| 1. |
- Almstedt, Karin, 1980-, et al.
(författare)
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Unfolding a folding disease: folding, misfolding and aggregation of the marble brain syndrome-associated mutant H107Y of human carbonic anhydrase II
- 2004
-
Ingår i: Journal of Molecular Biology. - Oxford : Elsevier. - 0022-2836 .- 1089-8638. ; 342:2, s. 619-633
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Tidskriftsartikel (refereegranskat)abstract
- Most loss-of-function diseases are caused by aberrant folding of important proteins. These proteins often misfold due to mutations. The disease marble brain syndrome (MBS), known also as carbonic anhydrase II deficiency syndrome (CADS), can manifest in carriers of point mutations in the human carbonic anhydrase II (HCA II) gene. One mutation associated with MBS entails the His107Tyr substitution. Here, we demonstrate that this mutation is a remarkably destabilizing folding mutation. The loss-of-function is clearly a folding defect, since the mutant shows 64% of CO2 hydration activity compared to that of the wild-type at low temperature where the mutant is folded. On the contrary, its stability towards thermal and guanidine hydrochloride (GuHCl) denaturation is highly compromised. Using activity assays, CD, fluorescence, NMR, cross-linking, aggregation measurements and molecular modeling, we have mapped the properties of this remarkable mutant. Loss of enzymatic activity had a midpoint temperature of denaturation (Tm) of 16 °C for the mutant compared to 55 °C for the wild-type protein. GuHCl-denaturation (at 4 °C) showed that the native state of the mutant was destabilized by 9.2 kcal/mol. The mutant unfolds through at least two equilibrium intermediates; one novel intermediate that we have termed the molten globule light state and, after further denaturation, the classical molten globule state is populated. Under physiological conditions (neutral pH; 37 °C), the His107Tyr mutant will populate the molten globule light state, likely due to novel interactions between Tyr107 and the surroundings of the critical residue Ser29 that destabilize the native conformation. This intermediate binds the hydrophobic dye 8-anilino-1-naphthalene sulfonic acid (ANS) but not as strong as the molten globule state, and near-UV CD reveals the presence of significant tertiary structure. Notably, this intermediate is not as prone to aggregation as the classical molten globule. As a proof of concept for an intervention strategy with small molecules, we showed that binding of the CA inhibitor acetazolamide increases the stability of the native state of the mutant by 2.9 kcal/mol in accordance with its strong affinity. Acetazolamide shifts the Tm to 34 °C that protects from misfolding and will enable a substantial fraction of the enzyme pool to survive physiological conditions.
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| 2. |
- Napoleone, Antonino, et al.
(författare)
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Fed-batch production assessment of a tetravalent bispecific antibody : A case study on piggyBac stably transfected HEK293 cells
- 2021
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Ingår i: New Biotechnology. - : Elsevier BV. - 1871-6784 .- 1876-4347. ; 65, s. 9-19
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Tidskriftsartikel (refereegranskat)abstract
- The transition from preclinical biological drug development into clinical trials requires an efficient upscaling process. In this context, bispecific antibody drugs are particularly challenging due to their propensity to form aggregates and generally produce low titers. Here, the upscaling process for a tetravalent bispecific antibody expressed by a piggyBac transposon-mediated stable HEK293 cell pool has been evaluated. The project was performed as a case study at Testa Center, a non-GMP facility for scale-up testing of biologics in Sweden, and encompassed media adaptation strategies, fed-batch optimization and a novel antibody purification technology. The cell pool was adapted to different culture media for evaluation in terms of cell viability and titers compared to its original Expi293 Expression Medium. These parameters were assessed in both sequential stepwise adaption and direct media exchanges. By this, a more affordable medium was identified that did not require stepwise adaptation and with similar titers and viability as in the Expi293 Expression Medium. Fed-batch optimizations resulted in culture densities reaching up to 20 x 106 viable cells/mL with over 90 % viability 12 days postinoculum, and antibody titers three times higher than corresponding batch cultures. By implementing a novel high-speed protein A fiber technology (Fibro PrismA) with a capture residence time of only 7.5 s, 8 L of supernatant could be purified in 4.5 h without compromising the purity, structural integrity and function of the bispecific antibody. Results from this study related to medium adaptation and design of fed-batch protocols will be highly beneficial during the forthcoming scale-up of this therapeutic antibody.
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| 3. |
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| 4. |
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| 5. |
- Bao, Ling, 1980, et al.
