Coronaviruses comprise seven human viruses, some of them the common cold viruses, only causing mild symptoms in healthy individuals, while SARS-CoV, MERS-CoV, and SARS-CoV-2 can potentially cause... Show moreCoronaviruses comprise seven human viruses, some of them the common cold viruses, only causing mild symptoms in healthy individuals, while SARS-CoV, MERS-CoV, and SARS-CoV-2 can potentially cause severe disease and deadly pneumonia. The outbreak of SARS-CoV-2 in 2019 and its rapid worldwide spread has made apparent the need for a fast response to newly emerging viruses and to have effective therapies available. Although vaccines against SARS-CoV-2 were developed at an unprecedented speed, early patients would have benefitted from antiviral drugs. The respiratory tract is the first entry point for coronaviruses, where epithelial cells are infected and also represent the first barrier of defense. Primary human airway epithelial cells that are cultured and differentiated at the air-liquid interface (HAE-ALI) represent an advanced cell culture model recapitulating the human lung epithelium better than mono-cell cultures. In this thesis, four research projects conducted during the PhD track, are described and discussed, which focussed mainly on SARS-CoV-2. Chapter 1 gives an introduction to the overall research topic of coronavirus biology and antiviral drug discovery, and the use of HAE-ALI to study both. Chapter 2 describes the characterization of SARS-oV-2 infection in HAE-ALI. Changes in the cellular composition, caused by culture time or drug treatment, impacted virus replication, and this correlated with the presence of the main susceptible cells, ciliated cells and goblet cells, as well as expression of virus cell-entry factors. Furthermore, the importance of having a diverse epithelium in the cultures was identified, where likely goblet cells play a supportive role in infection. The findings contribute to the understanding of the variable susceptibility to SARS-CoV-2 infection between individuals and across anatomical locations in the respiratory tract, and possibly in chronic lung diseases affecting the epithelium. Chapter 3 then aimed to conduct a comparative study between SARS-CoV, MERS-CoV, and SARS-CoV-2, and two common cold coronaviruses. We employed the HAE-ALI cell culture model to decipher differences in the epithelial transcriptional response upon coronavirus infection. RNA sequencing data showed limited expression of interferon genes in infections with SARS-CoV, MERS-CoV, and SARS-CoV-2, as opposed to the common cold coronaviruses, which corroborated previous studies showing suppression of interferon responses by the these three coronaviruses. Furthermore, SARSCoV-2 infection uniquely lacked the expression of a set of immediate early genes, which are expressed in response to stressors like infection. By utilizing the findings about one of these genes, NR4A1, an inhibitor was identified that blocks SARS-CoV-2 and MERS-CoV replication. Chapters 4 and 5 describe two antiviral drugs that efficiently block the replication of SARS-CoV-2 and other coronaviruses. The first, R-Propranolol, is part of a drug that is approved for the treatment of hemangioma (benign vascular tumor), besides various medical conditions like cardiovascular diseases. R-Propranolol was shown to reduce a proangiogenic factor, which was recently reported to be associated with an increased rate of severe lung pathology in COVID-19. Therefore, this drug could be an interesting candidate to investigate further as host-directed therapy to reduce vascular damage in COVID-19, caused by endothelial dysfunction and pathological angiogenesis. Additionally, a potent antiviral effect of R-Propranolol against SARS-CoV-2 and other coronaviruses was observed, which makes the drug an interesting antiviral with two potential angles of activity. Chapter 5 describes a class of host-directed antivirals, glucosidase inhibitors, which inhibit endoplasmic reticulum (ER) resident alpha-glucosidases, important for protein folding in the ER and quality control. Many viruses, including coronaviruses, use the host’s ER protein quality control machinery for their glycoproteins. For SARS-CoV-2, especially the spike protein, which is crucial for virus attachment and entry into the host cell, is heavily glycosylated and dependent on processing in the ER and Golgi. Several compounds were tested, belonging to two classes, iminosugars and cyclitols. While iminosugars have been studied for decades as potential antiviral drugs, we identified 1,6-epi-cyclophellitol cyclosulfate, a candidate of a new class of glucosidase inhibitors, as superior due to its high specificity for ER alpha-glucosidase II and potent antiviral efficacy. Inhibition of ER alphaglucosidases led to a reduction in spike protein generation and subsequently to a reduced production of infectious virus particles. In addition to SARS-CoV-2, 1,6-epi-cyclophellitol cyclosulfate also blocks the production of SARS-CoV and MERS-CoV progeny, rendering this class of compounds promising broad-spectrum antivirals. In the final chapter, the main findings of the research projects are discussed in the context of recently published studies. Furthermore, the current landscape of SARS-CoV-2 host-directed antiviral therapy and the benefits of using the most relevant cell culture models in antiviral drug discovery are discussed. Show less
