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Israelsson, Stina
Publications (10 of 11) Show all publications
Bunse, C., Israelsson, S., Baltar, F., Bertos-Fortis, M., Fridolfsson, E., Legrand, C., . . . Pinhassi, J. (2019). High Frequency Multi-Year Variability in Baltic Sea Microbial Plankton Stocks and Activities. Frontiers in Microbiology, 9, Article ID 3296.
Open this publication in new window or tab >>High Frequency Multi-Year Variability in Baltic Sea Microbial Plankton Stocks and Activities
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2019 (English)In: Frontiers in Microbiology, ISSN 1664-302X, E-ISSN 1664-302X, Vol. 9, article id 3296Article in journal (Refereed) Published
Abstract [en]

Marine bacterioplankton are essential in global nutrient cycling and organic matter turnover. Time-series analyses, often at monthly sampling frequencies, have established the paramount role of abiotic and biotic variables in structuring bacterioplankton communities and productivities. However, fine-scale seasonal microbial activities, and underlying biological principles, are not fully understood. We report results from four consecutive years of high-frequency time-series sampling in the Baltic Proper. Pronounced temporal dynamics in most investigated microbial variables were observed, including bacterial heterotrophic production, plankton biomass, extracellular enzyme activities, substrate uptake rate constants of glucose, pyruvate, acetate, amino acids, and leucine, as well as nutrient limitation bioassays. Spring blooms consisting of diatoms and dinoflagellates were followed by elevated bacterial heterotrophic production and abundances. During summer, bacterial productivity estimates increased even further, coinciding with an initial cyanobacterial bloom in early July. However, bacterial abundances only increased following a second cyanobacterial bloom, peaking in August. Uptake rate constants for the different measured carbon compounds varied seasonally and inter-annually and were highly correlated to bacterial productivity estimates, temperature, and cyanobacterial abundances. Further, we detected nutrient limitation in response to environmental conditions in a multitude of microbial variables, such as elevated productivities in nutrient bioassays, changes in enzymatic activities, or substrate preferences. Variations among biotic variables often occurred on time scales of days to a few weeks, yet often spanning several sampling occasions. Such dynamics might not have been captured by sampling at monthly intervals, as compared to more predictable transitions in abiotic variables such as temperature or nutrient concentrations. Our study indicates that high resolution analyses of microbial biomass and productivity parameters can help out in the development of biogeochemical and food web models disentangling the microbial black box.

Place, publisher, year, edition, pages
Frontiers Media S.A., 2019
Keywords
marine bacteria, phytoplankton, cyanobacteria, production, substrate uptake, enzyme activity, biogeochemistry
National Category
Microbiology Ecology
Research subject
Ecology, Microbiology; Ecology, Microbiology
Identifiers
urn:nbn:se:lnu:diva-80150 (URN)10.3389/fmicb.2018.03296 (DOI)000455948100001 ()2-s2.0-85064405301 (Scopus ID)
Available from: 2019-02-05 Created: 2019-02-05 Last updated: 2019-08-29Bibliographically approved
Israelsson, S., Sävneby, A., Ekström, J.-O., Jonsson, N., Edman, K. & Lindberg, A. M. (2014). Improved replication efficiency of echovirus 5 after transfection of colon cancer cells using an authentic 5' RNA genome end methodology. Investigational new drugs, 32(6), 1063-1070
Open this publication in new window or tab >>Improved replication efficiency of echovirus 5 after transfection of colon cancer cells using an authentic 5' RNA genome end methodology
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2014 (English)In: Investigational new drugs, ISSN 0167-6997, E-ISSN 1573-0646, Vol. 32, no 6, p. 1063-1070Article in journal (Refereed) Published
Abstract [en]

Oncolytic virotherapy is a promising novel form of cancer treatment, but the therapeutic efficiency needs improvement. A potential strategy to enhance the therapeutic effect of oncolytic viruses is to use infectious nucleic acid as therapeutic agent to initiate an oncolytic infection, without administrating infectious viral particles. Here we demonstrate improved viral replication activation efficiency when transfecting cells with 5’ end authentic in vitro transcribed enterovirus RNA as compared to genomic RNA with additional non-genomic 5’ nucleotides generated by conventional cloning methods. We used echovirus 5 (E5) as an oncolytoc model virus due to its ability to replicate in and completely destroy five out of six colon cancer cell lines and kill artificial colon cancer tumors (HT29 spheroids), as shown here. An E5 infectious cDNA clone including a hammerhead ribozyme sequence was used to generate in vitro transcripts with native 5’ genome ends. In HT29 cells, activation of virus replication is approximately 20-fold more efficient for virus genome transcripts with native 5’ genome ends compared to E5 transcripts generated from a standard cDNA clone. This replication advantage remains when viral progeny release starts by cellular lysis 22 h post transfection. Hence, a native 5’ genomic end improves infection activation efficacy of infectious nucleic acid, potentially enhancing its therapeutic effect when used for cancer treatment. The clone design with a hammerhead ribozyme is likely to be applicable to a variety of oncolytic positive sense RNA viruses for the purpose of improving the efficacy of oncolytic virotherapy.

