| 1. |
- Chan, Sherwin, et al.
(författare)
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Regulation of PfEMP1-VAR2CSA translation by a Plasmodium translation-enhancing factor
- 2017
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Ingår i: Nature Microbiology. - : Springer Science and Business Media LLC. - 2058-5276. ; 2:7
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Tidskriftsartikel (refereegranskat)abstract
- Pregnancy-associated malaria commonly involves the binding of Plasmodium falciparum-infected erythrocytes to placental chondroitin sulfate A (CSA) through the PfEMP1-VAR2CSA protein. VAR2CSA is translationally repressed by an upstream open reading frame. In this study, we report that the P. falciparum translation enhancing factor (PTEF) relieves upstream open reading frame repression and thereby facilitates VAR2CSA translation. VAR2CSA protein levels in var2csa-transcribing parasites are dependent on the expression level of PTEF, and the alleviation of upstream open reading frame repression requires the proteolytic processing of PTEF by PfCalpain. Cleavage generates a C-terminal domain that contains a sterile-alpha-motif-like domain. The C-terminal domain is permissive to cytoplasmic shuttling and interacts with ribosomes to facilitate translational derepression of the var2csa coding sequence. It also enhances translation in a heterologous translation system and thus represents the first non-canonical translation enhancing factor to be found in a protozoan. Our results implicate PTEF in regulating placental CSA binding of infected erythrocytes.
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| 2. |
- Ch'ng, Jun-Hong, et al.
(författare)
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Epitopes of anti-RIFIN antibodies and characterization of rif-expressing Plasmodium falciparum parasites by RNA sequencing
- 2017
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Variable surface antigens of Plasmodium falciparum have been a major research focus since they facilitate parasite sequestration and give rise to deadly malaria complications. Coupled with its potential use as a vaccine candidate, the recent suggestion that the repetitive interspersed families of polypeptides (RIFINs) mediate blood group A rosetting and influence blood group distribution has raised the research profile of these adhesins. Nevertheless, detailed investigations into the functions of this highly diverse multigene family remain hampered by the limited number of validated reagents. In this study, we assess the specificities of three promising polyclonal anti-RIFIN antibodies that were IgG-purified from sera of immunized animals. Their epitope regions were mapped using a 175,000-peptide microarray holding overlapping peptides of the P. falciparum variable surface antigens. Through immunoblotting and immunofluorescence imaging, we show that different antibodies give varying results in different applications/assays. Finally, we authenticate the antibody-based detection of RIFINs in two previously uncharacterized non-rosetting parasite lines by identifying the dominant rif transcripts using RNA sequencing.
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| 3. |
- Goel, Suchi, et al.
(författare)
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RIFINs are adhesins implicated in severe Plasmodium falciparum malaria
- 2015
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Ingår i: Nature Medicine. - : Springer Science and Business Media LLC. - 1078-8956 .- 1546-170X. ; 21:4, s. 314-317
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Tidskriftsartikel (refereegranskat)abstract
- Rosetting is a virulent Plasmodium falciparum phenomenon associated with severe malaria. Here we demonstrate that P. falciparum-encoded repetitive interspersed families of polypeptides (RIFINs) are expressed on the surface of infected red blood cells (iRBCs), bind to RBCs-preferentially of blood group A-to form large rosettes and mediate microvascular binding of iRBCs. We suggest that RIFINs have a fundamental role in the development of severe malaria and thereby contribute to the varying global distribution of ABO blood groups in the human population.
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| 4. |
- Kaddumukasa, Mark, et al.
(författare)
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Parasite Specific Antibody Increase Induced by an Episode of Acute P. falciparum Uncomplicated Malaria.
- 2015
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 10:4
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Tidskriftsartikel (refereegranskat)abstract
- There is no approved vaccine for malaria, and precisely how human antibody responses to malaria parasite components and potential vaccine molecules are developed and maintained remains poorly defined. In this study, antibody anamnestic or memory response elicited by a single episode of P. falciparum infection was investigated.
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| 5. |
- Lugaajju, Allan, et al.
(författare)
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Development of Plasmodium falciparum specific naïve, atypical, memory and plasma B cells during infancy and in adults in an endemic area
- 2017
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Ingår i: Malaria Journal. - : Springer Science and Business Media LLC. - 1475-2875. ; 16:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: B-cells are essential in immunity against malaria, but which sub-sets of B-cells specifically recognize Plasmodium falciparum and when they appear is still largely unknown. Results: Using the flow cytometry technique for detection of P. falciparum specific (Pf+) B-cells, this study for the first time measured the development of Pf+ B cell (CD19+) phenotypes in Ugandan babies from birth up to nine months, and in their mothers. The babies showed increases in Pf+ IgG memory B-cells (MBCs), atypical MBCs, and plasma cells/blasts over time, but the proportion of these cells were still lower than in the mothers who displayed stable levels (5, 18, and 3%, respectively). Pf+ non-IgG+ MBCs and naïve B-cells binding to P. falciparum antigens were higher in the babies compared to the mothers (12 and 50%). In ELISA there was an increase in IgG and IgM antibodies over time in babies, and stable levels in mothers. At baby delivery, multigravidae mothers had a higher proportion of Pf+ IgG MBCs and less Pf+ naïve B-cells than primigravidae mothers. Conclusions: In newborns, naïve B-cells are a major player in recognizing P. falciparum. In adults, the high proportion of Pf+ atypical MBCs suggests a major role for these cells. Both in infants and adults, non-IgG+ MBCs were higher than IgG MBCs, indicating that these cells deserve more focus in future.