This thesis describes the cryo-electron microscopic (cryo-EM) analyses of intracellular viral replication structures. The main methodology used for the analyses was cellular electron cryo... Show moreThis thesis describes the cryo-electron microscopic (cryo-EM) analyses of intracellular viral replication structures. The main methodology used for the analyses was cellular electron cryo-tomography (cryo-ET) to study the replication organelles induced by cornoa- and arteriviruses at macromolecular resolution. Cellular cryo-ET is a young technique incorporating focused ion beam (FIB) milling of 100-300 nm thin cryo-lamellae containing intracellular material readily imageble by high-resolution cryo-EM. However, this workflow is low in throughput and error-prone. Part of the thesis describes an improved sample-preparation strategy that successfully increased the throughput of this workflow. Furthermore, this method was applied on cells infected by coronaviruses and unveiled so far unseen protein complexes that seem to shuttle viral RNA across the double-membranes of the viral replication organelles. It was found that these molecular pores are (partially) formed by viral proteins containing transmembrane-domains. The molecular pores appear to be a central component in the replication cycle of corona- and arteriviruses, two virus families united in the virus order Nidovirales. Finally, the structure and function of the viral replication organelles are reviewed and how past and future technical developments in EM did and likely will contribute to our growing understanding of these. Show less
Fischer, K.; Tieskens, J.M.; Luijten, M.A.J.; Zijlmans, J.; Oers, H.A. van; Groot, R. de; ... ; Popma, A. 2022
The aim of the study was to assess internalizing problems before and during the pandemic with data from Dutch consortium Child and adolescent mental health and wellbeing in times of the COVID-19... Show moreThe aim of the study was to assess internalizing problems before and during the pandemic with data from Dutch consortium Child and adolescent mental health and wellbeing in times of the COVID-19 pandemic, consisting of two Dutch general population samples (GS) and two clinical samples (CS) referred to youth/psychiatric care. Measures of internalizing problems were obtained from ongoing data collections pre-pandemic (N-GS = 35,357; N-CS = 4487) and twice during the pandemic, in Apr-May 2020 (N-GS = 3938; clinical: N-CS = 1008) and in Nov-Dec 2020 (N-GS = 1489; N-CS = 1536), in children and adolescents (8-18 years) with parent (Brief Problem Monitor) and/or child reports (Patient-Reported Outcomes Measurement Information System (R)). Results show that, in the general population, internalizing problems were higher during the first peak of the pandemic compared to pre-pandemic based on both child and parent reports. Yet, over the course of the pandemic, on both child and parent reports, similar or lower levels of internalizing problems were observed. Children in the clinical population reported more internalizing symptoms over the course of the pandemic while parents did not report differences in internalizing symptoms from pre-pandemic to the first peak of the pandemic nor over the course of the pandemic. Overall, the findings indicate that children and adolescents of both the general and clinical population were affected negatively by the pandemic in terms of their internalizing problems. Attention is therefore warranted to investigate long-term effects and to monitor if internalizing problems return to pre-pandemic levels or if they remain elevated post-pandemic. Show less