(författare)
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U-Duality and the Compactified Gauss-Bonnet Term
- 2007
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Ingår i: Journal of High Energy Physics.
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Tidskriftsartikel (refereegranskat)abstract
- We present the complete toroidal compactification of the Gauss-Bonnet Lagrangian from D dimensions to D-n dimensions. Our goal is to investigate the resulting action from the point of view of the "U-duality" symmetry SL(n+1,R) which is present in the tree-level Lagrangian when D-n=3. The analysis builds upon and extends the investigation of the paper [arXiv:0706.1183], by computing in detail the full structure of the compactified Gauss-Bonnet term, including the contribution from the dilaton exponents. We analyze these exponents using the representation theory of the Lie algebra sl(n+1,R) and determine which representation is the relevant one for quadratic curvature corrections. By interpreting the result of the compactification as a leading term in a large volume expansion of an SL(n+1,Z)-invariant action, we conclude that the overall exponential dilaton factor should not be included in the representation structure. As a consequence, all dilaton exponents correspond to weights of sl(n+1,R), which, nevertheless, remain on the positive side of the root lattice.
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| 6. |
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| 7. |
- Fagerström, Anna, 1980-
(författare)
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Long-term molecular epidemiology of extended-spectrum β-lactamase producing Escherichia coli in a low-endemic setting
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Escherichia coli is a commensal inhabitant in the gastro-intestinal tract of humans and animals but it is also the most common bacterial species causing urinary tract infection, which ranges in severity from distal cystitis to urosepsis and septic shock. During the past decades, the prevalence of antibiotic resistant E. coli has increased worldwide. Extended-spectrum β-lactamases (ESBL) causes resistance to β-lactam antibiotics, the most widely used class of antibiotics. The genes encoding ESBL, bla, are usually carried on conjugative plasmids, which can be transferred between different bacterial lineages and different species. These plasmids frequently also carry resistance genes to additional antibiotic classes, and ESBL-producing E. coli are therefore often multidrug-resistant. The aim of this thesis was to describe the long-term molecular epidemiology of ESBL-producing E. coli in Örebro County during the time when they first started to emerge. In addition, potential transmission to the environment was investigated by performing a comparative analysis on ESBL-producing E. coli isolated from patients and from the aquatic environment in Örebro city. In general, the E. coli population was genetically diverse, but the pandemic lineage ST131, first identified in 2004, appears to have been responsible for the dramatic increase of CTX-M-15-producing E.coli observed during the late 2000s. CTX-M-15 was the most prevalent ESBL-type followed by CTX-M-14 and these genes were mainly found on plasmids belonging to the IncF or IncI1 families. Continuous horizontal transmission of IncI1 ST31 and ST37 plasmids between diverse E. coli lineages have also contributed to the dissemination of blaCTX-M-15 in Örebro County. Extended spectrum β-lactamase-producing E. coli were found to be common in the aquatic environment in Örebro city and E. coli lineages genetically similar to those causing infections in humans were present in environmental waters indicating that transmission of ESBL-producing E. colifrom humans to the aquatic environment likely has occurred.
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| 8. |
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| 9. |
- Lewis, Jeffrey, et al.
(författare)
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PFAS – A threat for groundwater and drinking water supply in Sweden?