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| 6. |
- Lugaajju, Allan, et al.
(författare)
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Novel flow cytometry technique for detection of Plasmodium falciparum specific B-cells in humans: increased levels of specific B-cells in ongoing infection.
- 2015
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Ingår i: Malaria Journal. - : Springer Science and Business Media LLC. - 1475-2875. ; 14:1
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Tidskriftsartikel (refereegranskat)abstract
- Malaria caused by Plasmodium falciparum is still a major health threat in endemic areas especially for children below 5 years of age. While it is recognized that antibody immunity plays an important role in controlling the disease, knowledge of the mechanisms of sustenance and natural boosting of immunity is very limited. Before, it has not been possible to investigate malaria specific B-cells directly in flow cytometry, making it difficult to know how much of a B cell response is due to malaria, or how much is due to other immunological stimulators.
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| 7. |
- Ngara, Mtakai, et al.
(författare)
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Exploring parasite heterogeneity using single-cell RNA-seq reveals a gene signature among sexual stage Plasmodium falciparum parasites
- 2018
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Ingår i: Experimental Cell Research. - : Elsevier BV. - 0014-4827 .- 1090-2422. ; 371:1, s. 130-138
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Tidskriftsartikel (refereegranskat)abstract
- The malaria parasite has a complex lifecycle, including several events of differentiation and stage progression, while actively evading immunity in both its mosquito and human hosts. Important parasite gene expression and regulation during these events remain hidden in rare populations of cells. Here, we combine a capillary-based platform for cell isolation with single-cell RNA-sequencing to transcriptionally profile 165 single infected red blood cells (iRBCs) during the intra-erythrocytic developmental cycle (IDC). Unbiased analyses of single-cell data grouped the cells into eight transcriptional states during IDC. Interestingly, we uncovered a gene signature from the single iRBC analyses that can successfully discriminate between developing asexual and sexual stage parasites at cellular resolution, and we verify five, previously undefined, gametocyte stage specific genes. Moreover, we show the capacity of detecting expressed genes from the variable gene families in single parasites, despite the sparse nature of data. In total, the single parasite transcriptomics holds promise for molecular dissection of rare parasite phenotypes throughout the malaria lifecycle.
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| 8. |
- Nordenfelt, Patrik, et al.
(författare)
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Health-related quality of life in relation to disease activity in adults with hereditary angioedema in Sweden
- 2017
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Ingår i: Allergy and Asthma Proceedings. - : OceanSide Publications. - 1088-5412 .- 1539-6304. ; 38:6, s. 447-455
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Tidskriftsartikel (refereegranskat)abstract
- Background: Health-related quality of life (HR-QoL) is impaired in patients with hereditary angioedema (HAE) but has not yet been satisfactorily described.Objective: To study HR-QoL in patients with HAE by combining different HR-QoL instruments with disease activity assessment. Methods: All adults in the Swedish HAE registry were invited to take part in this questionnaire study, which used the generic HR-QoL instruments, EuroQol 5 Dimensions 5 Level (EQ-5D-5L) and the RAND Corporation Short Form 36 (RAND-36), the disease-specific Angioedema Quality of Life instrument (AE-QoL), the recently introduced Angioedema Activity Score (AAS) form, and questionnaires on sick leave and prophylactic medication.Results: Sixty-four of 133 adults (26 men, 38 women) between 18 and 91 years old responded. The most affected HR-QoL dimensions in the EQ-5D-5L were pain/discomfort and anxiety/depression; in the RAND-36, energy/fatigue, general health, pain; and, in the AE-QoL, fears/shame and fatigue/mood. Women had lower HR-QoL in the RAND-36 for general health and energy/fatigue (p < 0.05). Patients who reported any AAS of >0 had significantly impaired HR-QoL. There were significant associations (p < 0.05) between the AAS and EQ-5D-5L, between the AAS and all dimensions of the RAND-36 except physical function, and between the AAS and AE-QoL in all dimensions. Nine of 36 patients who reported sick leave during the previous 4 weeks had significantly impaired HR-QoL in all the instruments (p < 0.05). There was no significant difference in HR-QoL in the patients with and the patients without prophylactic medication, except for the nutrition dimension of the AE-QoL (p < 0.05).Conclusion: Comprehensive information is obtained by combining different HR-QoL instruments. Pain, anxiety/depression, and fatigue/mood are important aspects of HAE but the AE-QoL disregards pain. HR-QoL was not significantly affected by prophylaxis. Increased disease activity was associated with impaired HR-QoL, which justifies more active disease management.
