| 1. |
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| 2. |
- Arai, Meiji, et al.
(författare)
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Isonicotinic acid hydrazide : an anti-tuberculosis drug inhibits malarial transmission in the mosquito gut
- 2004
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Ingår i: Experimental parasitology. - : Elsevier BV. - 0014-4894 .- 1090-2449. ; 106:1-2, s. 30-36
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Tidskriftsartikel (refereegranskat)abstract
- We studied the transmission-blocking effect of isonicotinic acid hydrazide (INH), a widely used anti-tuberculosis drug, against Plasmodium gallinaceum and Plasmodium berghei. INH-treatment of infected animals did not inhibit parasite development in the blood of the vertebrate host, but did inhibit exflagellation, ookinete formation, and oocyst development in the mosquito. Oocyst development was inhibited in a dose-dependent manner. The ED(50) in the P. gallinaceum/chicken/Aedes aegypti model and P. berghei/mouse/Anopheles stephensi model was 72 and 109 mg/kg, respectively. In marked contrast, in vitro exflagellation and ookinete development were not directly affected by physiological concentrations of INH. We suggest that INH exerts its inhibitory effects on the mosquito stages of the malaria parasite by an indirect, and at present undefined mechanism. Further elucidation of the mechanism how INH inhibits parasite development specifically on mosquito stages may allow us to identify new targets for malaria control strategy.
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| 3. |
- Axelsson Olsson, Diana, et al.
(författare)
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Amoebae and algae can prolong the survival of Campylobacter species in co-culture
- 2010
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Ingår i: Experimental parasitology. - : Elsevier BV. - 0014-4894 .- 1090-2449. ; 126:1, s. 59-64
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Tidskriftsartikel (refereegranskat)abstract
- Several species of free-living amoebae can cause disease in humans. However, in addition to the direct pathogenicity of e.g. Acanthamoebae and Naegleria species, they are recognized as environmental hosts, indirectly involved in the epidemiology of many pathogenic bacteria. Although several studies have demonstrated intracellular survival of many different bacteria in these species, the extent of such interactions as well as the implications for the epidemiology of the bacterial species involved, are largely unknown and probably underestimated. In this study, we evaluated eight different unicellular eukaryotic organisms, for their potential to serve as environmental hosts for Campylobacter species. These organisms include four amoebozoas (Acanthamoeba polyphaga, Acanthamoeba castellanii, Acanthamoeba rhysodes and Hartmanella vermiformis), one alveolate (Tetrahymena pyriformis), one stramenopile (Dinobryon sertularia), one eugoenozoa (Euglena gracilis) and one heterolobosea (Naegleria americana). Campylobacter spp. including Campylobacter jejuni, Campylobacter coli and Campylobacter lari are the most common cause of gastroenteritis in the western world. Survival and replication of these three species as well as Campylobacter hyointestinalis were assessed in co-cultures with the eukaryotic organisms. Campylobacter spp. generally survived longer in co-cultures, compared to when incubated in the corresponding growth media. The eukaryotic species that best promoted bacterial survival was the golden algae D. sertularia. Three species of amoebozoas, of the genus Acanthamoeba promoted both prolonged survival and replication of Campylobacter spp. The high abundance in lakes, ponds and water distribution networks of these organisms indicate that they might have a role in the epidemiology of campylobacteriosis, possibly contributing to survival and dissemination of these intestinal pathogens to humans and other animals. The results suggest that not only C. jejuni, but a variety of Campylobacter spp. can interact with different eukaryotic unicellular organisms.
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| 4. |
- Baltrusis, Paulius, et al.
(författare)
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Assessment of the F200Y mutation frequency in the beta tubulin gene of Haemonchus contortus following the exposure to a discriminating concentration of thiabendazole in the egg hatch test
- 2020
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Ingår i: Experimental Parasitology. - : Elsevier BV. - 0014-4894 .- 1090-2449. ; 217
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Tidskriftsartikel (refereegranskat)abstract
- The ruminant livestock production sector is under threat due to the infections with gastrointestinal nematode parasites and the subsequent development of anthelmintic resistance. One of most common and pathogenic species in small ruminants is Haemonchus contortus. The ability to control the infections with this and other gastrointestinal nematodes relies heavily on the use of anthelmintic drugs. Although resistance to all major classes of anthelmintics has been shown in H. contortus, the precise mechanism of resistance acquisition is only known for benzimidazoles. F200Y (TAC) is a common point mutation in the isotype 1 beta tubulin gene which is associated with an effective increase in the resistance towards benzimidazole drugs. Here, we show the utility of using this mutation as a marker in a droplet digital PCR assay to track how two H. contortus laboratory strains, characterized by different resistance levels, change with respect to this mutation, when subjected to increasing concentrations of thiabendazole. Additionally, we wanted to investigate whether exposure to a discriminating dose of thiabendazole in the egg hatch test resulted in the death of all H. contortus eggs with a susceptible genotype. We found the MHco5 strain to maintain an overall higher frequency of the F200Y mutation (80-100%) over all drug concentrations, whilst a steady, gradual increase from around 30%-60% was observed in the case of the MHco4 strain. This is further supported by the dose-response curves, displaying a much higher tolerance of the MHco5 strain (LD50 = 0.38 mu g/ml) in comparison to the MHco4 strain (LD50 = 0.07 mu g/ml) to the effects of thiabendazole. All things considered, we show that the F200Y mutation is still a viable and reliable marker for the detection and surveillance of benzimidazole drug resistance in H. contortus in Europe.