- 2015
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Ingår i: EGU General Assembly 2015. ; 17
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Perfluoroalkyl substances (PFAS) are a group of anthropogenic environmental pollutants that are widely distributed in the global environment. They have multiple industrial uses, including water repellents in clothing, paper coatings and firefighting foam. According to a study released by the Environmental Directorate of the OECD, they are persistent, bioaccumulative and toxic to mammalian species (OECD, 2002). In some municipal drinking water wells in Sweden, measured concentrations of PFAS found to be several hundred times higher than the allowed threshold values. This has created a huge public concern and has recently attracted much media attention in Sweden (e.g. Afzelius et al., 2014; Bergman et al., 2014; Lewis et al., 2014). PFAS findings raised questions such as “What can we do to solve the problem?” When it comes to drinking water, there are a number of techniques that can ensure that PFAS levels are reduced to acceptable levels. This may be a costly challenge, but from a technical point of view it is possible. To ensure the safety of drinking water from a public health perspective is obviously a top priority. However, international experience shows that the cost of cleaning up PFAS in groundwater may be significantly higher than continuously treat drinking water in water works. Approximately fifty percent of Sweden’s drinking water comes from groundwater. As a result, there are several ongoing and planned PFAS-related environmental and drinking-water investigations in Sweden. Many aquifers that supply municipal water plants are located in areas of sand and gravel deposits. Such soils have relatively high permeabilities, which permits extraction of large volumes of water. However, the downside to high permeabilities is that they also allow dissolved contaminants as PFAS to spread over large areas. If one disregards the health risks linked to its presence in drinking water, PFAS have an impact on three of Sweden’s national environmental quality objectives, namely, A Non-Toxic Environment, Flourishing Lakes and Streams and Good-Quality Groundwater. Although the survey of PFAS in our groundwater supplies will take time, it is feasible. Much research in the field of hydrogeology and geochemistry remains before a viable and cost-effective groundwater remediation method can be operational. Until then, it is essential that measures are taken to identify the present distribution and magnitude of PFAS in groundwater and prevents its further spread in our most important aquifers. Afzelius, H. et al., 2014. Vågar vi dricka kranvattnet? (Do we dare drinking tap water?), Svenska Dagbladet. Bergman, Å., Hansson, S.O., Hellsten, E., 2014. En miljöskandal av historiska mått (An environmental scandal of historic proportions), Svenska Dagbladet. Lewis, J. et al., 2014. Kartlägg det förorenade dricksvattnet (Survey the contaminated drinking water), Svenska Dagbladet. OECD, 2002. Hazard Assessment of Perfluorooctane Sulfonate (PFOS) and its Salt.
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| 10. |
- Längkvist, Martin, 1983-, et al.
(författare)
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Learning Generative Image Manipulations from Language Instructions
- 2020
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Konferensbidrag (refereegranskat)abstract
- This paper studies whether a perceptual visual system can simulate human-like cognitive capabilities by training a computational model to predict the output of an action using language instruction. The aim is to ground action words such that an AI is able to generate an output image that outputs the effect of a certain action on an given object. The output of the model is a synthetic generated image that demonstrates the effect that the action has on the scene. This work combines an image encoder, language encoder, relational network, and image generator to ground action words, and then visualize the effect an action would have on a simulated scene. The focus in this work is to learn meaningful shared image and text representations for relational learning and object manipulation.
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| 11. |
- Meshkian, Rahele, et al.
(författare)
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W-Based Atomic Laminates and Their 2D Derivative W1.33C MXene with Vacancy Ordering
- 2018
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Ingår i: Advanced Materials. - : Wiley. - 0935-9648 .- 1521-4095. ; 30:21
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Tidskriftsartikel (refereegranskat)abstract
- Structural design on the atomic level can provide novel chemistries of hybrid MAX phases and their MXenes. Herein, density functional theory is used to predict phase stability of quaternary i-MAX phases with in-plane chemical order and a general chemistry (W 2/3 M 2 1/3 ) 2 AC, where M 2 = Sc, Y (W), and A = Al, Si, Ga, Ge, In, and Sn. Of over 18 compositions probed, only two—with a monoclinic C2/c structure—are predicted to be stable: (W 2/3 Sc 1/3 ) 2 AlC and (W 2/3 Y 1/3 ) 2 AlC and indeed found to exist. Selectively etching the Al and Sc/Y atoms from these 3D laminates results in W 1.33 C-based MXene sheets with ordered metal divacancies. Using electrochemical experiments, this MXene is shown to be a new, promising catalyst for the hydrogen evolution reaction. The addition of yet one more element, W, to the stable of M elements known to form MAX phases, and the synthesis of a pure W-based MXene establishes that the etching of i-MAX phases is a fruitful path for creating new MXene chemistries that has hitherto been not possible, a fact that perforce increases the potential of tuning MXene properties for myriad applications.
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| 12. |
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Perspektiv på offentlig verksamhet i utveckling : tolv kapitel om demokrati, styrning och effektivitet
- 2011. - 1
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Samlingsverk (redaktörskap) (övrigt vetenskapligt/konstnärligt)abstract
- Perspektiv på offentlig verksamhet i utveckling - Tolv kapitel om demokrati, styrning och effektivitet samlar texter från doktorander och forskare knutna till Forskarskolan Offentlig verksamhet i utveckling (FOVU) vid Örebro Universitet. Antologin erbjuder en mångdisciplinär och omfångsrik behandling av en rad viktiga utmaningar för dagens offentlig verksamhet. I boken behandlas ämnen som korruption, jämställdhet, trygghet, medborgardialog, sjukskrivning och högerextremism. Målsättningen med boken är att skapa en bro mellan inomvetenskapliga debatter, offentlig praktik och politik. Här erbjuds kortare texter som på ett överskådligt sätt angriper praktikrelevanta ämnen utan att göra avkall på den vetenskapliga kvaliteten. Vissa texter erbjuder forskningsöversikter och reder ut oklarheter i teoretiska debatter, medan andra presenterar resultat av empirisk forskning.
