| 1. |
- Bjerg, Anders, 1982, et al.
(författare)
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Increase in pollen sensitization in Swedish adults and protective effect of keeping animals in childhood
- 2016
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Ingår i: Clinical and Experimental Allergy. - : Wiley. - 0954-7894 .- 1365-2222. ; 46:10, s. 1328-1336
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: To date, most studies of the "allergy epidemic" have been based on self-reported data. There is still limited knowledge on time trends in allergic sensitization, especially among adults.OBJECTIVE: To study allergic sensitization, its risk factors, and time trends in prevalence.METHODS: Within West Sweden Asthma Study (WSAS) a population-based sample of 788 adults (17-60y) underwent skin prick tests (SPT) for 11 aeroallergens 2009-2012. Specific IgE was analyzed in 750 of the participants. Those aged 20-46y (n=379) were compared with the European Community Respiratory Health Survey sample aged 20-46y from the same area (n=591) in 1991-1992.RESULTS: Among those aged 20-46y the prevalence of positive SPT to pollen increased; timothy from 17.1% to 29.0% (p<0.001) and birch from 15.6% to 23.7% (p=0.002) between 1991-1992 and 2009-2012. Measurements of specific IgE confirmed these increases. Prevalence of sensitization to all other tested allergens was unchanged. In the full WSAS sample aged 17-60y any positive SPT was seen in 41.9%, and the dominating sensitizers were pollen (34.3%), animals (22.8%) and mites (12.6%). Pollen sensitization was strongly associated with rhinitis, whereas indoor allergens were more associated with asthma. Growing up with livestock or furred pets decreased the risk of sensitization, adjusted odds ratio 0.53 (0.28-0.995) and 0.68 (0.47-0.98) respectively.CONCLUSION: Pollen sensitization has increased in Swedish adults since the early 1990's, while the prevalence of sensitization to other allergens has remained unchanged. This is one plausible explanation for the increase in rhinitis 1990-2008 in Swedish adults, during which time the prevalence of asthma, which is more associated with perennial allergens, was stable. Contact with animals in childhood seems to reduce the risk of sensitization well into adulthood. One major factor contributing to the rise in pollen allergy is a significant increase in levels of birch and grass pollen over the past three decades.
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| 2. |
- Lagerqvist, Nina, 1979-, et al.
(författare)
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Characterisation of immune responses and protective efficacy in mice after immunisation with Rift Valley Fever virus cDNA constructs
- 2009
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Ingår i: Virology Journal. - 1743-422X. ; 6, s. 6-
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Affecting both livestock and humans, Rift Valley Fever is considered as one of the most important viral zoonoses in Africa. However, no licensed vaccines or effective treatments are yet available for human use. Naked DNA vaccines are an interesting approach since the virus is highly infectious and existing attenuated Rift Valley Fever virus vaccine strains display adverse effects in animal trials. In this study, gene-gun immunisations with cDNA encoding structural proteins of the Rift Valley Fever virus were evaluated in mice. The induced immune responses were analysed for the ability to protect mice against virus challenge. RESULTS: Immunisation with cDNA encoding the nucleocapsid protein induced strong humoral and lymphocyte proliferative immune responses, and virus neutralising antibodies were acquired after vaccination with cDNA encoding the glycoproteins. Even though complete protection was not achieved by genetic immunisation, four out of eight, and five out of eight mice vaccinated with cDNA encoding the nucleocapsid protein or the glycoproteins, respectively, displayed no clinical signs of infection after challenge. In contrast, all fourteen control animals displayed clinical manifestations of Rift Valley Fever after challenge. CONCLUSION: The appearance of Rift Valley Fever associated clinical signs were significantly decreased among the DNA vaccinated mice and further adjustment of this strategy may result in full protection against Rift Valley Fever.
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| 3. |
- Lwande, Olivia Wesula, et al.