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| 5. |
- Barragan, Antonio, et al.
(författare)
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Erythrocyte Glycans as Plasmodium falciparum Rosetting Receptors : Molecular Background of Strain Specific Rosette Disruption by Glycosaminoglycans and Sulfated Glycoconjugates
- 1999
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Ingår i: Experimental parasitology. - : Elsevier BV. - 0014-4894 .- 1090-2449. ; 91:2, s. 133-143
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Tidskriftsartikel (refereegranskat)abstract
- Rosetting, the adhesion of Plasmodium falciparum-infected erythrocytes to uninfected erythrocytes, is a virulent parasite phenotype associated with the occurrence of severe malaria, e.g., cerebral malaria. Compounds with specific anti-rosetting activity are potential therapeutic agents. Glycosaminoglycans and sulfated glycoconjugates were found to disrupt rosettes in a strain- and isolate-specific manner. Rosette disruption was strongly connected to the presence of N-sulfate groups in heparin/heparan sulfate as demonstrated by modified heparin preparations. This finding was corroborated by the disruption of rosettes with mono- and disaccharides derived from heparin/heparan sulfate that contained N-sulfated glucosamine. Furthermore, heparinase III treatment of erythrocyte cultures infected by FCR3S1 (and to some extent TM 284) P. falciparum strains abolished rosetting. Heparinase III treatment of the uninfected erythrocytes prior to mixing with the infected culture impeded formation of rosettes, indicating that the rosetting receptors at least partially are of glycosaminoglycan nature.
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| 6. |
- Barragan, A, et al.
(författare)
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Plasmodium falciparum: molecular background to strain-specific rosettedisruption by glycosaminoglycans and sulfated glycoconjugates
- 1999
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Ingår i: Experimental parasitology. - : Elsevier BV. - 0014-4894 .- 1090-2449. ; 91:2, s. 133-143
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Tidskriftsartikel (refereegranskat)abstract
- Rosetting, the adhesion of Plasmodium falciparum-infected erythrocytes to uninfected erythrocytes, is a virulent parasite phenotype associated with the occurrence of severe malaria, e.g., cerebral malaria. Compounds with specific anti-rosetting activity are potential therapeutic agents. Glycosaminoglycans and sulfated glycoconjugates were found to disrupt rosettes in a strain- and isolate-specific manner. Rosette disruption was strongly connected to the presence of N-sulfate groups in heparin/heparan sulfate as demonstrated by modified heparin preparations. This finding was corroborated by the disruption of rosettes with mono- and disaccharides derived from heparin/heparan sulfate that contained N-sulfated glucosamine. Furthermore, heparinase III treatment of erythrocyte cultures infected by FCR3S1 (and to some extent TM 284) P. falciparum strains abolished rosetting. Heparinase III treatment of the uninfected erythrocytes prior to mixing with the infected culture impeded formation of rosettes, indicating that the rosetting receptors at least partially are of glycosaminoglycan nature.
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| 7. |
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| 8. |
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| 9. |
- Butcher, G A, et al.
(författare)
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Plasmodium berghei : infectivity of mice to Anopheles stephensi mosquitoes
- 1996
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Ingår i: Experimental parasitology. - : Elsevier BV. - 0014-4894 .- 1090-2449. ; 84:3, s. 371-379
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Tidskriftsartikel (refereegranskat)abstract
- The infectivity of P. berghei-infected TO mice to mosquitoes declines rapidly 2 to 5 days after blood inoculation, in spite of rising numbers of gametocytes in the blood. This pattern is typical of many malaria infections and various factors, particularly specific and nonspecific immune responses, have previously been implicated in the decline. Here we report that (1) simple physiological changes in the mouse blood, namely, falling pH and bicarbonate levels induced by high parasitaemias, are responsible for the sustained inhibition of infectivity; (2) the inhibition is reversible in vivo by the addition of sodium bicarbonate alone; (3) the inhibition occurs at the point of exflagellation; (4) contrary to previous observations (Kawamoto et al. 1992), exflagellation in P. berghei, like that in P. gallinaceum (Bishop and McConnachie 1956; Nijhout and Carter 1978; Nijhout 1979) and P. falciparum (Ogwan'g et al. 1993), is dependent on extracellular bicarbonate; and (5) induction of exflagellation by a mosquito factor is bicarbonate dependent. These new observations are critical to the design and interpretation of experiments on other transmission blocking phenomena.
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| 10. |
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| 11. |
- Dimitrov, Dimitar, et al.
(författare)
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Plasmodium spp.: An experimental study on vertebrate host susceptibility to avian malaria.
