| 1. |
- Grahn, Anna, 1973, et al.
(författare)
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Imported case of lassa fever in Sweden with encephalopathy and sensorineural hearing deficit
- 2016
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Ingår i: Open Forum Infectious Diseases. - : Oxford University Press (OUP). - 2328-8957. ; 3:4
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Tidskriftsartikel (refereegranskat)abstract
- © The Author 2016.We describe an imported case of Lassa fever with both encephalopathy and bilateral sensorineural hearing deficit. Absence of fever during hospitalization, initially nonspecific symptoms, and onset of hearing deficit in a late stage of disease probably contributed to delayed diagnosis (14 days after admittance to hospital). The pathogenesis of neurological manifestations of Lassa fever is poorly understood and no specific treatment was given. A total of 118 personnel had close contact with the patient, but no secondary cases occurred. This case highlights the importance of considering Lassa fever as a differential diagnosis in patients with recent travel to endemic areas.
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| 2. |
- Hinkula, Jorma, et al.
(författare)
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Immunization with DNA Plasmids Coding for Crimean-Congo Hemorrhagic Fever Virus Capsid and Envelope Proteins and/or Virus-Like Particles Induces Protection and Survival in Challenged Mice
- 2017
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Ingår i: Journal of Virology. - : AMER SOC MICROBIOLOGY. - 0022-538X .- 1098-5514. ; 91:10
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Tidskriftsartikel (refereegranskat)abstract
- Crimean-Congo hemorrhagic fever virus (CCHFV) is a bunyavirus causing severe hemorrhagic fever disease in humans, with high mortality rates. The requirement of a high-containment laboratory and the lack of an animal model hampered the study of the immune response and protection of vaccine candidates. Using the recently developed interferon alpha receptor knockout (IFNAR(- / -)) mouse model, which replicates human disease, we investigated the immunogenicity and protection of two novel CCHFV vaccine candidates: a DNA vaccine encoding a ubiquitin-linked version of CCHFV Gc, Gn, and N and one using transcriptionally competent virus-like particles (tc-VLPs). In contrast to most studies that focus on neutralizing antibodies, we measured both humoral and cellular immune responses. We demonstrated a clear and 100% efficient preventive immunity against lethal CCHFV challenge with the DNA vaccine. Interestingly, there was no correlation with the neutralizing antibody titers alone, which were higher in the tc-VLP-vaccinated mice. However, the animals with a lower neutralizing titer, but a dominant cell-mediated Th1 response and a balanced Th2 response, resisted the CCHFV challenge. Moreover, we found that in challenged mice with a Th1 response (immunized by DNA/DNA and boosted by tc-VLPs), the immune response changed to Th2 at day 9 postchallenge. In addition, we were able to identify new linear B-cell epitope regions that are highly conserved between CCHFV strains. Altogether, our results suggest that a predominantly Th1-type immune response provides the most efficient protective immunity against CCHFV challenge. However, we cannot exclude the importance of the neutralizing antibodies as the surviving immunized mice exhibited substantial amounts of them. IMPORTANCE Crimean-Congo hemorrhagic fever virus (CCHFV) is responsible for hemorrhagic diseases in humans, with a high mortality rate. There is no FDAapproved vaccine, and there are still gaps in our knowledge of the immune responses to infection. The recently developed mouse models mimic human CCHF disease and are useful to study the immunogenicity and the protection by vaccine candidates. Our study shows that mice vaccinated with a specific DNA vaccine were fully protected. Importantly, we show that neutralizing antibodies are not sufficient for protection against CCHFV challenge but that an extra Th1-specific cellular response is required. Moreover, we describe the identification of five conserved B-cell epitopes, of which only one was previously known, that could be of great importance for the development of diagnostics tools and the improvement of vaccine candidates.