Keywords
Picornavirus, RNA virus, Enterovirus, Oncolytic virotherapy, Hammerhead ribozyme, Infectious nucleic acid
National Category
Biochemistry and Molecular Biology
Research subject
Biomedical Sciences, Virology
Identifiers
urn:nbn:se:lnu:diva-41541 (URN)10.1007/s10637-014-0136-z (DOI)000345142300002 ()2-s2.0-84938677294 (Scopus ID)
Available from: 2015-04-01 Created: 2015-04-01 Last updated: 2017-12-04Bibliographically approved
Israelsson, S. (2012). Tissue tropism and oncolytic potential of enteroviruses. (Doctoral dissertation). Växjö, Kalmar: Linnaeus University Press
Open this publication in new window or tab >>Tissue tropism and oncolytic potential of enteroviruses
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Alternative title[sv]
Vävnadstropism och onkolytisk potential hos enterovirus
Place, publisher, year, edition, pages
Växjö, Kalmar: Linnaeus University Press, 2012
Series
Linnaeus University Dissertations ; 77/2012
Keywords
picornavirus, enterovirus, echovirus, receptor, tropism, viral oncolysis, quantification, receptor interactions, colon cancer
National Category
Other Natural Sciences
Research subject
Natural Science, Biomedical Sciences
Identifiers
urn:nbn:se:lnu:diva-17721 (URN)978-91-86983-32-1 (ISBN)
Public defence
2012-03-09, N2007, Smålandsgatan 26B, Kalmar, 09:00 (Swedish)
Opponent
Supervisors
Available from: 2012-02-28 Created: 2012-02-22 Last updated: 2012-02-28Bibliographically approved
Israelsson, S., Jonsson, N., Gullberg, M. & Lindberg, A. M. (2011). Cytolytic replication of echoviruses in colon cancer cell lines. Virology Journal, 8, Article ID e473.
Open this publication in new window or tab >>Cytolytic replication of echoviruses in colon cancer cell lines
2011 (English)In: Virology Journal, ISSN 1743-422X, E-ISSN 1743-422X, Vol. 8, article id e473Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: Colorectal cancer is one of the most common cancers in the world, killing nearly 50% of patients afflicted. Though progress is being made within surgery and other complementary treatments, there is still need for new and more effective treatments. Oncolytic virotherapy, meaning that a cancer is cured by viral infection, is a promising field for finding new and improved treatments. We have investigated the oncolytic potential of several low-pathogenic echoviruses with rare clinical occurrence. Echoviruses are members of the enterovirus genus within the family Picornaviridae.

METHODS: Six colon cancer cell lines (CaCo-2, HT29, LoVo, SW480, SW620 and T84) were infected by the human enterovirus B species echovirus 12, 15, 17, 26 and 29, and cytopathic effects as well as viral replication efficacy were investigated. Infectivity was also tested in spheroids grown from HT29 cells.

RESULTS: Echovirus 12, 17, 26 and 29 replicated efficiently in almost all cell lines and were considered highly cytolytic. The infectivity of these four viruses was further evaluated in artificial tumors (spheroids), where it was found that echovirus 12, 17 and 26 easily infected the spheroids.

CONCLUSIONS: We have found that echovirus 12, 17 and 26 have potential as oncolytic agents against colon cancer, by comparing the cytolytic capacity of five low-pathogenic echoviruses in six colon cancer cell lines and in artificial tumors.

National Category
Microbiology
Research subject
Natural Science, Biomedical Sciences
Identifiers
urn:nbn:se:lnu:diva-16513 (URN)10.1186/1743-422X-8-473 (DOI)21999585 (PubMedID)2-s2.0-80054008339 (Scopus ID)
Available from: 2012-01-03 Created: 2012-01-03 Last updated: 2017-12-08Bibliographically approved
Gullberg, M., Tolf, C., Jonsson, N., Polacek, C., Precechtelova, J., Badurova, M., . . . Lindberg, A. M. (2010). A single coxsackievirus B2 capsid residue controls cytolysis and apoptosis in rhabdomyosarcoma cells.. Journal of Virology, 84(12), 5868-5879
Open this publication in new window or tab >>A single coxsackievirus B2 capsid residue controls cytolysis and apoptosis in rhabdomyosarcoma cells.
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2010 (English)In: Journal of Virology, ISSN 0022-538X, E-ISSN 1098-5514, Vol. 84, no 12, p. 5868-5879Article in journal (Refereed) Published
Abstract [en]