- 2015
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Ingår i: Experimental Parasitology. - : Elsevier BV. - 0014-4894. ; 148, s. 1-16
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Tidskriftsartikel (refereegranskat)abstract
- The interest in experimental studies on avian malaria caused by Plasmodium species has increased recently due to the need of direct information about host-parasite interactions. Numerous important issues (host susceptibility, development of infection, the resistance and tolerance to avian malaria) can be answered using experimental infections. However, specificity of genetically different lineages of malaria parasites and their isolates is largely unknown. This study reviews recent experimental studies and offers additional data about susceptibility of birds to several widespread cytochrome b (cyt b) lineages of Plasmodium species belonging to four subgenera. We exposed two domesticated avian hosts (canaries Serinus canaria and ducklings Anas platyrhynchos) and also 16 species of common wild European birds to malaria infections by intramuscular injection of infected blood and then tested them by microscopic examination and PCR-based methods. Our study confirms former field and experimental observations about low specificity and wide host-range of Plasmodium relictum (lineages SGS1 and GRW11) and P. circumflexum (lineage TURDUS1) belonging to the subgenera Haemamoeba and Giovannolaia, respectively. However, the specificity of different lineages and isolates of the same parasite lineage differed between species of exposed hosts. Several tested Novyella lineages were species specific, with a few cases of successful development in experimentally exposed birds. The majority of reported cases of mortality and high parasitaemia were observed during parasite co-infections. Canaries were susceptible mainly for the species of Haemamoeba and Giovannolaia, but were refractory to the majority of Novyella isolates. Ducklings were susceptible to three malaria infections (SGS1, TURDUS1 and COLL4), but parasitaemia was light (<0.01%) and transient in all exposed birds. This study provides novel information about susceptibility of avian hosts to a wide array of malaria parasite lineages, outlining directions for future experimental research on various aspects of biology and epidemiology of avian malaria.
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| 12. |
- Einarsson, Elin, et al.
(författare)
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UV irradiation responses in Giardia intestinalis
- 2015
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Ingår i: Experimental parasitology. - : Elsevier BV. - 0014-4894 .- 1090-2449. ; 154, s. 25-32
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Tidskriftsartikel (refereegranskat)abstract
- The response to ultraviolet light (UV) radiation, a natural stressor to the intestinal protozoan parasite Giardia intestinalis, was studied to deepen the understanding of how the surrounding environment affects the parasite during transmission. UV radiation at 10 mJ/cm(2) kills Giardia cysts effectively whereas trophozoites and encysting parasites can recover from UV treatment at 100 mJ/cm(2) and 50 mJ/cm(2) respectively. Staining for phosphorylated histone H2A showed that UV treatment induces double-stranded DNA breaks and flow cytometry analyses revealed that UV treatment of trophozoites induces DNA replication arrest. Active DNA replication coupled to DNA repair could be an explanation to why UV light does not kill trophozoites and encysting cells as efficiently as the non-replicating cysts. We also examined UV-induced gene expression responses in both trophozoites and cysts using RNA sequencing (RNA seq). UV radiation induces small overall changes in gene expression in Giardia but cysts show a stronger response than trophozoites. Heat shock proteins, kinesins and Nek kinases are up-regulated, whereas alpha-giardins and histones are down-regulated in UV treated trophozoites. Expression of variable surface proteins (VSPs) is changed in both trophozoites and cysts. Our data show that Giardia cysts have limited ability to repair UV-induced damage and this may have implications for drinking- and waste-water treatment when setting criteria for the use of UV disinfection to ensure safe water.
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| 13. |
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| 14. |
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| 15. |
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| 16. |
- Hofstetrova, Klara, et al.
(författare)
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Giardia intestinalis : Aphidicolin influence on the trophozoite cell cycle
- 2010
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Ingår i: Experimental parasitology. - : Elsevier BV. - 0014-4894 .- 1090-2449. ; 124:2, s. 159-166
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Tidskriftsartikel (refereegranskat)abstract
- This study is a thorough examination of the effects of the DNA polymerase inhibitor aphidicolin on the nuclear cycle and cell cycle progression characteristics, as well as their reversibility, in Giardia intestinalis. Giardia trophozoites are arrested in the G1/S-junction after aphidicolin treatment according to their DNA content. However, cell growth continues and trophozoites arrested with aphidicolin resemble cells in the G2 phase and trophozoites in ageing cultures. Extensive treatment with aphidicolin causes side effects and we detected positive signals for phosphorylated histone H2A, which, in mammalian cells. is involved in a signalling pathway triggered as a reaction to double stranded DNA breaks. These results suggest that aphidicolin causes dissociation of the nuclear and cytoplasmic cycles, a phenomenon that has also been described for other inhibitors in mammalian cell lines. Thus, if aphidicolin is used for synchronization of Giardia trophozoites, this fact must be accounted for, and treatment with aphidicolin must be minimal. (C) 2009 Elsevier Inc. All rights reserved.
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| 17. |
- Höglund, Johan
(författare)
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Small animal in vivo imaging of parasitic infections: A systematic review
- 2020
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Ingår i: Experimental Parasitology. - : Elsevier BV. - 0014-4894 .- 1090-2449. ; 214
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Forskningsöversikt (refereegranskat)abstract
- Non-invasive small animal in vivo imaging is an essential tool in a broad variety of biomedical sciences and enables continuous monitoring of disease progression in order to develop and improve diagnostic, therapeutic and preventive measures. Imaging parasites non-invasively in live animals allows efficient parasite distribution evaluation in the host organism and objective evaluation of parasitic diseases' burden and progression in individual animals. The aim of this systematic review was to summarize recent trends in small animal in vivo imaging and compare and discuss imaging of single-cell and multicellular eukaryotic parasites. A literature survey was performed using Web of Science and PubMed databases in research articles published between 1990 and 2018. The inclusion criteria were using any imaging method to visualize a range of protozoan and helminth parasites in laboratory animals in vivo. A total of 92 studies ma our inclusion criteria. Protozoans and helminths were imaged in 88% and 12% of 92 studies, respectively. The most common parasite genus studied was the protozoan Plasmodium followed by Trypanosoma and Leishmania. The most frequent imaging method was bioluminescence. Among the helminths, Schistosoma and Echinococcus were the most studied organisms. In vivo imaging is applicable in both protozoans and helminths. In helminths, however, the use of in vivo imaging methods is limited to some extent. Imaging parasites in small animal models is a powerful tool in preclinical research aiming to develop novel therapeutic and preventive strategies for parasitic diseases of interest both in human and veterinary medicine.
