| 1. |
- Holmberg, Rebecka, et al.
(författare)
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Antiviral treatments reduce severity of diabetes in Ljungan virus-infected CD-1 mice and delay onset in diabetes-prone BB rats
- 2009
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Ingår i: Microbiology and immunology. - : Wiley. - 0385-5600 .- 1348-0421. ; 53:10, s. 567-572
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Tidskriftsartikel (refereegranskat)abstract
- The effects of LV in two different species, CD-1 mice, without a genetic disposition for diabetes, and BB rats prone to T1D were examined. Male CD-1 mice that had been exposed to LV in utero developed a type 2-like diabetes with increased blood glucose, insulin levels and epididymal fat at the age of 10-15 weeks. Combination therapy including LV-antiserum and an antiviral drug, Pleconaril, significantly reduced the levels of blood glucose and insulin and the amount of abdominal fat. In BB rats, LV has been found in both prediabetic- and diabetic diabetes-prone rats, as well as in diabetes-resistant rats. To evaluate whether the presence of LV has any influence on the onset of T1D, prediabetic BB rats were treated with an antiserum against LV or a combination of the antiviral drugs Pleconaril and Ribavirin. In the group treated with antiviral drugs, the onset was significantly delayed. These results indicate that the presence of LV can be involved in the pathogenesis of diabetes in these animal models.
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| 2. |
- Niklasson, Bo, et al.
(författare)
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Association of zoonotic Ljungan virus with intrauterine fetal deaths
- 2007
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Ingår i: Birth defects research. Clinical and molecular teratology. - : Wiley. - 1542-0752 .- 1542-0760. ; 79, s. 488-493
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: It has recently been shown that Ljungan virus (LV) is associated with disease in its wild rodent reservoir. In addition, it has been demonstrated that LV causes malformations and perinatal death in a mouse model. The question was therefore raised whether LV is a zoonotic agent in humans. METHODS: Population fluctuations of native rodents in Sweden were compared to the incidence of intrauterine fetal deaths (IUFDs) using the Swedish national hospitalization database. Formalin-fixed tissues from cases of IUFD were investigated using LV-specific immunohistochemistry. RESULTS: Variation in the incidence of IU-FDs closely tracked the fluctuations in native rodent populations. LV was detected in the brain tissue in 4 of 10 cases of IUFDs investigated by immunochemistry. LV was also detected in the placenta in 5 of the 10 IUFD cases, but in none of 20 placentas from normal pregnancies. CONCLUSIONS: LV may play an important role in IUFDs.
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| 3. |
- Niklasson, Bo, et al.
(författare)
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Diabetes and myocarditis in voles and lemmings at cyclic peak densities--induced by Ljungan virus?
- 2006
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Ingår i: Oecologia. - : Springer Science and Business Media LLC. - 0029-8549 .- 1432-1939. ; 150:1, s. 1-7
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Tidskriftsartikel (refereegranskat)abstract
- Although it is well-documented from theoretical studies that pathogens have the capacity to generate cycles, the occurrence and role of pathogens and disease have been poorly empirically studied in cyclic voles and lemmings. In screening for the occurrence of disease in cyclic vole and lemming populations, we found that a high proportion of live-trapped Clethrionomys glareolus, C. rufocanus, Microtus agrestis and Lemmus lemmus at high collective peak density, shortly before the decline, suffered from diabetes or myocarditis in northern Scandinavia. A high frequency of animals had abnormal blood glucose (BG) levels at the time of trapping (5-33%). In contrast, C. rufocanus individuals tested at a much lower overall density, and at an earlier stage relative to the decline in the following cycle, showed normal BG concentrations. However, a high proportion (43%) of a sample of these individuals kept in captivity developed clinical diabetes within five weeks, as determined by BG levels and a glucose tolerance test performed at that later time. A new picornavirus isolated from the rodents, Ljungan virus (LV), was assumed to cause the diseases, as LV-induced diabetes and myocarditis, as well as encephalitis and fetal deaths, were observed in laboratory mice. We hypothesize that LV infection significantly affects morbidity and mortality rates in the wild, either directly or indirectly, by predisposing the rodents to predation, and is at least involved in causing the regular, rapid population declines of these cyclic voles and lemmings. Increased stress at peak densities is thought to be an important trigger for the development of disease, as the occurrence of disease in laboratory mice has been found to be triggered by introducing stress to LV-infected animals.
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| 4. |
- Niklasson, Bo, et al.