Background: Immunoglobulin G1 (IgG1) effector functions are impacted by the structure of fragment crystallizable (Fc) tail-linked N-glycans. Low fucosylation levels on severe acute respiratory... Show moreBackground: Immunoglobulin G1 (IgG1) effector functions are impacted by the structure of fragment crystallizable (Fc) tail-linked N-glycans. Low fucosylation levels on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike (S) protein-specific IgG1 has been described as a hallmark of severe coronavirus disease 2019 (COVID-19) and may lead to activation of macrophages via immune complexes thereby promoting inflammatory responses, altogether suggesting involvement of IgG1 Fc glycosylation modulated immune mechanisms in COVID-19. Methods: In this prospective, observational single center cohort study, IgG1 Fc glycosylation was analyzed by liquid chromatography-mass spectrometry following affinity capturing from serial plasma samples of 159 SARS-CoV-2 infected hospitalized patients. Findings: At baseline close to disease onset, anti-S IgG1 glycosylation was highly skewed when compared to total plasma IgG1. A rapid, general reduction in glycosylation skewing was observed during the disease course. Low anti S IgG1 galactosylation and sialylation as well as high bisection were early hallmarks of disease severity, whilst high galactosylation and sialylation and low bisection were found in patients with low disease severity. In line with these observations, anti-S IgG1 glycosylation correlated with various inflammatory markers. Interpretation: Association of low galactosylation, sialylation as well as high bisection with disease severity and inflammatory markers suggests that further studies are needed to understand how anti-S IgG1 glycosylation may contribute to disease mechanism and to evaluate its biomarker potential. Copyright (c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/) Show less
Purpose: Describe the differences in characteristics and outcomes between COVID-19 and other viral pneumonia patients admitted to Dutch ICUs. Materials and methods: Data from the National-Intensive... Show morePurpose: Describe the differences in characteristics and outcomes between COVID-19 and other viral pneumonia patients admitted to Dutch ICUs. Materials and methods: Data from the National-Intensive-Care-Evaluation-registry of COVID-19 patients admitted between February 15th and January 1th 2021 and other viral pneumonia patients admitted between January 1st 2017 and January 1st 2020 were used. Patients' characteristics, the unadjusted, and adjusted in-hospital mortality were compared. Results: 6343 COVID-19 and 2256 other viral pneumonia patients from 79 ICUs were included. The COVID-19 patients included more male (71.3 vs 49.8%), had a higher Body-Mass-Index (28.1 vs 25.5), less comorbidities (42.2 vs 72.7%), and a prolonged hospital length of stay (19 vs 9 days). The COVID-19 patients had a significantly higher crude in-hospital mortality rate (Odds ratio (OR) = 1.80), after adjustment for patient characteristics and ICU occupancy rate the OR was respectively 3.62 and 3.58. Conclusion: Higher mortality among COVID-19 patients could not be explained by patient characteristics and higher ICU occupancy rates, indicating that COVID-19 is more severe compared to other viral pneumonia. Our findings confirm earlier warnings of a high need of ICU capacity and high mortality rates among relatively healthy COVID-19 patients as this may lead to a higher mental workload for the staff. (c) 2021 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/). Show less
Kok, A.A.L.; Pan, K.Y.; Rius-Ottenheim, N.; Jorg, F.; Eikelenboom, M.; Horsfall, M.; ... ; Penninx, B.W.J.H. 2022
Background: Little is known about the longer-term impact of the Covid-19 pandemic beyond the first months of 2020, particularly for people with pre-existing mental health disorders. Studies... Show moreBackground: Little is known about the longer-term impact of the Covid-19 pandemic beyond the first months of 2020, particularly for people with pre-existing mental health disorders. Studies including pre-pandemic data from large psychiatric cohorts are scarce. Methods: Between April 2020 and February 2021, twelve successive online questionnaires were distributed among participants of the Netherlands Study of Depression and Anxiety, Netherlands Study of Depression in Older Persons, and Netherlands Obsessive Compulsive Disorder Association Study (N = 1714, response rate 62%). Outcomes were depressive symptoms, anxiety, worry, loneliness, perceived mental health impact of the pandemic, fear of Covid-19, positive coping, and happiness. Using linear mixed models we compared trajectories between subgroups with different pre-pandemic chronicity of disorders and healthy controls. Results: Depressive, anxiety and worry symptoms were stable since April-May 2020 whereas happiness slightly decreased. Furthermore, positive coping steadily decreased and loneliness increased - exceeding pre-Covid and April-May 2020 levels. Perceived mental health impact and fear of Covid-19 fluctuated in accordance with national Covid-19 mortality rate changes. Absolute levels of all outcomes were poorer with higher chronicity of disorders, yet trajectories did not differ among subgroups. Limitations: The most vulnerable psychiatric groups may have been underrepresented and results may not be generalizable to lower income countries. Conclusions: After a year, levels of depressive and worry symptoms remained higher than before the pandemic in healthy control groups, yet not in psychiatric groups. Nevertheless, persistent high symptoms in psychiatric groups and increasing loneliness in all groups are specific points of concern for mental health care professionals. Show less