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| 18. |
- Iqbal, Sajid, et al.
(författare)
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Essential oils of four wild plants inhibit the blood seeking behaviour of female Aedes aegytpi
- 2023
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Ingår i: Experimental parasitology. - : Elsevier BV. - 0014-4894 .- 1090-2449. ; 244
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Tidskriftsartikel (refereegranskat)abstract
- Aedes aegypti (Diptera: Culicidae) mosquito is an important vector of many disease-causing pathogens. An effective way to escape from these mosquito-borne diseases is to prevent mosquito bites. In the current study, essential oils of Lepidium pinnatifidum, Mentha longifolia, Origanum vulgare, and Agrimonia eupatoria were evaluated for their repellent potential against Ae. aegypti females. Essential oils were extracted using steam distillation from freshly collected aerial parts of the plants and tested against 4–5 day old females of Ae. aegypti through the human bait technique for repellency and repellent longevity assays. The chemical composition of extracted essential oils was explored by gas chromatography coupled with mass spectrometry (GC-MS). The essential oils of L. pinnatifidum, M. longifolia, O. vulgare, and A. eupatoria at a dose of 33 μg/cm2 showed 100%, 94%, 87%, and 83% mosquito repellent activity, respectively. Furthermore, M. longifolia and O. vulgare essential oils exhibited 100% repellency at a dose of 165 μg/cm2, whereas A. eupatoria essential oil showed 100% repellency only at 330 μg/cm2. In the time-span bioassay, M. longifolia and O. vulgare essential oils showed protection against Ae. aegypti bites for 90 and 75 min, respectively whereas both A. eupatoria and L. pinnatifidum were found active for 45 min. Phenylacetonitrile (94%), piperitone oxide (34%), carvacrol (20%) and α-pinene (62%) were the most abundant compounds in L. pinnatifidum, M. longifolia, O. vulgare and A. eupatoria essential oils, respectively. The current study demonstrates that M. longifolia and O. vulgare essential oils possess the potential to be used as an alternative to synthetic chemicals to protect humans from mosquito bites.
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| 19. |
- Lagunas-Rangel, Francisco Alejandro, et al.
(författare)
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Nicotinamide induces G2 cell cycle arrest in Giardia duodenalis trophozoites and promotes changes in sirtuins transcriptional expression
- 2020
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Ingår i: Experimental parasitology. - : Elsevier BV. - 0014-4894 .- 1090-2449. ; 209:2508
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Tidskriftsartikel (refereegranskat)abstract
- Giardia duodenalis is a flagellated unicellular eukaryotic microorganism that commonly causes diarrheal disease throughout the world. Treatment of giardiasis is limited to nitroheterocyclic compounds as metronidazole and benzimidazoles as albendazole, where remarkably treatment failure is relatively common. Consequently, the need for new options to treat this disease is underscored. We predicted by a bioinformatic approach that nicotinamide inhibits Giardia sirtuins by the nicotinamide exchange pathway, and since sirtuins are involved in cell cycle control, they could be related with arrest and decrease of viability. When trophozoites were treated with nicotinamide (NAM), a strong arrest of Giardia trophozoites in G2 phase was observed and at the same time changes in transcriptional expression of sirtuins were produced. Interestingly, the G2 arrest is not related to double-strand breaks, which strengthens the role of sirtuins in the control of the Giardia cell cycle. Results with NAM-treated trophozoites as predicted demonstrate antigiardial effects and thus open new options for the treatment of giardiasis, either with the combination of nicotinamide with another antigiardial drug, or with the design of specific inhibitors for Giardia sirtuins.
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| 20. |
- Maal-Bared, Rasha, et al.