Coxsackievirus B2 (CVB2), one of six human pathogens of the group B coxsackieviruses within the enterovirus genus of Picornaviridae, causes a wide spectrum of human diseases ranging from mild upper respiratory illnesses to myocarditis and meningitis. The CVB2 prototype strain Ohio-1 (CVB2O) was originally isolated from a patient with summer grippe in the 1950s. Later on, CVB2O was adapted to cytolytic replication in rhabdomyosarcoma (RD) cells. Here, we present analyses of the correlation between the adaptive mutations of this RD variant and the cytolytic infection in RD cells. Using reverse genetics, we identified a single amino acid change within the exposed region of the VP1 protein (glutamine to lysine at position 164) as the determinant for the acquired cytolytic trait. Moreover, this cytolytic virus induced apoptosis, including caspase activation and DNA degradation, in RD cells. These findings contribute to our understanding of the host cell adaptation process of CVB2O and provide a valuable tool for further studies of virus-host interactions.

National Category
Microbiology in the medical area
Research subject
Biomedical Sciences, Virology
Identifiers
urn:nbn:se:lnu:diva-7168 (URN)10.1128/JVI.02383-09 (DOI)20375176 (PubMedID)2-s2.0-77952716030 (Scopus ID)
Available from: 2010-08-13 Created: 2010-08-13 Last updated: 2018-01-12Bibliographically approved
Israelsson, S., Gullberg, M., Jonsson, N., Roivainen, M., Edman, K. & Lindberg, A. M. (2010). Studies of Echovirus 5 interactions with the cell surface: Heparan sulfate mediates attachment to the host cell.. Virus Research, 151(2), 170-176
Open this publication in new window or tab >>Studies of Echovirus 5 interactions with the cell surface: Heparan sulfate mediates attachment to the host cell.
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2010 (English)In: Virus Research, ISSN 0168-1702, E-ISSN 1872-7492, Vol. 151, no 2, p. 170-176Article in journal (Refereed) Published
Abstract [en]

Infections caused by Echovirus 5 (E5), an enterovirus of the Picornaviridae family, have been associated with fever, rashes and sporadic cases of aseptic meningitis. To elucidate the receptor usage of this virus, the significance of a previously proposed integrin binding arginine-glycine-aspartic acid (RGD) motif found in the VP3 capsid protein was investigated, as well as the capacity of E5 to interact with heparan sulfate on the cell surface. Using the prototype strain E5 Noyce (E5N), an E5N mutant where the aspartic acid of the RGD motif has been substituted to a glutamic acid and clinical E5 isolates, the RGD motif of VP3 was found to be non-essential and hence not involved in integrin receptor binding. However, E5N and clinical E5 isolates interact with heparan sulfate at the cell surface, as demonstrated by virus replication inhibition assays using heparin and heparinase III, and studies of E5 interactions at the cell surface measured by real-time PCR analysis. In conclusion, E5 utilizes heparan sulfate as a cellular receptor, but the RGD motif of VP3 is not essential for E5 infectivity.

National Category
Microbiology in the medical area
Research subject
Biomedical Sciences, Virology
Identifiers
urn:nbn:se:lnu:diva-7169 (URN)10.1016/j.virusres.2010.05.001 (DOI)20466025 (PubMedID)2-s2.0-77954219093 (Scopus ID)
Available from: 2010-08-13 Created: 2010-08-13 Last updated: 2018-01-12Bibliographically approved
Jonsson, N., Gullberg, M., Israelsson, S. & Lindberg, A. M. (2009). A rapid and efficient method for studies of virus interaction at the host cell surface using enteroviruses and real-time PCR. Virology Journal, 6(Article ID: 217)
Open this publication in new window or tab >>A rapid and efficient method for studies of virus interaction at the host cell surface using enteroviruses and real-time PCR
2009 (English)In: Virology Journal, ISSN 1743-422X, E-ISSN 1743-422X, Vol. 6, no Article ID: 217Article in journal (Refereed) Published
Abstract [en]