Background To assess trends in the quality of care for COVID-19 patients at the ICU over the course of time in the Netherlands. Methods Data from the National Intensive Care Evaluation (NICE)... Show moreBackground To assess trends in the quality of care for COVID-19 patients at the ICU over the course of time in the Netherlands. Methods Data from the National Intensive Care Evaluation (NICE)-registry of all COVID-19 patients admitted to an ICU in the Netherlands were used. Patient characteristics and indicators of quality of care during the first two upsurges (N = 4215: October 5, 2020-January 31, 2021) and the final upsurge of the second wave, called the 'third wave' (N = 4602: February 1, 2021-June 30, 2021) were compared with those during the first wave (N = 2733, February-May 24, 2020). Results During the second and third wave, there were less patients treated with mechanical ventilation (58.1 and 58.2%) and vasoactive drugs (48.0 and 44.7%) compared to the first wave (79.1% and 67.2%, respectively). The occupancy rates as fraction of occupancy in 2019 (1.68 and 1.55 vs. 1.83), the numbers of ICU relocations (23.8 and 27.6 vs. 32.3%) and the mean length of stay at the ICU (HRs of ICU discharge = 1.26 and 1.42) were lower during the second and third wave. No difference in adjusted hospital mortality between the second wave and the first wave was found, whereas the mortality during the third wave was considerably lower (OR = 0.80, 95% CI [0.71-0.90]). Conclusions These data show favorable shifts in the treatment of COVID-19 patients at the ICU over time. The adjusted mortality decreased in the third wave. The high ICU occupancy rate early in the pandemic does probably not explain the high mortality associated with COVID-19. Show less
What determined how governments in the Middle East and North Africa reacted to the global COVID-19 pandemic? We develop a theoretical argument based on the political costs of different policy... Show moreWhat determined how governments in the Middle East and North Africa reacted to the global COVID-19 pandemic? We develop a theoretical argument based on the political costs of different policy options and assess its empirical relevance. Distinguishing between the immediate costs associated with decisive action and the potential costs of uncontrolled spread that are likely to accrue over the long term, we argue that leaders who have fewer incentives to provide public goods to stay in power will lock down later than their more constrained counterparts. We find empirical support for this argument in statistical analyses covering the 1 January – 30 November 2020 period using the Oxford covid-19 Government Response Tracker (OxCGRT) and our own original data on the timing of mosque closures and strict lockdowns across the region. We also illustrate our argument with a description of the response to the pandemic in Egypt. Show less
Dell'Oglio, P.; Cacciamani, G.E.; Muttin, F.; Mirabella, G.; Secco, S.; Roscigno, M.; ... ; COVID-19 Niguarda Working Grp 2021
Background: Lombardy has been the first and one of the most affected European regions during the first and second waves of the novel coronavirus (severe acute respiratory syndrome coronavirus 2 ... Show moreBackground: Lombardy has been the first and one of the most affected European regions during the first and second waves of the novel coronavirus (severe acute respiratory syndrome coronavirus 2 [SARS-CoV-2]).Objective: To evaluate the impact of coronavirus disease 2019 (COVID-19) on all urologic activities over a 17-wk period in the three largest public hospitals in Lombardy located in the worst hit area in Italy, and to assess the applicability of the authorities' recommendations provided for reorganising urology practice.Design, setting, and participants: A retrospective analysis of all urologic activities performed at three major public hospitals in Lombardy (Brescia, Bergamo, and Milan), from January 1 to April 28, 2020, was performed.Outcome measurements and statistical analysis: Join-point regression was used to identify significant changes in trends for all urologic activities. Average weekly percentage changes (AWPCs) were estimated to summarise linear trends. Uro-oncologic surgeries performed during the pandemic were tabulated and stratified according to the first preliminary recommendations by Stensland et al (Stensland KD, Morgan TM, Moinzadeh A, et al. Considerations in the triage of urologic surgeries during the COVID-19 pandemic. Eur Urol 2020;77:663-6) and according to the level of priority recommended by European Association of Urology guidelines.Results and limitations: The trend for 2020 urologic activities decreased constantly from weeks 8-9 