(författare)
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Experimental Infection and Transmission Competence of Sindbis Virus in Culex torrentium and Culex pipiens Mosquitoes from Northern Sweden
- 2019
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Ingår i: Vector Borne and Zoonotic Diseases. - : Mary Ann Liebert. - 1530-3667 .- 1557-7759. ; 19:2, s. 128-133
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Sindbis virus (SINV) is a mosquito-borne Alphavirus known to infect birds and cause intermittent outbreaks among humans in Fenno-Scandia. In Sweden, the endemic area has mainly been in central Sweden. Recently, SINV infections have emerged to northern Sweden, but the vectorial efficiency for SINV of mosquito species in this northern region has not yet been ascertained.Objective: Mosquito larvae were sampled from the Umea region in northern Sweden and propagated in a laboratory to adult stage to investigate the infection, dissemination, and transmission efficiency of SINV in mosquitoes.Materials and Methods: The mosquito species were identified by DNA barcoding of the cytochrome oxidase I gene. Culex torrentium was the most abundant (82.2%) followed by Culex pipiens (14.4%), Aedes annulipes (1.1%), Anopheles claviger (1.1%), Culiseta bergrothi (1.1%), or other unidentified species (1.1%). Mosquitoes were fed with SINV-infected blood and monitored for 29 days to determine the viral extrinsic incubation period. Infection and dissemination were determined by RT-qPCR screening of dissected body parts of individual mosquitoes. Viral transmission was determined from saliva collected from individual mosquitoes at 7, 14, and 29 days. SINV was detected by cell culture using BHK-21 cells, RT-qPCR, and sequencing.Results: Cx. torrentium was the only mosquito species in our study that was able to transmit SINV. The overall transmission efficiency of SINV in Cx. torrentium was 6.8%. The rates of SINV infection, dissemination, and transmission in Cx. torrentium were 11%, 75%, and 83%, respectively.Conclusions: Cx. torrentium may be the key vector involved in SINV transmission in northern Sweden.
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| 4. |
- Lwande, Olivia Wesula, 1986-, et al.
(författare)
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Globe-Trotting Aedes aegypti and Aedes albopictus : Risk Factors for Arbovirus Pandemics
- 2020
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Ingår i: Vector Borne and Zoonotic Diseases. - : Mary Ann Liebert Inc. - 1530-3667 .- 1557-7759. ; 20:2, s. 71-81
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Two species of Aedes (Ae.) mosquitoes (Ae. aegypti and Ae. albopictus) are primary vectors for emerging arboviruses that are a significant threat to public health and economic burden worldwide. Distribution of these vectors and the associated arboviruses, such as dengue virus, chikungunya virus, yellow fever virus, and Zika virus, was for a long time restricted by geographical, ecological, and biological factors. Presently, arbovirus emergence and dispersion are more rapid and geographically widespread, largely due to expansion of the range for these two mosquitoes that have exploited the global transportation network, land perturbation, and failure to contain the mosquito population coupled with enhanced vector competence. Ae. aegypti and Ae. albopictus may also sustain transmission between humans without having to depend on their natural reservoir forest cycles due to arthropod adaptation to urbanization. Currently, there is no single strategy that is adequate to control these vectors, especially when managing arbovirus outbreaks. Objective: This review aimed at presenting the characteristics and abilities of Ae. aegypti and Ae. albopictus, which can drive a global public health risk, and suggests strategies for prevention and control. Methods: This review presents the geographic range, reproduction and ecology, vector competence, genetic evolution, and biological and chemical control of these two mosquito species and how they have changed and developed over time combined with factors that may drive pandemics and mitigation measures. Conclusion: We suggest that more efforts should be geared toward the development of a concerted multidisciplinary approach.
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| 5. |
- Näslund, Jonas, 1979-, et al.