(författare)
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Diabetes Prevention Through Antiviral Treatment in Biobreeding Rats
- 2016
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Ingår i: Viral immunology. - : Mary Ann Liebert Inc. - 0882-8245 .- 1557-8976. ; 29:8, s. 452-458
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Tidskriftsartikel (refereegranskat)abstract
- A picornavirus (Ljungan virus) has been associated with diabetes in its wild rodent reservoir and in diabetesprone biobreeding (DP-BB) rats. We attempted to alter the development of diabetes in DP-BB rats using two anti-picornavirus compounds (pleconaril and APO-N039), singly or in combination. Antiviral therapy was initiated 2 weeks before expected onset of diabetes. Pleconaril or APO-N039 alone did not affect the debut of diabetes. However, animals receiving a combination of both compounds were protected for at least the entire period of treatment (4 weeks after expected time of diabetes onset). Immunohistochemistry demonstrated that the presence and distribution of virus antigen in the pancreatic islets coincided with the clinical status of the animal. Data indicate that a treatable picornavirus can be involved in the cellular assault resulting in diabetes and in these cases the disease mechanism appears to involve a virus present in the pancreatic beta cell mass itself.
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| 5. |
- Niklasson, Bo, et al.
(författare)
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Picornavirus May Be Linked to Parkinson’s Disease through Viral Antigen in Dopamine-Containing Neurons of Substantia Nigra
- 2022
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Ingår i: Microorganisms. - : MDPI AG. - 2076-2607. ; 10:3
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Tidskriftsartikel (refereegranskat)abstract
- Parkinson’s disease (PD) is a neurodegenerative disease linked with the loss of dopaminer-gic neurons in the brain region called substantia nigra and caused by unknown pathogenic mecha-nisms. Two currently recognized prominent features of PD are an inflammatory response manifested by glial reaction and T-cell infiltration, as well as the presence of various toxic mediators derived from activated glial cells. PD or parkinsonism has been described after infection with several different viruses and it has therefore been hypothesized that a viral infection might play a role in the pathogen-esis of the disease. We investigated formalin-fixed post-mortem brain tissue from 9 patients with Parkinson’s disease and 11 controls for the presence of Ljungan virus (LV) antigen using a polyclonal antibody against the capsid protein of this recently identified picornavirus with neurotropic proper-ties, suspected of being both a human and an animal pathogen. Evidence of viral antigen was found in 7 out of 9 Parkinson’s disease cases and in only 1 out of 11 controls (p = 0.005). The picornavirus antigen was present in dopamine-containing neurons of the substantia nigra. We propose that LV or an LV-related virus initiates the pathological process underlying sporadic PD. LV-related picornavirus antigen has also been reported in patients with Alzheimer’s disease. Potentially successful antiviral treatment in Alzheimer’s disease suggests a similar treatment for Parkinson's disease. Amanta-dine, originally developed as an antiviral drug against influenza infection, has also been used for symptomatic treatment of patients with PD for more than 50 years and is still commonly used by neurologists today. The fact that amantadine also has an antiviral effect on picornaviruses opens the question of this drug being re-evaluated as potential PD therapy in combination with other antiviral compounds directed against picornaviruses.
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| 6. |
- Niklasson, Bo, et al.
(författare)
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Prenatal viral exposure followed by adult stress produces glucose intolerance in a mouse model
- 2006
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Ingår i: Diabetologia. - : Springer Science and Business Media LLC. - 0012-186X .- 1432-0428. ; 49:9, s. 2192-2199
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Tidskriftsartikel (refereegranskat)abstract
- Aims/hypothesis: It has been suggested that the uterine environment may influence metabolic disease occurring later in adult life, and that adult stress may promote disease outcome. Using a mouse model, we tested whether in utero exposure to Ljungan virus (LV) followed by adult exposure to stress produces diabetes. The influence of the timing of viral exposure over the course of pregnancy was also tested. Materials and methods: Pregnant CD-1 mice were exposed i.p. to LV on pregnancy days 4, 8, 12 or 17. Adult male mice from these pregnancies were stressed by being kept in shared cages. Stress only, LV exposure in utero only, and no-stress/no virus exposure groups were also followed. Outcome variables included bodyweight, epididymal fat weight, baseline glucose, glucose tolerance tests (60 and 120 min) and serum insulin. Results: We demonstrated that male mice developed a type 2-like diabetes, including obesity, as adults if infected during pregnancy with LV. Diabetes at the age of 11 weeks was more severe in mice whose mothers were infected earlier than in those whose mothers were infected later in pregnancy. Only animals infected in utero and kept under stress developed diabetes; infection or stress alone did not cause disease. Conclusions/interpretation: This work demonstrates that a type 2 diabetes-like disease can be virus-induced in a mouse model. Early in utero viral insults can set the stage for disease occurring during adult life, but the final manifestation of diabetes is dependent on the combination of early viral exposure and stress in adult life.