up to weeks 11-13 (AWPC range -41%, -29.9%; p < 0.001). One-third of uro-oncologic surgeries performed were treatments that could have been postponed, according to the preliminary urologic recommendations. High applicability to recommendations was observed for non-muscle-invasive bladder cancer (NMIBC) patients with intermediate/emergency level of priority, penile and testicular cancer patients, and upper tract urothelial cell carcinoma (UTUC) and renal cell carcinoma (RCC) patients with intermediate level of priority. Low applicability was observed for NMIBC patients with low/high level of priority, UTUC patients with high level of priority, prostate cancer patients with intermediate/high level of priority, and RCC patients with low level of priority.Conclusions: During COVID-19, we found a reduction in all urologic activities. High-priority surgeries and timing of treatment recommended by the authorities require adaptation according to hospital resources and local incidence.Patient summary: We assessed the urologic surgeries that were privileged during the first wave of coronavirus disease 2019 (COVID-19) in the three largest public hospitals in Lombardy, worst hit by the pandemic, to evaluate whether high-priority surgeries and timing of treatment recommended by the authorities are applicable. Pandemic recommendations provided by experts should be tailored according to hospital capacity and different levels of the pandemic. (C) 2021 The Author(s). Published by Elsevier B.V. on behalf of European Association of Urology. Show less
BackgroundIn the current SARS-CoV-2 pandemic, there has been worldwide debate on the use of corticosteroids in COVID-19. In the recent RECOVERY trial, evaluating the effect of dexamethasone, a... Show moreBackgroundIn the current SARS-CoV-2 pandemic, there has been worldwide debate on the use of corticosteroids in COVID-19. In the recent RECOVERY trial, evaluating the effect of dexamethasone, a reduced 28-day mortality in patients requiring oxygen therapy or mechanical ventilation was shown. Their results have led to considering amendments in guidelines or actually already recommending corticosteroids in COVID-19. However, the effectiveness and safety of corticosteroids still remain uncertain, and reliable data to further shed light on the benefit and harm are needed.ObjectivesThe aim of this systematic review and meta-analysis was to evaluate the effectiveness and safety of corticosteroids in COVID-19.MethodsA systematic literature search of RCTS and observational studies on adult patients was performed across Medline/PubMed, Embase and Web of Science from December 1, 2019, until October 1, 2020, according to the PRISMA guidelines. Primary outcomes were short-term mortality and viral clearance (based on RT-PCR in respiratory specimens). Secondary outcomes were: need for mechanical ventilation, need for other oxygen therapy, length of hospital stay and secondary infections.ResultsForty-four studies were included, covering 20.197 patients. In twenty-two studies, the effect of corticosteroid use on mortality was quantified. The overall pooled estimate (observational studies and RCTs) showed a significant reduced mortality in the corticosteroid group (OR 0.72 (95%CI 0.57-0.87). Furthermore, viral clearance time ranged from 10 to 29 days in the corticosteroid group and from 8 to 24 days in the standard of care group. Fourteen studies reported a positive effect of corticosteroids on need for and duration of mechanical ventilation. A trend toward more infections and antibiotic use was present.ConclusionsOur findings from both observational studies and RCTs confirm a beneficial effect of corticosteroids on short-term mortality and a reduction in need for mechanical ventilation. And although data in the studies were too sparse to draw any firm conclusions, there might be a signal of delayed viral clearance and an increase in secondary infections. Show less
Hoogen, B. van den; Santoni, A.; Sciume, G.; Bowie, A.; O'Farrelly, C.; O'Neill, L.; ... ; Hiscott, J. 2020
The past century has witnessed major advances in the control of many infectious diseases, yet outbreaks and epidemics caused by (re-) emerging RNA viruses continue to pose a global threat to human... Show moreThe past century has witnessed major advances in the control of many infectious diseases, yet outbreaks and epidemics caused by (re-) emerging RNA viruses continue to pose a global threat to human health. As illustrated by the global COVID19 pandemic, high healthcare costs, economic disruption and loss of productivity reinforce the unmet medical need to develop new antiviral strategies to combat not only the current pandemic but also future viral outbreaks.Pivotal for effective anti-viral defense is the innate immune system, a first line host response that senses and responds to virus infection. While molecular details of