(författare)
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Fate of internalized Campylobacter jejuni and Mycobacterium avium from encysted and excysted Acanthamoeba polyphaga
- 2019
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Ingår i: Experimental parasitology. - : Elsevier. - 0014-4894 .- 1090-2449. ; 199, s. 104-110
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Tidskriftsartikel (refereegranskat)abstract
- Association of the water- and foodborne pathogen Campylobacter jejuni with free-living Acanthamoeba spp. trophozoites enhances C. jejuni survival and resistance to biocides and starvation. When facing less than optimal environmental conditions, however, the Acanthamoeba spp. host can temporarily transform from trophozoite to cyst and back to trophozoite, calling the survival of the internalized symbiont and resulting public health risk into question. Studies investigating internalized C. jejuni survival after A. castellanii trophozoite transformation have neither been able to detect its presence inside the Acanthamoeba cyst after encystation nor to confirm its presence upon excystation of trophozoites through culture-based techniques. The purpose of this study was to detect C. jejuni and Mycobacterium avium recovered from A. polyphaga trophozoites after co-culture and induction of trophozoite encystation using three different encystation methods (Neff's medium, McMillen's medium and refrigeration), as well as after cyst excystation. Internalized M. avium was used as a positive control, since studies have consistently detected the organism after co-culture and after host excystation. Concentrations of C. jejuni in A. polyphaga trophozoites were 4.5 × 105 CFU/ml, but it was not detected by PCR or culture post-encystation. This supports the hypothesis that C. jejuni may be digested during encystation of the amoebae. M. avium was recovered at a mean concentration of 1.9 × 104 from co-cultured trophozoites and 4.4 × 101 CFU/ml after excystation. The results also suggest that M. avium recovery post-excystation was statistically significantly different based on which encystation method was used, ranging from 1.3 × 101 for Neff's medium to 5.4 × 101 CFU/ml for refrigeration. No M. avium was recovered from A. polyphaga cysts when trophozoites were encysted by McMillen's medium. Since C. jejuni internalized in cysts would be more likely to survive harsh environmental conditions and disinfection, a better understanding of potential symbioses between free-living amoebae and campylobacters in drinking water distribution systems and food processing environments is needed to protect public health. Future co-culture experiments examining survival of internalized C. jejuni should carefully consider the encystation media used, and include molecular detection tools to falsify the hypothesis that C. jejuni may be present in a viable but not culturable state.
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| 21. |
- Nhancupe, Noémia, et al.
(författare)
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Further characterization of Tsol-p27 as a diagnostic antigen in sub-Saharan Africa
- 2013
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Ingår i: Experimental parasitology. - : Elsevier. - 0014-4894 .- 1090-2449. ; 135:3, s. 573-9
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Tidskriftsartikel (refereegranskat)abstract
- Commercial antigens used to diagnose human neurocysticercosis are obtained from either a soluble parasite extract or a parasite-derived glycoprotein fraction. The aim of the present study was to identify antigenic proteins as potential diagnostic candidates in Mozambique. Soluble proteins from Taenia solium cysticerci were separated by two-dimensional electrophoresis and blotted onto nitrocellulose membranes. Subtracted hybridization was performed with serum samples obtained from patients with neurocysticercosis (NCC) and from a NCC-negative control group. Six antigenic proteins were identified and sequenced by liquid chromatography-mass spectrometry. Among these we found Tsol-p27, which was previously identified as a diagnostic candidate in a study conducted in Nicaragua, Central America. Here, we evaluated Tsol-p27 and the antigen cC1 as potential recombinant diagnostic reagents, and also investigated the localization and partial function of Tsol-p27. Immunoblotting demonstrated that Tsol-p27 was recognized by all 10 serum samples from NCC-positive individuals, whereas cC1 was identified by only five of the 10 positive sera. None of the antigens were recognized by negative control sera. Despite the limited number of serum samples evaluated in this study, the results suggest that Tsol-p27 can be a suitable candidate for diagnosis of human NCC, not only in Central America but also in sub-Saharan Africa.
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| 22. |
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| 23. |
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| 24. |
- Palinauskas, Vaidas, et al.
(författare)
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A new method for isolation of purified genomic DNA from haemosporidian parasites inhabiting nucleated red blood cells
- 2013
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Ingår i: Experimental Parasitology. - : Elsevier BV. - 0014-4894. ; 133:3, s. 275-280
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Tidskriftsartikel (refereegranskat)abstract
- During the last 10 years, whole genomes have been sequenced from an increasing number of organisms. However, there is still no data on complete genomes of avian and lizard Plasmodium spp. or other haemosporidian parasites. In contrast to mammals, bird and reptile red blood cells have nuclei and thus blood of these vertebrates contains high amount of host DNA; that complicates preparation of purified template DNA from haemosporidian parasites, which has been the main obstacle for genomic studies of these parasites. In the present study we describe a method that generates large amount of purified avian haemosporidian DNA. The method is based on a unique biological feature of haemosporidian parasites, namely that mature gametocytes in blood can be induced to exflagellate in vitro. This results in the development of numerous microgametes, which can be separated from host blood cells by simple centrifugation. Our results reveal that this straight forward method provides opportunities to collect pure parasite DNA material, which can be used as a template for various genetic analyses including whole genome sequencing of haemosporidians infecting birds and lizards. (c) 2012 Elsevier Inc. All rights reserved.
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| 25. |
- Palinauskas, Vaidas, et al.
(författare)
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Plasmodium relictum (lineage P-SGS1): Effects on experimentally infected passerine birds
- 2008
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Ingår i: Experimental Parasitology. - : Elsevier BV. - 0014-4894. ; 120:4, s. 372-380
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Tidskriftsartikel (refereegranskat)abstract
- We evaluated the effects of Plasmodium relictum (lineage P-SGS1), which is a host generalist, to five species of passerine birds. Light infection of P. relictum was isolated from a naturally infected adult reed warbler Acrocephalus scirpaceus. The parasites were inoculated to naive juveniles of the chaffinch Fringilla coelebs, common crossbill Loxia curvirostra, house sparrow Passer domesticus. siskin Spinus spinus and starling Sturnus vulgaris. Susceptibility of these birds to the infection of P. relictum was markedly different. This parasite developed in birds belonging to the Fringillidae and Passeridae but the starlings (Sturnidae) were resistant. Only 50% of experimental house sparrows were susceptible to the infection. The intensity of parasitemia varied markedly inside and between different susceptible bird species. There were no effects of the infection on body mass or temperature of experimentally infected birds. Infection of P. relictum leads to the significant decrease of haematocrit value and hypertrophy of spleen and liver in heavily infected common crossbills and siskins. This study shows that infection of the same lineage of P. relictum causes diseases of different severity in different avian hosts: that might have different evolutionary consequences and should be taken in consideration in conservation projects. (C) 2008 Elsevier Inc. All rights reserved.