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| 13. |
- Persson, Andreas, 1980-, et al.
(författare)
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Learning Actions to Improve the Perceptual Anchoring of Object
- 2017
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Ingår i: Frontiers in Robotics and AI. - Lausanne : Frontiers Media S.A.. - 2296-9144. ; 3:76
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we examine how to ground symbols referring to objects in perceptual data from a robot system by examining object entities and their changes over time. In particular, we approach the challenge by 1) tracking and maintaining object entities over time; and 2) utilizing an artificial neural network to learn the coupling between words referring to actions and movement patterns of tracked object entities. For this purpose, we propose a framework which relies on the notations presented in perceptual anchoring. We further present a practical extension of the notation such that our framework can track and maintain the history of detected object entities. Our approach is evaluated using everyday objects typically found in a home environment. Our object classification module has the possibility to detect and classify over several hundred object categories. We demonstrate how the framework creates and maintains, both in space and time, representations of objects such as 'spoon' and 'coffee mug'. These representations are later used for training of different sequential learning algorithms in order to learn movement actions such as 'pour' and 'stir'. We finally exemplify how learned movements actions, combined with common-sense knowledge, further can be used to improve the anchoring process per se.
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| 14. |
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| 15. |
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| 16. |
- Persson, Martin, 1980, et al.
(författare)
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Parameterization in Quick Clay Modeling – Introducing Stratigraphic Detail
- 2010
-
Ingår i: Abstracts and Proceedings of the Geological Society of Norway - 29th Nordic Geological Winter Meeting.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Quick clay landslides are a potential hazard in southwestern Sweden. While the general theory of formation is well developed, spatial modeling of the processes and different factors controlling the clay leaching and the resulting quick clay properties has largely been neglected. We suggest a modeling approach aiming to specify the relative importance of different factors and their spatial and stratigraphic variance related to quick clay formation. The model should ultimately combine stratigraphic data from more than 200 Swedish geotechnical site investigations. Together with quick clay theory and knowledge about sedimentary paleoenvironments and processes, the model will predict quick clay distribution, or at least sites with favorable conditions for its development. Identified factors have been grouped together in the following sets: groundwater flux, exposure to leaching, time available for leaching, textural character and geochemical properties of the pore fluid. These groups have been weighted by importance and further subdivided. The importance of each subfactor has been derived from stratigraphic, geotechnical and geomorphologic data using factor analysis. To be able to compare different factors, utility functions have been constructed to translate observed values into a uniform scale ranging from 0-1, where 0 indicates no elevated probability and 1 means that the factor range is optimum for quick clay formation. This step of the process is largely statistical. A single factor’s weight and utility score are multiplied to express the factor’s possibility to affect the system. When combining the weights and utilities for all factors the final score describes the possibility for leaching and thus quick clay development at a specific site. Utilizing knowledge of quick clay formation and stratigraphic data allows an improved landslide susceptibility modeling in areas with known or unknown prerequisites for quick clay formation. The factors ratings and the interdependence between them was, in part, used in selecting and refining these parameters for GIS modeling. Type settings with high probability for quick clay formation have been defined from the statistical factor weighting. The overall goal is to improve today’s landslide susceptibility mapping by quantifying the site-specific prerequisites for quick clay formation.
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| 17. |
- Persson, Martin, 1980
(författare)
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Predicting Spatial and Stratigraphic Quick-clay Distribution in SW Sweden
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Clay sediments are associated with a wide variety of engineering problems, of which landslides, together with settlement, are the most investigated due to the large associated costs. Quick-clay deposits, which if disturbed can transform into a liquid, pose a serious threat to society in southwestern Sweden and have been involved in several large landslides, sometimes with fatal consequences. Even though the theories that explain quick-clay formation are well advanced, no modeling that combine geologic information and reasoning with hard geotechnical data to predict its distribution has previously been done. The stepwise multi-criteria evaluation technique suggested here involves identification of quick-clay preconditions from the literature. Then to derive criteria priorities, an expert group consisting mostly of geologists and geotechnical engineers carried out pairwise comparisons using matrices from which weights were calculated. The same group also participated in the development of the utility functions used to standardize the criteria to allow direct criteria comparisons. To populate the model, all criteria were quantified using empirical geotechnical data, existing geological documentation and/or environmental proxy data. The model results were later cross-checked at selected sites with geophysical methods. Finally, a rather large geotechnical data set was divided and used to add a depth dimension to the model results and to test the predic-tive powers of 2D and 3D models. Quick-clay type settings were separately defined to facilitate clear communication of quick-clay predictions to non-specialists and to provide a structure for comparisons to the depositionary and post-depositionary conditions in well-studied east-Canadian or mid-and Norwegian quick-clay areas. These settings were derived from trends observed in geotechnical, geologic, geophysical and modeling records. Results of the predictive modeling were subsequently applied to landslide hazard zonation in SW Sweden. However, the framework could, with slight regional adaptionadaptation, also be applied in other areas (e.g. eastern Canada and coastal mid-Norway) or even to other issues, wherever groundwater fluxes and ground conditions are of interest (e.g. in contaminant transport, geological process studies and groundwater resource exploration).
