, Di Cristina M, Dogga SK, Marq JB, Romano J, Tosetti N, Dubrot J, Emre Y, Lunghi M, Coppens I, Yamamoto M, Sojka D, Pino P, and Soldati-Favre D
- Subjects
- Animals, Blotting, Western, Cells, Cultured, Enzyme-Linked Immunosorbent Assay, Fluorescent Antibody Technique, Gene Knockout Techniques, Humans, Mice, Mice, Inbred C57BL, Microscopy, Electron, Transmission, Molecular Sequence Data, Protein Transport, Real-Time Polymerase Chain Reaction, Toxoplasma enzymology, Transfection, Aspartic Acid Proteases metabolism, Golgi Apparatus enzymology, Host-Parasite Interactions physiology, Toxoplasma pathogenicity, Toxoplasmosis enzymology
- Abstract
Toxoplasma gondii possesses sets of dense granule proteins (GRAs) that either assemble at, or cross the parasitophorous vacuole membrane (PVM) and exhibit motifs resembling the HT/PEXEL previously identified in a repertoire of exported Plasmodium proteins. Within Plasmodium spp., cleavage of the HT/PEXEL motif by the endoplasmic reticulum-resident protease Plasmepsin V precedes trafficking to and export across the PVM of proteins involved in pathogenicity and host cell remodelling. Here, we have functionally characterized the T. gondii aspartyl protease 5 (ASP5), a Golgi-resident protease that is phylogenetically related to Plasmepsin V. We show that deletion of ASP5 causes a significant loss in parasite fitness in vitro and an altered virulence in vivo. Furthermore, we reveal that ASP5 is necessary for the cleavage of GRA16, GRA19 and GRA20 at the PEXEL-like motif. In the absence of ASP5, the intravacuolar nanotubular network disappears and several GRAs fail to localize to the PVM, while GRA16 and GRA24, both known to be targeted to the host cell nucleus, are retained within the vacuolar space. Additionally, hypermigration of dendritic cells and bradyzoite cyst wall formation are impaired, critically impacting on parasite dissemination and persistence. Overall, the absence of ASP5 dramatically compromises the parasite's ability to modulate host signalling pathways and immune responses.
- Published
- 2015
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33. Plasticity between MyoC- and MyoA-glideosomes: an example of functional compensation in Toxoplasma gondii invasion.
- Author
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Frénal K, Marq JB, Jacot D, Polonais V, and Soldati-Favre D
- Subjects
- Actin Cytoskeleton genetics, Actin Cytoskeleton metabolism, Base Sequence, Cell Membrane metabolism, Cell Movement, Genes, Reporter, Host-Parasite Interactions, Humans, Membrane Proteins genetics, Models, Biological, Molecular Sequence Data, Multiprotein Complexes metabolism, Myosin Light Chains metabolism, Myosins genetics, Nonmuscle Myosin Type IIA genetics, Nonmuscle Myosin Type IIA metabolism, Protozoan Proteins genetics, Protozoan Proteins metabolism, Sequence Analysis, DNA, Sequence Deletion, Toxoplasma genetics, Membrane Proteins metabolism, Myosins metabolism, Toxoplasma metabolism, Toxoplasmosis parasitology
- Abstract
The glideosome is an actomyosin-based machinery that powers motility in Apicomplexa and participates in host cell invasion and egress from infected cells. The central component of the glideosome, myosin A (MyoA), is a motor recruited at the pellicle by the acylated gliding-associated protein GAP45. In Toxoplasma gondii, GAP45 also contributes to the cohesion of the pellicle, composed of the inner membrane complex (IMC) and the plasma membrane, during motor traction. GAP70 was previously identified as a paralog of GAP45 that is tailored to recruit MyoA at the apical cap in the coccidian subgroup of the Apicomplexa. A third member of this family, GAP80, is demonstrated here to assemble a new glideosome, which recruits the class XIV myosin C (MyoC) at the basal polar ring. MyoC shares the same myosin light chains as MyoA and also interacts with the integral IMC proteins GAP50 and GAP40. Moreover, a central component of this complex, the IMC-associated protein 1 (IAP1), acts as the key determinant for the restricted localization of MyoC to the posterior pole. Deletion of specific components of the MyoC-glideosome underscores the installation of compensatory mechanisms with components of the MyoA-glideosome. Conversely, removal of MyoA leads to the relocalization of MyoC along the pellicle and at the apical cap that accounts for residual invasion. The two glideosomes exhibit a considerable level of plasticity to ensure parasite survival.
- Published
- 2014
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34. Assessment of phosphorylation in Toxoplasma glideosome assembly and function.
