Publications
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Kloster, Hanne; Stormo, Camilla; Jenkins, Andrew; Soleng, Arnulf; Andreassen, Åshild Kristine & Kjelland, Vivian
(2026).
Distribution of Rickettsia spp. and Bartonella spp. in questing Ixodes ricinus ticks in Norway.
International Journal for Parasitology: Parasites and Wildlife.
31.
doi:
10.1016/j.ijppaw.2026.101271.
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Ticks are important vectors of zoonotic pathogens in Europe, but knowledge regarding the presence of Rickettsia spp. and Bartonella spp. in questing Ixodes ricinus in Norway remains limited. This study investigated the occurrence of these bacteria in ticks collected across the Norwegian distribution range of I. ricinus.
A total of 564 adult ticks and 3930 nymphs (393 pools) collected in seven counties were analysed by real-time PCR. Rickettsia spp. were detected only in adult ticks, with an overall prevalence of 3.9 % (22/564). Infected ticks were identified in only two counties, Østfold and Agder, with a prevalence of 11.2 and 10.9 %, respectively. Species-specific analysis confirmed R. helvetica in 77.3 % (17/22) of the positive samples. Rickettsia spp. were not detected in any nymph pools. Bartonella spp. were detected in 0.5 % (3/564) of adult ticks, representing the first report of Bartonella spp. in questing I. ricinus in Norway. Infected ticks were found in three counties, Østfold, Telemark, and Nordland. Bartonella spp. were not detected in any nymph pools.
These findings demonstrate that Rickettsia spp. and Bartonella spp. are present in questing adult ticks in Norway, highlighting the importance of continued surveillance of emerging tick-borne pathogens in northern Europe.
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Kloster, Hanne; Stormo, Camilla; Haaland, Anita Haug; Okstad, Wenche; Andreassen, Åshild Kristine & Stuen, Snorre
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(2026).
Antibodies against tick-borne pathogens in domestic dogs in Norway: Borrelia burgdorferi sensu lato, tick-borne encephalitis virus, and Anaplasma phagocytophilum.
Acta Veterinaria Scandinavica (AVS).
ISSN 0044-605X.
68.
doi:
10.1186/s13028-026-00863-8.
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Background Ticks are important vectors of zoonotic pathogens, posing a growing threat to animals and humans in Europe. In Norway, the tick species Ixodes ricinus is expanding its range, increasing the risk of tick-borne infections. This study aimed to estimate the seroprevalence of IgG antibodies against Borrelia burgdorferi sensu lato (s. l.), tick-borne encephalitis virus (TBEV), and Anaplasma phagocytophilum in domestic dogs residing in Norway, and to assess their potential role as sentinel species for tick-borne pathogen surveillance at the northernmost limit of I. ricinus’ geographical range. Serum samples (n = 433) from domestic dogs were collected across 15 counties between 2016 and 2023 and analysed using immunoblot assays. Results Overall, 38% of the dogs were seropositive for one or more tick-borne pathogens. The seroprevalence was 20% for B. burgdorferi s. l., 19% for TBEV, and 11% for A. phagocytophilum. Statistically significant regional differences were observed for the latter two pathogens. Conclusions The findings indicated widespread exposure of Norwegian dogs to tick-borne pathogens and support their role as sentinel species for assessing human risk. Continued surveillance and preventive measures are recommended to reduce tick infestation and pathogen transmission to both dogs and humans.
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Kloster, Hanne; Stormo, Camilla; Haaland, Anita Haug; Stuen, Snorre & Kjelland, Vivian
(2025).
Seroprevalence of IgG Antibodies Against Borrelia burgdorferi Sensu Lato, Anaplasma phagocytophilum, and Tick-Borne Encephalitis (TBE) Virus in Horses in Southern Norway.
Microorganisms.
13(4).
doi:
10.3390/microorganisms13040771.