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| 3. |
- Karlberg, Helen
(författare)
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Crimean-Congo hemorragic fever virus : studies on molecular pathogenesis and host-cell interactions
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Crimean-Congo haemorrhagic fever (CCHF) disease in humans shows a spectrum of severity, from mild to acute. The pathogenesis of this and other viral haemorrhagic fevers (VHF) is associated with alteration of vascular barrier function and haemorrhage, but the specific underlying mechanism is unknown. This thesis examines the progression of the disease, in particular virus-host cell interactions and how CCHFV modulates the function of both Type I IFN response and apoptotic pathways. Programmed cell death and regulation of apoptosis in response to viral infection is an important factor for host or virus survival. In order to establish viral infection and to keep the virus contagious, it is also important to evade antiviral responses such as Type I IFN response. An initial study showed that replicating CCHFV delays the Type I IFN response, possibly by interfering with the activation pathway of IRF-3. A second study revealed that the coding sequence of the S segment of CCHFV contains a proteolytic cleavage site, DEVD, which is conserved in all CCHFV strains. By using different recombinant expression systems and site-directed mutagenesis, it was demonstrated that this motif is subject to caspase cleavage. It was also demonstrated that CCHFV nucleocapsid (N) protein is cleaved into a 30-kDa fragment while caspase activity is induced during infection and that CCHFV infection induces caspase-3-dependent apoptosis at late post infection. Using caspase inhibitors and cells lacking caspase-3, it was shown that the cleavage of N protein is caspase-3-dependent. The inhibition of apoptosis induced progeny viral titres. A study examining the crystal structures of CCHFV N revealed two distinct forms, an oligomeric form comprised of double antiparallel superhelices and a monomeric form. The head-to-tail interaction of the stalk region of one CCHFV N subunit and the base of the globular body of the adjacent subunit stabilises the helical organisation of the oligomeric form of CCHFV N. It also masks the conserved caspase-3 cleavage site present at the tip of the stalk region from host cell caspase-3 interaction and cleavage. Incubation with primer-length ssRNAs revealed the crystal structure of CCHFV N in its monomeric form, which is similar to a recently published structure. The conformational change in CCHFV N upon deoligomerisation results in exposure of the caspase-3 cleavage site and subjects CCHFV N to caspase-3 cleavage. Mutations of this cleavage site inhibit cleavage by caspase-3 and result in enhanced viral polymerase activity. These structural findings extend current knowledge regarding CCHFV N structure. Based on the high degree of structural similarity between CCHFV and LASV N proteins, they may have an ancestor in common. A final study showed that CCHFV has strategies for interplaying with apoptosis pathways, thereby regulating the caspase cascade. There were indications that CCHFV suppresses caspase activation at early stages of the CCHFV replication cycle, which perhaps benefits the establishment of infection. Furthermore, the host cellular response at late post infection appears to induce host cellular pro-apoptotic molecules through the death receptor pathway. External host-derived stimuli probably initiate the apoptotic process and the route continues either by crosstalk between the death receptor and mitochondria routes, or separately.
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| 4. |
- Karlberg, Helen, et al.
(författare)
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Molecular and Serological Findings in Suspected Patients With Crimean-Congo Hemorrhagic Fever Virus in Iran
- 2015
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Ingår i: Journal of Medical Virology. - : Wiley: 12 months. - 0146-6615 .- 1096-9071. ; 87:4, s. 686-693
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Tidskriftsartikel (refereegranskat)abstract
- Crimean-Congo hemorrhagic fever (CCHF) is an arthropod-borne disease of humans associated with a severe clinical picture, including hemorrhagic syndrome and a high mortality rate. CCHF virus is widely distributed throughout large areas of the world. To characterize the serological status in CCHF patients, paired clinical samples were collected from suspected CCHF patients and analyzed by microbiological and other laboratory analyses with the aim of: determining the presence of neutralizing antibodies against CCHF virus; investigating the cross-reactivity of these neutralizing antibodies against virus isolated from the same outbreak and against other available laboratory strain; and studying the relationship between the isolated virus with other virus by whole genome sequencing. Patients at Boo-Ali Hospital, Zahedan, Iran, with clinical symptoms ranging from mild to severe hemorrhagic fever were included in the study. Two serum samples were taken from each patient, the first as soon as the patient matched the criteria for CCHF notification and the second when the patient was discharged from hospital (2 weeks later). Commercial and in-house assays revealed a positive IgM signal in acute serum samples from six patients. A novel finding was that CCHF patients develop neutralizing antibodies soon after infection. Interestingly these antibodies were able to neutralize other CCHF virus strains too. The complete sequence of the Zahedan 2007 isolate, including the hitherto unknown first L-segment sequence, was identified using an original clinical sample from one patient with confirmed CCHF infection.
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| 5. |
- Loseva, Olga, et al.