Background: Measuring virus attachment to host cells is of great importance when trying to identify novel receptors. The presence of a usable receptor is a major determinant of viral host range and cell tropism. Furthermore, identification of appropriate receptors is central for the understanding of viral pathogenesis and gives possibilities to develop antiviral drugs. Attachment is presently measured using radiolabeled and subsequently gradient purified viruses. Traditional methods are expensive and time-consuming and not all viruses are stable during a purification procedure; hence there is room for improvement. Real-time PCR (RT-PCR) has become the standard method to detect and quantify virus infections, including enteroviruses, in clinical samples. For instance, primers directed to the highly conserved 5' untranslated region (5'UTR) of the enterovirus genome enable detection of a wide spectrum of enteroviruses. Here, we evaluate the capacity of the RT-PCR technology to study enterovirus host cell interactions at the cell surface and compare this novel implementation with an established assay using radiolabeled viruses. Results: Both purified and crude viral extracts of CVB5 generated comparable results in attachment studies when analyzed with RT-PCR. In addition, receptor binding studies regarding viruses with coxsackie- nd adenovirus receptor (CAR) and/or decay accelerating factor (DAF) affinity, further demonstrated the possibility to use RT-PCR to measure virus attachment to host cells. Furthermore, the RT-PCR technology and crude viral extracts was used to study attachment with low multiplicity of infection (0.05 x 10(-4)TCID(50)/cell) and low cell numbers (250), which implies the range of potential implementations of the presented technique. Conclusion: We have implemented the well-established RT-PCR technique to measure viral attachment to host cells with high accuracy and reproducibility, at low cost and with less effort than traditional methods. Furthermore, replacing traditional methods with RT-PCR offers the opportunity to use crude virus containing extracts to investigate attachment, which could be considered as a step towards viral attachment studies in a more natural state.

National Category
Microbiology
Research subject
Biomedical Sciences, Virology; Natural Science, Microbiology; Natural Science, Biomedical Sciences
Identifiers
urn:nbn:se:lnu:diva-2142 (URN)10.1186/1743-422X-6-217 (DOI)000273070600001 ()
Available from: 2010-04-06 Created: 2010-04-06 Last updated: 2017-12-12Bibliographically approved
Johannesson, P., Israelsson, S., Edman, K. & Lindberg, A. M. (2005). A novel and rapid method to quantify cytolytic replication of picornaviruses in cell culture. Journal of virological methods, 130, 117-123
Open this publication in new window or tab >>A novel and rapid method to quantify cytolytic replication of picornaviruses in cell culture
2005 (English)In: Journal of virological methods, Vol. 130, p. 117-123Article in journal (Refereed) Published
Abstract [en]

Determining viral titers is a key issue in a wide variety of studies regarding different aspects of virology. The standard methods used for determining picornavirus titers are endpoint titration assay and plaque assay, both time consuming and laborious. The method described uses the tetrazolium salt MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium-bromide) that is reduced to formazane by cellular dehydrogenase, genes shown to be down-regulated during picornavirus infection. The amount formazane produced correlates with the viral titers obtained and can easily be measured using an ELISA plate reader. The colorimetric method has been evaluated using virus types from different genera of the Picornaviridae family. The MTT method reduces the time spent on determining the viral titers and still maintains a reliable accuracy.

National Category
Microbiology in the medical area
Research subject
Biomedical Sciences, Virology; Natural Science, Biomedical Sciences; Natural Science, Microbiology
Identifiers
urn:nbn:se:lnu:diva-564 (URN)10.1016/j.jviromet.2005.06.016 (DOI)
Available from: 2010-04-01 Created: 2010-04-01 Last updated: 2018-01-12Bibliographically approved
Israelsson, S., Bunse, C., Baltar, F., Bertos-Fortis, M., Fridolfsson, E., Legrand, C., . . . Pinhassi, J.Seasonal dynamics of Baltic Sea plankton activities: heterotrophic bacterial function under different biological and environmental conditions.
Open this publication in new window or tab >>Seasonal dynamics of Baltic Sea plankton activities: heterotrophic bacterial function under different biological and environmental conditions
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(English)Manuscript (preprint) (Other academic)
National Category
Microbiology Oceanography, Hydrology and Water Resources Environmental Sciences
Research subject
Ecology, Microbiology
Identifiers
urn:nbn:se:lnu:diva-69151 (URN)
Available from: 2017-12-11 Created: 2017-12-11 Last updated: 2018-02-26Bibliographically approved
Bunse, C., Lundin, D., Lindh, M. V., Sjöstedt, J., Israelsson, S., Martínez-García, S., . . . Pinhassi, J.Seasonality and co-occurrences of free-living Baltic Sea bacterioplankton.
Open this publication in new window or tab >>Seasonality and co-occurrences of free-living Baltic Sea bacterioplankton
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(English)Manuscript (preprint) (Other academic)
Keywords
seasonal succession, marine bacteria, amplicon 16S rRNA, microbial time series, highfrequency sampling
National Category
Environmental Sciences Microbiology Oceanography, Hydrology and Water Resources
Research subject
Ecology, Microbiology
Identifiers
urn:nbn:se:lnu:diva-69150 (URN)
Available from: 2017-12-11 Created: 2017-12-11 Last updated: 2019-02-27Bibliographically approved
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