the innate immune response are well characterized, this research field is now being revolutionized with the recognition that cell metabolism has a major impact on the antiviral and inflammatory responses to virus infections. A detailed understanding of the role of metabolic regulation with respect to antiviral and inflammatory responses, together with knowledge of the strategies used by viruses to exploit immunometabolic pathways, will ultimately change our understanding and treatment of pathogenic viral diseases.INITIATE is a Marie Sklodowska-Curie Actions Innovative Training Network (MSCA-ITN), with the goal to train 15 early stage PhD researchers (ESRs) to become experts in antiviral immunometabolism (https://initiateitn.eu/). To this end, INITIATE brings together a highly complementary international team of academic and corporate leaders from 7 European countries, with outstanding track records in the historically distinct research fields of virology, immunology and metabolism. The ESRs of INITIATE are trained in these interdisciplinary research fields through individual investigator-driven research projects, specialized scientific training events, workshops on academia-industry interactions, outreach & communication. INITIATE will deliver a new generation of creative and entrepreneurial researchers who will be able to face the inevitable future challenges in combating viral diseases. Show less
Objective: Contagious disease outbreaks and related restrictions can lead to negative psychological outcomes, particularly in vulnerable populations at risk due to pre-existing medical conditions.... Show moreObjective: Contagious disease outbreaks and related restrictions can lead to negative psychological outcomes, particularly in vulnerable populations at risk due to pre-existing medical conditions. No randomised controlled trials (RCTs) have tested interventions to reduce mental health consequences of contagious disease outbreaks. The primary objective of the Scleroderma Patient-centered Intervention Network COVID-19 Home-isolation Activities Together (SPIN-CHAT) Trial is to evaluate the effect of a videoconference-based program on symptoms of anxiety. Secondary objectives include evaluating effects on symptoms of depression, stress, loneliness, boredom, physical activity, and social interaction.Methods: The SPIN-CHAT Trial is a pragmatic RCT that will be conducted using the SPIN-COVID-19 Cohort, a sub-cohort of the SPIN Cohort. Eligible participants will be SPIN-COVID-19 Cohort participants without a positive COVID-19 test, with at least mild anxiety (PROMIS Anxiety 4a v1.0 T-score >= 55), not working from home, and not receiving current counselling or psychotherapy. We will randomly assign 162 participants to intervention groups of 7 to 10 participants each or waitlist control. We will use a partially nested RCT design to reflect dependence between individuals in training groups but not in the waitlist control. The SPIN-CHAT Program includes activity engagement, education on strategies to support mental health, and mutual participant support. Intervention participants will receive the 4-week (3 sessions per week) SPIN-CHAT Program via video-conference. The primary outcome is PROMIS Anxiety 4a score immediately post-intervention.Ethics and dissemination: The SPIN-CHAT Trial will test whether a brief videoconference-based intervention will improve mental health outcomes among at-risk individuals during contagious disease outbreak. Show less
Vinkers, C.H.; Amelsvoort, T. van; Bisson, J.I.; Branchi, I.; Cryan, J.F.; Domschke, K.; ... ; Wee, N.J.A. van der 2020
The epidemic of the 2019 novel coronavirus SARS-CoV-2, causing the coronavirus disease 2019 (COVID-19) is a global public health emergency with multifaceted severe consequences for people's lives... Show moreThe epidemic of the 2019 novel coronavirus SARS-CoV-2, causing the coronavirus disease 2019 (COVID-19) is a global public health emergency with multifaceted severe consequences for people's lives and their mental health. In this article, as members of the European College of Neuropsychopharmacology (ECNP) Resilience, we will discuss the urgent need for a focus on resilience during the current coronavirus pandemic. Resilience is pivotal to cope with stress and vital to stay in balance. We will discuss the importance of resilience at the individual and societal level, but also the implication for patients with a psychiatric condition and health care workers. We not only advocate for an increased focus on mental health during the coronavirus pandemic but also highlight the urgent need of augmenting our focus on resilience and on strategies to enhance it. (C) 2020 The Authors. Published by Elsevier B.V. Show less