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| 18. |
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| 19. |
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| 20. |
- Persson, Martin, 1980, et al.
(författare)
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Spatial quick-clay predictions using multi-criteria evaluation in SW Sweden
- 2014
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Ingår i: Landslides. - : Springer Science and Business Media LLC. - 1612-510X .- 1612-5118. ; 11:2, s. 263-279
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Tidskriftsartikel (refereegranskat)abstract
- The transformation of marine and glaciomarine clay deposits into high sensitive and quick clays is largely dependent on the influence of local and regional geologic history and the resulting stratigraphy. The general conditions that facilitate quick-clay development are well known from numerous laboratory investigations during the last century, but their local and regional in-field variation is less understood. In this study, the geographic distribution of quick clay in SW Sweden is predicted using a multicriteria evaluation model that incorporates both qualitative information (established theory and expert judgment concerning the influences on both quick-clay development and the stratigraphic and geomorphologic distribution of sediment types) and observational data (maps of surficial deposits, geotechnical records and digital elevation data). This information duality cannot be avoided if knowledge from different disciplines is utilized. Considering this, model transparency is important for improvements and for characterizing its reliability for risk analysis. The model was constructed stepwise by an initial parameterization with subsequent hierarchical structuring, weighting and standardization of criteria, before running the full analysis. Comparisons between regional model results and geotechnically documented localities have yielded promising results concerning the model's ability to predict general trends. However, the large natural and site-specific variability of clay sensitivities is not always captured by the model. These deviations are examined and suggestions are given for minimizing their effect. Applications of model methodology and results are briefly discussed.
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| 21. |
- Persson, Martin, 1980
(författare)
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Three-Dimensional Quick-Clay Modeling of the Gothenburg Region, Sweden
- 2014
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Ingår i: Landslides in Sensitive Clays. From Geosciences to Risk Management. L'Heureux, Jean-Sébastien et al. (Eds.). - Dordrecht Heidelberg New York London : Springer. - 9789400770782 ; , s. 39-50
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Bokkapitel (refereegranskat)abstract
- En 3D GIS-modellering av kriterier som bidrar till kvicklerebildning har utförts för att förutsäga känsliga lerors geografiska utbredning. Detta har gjorts i tre steg. 1. Geotekniska arkivuppgifter har sammanställts för att kvantifiera lerornas stratigrafiska läge och sensitivitet. 2. Resultaten kombineras med tidigare 2D resultat. 3. Det kombinerade resultatet presenteras och testas mot empiriska datakällor.
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| 22. |
- Persson, Martin, 1976, et al.
(författare)
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Trading Forests: Quantifying the Contribution of Global Commodity Markets to Emissions from Tropical Deforestation
- 2014
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This paper aims to improve our understanding of how and where global supply-chains linkconsumers of agricultural and forest commodities across the world to forest destruction in tropicalcountries. A better understanding of these linkages can help inform and support the design ofdemand-side interventions to reduce tropical deforestation. To that end, we map the link betweendeforestation for four commodities (beef, soybeans, palm oil, and wood products) in eight casecountries (Argentina, Bolivia, Brazil, Paraguay, Democratic Republic of the Congo, Indonesia,Malaysia, and Papua New Guinea) to consumption, through international trade. Although few,the studied countries comprise a large share of the internationally traded volumes of the analyzedcommodities: 83% of beef and 99% of soybean exports from Latin America, 97% of global palmoil exports, and roughly half of (official) tropical wood products trade. The analysis covers theperiod 2000-2009. We find that roughly a third of tropical deforestation and associated carbonemissions (3.9 Mha and 1.7 GtCO2) in 2009 can be attributed to our four case commodities in oureight case countries. On average a third of analyzed deforestation was embodied in agriculturalexports, mainly to the EU and China. However, in all countries but Bolivia and Brazil, exportmarkets are dominant drivers of forest clearing for our case commodities. If one excludes Brazilianbeef on average 57% of deforestation attributed to our case commodities was embodied in exports.The share of emissions that was embodied in exported commodities increased between 2000 and2009 for every country in our study except Bolivia and Malaysia.