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| 26. |
- Palinauskas, Vaidas, et al.
(författare)
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Plasmodium relictum (lineage P-SGS1): Further observation of effects on experimentally infected passeriform birds, with remarks on treatment with Malarone (TM)
- 2009
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Ingår i: Experimental Parasitology. - : Elsevier BV. - 0014-4894. ; 123:2, s. 134-139
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Tidskriftsartikel (refereegranskat)abstract
- Plasmodium relictum (lineage P-SGS1) is a widespread malaria parasite that causes disease of different severity in different species of birds. However, experimental studies on the effects of this parasite on avian hosts are uncommon. We investigated development of this lineage in experimentally infected greenfinches Carduelis chloris and compared the obtained data with the literature information about the virulence of the same parasite lineage for phylogenetically closely related bird species. We also used an opportunity to test the efficacy of the antimalarial drug Malarone (TM) in treatment of the experimental infection. The cryopreserved strain of the lineage P-SGS1 was multiplied in 4 experimentally infected chaffinches. Light parasitemia developed in these birds; the parasites were then inoculated to 6 uninfected recipient greenfinches. Six uninfected greenfinches were used as negative controls. Light parasitemia developed in all experimental greenfinches. There were no significant effects of malaria on the body mass of greenfinches, but haematocrit value was slightly lower in experimental birds than in control ones; the infection did not cause mortality or morbidity in these birds. According to available data, all investigated fringillid birds are susceptible to P. relictum (P-SGS1), but the same malaria parasite develops markedly differently in different bird species, even closely related hosts. Thus, the observed effects of the same malaria lineage on one species of bird cannot be generalized to others, even closely related ones. The cure with Malarone (TM) was highly efficient for blood stages of P. relictum, but exoerythrocytic stages were unaffected. (C) 2009 Elsevier Inc. All rights reserved.
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| 27. |
- Palinauskas, Vaidas, et al.
(författare)
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Plasmodium relictum (lineage SGS1) and Plasmodium ashfordi (lineage GRW2): The effects of the co-infection on experimentally infected passerine birds
- 2011
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Ingår i: Experimental Parasitology. - : Elsevier BV. - 0014-4894. ; 127:2, s. 527-533
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Tidskriftsartikel (refereegranskat)abstract
- The effects of avian malaria parasites of the genus Plasmodium on their hosts are insufficiently understood. This is particularly true for malarial co-infections, which predominant in many bird populations. We investigated effects of primary co-infection of Plasmodium relictum (lineage SGS1) and Plasmodium ashfordi (GRW2) on experimentally infected naive juveniles of siskin Spin us spinus, crossbill Loxia curvirostra and starling Sturnus vulgaris. All siskins and crossbills were susceptible but starlings resistant to both these infections. A general pattern of the co-infections was that heavy parasitemia (over 35% during peaks) of both parasites developed in both susceptible host species. There were no significant effects of the co-infections on mean body mass of the majority of infected birds. Mean haematocrit value decreased approximately 1.5 and 3 times in siskins and crossbills at the peak of parasitemia, respectively. Mortality was recorded among infected crossbills. We conclude that co-infections of P. relictum and P. ashfordi are highly virulent and act synergetically during primary infections in some but not all passerine birds. (C) 2010 Elsevier Inc. All rights reserved.
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| 28. |
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| 29. |
- Porcel, Betina, et al.
(författare)
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Trypanosoma rangeli and Trypanosoma cruzi : molecular characterization of genes encoding putative calcium-binding proteins, highly conserved in typanosomatids
- 1996
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Ingår i: Experimental parasitology. - : Elsevier BV. - 0014-4894 .- 1090-2449. ; 84:3, s. 387-399
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Tidskriftsartikel (refereegranskat)abstract
- Genes encoding a 29-kDa flagellar calcium-binding protein (F29) in Trypanosoma cruzi, strongly homologous to EF-hand calcium-binding protein-encoding genes previously reported in this parasite, were isolated by immunoscreening. F29 is encoded by a number of very similar genes, highly conserved among different T. cruzi isolates. The genes are located on a pair of homologous chromosomes, arranged in one or two clusters of tandem repeats. PCR amplification of Trypanosoma rangeli genomic DNA, using primers derived from the T. cruzi F29 sequence made it possible to isolate the homologous gene in T. rangeli, encoding a 23-kDa protein called TrCaBP. Gene sequence comparisons showed homology to EF-hand calcium-binding proteins from T. cruzi (82.8%), Trypanosoma brucei brucei (60.2%), and Entamoeba histolytica (28.4%). Northern blot analysis revealed that the TrCaBP gene is expressed in T. rangeli as a polyadenylated transcript. The TrCaBP-encoding genes are present in at least 20 copies per cell, organized in tandem arrays, on large T. rangeli chromosomes in some isolates and on two smaller ones in others. This gene, however, seems to be absent from Leishmania.
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| 30. |
- Raabe, Andreas, et al.