(författare)
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PARP-3 Is a Mono-ADP-ribosylase That Activates PARP-1 in the Absence of DNA
- 2010
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 285:11, s. 8054-8060
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Tidskriftsartikel (refereegranskat)abstract
- The PARP-3 protein is closely related to the PARP-1 and PARP-2 proteins, which are involved in DNA repair and genome maintenance. Here, we characterized the biochemical properties of human PARP-3. PARP-3 is able to ADP-ribosylate itself as well as histone H1, a previously unknown substrate for PARP-3. PARP-3 is not activated upon binding to DNA and is a mono-ADP-ribosylase, in contrast to PARP-1 and PARP-2. PARP-3 interacts with PARP-1 and activates PARP-1 in the absence of DNA, resulting in synthesis of polymers of ADPribose. The N-terminal WGR domain of PARP-3 is involved in this activation. The functional interaction between PARP-3 and PARP-1 suggests that it may have a role in DNA repair. However, here we report that PARP-3 small interfering RNA-depleted cells are not sensitive to the topoisomerase I poison camptothecin, inducing DNA single-strand breaks, and repair these lesions as efficiently as wild-type cells. Altogether, these results suggest that the interaction between PARP-1 and PARP-3 is unrelated to DNA single-strand break repair.
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| 6. |
- Mousavi-Jazi, Mehrdad, et al.
(författare)
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Healthy individuals immune response to the Bulgarian Crimean-Congo hemorrhagic fever virus vaccine
- 2012
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Ingår i: Vaccine. - : Elsevier. - 0264-410X .- 1873-2518. ; 30:44, s. 6225-6229
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Tidskriftsartikel (refereegranskat)abstract
- Crimean-Congo hemorrhagic fever virus (CCHFV) poses a great threat to public health due to its high mortality and transmission rate and wide geographical distribution. There is currently no specific antiviral therapy for CCHF. This study provides the first in-depth analysis of the cellular and humoral immune response in healthy individuals following injection of inactivated Bulgarian vaccine, the only CCHFV vaccine available at present. Vaccinated individuals developed robust, anti-CCHFV-specific T-cell activity as measured by IFN-gamma ELISpot assay. The frequency of IFN-gamma secreting T-cells was 10-fold higher in individuals after vaccination with four doses than after one single dose. High levels of CCHFV antibodies were observed following the first dose, but repeated doses were required to achieve antibodies with neutralizing activity against CCHFV. However, the neutralizing activity in these groups was low.
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| 7. |
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| 8. |
- Wang, Yi, et al.
(författare)
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Structure of Crimean-Congo Hemorrhagic Fever Virus Nucleoprotein: Superhelical Homo-Oligomers and the Role of Caspase-3 Cleavage
- 2012
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Ingår i: Journal of Virology. - : American Society for Microbiology. - 0022-538X .- 1098-5514. ; 86:22, s. 12294-12303
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Tidskriftsartikel (refereegranskat)abstract
- Crimean-Congo hemorrhagic fever, a severe hemorrhagic disease found throughout Africa, Europe, and Asia, is caused by the tick-borne Crimean-Congo hemorrhagic fever virus (CCHFV). CCHFV is a negative-sense single-stranded RNA (ssRNA) virus belonging to the Nairovirus genus of the Bunyaviridae family. Its genome of three single-stranded RNA segments is encapsidated by the nucleocapsid protein (CCHFV N) to form the ribonucleoprotein complex. This ribonucleoprotein complex is required during replication and transcription of the viral genomic RNA. Here, we present the crystal structures of the CCHFV N in two distinct forms, an oligomeric form comprised of double antiparallel superhelices and a monomeric form. The head-to-tail interaction of the stalk region of one CCHFV N subunit with the base of the globular body of the adjacent subunit stabilizes the helical organization of the oligomeric form of CCHFV N. It also masks the conserved caspase-3 cleavage site present at the tip of the stalk region from host cell caspase-3 interaction and cleavage. By incubation with primer-length ssRNAs, we also obtained the crystal structure of CCHFV N in its monomeric form, which is similar to a recently published structure. The conformational change of CCHFV N upon deoligomerization results in the exposure of the caspase-3 cleavage site and subjects CCHFV N to caspase-3 cleavage. Mutations of this cleavage site inhibit cleavage by caspase-3 and result in enhanced viral polymerase activity. Thus, cleavage of CCHFV N by host cell caspase-3 appears to be crucial for controlling viral RNA synthesis and represents an important host defense mechanism against CCHFV infection.
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