- Author
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Jacot D, Frénal K, Marq JB, Sharma P, and Soldati-Favre D
- Subjects
- Antigens, Protozoan genetics, Antigens, Protozoan metabolism, Cell Membrane, Cell Movement genetics, Host-Parasite Interactions, Membrane Proteins genetics, Membrane Proteins metabolism, Molecular Motor Proteins genetics, Phosphorylation, Protozoan Proteins genetics, Cell Movement physiology, Molecular Motor Proteins metabolism, Protein Processing, Post-Translational physiology, Protozoan Proteins metabolism, Toxoplasma physiology
- Abstract
Members of the phylum Apicomplexa possess a highly conserved molecular motor complex anchored in the parasite pellicle and associated with gliding motility, invasion and egress from infected cells. This machinery, called the glideosome, is structured around the acylated gliding-associated protein GAP45 that recruits the motor complex composed of myosin A and two associated myosin light chains (TgMLC1 and TgELC1). This motor is presumably firmly anchored to the inner membrane complex underneath the plasma membrane via an interaction with two integral membrane proteins, GAP50 and GAP40. To determine if the previously mapped phosphorylation sites on TgGAP45 and TgMLC1 have a direct significance for glideosome assembly and function, a series of phospho-mimetic and phospho-null mutants were generated. Neither the overexpression nor the allelic replacement of TgMLC1 with phospho-mutants impacted on glideosome assembly and parasite motility. TgGAP45 phosphorylation mutants were functionally investigated using a complementation strategy in a TgGAP45 inducible knockout background. The loss of interaction with TgGAP50 by one previously reported GAP45-mutant appeared to depend only on the presence of a remaining competing wild type copy of TgGAP45. Accordingly, this mutant displayed no phenotype in complementation experiments. Unexpectedly, GAP45 lacking the region encompassing the cluster of twelve phosphorylation sites did not impact on its dual function in motor recruitment and pellicle integrity. Despite the extensive phosphorylation of TgMLC1 and TgGAP45, this post-translational modification does not appear to be critical for the assembly and function of the glideosome., (© 2014 John Wiley & Sons Ltd.)
- Published
- 2014
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35. Toxoplasma gondii myosin F, an essential motor for centrosomes positioning and apicoplast inheritance.
- Author
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Jacot D, Daher W, and Soldati-Favre D
- Subjects
- Destrin genetics, Destrin metabolism, Gene Deletion, Myosins genetics, Profilins genetics, Profilins metabolism, Protozoan Proteins genetics, Toxoplasma genetics, Centrosome metabolism, Myosins metabolism, Protein Multimerization, Protozoan Proteins metabolism, Toxoplasma metabolism
- Abstract
Members of the Apicomplexa phylum possess an organelle surrounded by four membranes, originating from the secondary endosymbiosis of a red alga. This so-called apicoplast hosts essential metabolic pathways. We report here that apicoplast inheritance is an actin-based process. Concordantly, parasites depleted in either profilin or actin depolymerizing factor, or parasites overexpressing the FH2 domain of formin 2, result in loss of the apicoplast. The class XXII myosin F (MyoF) is conserved across the phylum and localizes in the vicinity of the Toxoplasma gondii apicoplast during division. Conditional knockdown of TgMyoF severely affects apicoplast turnover, leading to parasite death. This recapitulates the phenotype observed upon perturbation of actin dynamics that led to the accumulation of the apicoplast and secretory organelles in enlarged residual bodies. To further dissect the mode of action of this motor, we conditionally stabilized the tail of MyoF, which forms an inactive heterodimer with endogenous TgMyoF. This dominant negative mutant reveals a central role of this motor in the positioning of the two centrosomes prior to daughter cell formation and in apicoplast segregation.
- Published
- 2013
- Full Text
- View/download PDF
36. The Toxoplasma protein ARO mediates the apical positioning of rhoptry organelles, a prerequisite for host cell invasion.
- Author
-
Mueller C, Klages N, Jacot D, Santos JM, Cabrera A, Gilberger TW, Dubremetz JF, and Soldati-Favre D
- Subjects
- Humans, Molecular Sequence Data, Organelles genetics, Protozoan Proteins genetics, Toxoplasma genetics, Toxoplasma growth & development, Virulence, Organelles metabolism, Protozoan Proteins metabolism, Toxoplasma metabolism, Toxoplasma pathogenicity, Toxoplasmosis parasitology
- Abstract
Members of the phylum Apicomplexa actively enter host cells by a process involving the discharge of the apically localized microneme and rhoptry organelles. To unravel the processes involved in rhoptry organelle biogenesis, we focused on the Toxoplasma gondii armadillo repeats only protein (TgARO), a conserved acylated protein homogenously anchored to the rhoptry membrane. Conditional disruption of TgARO results in the random cytosolic dispersion of rhoptries and a severe defect in T. gondii invasion, with no effects on intracellular growth or host cell egress. Importantly, rhoptry displacement upon ARO depletion can be functionally complemented with wild-type TgARO but not an acylation mutant. TgARO interacts with myosin F, and inhibition of actin polymerization or myosin function also results in rhoptry dispersal, indicating that the apical positioning of rhoptries is an actomyosin-based process. Thus, TgARO mediates the apical localization of rhoptries, which is specifically required for host cell invasion., (Copyright © 2013 Elsevier Inc. All rights reserved.)
- Published
- 2013
- Full Text
- View/download PDF
37. Does protein phosphorylation govern host cell entry and egress by the Apicomplexa?
- Author
-
Jacot D and Soldati-Favre D
- Subjects
- Actins chemistry, Animals, Antigens, Protozoan chemistry, Binding Sites, Calcium chemistry, Calcium Signaling, Host-Parasite Interactions, Humans, Membrane Proteins chemistry, Phosphoproteins chemistry, Phosphorylation, Protein Kinases chemistry, Protozoan Proteins chemistry, Apicomplexa chemistry, Apicomplexa pathogenicity, Protozoan Infections parasitology
- Abstract
Members of the phylum Apicomplexa are responsible for a wide range of diseases in humans and animals. The absence of an effective vaccine or safe curing drugs and the continuous emergence of resistant parasites to available treatments impose a high demand on the identification of novel targets for intervention against the apicomplexans. Protein kinases are considered attractive potential therapeutic targets not only against cancers but also to combat infectious diseases. The scope and aim of this review is to report on the recent progress in dissecting the impact of protein phosphorylation in regulating motility and invasion., (Copyright © 2012 Elsevier GmbH. All rights reserved.)
- Published
- 2012
- Full Text
- View/download PDF
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