The impact of respiratory virus infections on the health of children and adults can be very significant. Yet, in contrast to most other childhood infections as well as other viral and bacterial... Show moreThe impact of respiratory virus infections on the health of children and adults can be very significant. Yet, in contrast to most other childhood infections as well as other viral and bacterial diseases, prophylactic vaccines or effective antiviral treatments against viral respiratory infections are either still not available, or provide only limited protection. Given the widespread prevalence, a general lack of natural sterilizing immunity, and/or high morbidity and lethality rates of diseases caused by influenza, respiratory syncytial virus, coronaviruses, and rhinoviruses, this difficult situation is a genuine societal challenge. A thorough understanding of the virus-host interactions during these respiratory infections will most probably be pivotal to ultimately meet these challenges. This review attempts to provide a comparative overview of the knowledge about an important part of the interaction between respiratory viruses and their host: the arms race between host innate immunity and viral innate immune evasion. Many, if not all, viruses, including the respiratory viruses listed above, suppress innate immune responses to gain a window of opportunity for efficient virus replication and setting-up of the infection. The consequences for the host's immune response are that it is often incomplete, delayed or diminished, or displays overly strong induction (after the delay) that may cause tissue damage. The affected innate immune response also impacts subsequent adaptive responses, and therefore viral innate immune evasion often undermines fully protective immunity. In this review, innate immune responses relevant for respiratory viruses with an RNA genome will briefly be summarized, and viral innate immune evasion based on shielding viral RNA species away from cellular innate immune sensors will be discussed from different angles. Subsequently, viral enzymatic activities that suppress innate immune responses will be discussed, including activities causing host shut-off and manipulation of stress granule formation. Furthermore, viral protease-mediated immune evasion and viral manipulation of the ubiquitin system will be addressed. Finally, perspectives for use of the reviewed knowledge for the development of novel antiviral strategies will be sketched. Show less
The replication of all positive-stranded RNA viruses of eukaryotes is thought to take place at cytoplasmic membranous replication organelles. One of the most prominent types of viral ROs induced by... Show moreThe replication of all positive-stranded RNA viruses of eukaryotes is thought to take place at cytoplasmic membranous replication organelles. One of the most prominent types of viral ROs induced by a number of these viruses, including coronaviruses and arteriviruses, are double-membrane vesicles (DMVs) that contain viral double-stranded RNA. This thesis discusses the formation of these replication organelles by arteri- and coronaviruses and provides new insights in the viral proteins involved. The ultrastructure of the replication organelles was unravelled using both electron microscopy and tomography. Furthermore, this research described in this thesis also shows that the innate immune system in infected cells can prevent the formation of the membrane structures. Show less
The order Nidovirales comprises a monophyletic group of viruses with positive-stranded RNA genomes that are classified in the families Arteriviridae, Coronaviridae, Mesoniviridae, and Roniviridae.... Show moreThe order Nidovirales comprises a monophyletic group of viruses with positive-stranded RNA genomes that are classified in the families Arteriviridae, Coronaviridae, Mesoniviridae, and Roniviridae. They share a conserved genome organization and a characteristic set of key replicative proteins. Although, in principle, this suggests a conserved replication mechanism, it is currently unclear how far exactly the resemblance extends on a more detailed level. This is foremost due to our poor understanding of the role of most viral proteins in the replication cycle. In addition, most of the knowledge that was obtained predominantly derives from studies of only few coronaviruses, the nidovirus subgroup with the largest known genome and therefore presumably employing the most complex replication strategy. In contrast, thus far only limited attention was given to the RNA rep_licating and processing enzymes of arteriviruses, and none at all to those of mesoni- and roniviruses, whose genome sizes are (much) smaller than those of coronaviruses. The work described in this thesis addresses some poorly or uncharacterized (domains of ) nonstructural proteins (nsps) that are likely involved in one or multiple steps of RNA replication and/or transcription of the prototypic arterivirus equine arteritis virus (EAV). Show less