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| 23. |
- Schilke, Martin, 1980, et al.
(författare)
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Interaction between cracks and microstructure in three dimensions for rolling contact fatigue in railway rails
- 2014
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Ingår i: Fatigue and Fracture of Engineering Materials and Structures. - : Wiley. - 8756-758X .- 1460-2695. ; 37:3, s. 280-289
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Tidskriftsartikel (refereegranskat)abstract
- The rail–wheel contact generates plastic deformation and cracks in the top layer of a rail. Rolling contact fatigue (RCF) cracks in rail samples from track and from a full scale test rig were examined. Due to the shear forces arising in the wheel rail contact, the microstructure close to the surface becomes aligned in the shear direction. Thereby, the pearlite becomes anisotropic, and resistance to cracks is lower in certain directions. RCF cracks follow the weakest direction of the microstructure, which in pearlitic railway rails is the aligned pearlite structure or singular weaknesses such as pro-eutectoid ferritesor slags. The deformation of the microstructure is different depending on loading situation and original microstructure (rail grade). Once the plastic deformation is present, the cracks follow the path of the weakest crack resistance. Cracks close to each other can interact or shield each other; it is unclear, however, to what extent. In this paper, a new method is described that allows the presentation of RCF cracks in three dimensions.
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| 24. |
- Schilke, Martin, 1980, et al.
(författare)
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White etching layers on the Stockholm local traffic network
- 2012
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Ingår i: Proceedings 9th International Conference on Contact Mechanics and Wear of Rail/Wheel Systems. ; , s. 589-596
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Konferensbidrag (refereegranskat)abstract
- Top layers of railway rails are subjected to microstructural changes sometimes resulting in white etching layers. These thin layers are more brittle than the base material and show increased cracking and spalling. For the present study pearlitic rail samples from curves without corrugation from the Stockholm local traffic network (SL) have been investigated concerning their influence on the crack initiation and crack propagation into the base material. Samples with white etching layers were subjected to tensile loads. The white etching layers and crack surfaces were examined with light and scanning electron microscope. White etching layers with a thickness of 200µm were found. It can be concluded that they consist mostly of martensite with a hardness two to three times higher than the base material. Cracks growing through the white etching layer initiating cracks in the pearlite have been found. Also, the crack sensitivity is higher for the white etching layer as compared to the base material and it creates initiation points for cracks in the pearlitic part of the rail.
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| 25. |
- Säll, Olof, 1980-, et al.
(författare)
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Prevalence and persistence of Neisseria meningitidis carriage in Swedish university students
- 2023
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Ingår i: Epidemiology and Infection. - : Cambridge University Press. - 0950-2688 .- 1469-4409. ; 151
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Tidskriftsartikel (refereegranskat)abstract
- The bacterium Neisseria meningitidis causes life-threatening disease worldwide, typically with a clinical presentation of sepsis or meningitis, but can be carried asymptomatically as part of the normal human oropharyngeal microbiota. The aim of this study was to examine N. meningitidis carriage with regard to prevalence, risk factors for carriage, distribution of meningococcal lineages and persistence of meningococcal carriage. Throat samples and data from a self-reported questionnaire were obtained from 2744 university students (median age: 23 years) at a university in Sweden on four occasions during a 12-month period. Meningococcal isolates were characterised using whole-genome sequencing. The carriage rate among the students was 9.1% (319/3488; 95% CI 8.2-10.1). Factors associated with higher carriage rate were age ≤22 years, previous tonsillectomy, cigarette smoking, drinking alcohol and attending parties, pubs and clubs. Female gender and sharing a household with children aged 0-9 years were associated with lower carriage. The most frequent genogroups were capsule null locus (cnl), group B and group Y and the most commonly identified clonal complexes (cc) were cc198 and cc23. Persistent carriage with the same meningococcal strain for 12 months was observed in two students. Follow-up times exceeding 12 months are recommended for future studies investigating long-term carriage of N. meningitidis.
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