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Ixodes ricinus ticks play a crucial role as carriers of diseases, transmitting pathogens to vertebrate hosts, including horses. This study aimed to investigate the seroprevalence of IgG antibodies against Borrelia burgdorferi sensu lato (s. l.), Anaplasma phagocytophilum, and tick-borne encephalitis virus (TBE-virus) in equine sera collected in southern Norway. In total, sera from 331 horses stabled in four counties (Agder, Vestfold and Telemark, Vestland, and Viken) were analyzed by immunoblot. In total, 66% of the horses were IgG-seropositive for antibodies against one or multiple tick-borne pathogens. The highest seroprevalence was detected against B. burgdorferi s. l. (47%), followed by A. phagocytophilum (34%) and TBE-virus (10%). A significant difference between the counties regarding IgG antibodies against A. phagocytophilum was found, with the highest seroprevalence in horses stabled in the coastal areas of Agder and Vestland. In conclusion, the study demonstrates that horses in southern Norway are at high risk of contracting tick-borne infections.
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Kringen, Marianne K.; Stormo, Camilla; Berg, Jens Petter; Terry, Sharon F.; Vocke, Christine M. & Rizvi, Samar
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(2015).
Copy number variation in the ATP-binding cassette transporter ABCC6 gene and ABCC6 pseudogenes in patients with pseudoxanthoma elasticum.
Molecular Genetics & Genomic Medicine.
ISSN 2324-9269.
3(3),
p. 233–237.
doi:
10.1002/mgg3.137.
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Single mutations in the ATP-binding cassette transporter (ABCC6) gene (OMIM 603234) are known to cause the rare autosomal recessive disease pseudoxanthoma elasticum (PXE). Recently, we have found that copy number variations (CNVs) in pseudogenes of the ABCC6 gene are quite common. The aim of this study was to investigate the frequency and possible contribution of CNV in ABCC6 and its pseudogenes in PXE. Genomic DNA from 212 PXE individuals were examined for copy number by pyrosequencing and quantitative polymerase chain reaction (PCR) and compared with healthy individuals. The frequency of PXE individuals with any CNV was higher than in healthy individuals. The majority of variation comprised known and possibly new deletions in the ABCC6 gene and duplications of the ABCC6P1 and ABCC6P2 genes. ABCC6 deletions and ABCC6P2 duplications were not observed in 142 healthy individuals. In conclusion, by pyrosequencing and quantitative PCR, we were able to detect known and possibly new deletions in the ABCC6 gene that may have caused the PXE phenotype. Pyrosequencing may be used in PXE patients who have obtained incomplete genotype from conventional techniques. The frequency of ABCC6P2 pseudogene duplication was more common in PXE patients than healthy individuals and may affect the PXE phenotype.
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Stormo, Camilla; Kristiansen, Marianne; Lyle, Robert; Olstad, Ole Kristoffer; Sachse, Daniel & Berg, Jens Petter
[Show all 7 contributors for this article]
(2014).
RNA-sequencing analysis of HepG2 cells treated with atorvastatin.
PLOS ONE.
9:e0105836(8).
doi:
10.1371/journal.pone.0105836.
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The cholesterol-lowering drug atorvastatin is among the most prescribed drug in the world. Alternative splicing in a number of genes has been reported to be associated with variable statin response. RNA-seq has proven to be a powerful technique for genome-wide splice variant analysis. In the present study, we sought to investigate atorvastatin responsive splice variants in HepG2 cells using RNA-seq analysis to identify novel candidate genes implicated in cholesterol homeostasis and in the statin response. HepG2 cells were treated with 10 µM atorvastatin for 24 hours. RNA-seq and exon array analyses were performed. The validation of selected genes was performed using Taqman gene expression assays. RNA-seq analysis identified 121 genes and 98 specific splice variants, of which four were minor splice variants to be differentially expressed, 11 were genes with potential changes in their splicing patterns (SYCP3, ZNF195, ZNF674, MYD88, WHSC1, KIF16B, ZNF92, AGER, FCHO1, SLC6A12 and AKAP9), and one was a gene (RAP1GAP) with differential promoter usage. The IL21R transcript was detected to be differentially expressed via RNA-seq and RT-qPCR, but not in the exon array. In conclusion, several novel candidate genes that are affected by atorvastatin treatment were identified in this study. Further studies are needed to determine the biological significance of the atorvastatin responsive splice variants that have been uniquely identified using RNA-seq.
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Kristiansen, Marianne; Stormo, Camilla; Grimholt, Runa Marie; Berg, Jens Petter & Piehler, Armin
(2012).
Copy number variations of the ATP-binding cassette transporter ABCC6 gene and its pseudogenes.