(författare)
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Detection of Puumala and Rift Valley Fever virus by quantitative RT-PCR and virus viability tests in samples of blood dried and stored on filter paper
- 2011
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Ingår i: Journal of Virological Methods. - Amsterdam : Elsevier. - 0166-0934 .- 1879-0984. ; 178:1-2, s. 186-90
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Tidskriftsartikel (refereegranskat)abstract
- Haemorrhagic fever viruses cause emerging infections worldwide, and blood or serum is the main sample used for diagnosis. However, storage and transportation of such samples from remote areas to regional laboratories may be complicated and expensive. In this study, a novel approach was evaluated for the detection of Puumala hantavirus (PUUV) RNA and Rift Valley fever virus (RVFV) RNA. Whole-blood samples spiked with viable virus particles were tested in parallel with clinical samples from patients with acute haemorrhagic fever with renal syndrome (nephropathia epidemica). Individual blood samples were spotted on filter paper, dried, and used for RNA extraction at later time points. PUUV RNA was detected by RT-PCR after storage at room temperature for up to six weeks. In contrast, only low copy numbers of RVFV RNA were detected after 1-2 days even though viable RVFV was eluted from the dried filter papers after the same time. The use of filter paper to collect and store blood samples for PUUV RNA detection is therefore a simple and reliable procedure. This approach might facilitate sampling and analysis of other RNA viruses from human or animal sources and could be used for field studies in remote areas or in developing countries.
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| 6. |
- Näslund, Jonas, 1979-, et al.
(författare)
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Kinetics of Rift Valley fever virus in experimentally infected mice using quantitative real-time RT-PCR
- 2008
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Ingår i: Journal of Virological Methods. - : Elsevier BV. - 0166-0934 .- 1879-0984. ; 151:2, s. 277-282
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Tidskriftsartikel (refereegranskat)abstract
- Rift Valley Fever (RVF) is an important viral zoonosis in Africa affecting animals and humans. Since no protective vaccines or effective treatments are available for human use, accurate and reliable diagnostic methods are essential for surveillance of the disease in order to implement adequate public health actions. To study the kinetics of the RVF Virus (RVFV) infection, a SYBR Green-based quantitative real-time RT-PCR assay was developed. By using primers targeting the S-segment of RVFV, the detection limit of this assay was estimated to 30 RNA templates. Blood and organs of experimentally infected mice were sampled at different time points and RVFV RNA was quantified. High amounts of RVFV RNA were found in blood, brain, and liver samples shortly after infection with a 1-4 days post infection window for viral RNA detection. Mice developed symptoms after the appearance of serum antibodies, indicating that the host response plays an important role in the outcome of the disease. The RVFV quantitative RT-PCR proved to be a valuable diagnostic tool during the first days of infection, before detectable antibody levels and visual symptoms of RVF were observed.
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| 7. |
- Näslund, Jonas, 1979-, et al.
(författare)
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PCR detection of a hantavirus and Rift Valley fever virus using dried whole blood spotted on filter strips
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Viral hemorrhagic fevers are serious and emerging infections among humans and animals worldwide. Presently, blood or serum samples are the main source for diagnostics. However, transportation of such samples from remote areas may be complicated and expensive. Previously, filter strips soaked with blood have been used for detection of antibodies for diagnostics and epidemiological studies of several infectious diseases. In this study we evaluate if a similar approach could be applied for detection of viral RNA of Rift Valley Fever virus or Hantavirus (Puumala). We have used whole blood spiked with known amounts of viruses. In addition, clinical samples from patients with acute hemorrhagic fever with renal syndrome have been analysed. The samples were collected on filter strips and dried before RNA was extracted at different time-points. For Puumala, the sensitivity was acceptable, although the absolute levels of viral RNA were found to be considerable lower when using filter strips. The viral RNA could be detected and analysed after 2-3 weeks storage of the dried filter strips. In contrast, for RVFV, no or very low copy numbers of viral RNA were detected. Still, RVFV filter strips contained viable virus particles up to 48 h of storage. In conclusion, the use of dried whole blood samples spotted on filter strips for the detection of viral RNA seems to be a reliable and simple procedure for Hantaviruses. This procedure could be useful in field studies, especially in remote areas or low-income countries where transportation and storage of biological samples might be complicated. However, the result for RVFV was unexpected and further studies are needed to improve this technique.