(författare)
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Genetic and transcriptional analysis of phosphoinositide-specific phospholipase C in Plasmodium
- 2011
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Ingår i: Experimental parasitology. - : Elsevier BV. - 0014-4894 .- 1090-2449. ; 129:1, s. 75-80
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Tidskriftsartikel (refereegranskat)abstract
- Phosphoinositide-specific phospholipase C (PI-PLC) is a major regulator of calcium-dependent signal transduction, which has been shown to be important in various processes of the malaria parasite Plasmodium. PI-PLC is generally implicated in calcium liberation from intracellular stores through the action of its product, inositol-(1,4,5)-trisphosphate, and is itself dependent on calcium for its activation. Here we describe the plc genes from Plasmodium species. The encoded proteins contain all domains typically found in PI-PLCs of the δ class but are almost twice as long as their orthologues in mammals. Transcriptional analysis by qRT-PCR of plc during the erythrocytic cycle of P. falciparum revealed steady expression levels that increased at the late schizont stages. Genetic analysis in the P. berghei model revealed that the plc locus was targetable but that plc gene knock-outs could not be obtained, thereby strongly indicating that the gene is essential during blood stage development. Alternatively, we attempted to modify plc expression through a promoter exchange approach but found the gene to be refractory to over-expression indicating that plc expression levels might additionally be tightly controlled.
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| 31. |
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| 32. |
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| 33. |
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| 34. |
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| 35. |
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| 36. |
- Skarin, Hanna, et al.
(författare)
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Elongation factor 1-alpha is released into the culture medium during growth of Giardia intestinalis trophozoites
- 2011
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Ingår i: Experimental parasitology. - : Elsevier BV. - 0014-4894 .- 1090-2449. ; 127:4, s. 804-810
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Tidskriftsartikel (refereegranskat)abstract
- The molecular pathogenesis of the intestinal parasite Giardia intestinalis is still not fully understood but excretory-secretory products have been suggested to be important during host-parasite interactions. Here we used SOS-PAGE gels and MALDI-TOF analysis to identify proteins released by Giardia trophozoites during in vitro growth. Serum proteins (mainly bovine serum albumin) in the growth medium, bind to the parasite surface and they are continuously released, which interfere with parasite secretome characterization. However, we identified two released Giardia proteins: elongation factor-1 alpha (EF-1 alpha) and a 58 kDa protein, identified as arginine deiminase (ADI). This is the first description of EF-1 alpha as a released/secreted Giardia protein, whereas ADI has been identified in an earlier secretome study. Two genes encoding EF-1 alpha were detected in the Giardia WB genome 35 kbp apart with almost identical coding sequences but with different promoter and 3' regions. Promoter luciferase-fusions showed that both genes are transcribed in trophozoites. The EF-1 alpha protein localizes to the nuclear region in trophozoites but it relocalizes to the cytoplasm during host-cell interaction. Recombinant EF-1 alpha is recognized by serum from giardiasis patients. Our results suggest that released EF-1 alpha protein can be important during Giardia infections.
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| 37. |
- Steverding, Dietmar, et al.
(författare)
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Trypanocidal and cell swelling activity of 20-deoxysalinomycin
- 2022
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Ingår i: Experimental Parasitology. - : Elsevier BV. - 0014-4894. ; 243
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Tidskriftsartikel (refereegranskat)abstract
- The naturally occurring polyether ionophore salinomycin was previously found to display promising anti-proliferative activity against bloodstream forms of Trypanosoma brucei. Here, we report the evaluation of 20-deoxysalinomycin, a naturally occurring homolog to salinomycin, for trypanocidal and cell swelling activity. The concentration of 20-deoxysalinomycin required to reduce the growth rate of bloodstream-form trypanosomes by 50% was determined to be 0.12 μM and found to be 8 times more trypanocidal than that of salinomycin. Moreover, 20-deoxysalinomycin and salinomycin displayed similar cytotoxic activity against human HL-60 cells. Measured as the ratio of cytotoxic to trypanocidal activity, 20-deoxysalinomycin thus exhibits a four-fold higher selectivity compared to salinomycin. The stronger trypanocidal activity of 20-deoxysalinomycin is attributed to an enhanced ability to induce cell swelling in trypanosomes. The findings support 20-deoxysalinomycin as a useful lead in the rational development of new and improved anti-trypanosomal drugs.
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| 38. |
- Tan Grahn, Hooi Min, et al.
(författare)
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Roxithromycin potentiates the effects of chloroquine and mefloquine on multidrug-resistant Plasmodium falciparum in vitro
- 2007
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Ingår i: Experimental Parasitology. - : Elsevier BV. - 0014-4894. ; 115:4, s. 387-392
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Tidskriftsartikel (refereegranskat)abstract
- Chloroquine (CQ) and mefloquine (MQ) are no longer potent antimalarial drugs due to the emergence of resistant Plasmodium falciparum. Combination therapy has become the standard for many regimes in overcoming drug resistance. Roxithromycin (ROM), a known p-glycoprotein inhibitor, is reported to have antimalarial activity and it is hoped it will potentiate the effects of both CQ/MQ and reverse CQ/MQ-resistance. We assayed the effects of CQ and MQ individually and in combination with ROM on synchronized P. falciparum (Dd2 strain) cultures. The IC(50) values of CQ and MQ were 60.0+/-5.0 and 16.0+/-3.0 ng/ml; these were decreased substantially when combined with ROM. Isobolograms indicate that CQ-ROM combinations were relatively more synergistic (mean FICI 0.70) than MQ-ROM (mean FICI 0.85) with their synergistic effect at par with CQ-verapamil (VRP) (mean FICI 0.64) and MQ-VRP (mean FICI 0.60) combinations. We conclude that ROM potentiates the CQ/MQ response on multidrug-resistant P. falciparum.