BMC Research Notes.
5.
doi:
10.1186/1756-0500-5-425.
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Background The ATP-binding cassette transporter ABCC6 gene is located on chromosome 16 between its two pseudogenes (ABCC6P1 and ABCC6P2). Previously, we have shown that ABCC6P1 is transcribed and affects ABCC6 at the transcriptional level. In this study we aimed to determine copy number variations of ABCC6, ABCC6P1 and ABCC6P2 in different populations. Moreover, we sought to study the transcription pattern of ABCC6 and ABCC6 pseudogenes in 39 different human tissues. Findings Genomic DNA from healthy individuals from five populations, Chinese (n = 24), Middle East (n = 20), Mexicans (n = 24), Caucasians (n = 50) and Africans (n = 24), were examined for copy number variations of ABCC6 and its pseudogenes by pyrosequencing and quantitative PCR. Copy number variation of ABCC6 was very rare (2/142; 1.4%). However, one or three copies of ABCC6P1 were relatively common (3% and 8%, respectively). Only one person had a single copy of ABCC6P2 while none had three copies. In Chinese, deletions or duplications of ABCC6P1 were more frequent than in any other population (9/24; 37.5%). The transcription pattern of ABCC6P2 was highly similar to ABCC6 and ABCC6P1, with highest transcription in liver and kidney. Interestingly, the total transcription level of pseudogenes, ABCC6P1 + ABCC6P2, was higher than ABCC6 in most tissues, including liver and kidney. Conclusions Copy number variations of the ABCC6 pseudogenes are quite common, especially in populations of Chinese ancestry. The expression pattern of ABCC6P2 in 39 human tissues was highly similar to that of ABCC6 and ABCC6P1 suggesting similar regulatory mechanisms for ABCC6 and its pseudogenes.
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Stormo, Camilla; Kristiansen, Marianne; Grimholt, Runa Marie; Berg, Jens Petter & Piehler, Armin
(2012).
A novel 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) splice variant with an alternative exon 1 potentially encoding an extended N-terminus.
BMC Molecular Biology.
13.
doi:
10.1186/1471-2199-13-29.
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Background The major rate-limiting enzyme for de novo cholesterol synthesis is 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR). HMGCR is sterically inhibited by statins, the most commonly prescribed drugs for the prevention of cardiovascular events. Alternative splicing of HMGCR has been implicated in the control of cholesterol homeostasis. The aim of this study was to identify novel alternatively spliced variants of HMGCR with potential physiological importance. Results Bioinformatic analyses predicted three novel HMGCR transcripts containing an alternative exon 1 (HMGCR-1b, -1c, -1d) compared with the canonical transcript (HMGCR-1a). The open reading frame of the HMGCR-1b transcript potentially encodes 20 additional amino acids at the N-terminus, compared with HMGCR-1a. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) was used to examine the mRNA levels of HMGCR in different tissues; HMGCR-1a was the most highly expressed variant in most tissues, with the exception of the skin, esophagus, and uterine cervix, in which HMGCR-1b was the most highly expressed transcript. Atorvastatin treatment of HepG2 cells resulted in increased HMGCR-1b mRNA levels, but unaltered proximal promoter activity compared to untreated cells. In contrast, HMGCR-1c showed a more restricted transcription pattern, but was also induced by atorvastatin treatment. Conclusions The gene encoding HMGCR uses alternative, mutually exclusive exon 1 sequences. This contributes to an increased complexity of HMGCR transcripts. Further studies are needed to investigate whether HMGCR splice variants identified in this study are physiologically functional.
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Kloster, Hanne; Nordli, Ine Emilie Olsen; Kjelland, Vivian & Stormo, Camilla
(2024).
Har årets harde vinter tatt knekken på flåtten? - fvn.no.
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Årets sørlandsvinter har vært preget av sprengkulde og meterhøy snø. Det er nok mange som ønsker at flåtten har strøket med under disse omstendighetene, men det korte svaret på spørsmålet er: Nei, de fleste flått har nok klart seg helt fint.
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Kvissel, Anne Katrine; Stormo, Camilla & Engeset, Dagrun
(2023).
Seminal microbiome. Method optimization for nanopore sequencing jn seminal fluid. A pilot study.
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Published
Apr. 16, 2024 11:29 AM