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| 8. |
- Näslund, Jonas, 1979-
(författare)
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Rift Valley fever : development of diagnostics and vaccines
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Rift Valley Fever virus (RVFV) causes an infection with severe impact on animal and human health. The disease is endemic throughout almost the entire African continent and large regions of the Arabian Peninsula. During epidemics, high mortality is observed in animals, especially among cattle, goats, and sheep. In humans, the symptoms vary from a benign influenza-like disease to a life-threatening hemorrhagic fever. Due to the devastating effect on communities in endemic regions and the possibility of further spread of this virus, there is an imperative need to improve and develop control measurements against this emerging disease. Therefore, this thesis focuses on diagnostics and vaccines against RVFV. RVFV infection kinetics was studied in a mouse model system by detection and quantification of viral genomes, using a developed quantitative real-time PCR (QRT-PCR) method. This novel QRT-PCR method proved to be reliable and serves as a supplement to standard diagnostics, direct virus isolation and serological methods. High levels of viral RNA were found in blood and liver samples from experimentally infected mice during the first days post infection. Thereafter the levels declined rapidly and dropped below detection limit approximately seven days post infection. The QRT-PCR technique was also used in a study aimed to improve diagnosis of RVFV from field samples collected on filter strips. Today, the available RVFV vaccines are only approved for animal use and these vaccines have several shortcomings. Since RVFV is a highly pathogenic organism requiring bio-safety level 3 laboratories, two different none-replicating vaccine approaches have been applied and evaluated using a mouse model. A DNA based vaccine, administered via gene-gun, and the use of virus-like particles (VLP), by the intra-peritoneal route. RVFV specific and neutralising antibodies were raised with both vaccine approaches. However, VLP vaccination against Rift valley Fever proved to be more promising as a future vaccine, since higher titres of neutralising antibodies and improved survival rate were found upon a lethal RVFV challenge in mice. In conclusion, a sensitive and specific method for quantifying RVFV infection and a promising vaccine candidate against RVFV were developed.
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| 9. |
- Näslund, Jonas, 1979-, et al.
(författare)
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Vaccination with virus-like particles protects mice from lethal infection of Rift Valley fever virus
- 2009
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Ingår i: Virology. - : Elsevier BV. - 0042-6822 .- 1096-0341. ; 385:2, s. 409-415
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Tidskriftsartikel (refereegranskat)abstract
- Rift Valley Fever virus (RVFV) regularly accounts for severe and often lethal outbreaks among livestock and humans in Africa. Safe and effective veterinarian and human vaccines are highly needed. We present evidence that administration of RVF virus-like particles (VLPs) induces protective immunity in mice. In an accompanying paper, (Habjan, M., Penski, N., Wagner, V., Spiegel, M., Overby, A.K., Kochs, G., Huiskonen, J., Weber, F., 2009. Efficient production of Rift Valley fever virus-like particles: the antiviral protein MxA can inhibit primary transcription of Bunyaviruses. Virology 385, 400-408) we report the production of these VLPs in mammalian cells. After three subsequent immunizations with 1x10(6) VLPs/dose, high titers of virus-neutralizing antibodies were detected; 11 out of 12 mice were protected from challenge and only 1 out of 12 mice survived infection in the control groups. VLP vaccination efficiently suppressed replication of the challenge virus, whereas in the control animals high RNA levels and increasing antibody titers against the nucleocapsid protein indicated extensive viral replication. Our study demonstrates that the RVF VLPs are highly immunogenic and confer protection against RVFV infection in mice. In the test groups, the vaccinated mice did not exhibit any side effects, and the lack of anti-nucleocapsid protein antibodies serologically distinguished vaccinated animals from experimentally infected animals.
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