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| 39. |
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| 40. |
- Winberg Tinnerfelt, Martin, et al.
(författare)
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Leishmania donovani : Inhibition of phagosomal maturation is rescued by nitric oxide in macrophages
- 2007
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Ingår i: Experimental parasitology. - : Elsevier BV. - 0014-4894 .- 1090-2449. ; 117:2, s. 165-170
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Tidskriftsartikel (refereegranskat)abstract
- Leishmania donovani promastigotes, the causative agent of visceral leishmaniasis, survive inside macrophages by inhibiting phagosomal maturation. The main surface glycoconjugate on promastigotes, lipophosphoglycan (LPG), is crucial for parasite survival. LPG has several detrimental effects on macrophage function, including inhibition of periphagosomal filamentous actin (F-actin) breakdown during phagosomal maturation. However, in RAW 264.7 macrophages pre-stimulated with lipopolysaccharide (LPS) and interferon ? (IFN?), known to up-regulate inducible nitric oxide synthase (iNOS) and nitric oxide (NO) production, L. donovani promastigotes are unable to inhibit periphagosomal F-actin breakdown and phagosomal maturation proceeds normally. Moreover, the iNOS inhibitor aminoguanidine, blocked the positive effects of LPS/IFN? suggesting that NO is a key player in F-actin remodeling. In conclusion, production of NO by stimulated macrophages seems to allow phagosomal maturation following uptake of L. donovani promastigotes, suggesting a novel mechanism whereby NO facilitates killing of an intracellular pathogen. © 2007 Elsevier Inc. All rights reserved.
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| 41. |
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| 42. |
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| 43. |
- Zehtindjiev, Pavel, et al.
(författare)
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Dynamics of parasitemia of malaria parasites in a naturally and experimentally infected migratory songbird, the great reed warbler Acrocephalus arundinaceus
- 2008
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Ingår i: Experimental Parasitology. - : Elsevier BV. - 0014-4894. ; 119:1, s. 99-110
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Tidskriftsartikel (refereegranskat)abstract
- Little is known about the development of infection of malaria parasites of the genus Plasmodium in wild birds. We used qPCR, targeting specific mitochondrial lineages of Plasmodium ashfordi (GRW2) and Plasmodium relictum (GRW4), to monitor changes in intensities of parasitemia in captive great reed warblers Acrocephalus arundinaceus from summer to spring. The study involved both naturally infected adults and experimentally infected juveniles. The experiment demonstrated that P. ashfordi and P. relictum lineages differ substantially in several life-history traits (e.g. prepatent period and dynamics of parasitemia) and that individual hosts show substantial differences in responses to these infections. The intensity of parasitemia of lineages in mixed infections co-varied positively, suggesting a control mechanism by the host that is general across the parasite lineages. The intensity of parasitemia for individual hosts was highly repeatable suggesting variation between the host individuals in their genetic or acquired control of the infections. In future studies, care must be taken to avoid mixed infections in wild caught donors, and when possible use mosquitoes for the experiments as inoculation of infectious blood ignores important initial stages of the contact between the bird and the parasite.
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| 44. |
- Patti, Giuseppe, et al.
(författare)
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Clustering of blood cell count abnormalities and future risk of death
- 2021
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Ingår i: European Journal of Clinical Investigation. - : Wiley. - 0014-2972 .- 1365-2362. ; 51:8
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The identification of novel predictors of poor outcome may help stratify cardiovascular risk. Aim was to evaluate the individual contribution of blood cell count parameters, as well as their clustering, on the risk of death and cardiovascular events over the long term in the population-based Malmö Diet and Cancer Study cohort.METHODS: In 30,447 individuals (age 57 ± 8 years), we assessed the incidence of all-cause death (primary endpoint) and major adverse cardiovascular events (MACE, secondary outcome measure) according to absence or presence of one, two and three factors at baseline out of the following: anaemia, leukocytosis and thrombocytosis. Median follow-up was 16 years.RESULTS: The percentages of all-cause death were 19.5% in individuals without factors, 21.3% in those with one factor, 27.4% with two and 46.4% with three (log-rank test P < .001). The crude incidence of MACE was 28.0%, 29.2%, 35.5% and 57.1%, respectively (log-rank test P < .001). At multivariate analysis, we found a stepwise increase in overall mortality with increasing number of prevalent factors (one factor: HR 1.23, 95% CI 1.14-1.31, P < .001; two factors: 1.61, 1.37-1.89, P < .001; three factors: 2.69, 1.44-5.01, P = .002, vs no factor). Similar findings were observed for the incidence of MACE (one factor: adjusted HR 1.18, 95% CI 1.11-1.24, P < .001; two factors: 1.52, 1.33-1.76, P < .001; three factors: 2.03, 1.21-3.67, P < .001, vs no factor).CONCLUSIONS: The easily assessable clustering of anaemia, leukocytosis and thrombocytosis heralds higher incidence of death and adverse cardiovascular events.
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