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| 7. |
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| 8. |
- Niklasson, Bo, et al.
(författare)
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Zoonotic Ljungan Virus Associated with Central Nervous System Malformations in Terminated Pregnancy
- 2009
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Ingår i: Birth defects research. Clinical and molecular teratology. - : Wiley. - 1542-0752 .- 1542-0760. ; 85:6, s. 542-545
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The Ljungan virus (LV) has been shown to cause central nervous system malformations in laboratory mouse models. The LV has also been associated with intrauterine fetal death in humans. We investigated the presence of LV in a series of human hydrocephaly and anencephaly cases from elective abortions. METHODS: A series of elective abortions owing to hydrocephaly, anencephaly, and similarly aged trisomy 21 elective abortions as controls were examined for LV by immunohistochemistry and real time RTPCR. A second experiment involved newborn mice exposed to LV. RESULTS: LV was diagnosed in 9 of 10 cases with hydrocephalus and in I of 18 trisomy 21 controls by immunohistochemistry. Five of nine cases with anencephaly had a positive PCR result, whereas none of the 12 trisomy 21 available for PCR testing had a positive result. The 47 newborn mice exposed to LV all developed encephalitis, with eight having hydrocephalus. None of the 52 control animals had encephalitis or hydrocephalus. CONCLUSION: The association between LV and both hydrocephaly and anencephaly suggests that LV may be playing an important role in central nervous system malformations in humans. Birth Defects Research (Part A) 85:542-545, 2009, (C) 2009 Wiley-Liss, Inc.
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| 9. |
- Samsioe, Annika, et al.
(författare)
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Fetal Death Persists Through Recurrent Pregnancies in Mice Following Ljungan Virus Infection
- 2008
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Ingår i: Birth defects research. Part B. Developmental and reproductice toxicology. - : Wiley. - 1542-9733 .- 1542-9741. ; 83:5, s. 507-510
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: Laboratory mice infected with Ljungan virus (LV) early in pregnancy suffer from perinatal death. Here we investigate the persistence of that effect through the outcome of consecutive pregnancies in LV-infected mice. STUDY DESIGN: CD-1 mice were infected while pregnant and their adult female offspring were followed in parallel with uninfected control mice during repeated pregnancies. Three mating attempts resulted in two or three pregnancies per dam. The outcome of the last pregnancy was carefully monitored. RESULTS: Both the dams infected as adults and their adult female offspring suffered perinatal deaths during the last pregnancy which occurred approximately 6 months after the original LV exposure and acute infection. The non-infected control animals experienced no perinatal death. CONCLUSIONS: Perinatal death persists across recurrent pregnancies in this mouse model of LV infection, both in animals infected as adults and in females exposed to the virus in utero. This implies that LV persists in mice long after intial infection, and is maintained in a quiescent state but can remain pathogenic in later pregnancies. Birth Defects Res (Part B) 83:507-510, 2008.
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| 10. |
- Samsioe, Annika, et al.
(författare)
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Intrauterine death, fetal malformation, and delayed pregnancy in Ljungan virus-infected mice
- 2006
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Ingår i: Birth defects research. Part B. Developmental and reproductice toxicology. - : Wiley. - 1542-9733 .- 1542-9741. ; 77:4, s. 251-256
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: A picornavirus (Ljunganvirus [LV]) has recently been associated with disease during pregnancy in its natural rodent reservoir and in humans. A study of laboratory mice infected under controlled conditions was therefore undertaken. METHODS: CD-1 female mice were infected gestational day two and subjected to varying regimes of stress. RESULTS: LV infection in combination with stress resulted in uterine resorptions, malformations, and neonatal death. A short delay in time to first pregnancy and births was observed in pairs infected in utero. CONCLUSIONS: LV is found in different species of native animals in both Europe and the United States and human epidemiological evidence connects LV and human reproduction, while the observations here indicate that LV is responsible for reproductive problems in a laboratory mouse model. The current findings suggest that the hypothesis that LV also causes disease in pregnant women and their offspring deserves further study.
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