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| 9. |
- Nordenfelt, Patrik
(författare)
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Hereditary Angioedema in Sweden : a National Project
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background: Hereditary angioedema (HAE) due to C1-inhibitor deficiency, type I and II, is a rare disease with an estimated prevalence of 1/50,000. Angioedema in the larynx can be life threatening and angioedema in the abdomen and skin can give severe and disabling pain. Data on patients with HAE in Sweden were scarce before our study.Aim: To study the prevalence of HAE, and to investigate clinical manifestations, treatments, and Health-Related Quality of Life (HR-QoL) in adults and children in Sweden.Method: In studies, I and II, all patients received a written questionnaire followed by a phone interview with questions about clinical manifestations, medication, sick leave and QoL. In study III the patients completed EuroQol 5 Dimensions 5 Levels (EQ-5D-5L) questionnaires for both the attack-free state (EQ5D today), and the last HAE attack (EQ5D attack). Questions were also asked about sick-leave. In study IV all adults received questionnaires with EQ-5D-5L and RAND-36, Angioedema Quality of Life instrument (AE-QoL), and Angioedema Activity Score (AAS) form, and questionnaires on sick leave and prophylactic medication.Results: We identified 146 patients, 110 adults and 36 children with HAE, type I (n=136) or II (n=10), giving a minimal HAE prevalence of 1.54/100,000. For adults, the median age at onset of symptoms was 12 years and median age at diagnosis was 22 years. Median age at onset of symptoms for children was 4 years and at diagnosis 3 years. During the previous year, 47% of adults experienced at least 12 attacks, 21% 4-11 attacks, 11% 1-3 attacks, while 22% were asymptomatic. For children, the corresponding figures were about the same. The median number of attacks in those having attacks was 14 in adults and 6 in children last year. Adult females reported on average 19 attacks the previous year versus nine for males. Irrespective of location nine out of 10 reported pain. Trigger factors were experienced in 95 % of adults and 74 % of children. Plasma-derived C1-inhibitor concentrate (pdC1INH) had a very good effect on acute attacks. Long-term prophylaxis with androgens and pdC1INH reduced the annual attack frequency by more than 50 %. Of the children’s parents, 73% had been on parental leave to care for the child due to HAE symptoms. Health and QoL were generally rated as good. In study III 103 of 139 responded and reported an EQ5D today score that was significantly higher than the EQ5D attack score. Attack frequency had a negative effect on EQ5D today. Children had significantly higher EQ-5D-5L than adults. Forty four percent had been absent from work or school during the latest attack. In study IV 64 of 133 adults responded. The most affected HR-QoL dimensions in EQ-5D-5L were pain/discomfort and anxiety/depression, in RAND-36 energy/fatigue, general health, health transition, pain, and in AE-QoL fears/shame and fatigue/mood. Females had significantly lower HR-QoL in RAND-36 for general health and energy/fatigue. There was an association between AAS and EQ-5D-5L/RAND-36 (except physical function) /AEQoL. There was no significant difference in HR-QoL in patients with and without prophylactic medication.Conclusion: The minimal prevalence of HAE type I and II in Sweden is 1.54/100,000. Median age at onset was 12 years. Adult females had twice as many attacks as males, adults had also twice as many attacks as children. For acute treatment, pdC1INH had a very good effect. For long term prophylaxis, androgens and pdC1INH had good effect. The most affected HR-QoL dimensions in EQ-5D-5L were pain/discomfort and anxiety/ depression, in RAND-36 energy/fatigue, general health, health transition and pain, and in AE-QoL fears/shame and fatigue/mood. Children reported better HR-QoL than adults. AE-QoL is more disease-specific in HAE than the generic instruments EQ-5D-5L and RAND-36. However, the latter highlights the pain aspect, whereas AE-QoL does not. Patients with high disease activity should thus be considered for more intensive treatment to improve their HR-QoL.
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| 10. |
- Nordenfelt, Patrik, et al.
(författare)
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Hereditary Angioedema in Swedish Adults: Report From the National Cohort
- 2016
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Ingår i: Acta Dermato-Venereologica. - : ACTA DERMATO-VENEREOLOGICA. - 0001-5555 .- 1651-2057. ; 96:4, s. 540-545
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Tidskriftsartikel (refereegranskat)abstract
- Hereditary angioedema (HAE) is rare, disabling and sometimes life-threatening. The aim of this study is to describe its prevalence, symptomatology and treatment in Sweden. A total of 146 patients were identified; 110 adults and 36 children with HAE type I (n = 136) or II (n = 10), giving a minimum HAE prevalence of 1.54/100,000. All patients received a written questionnaire followed by a structured telephone interview. This report focuses on the 102 adults who responded. Females reported 19 attacks in the previous year vs. 9 for males (p < 0.01), and females reported 10 days of sick leave vs. 4 days for males (p < 0.05). For all treated acute attacks, plasma-derived Cl-inhibitor concentrate (pdClINH) (used in 27% of patients) had a good effect. For maintenance treatment, 43% used attenuated androgens and 8% used pdClINH, which reduced their attack rate by more than 50%. In conclusion, the minimum HAE prevalence in Sweden was 1.54/100,000. HAE affected females more severely. Attenuated androgens and pdClINH had a good effect on preventing attacks.
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