| 1. |
- Gillman, Anna, et al.
(författare)
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Oseltamivir-Resistant Influenza A (H1N1) Virus Strain with an H274Y Mutation in Neuraminidase Persists without Drug Pressure in Infected Mallards
- 2015
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Ingår i: Applied and Environmental Microbiology. - : American Society for Microbiology. - 0099-2240 .- 1098-5336. ; 81:7, s. 2378-2383
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Tidskriftsartikel (refereegranskat)abstract
- Influenza A virus (IAV) has its natural reservoir in wild waterfowl and emerging human IAVs often contain gene segments from avian viruses. The active drug metabolite of oseltamivir (oseltamivir carboxylate (OC)), stockpiled as Tamiflu® for influenza pandemic preparedness, is not removed by conventional sewage treatment and has been detected in river water. There, it may there exert evolutionary pressure on avian IAV in waterfowl, resulting in development of resistant viral variants. A resistant avian IAV can circulate among wild birds only if resistance does not restrict viral fitness and if the resistant virus can persist without continuous drug pressure. In this in vivo Mallard (Anas platyrhynchos) study we tested if an OC-resistant avian IAV strain (A(H1N1)/NA-H274Y) could retain resistance while drug pressure was gradually removed. Successively infected Mallards were exposed to decreasing levels of OC, and fecal samples were analyzed for neuraminidase sequence and phenotypic resistance. No reversion to wild-type virus was observed during the experiment, which included 17 days of viral transmission in 10 ducks exposed to OC concentrations below resistance induction levels. We conclude that resistance in avian IAV, induced by OC exposure of the natural host, can persist in absence of the drug. Thus, there is a risk that human pathogenic IAVs that evolve from IAVs circulating among wild birds may contain resistance mutations. An oseltamivir resistant pandemic IAV would be a substantial public health threat. Therefore, our observations underscore the need for prudent oseltamivir use, upgraded sewage treatment and resistance surveillance of IAV in wild birds.
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| 2. |
- Tolf, Conny, et al.
(författare)
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Individual variation in influenza A virus infection histories and long-term immune responses in mallards
- 2013
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:4, s. e61201-
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Tidskriftsartikel (refereegranskat)abstract
- Wild dabbling ducks (genus Anas) are the main reservoir for influenza A virus (IAV) in the Northern Hemisphere. Current understanding of disease dynamics and epidemiology in this virus-host system has primarily been based on populationlevel ,surveillance studies and infection experiments conducted in laboratory settings. Using a combined experimentalnatural approach with wild-strain captive mallards (Anas platyrhynchos), we monitored individual IAV infection histories and immunological responses of 10 birds over the course of 15 months. This is the first detailed study to track natural IAV infection histories over several seasons amongst the same individuals growing from juvenile to adults. The general trends in the infection histories of the monitored birds reflected seasonal variation in prevalence at the population level. However, within the study group there were significant differences between individuals in infection frequency as well as in short and long term anti-IAV antibody response. Further observations included individual variation in the number of infecting virus subtypes, and a strong tendency for long-lasting hemagglutinin-related homosubtypic immunity. Specifically, all infections in the second autumn, except one, were of different subtypes compared to the first autumn. The variation among birds concerning these epidemiologically important traits illustrates the necessity for IAV studies to move from the level of populations to examine individuals in order to further our understanding of IAV disease and epidemiology.
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| 3. |
- Björklund, Erland, et al.
(författare)
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MORPHEUS success story Segesholmsån river and Degeberga WWTP, Skåne, Sweden
- 2021
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In the MORPHEUS project three Swedish Wastewater Treatment Plants (WWTPs) were investigated for their release of pharmaceuticals into the recipient. One of these was Degeberga WWTP which discharges its treated wastewater into the Segesholmsån river, ending in the Baltic Sea. Segesholmsån river has a length of 23 km and an average flow of roughly 0.6 m3/s (Figure 1).
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| 4. |
- Schill, Ralph O., et al.
(författare)
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Food of tardigrades : a case study to understand food choice, intake and digestion
- 2011
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Ingår i: Journal of Zoological Systematics and Evolutionary Research. - 0947-5745 .- 1439-0469. ; 49:Suppl. 1, s. 66-70
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Tidskriftsartikel (refereegranskat)abstract
- Mosses are an excellent habitat for tardigrades because of their ability to ensure a high humidity and to provide a rich food supply for both carnivorous and herbivorous species. Food choice can be correlated with the morphology of the buccal apparatus, and consequentially, their distribution is sometimes linked to food availability (nematodes, rotifers, plant cells, algae, yeast and bacteria). In many species, material containing chlorophyll is often observed in the midgut. However, little information has been available until now on the actual food preference of tardigrades. Since trophic interactions within soil food webs are difficult to study, here we use a polymerase chain reaction–based approach as a highly sensitive detection method. The study was carried out to investigate the presence of chlorophyll matter in the gut of active specimens, based on sequence analyses of the chloroplast ribulose 1,5-bisphosphate carboxylase/oxygenase large subunit (rbcL) gene from mosses and algae. The sequences found in the gut of Macrobiotus sapiens were derived from the moss families Pottiaceae and Erpodiaceae, in Macrobiotus persimilis and Echiniscus granulatus from the moss family Grimmiaceae, and in Richtersius coronifer from the green algae genus Trebouxia. Furthermore, we show the emission of green autofluorescence from the chloroplasts in the algae within the gut of tardigrades and followed the progress of digestion over a 48-h period. The autofluorescent emission level declined significantly, and after 2 days, the signal level was similar to the level of the starved control.
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| 5. |
- Möllenkvist, Andrea, et al.
(författare)
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The Moraxella catarrhalis immunoglobulin D-binding protein MID has conserved sequences and is regulated by a mechanism corresponding to phase variation
- 2003
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Ingår i: Journal of Bacteriology. - : American Society for Microbiology. - 0021-9193 .- 1098-5530. ; 185:7, s. 2285-2295
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Tidskriftsartikel (refereegranskat)abstract
- The prevalence of the Moraxella catarrhalis immunoglobulin D (IgD)-binding outer membrane protein MID and its gene was determined in 91 clinical isolates and in 7 culture collection strains. Eighty-four percent of the clinical Moraxella strains expressed MID-dependent IgD binding. The mid gene was detected in all strains as revealed by homology of the signal peptide sequence and a conserved area in the 3' end of the gene. When MID proteins from five different strains were compared, an identity of 65.3 to 85.0% and a similarity of 71.2 to 89.1% were detected. Gene analyses showed several amino acid repeat motifs in the open reading frames, and MID could be called a putative autotransport protein. Interestingly, homopolymeric [polyguanine [poly(G)]] tracts were detected at the 5' ends within the open reading frames. By flow cytometry, using human IgD and fluorescein isothiocyanate-conjugated anti-IgD polyclonal antibodies, most strains showed two peaks: one high- and one low-intensity peak. All isolates expressing high levels of MID had 1, 2, or 3 triplets of G's in their poly(G) tracts, while strains not expressing MID had 4, 7, 8, or 10 G's in their poly(G) tracts or point mutations causing a putative preterminated translation. Northern blot analysis revealed that the mid gene was regulated at the transcriptional level. Experiments with nonclumping variants of M. catarrhalis proved that bacteria lost their MID expression by removing a G in their poly(G) tracts. Moraxella strains isolated from the nasopharynx or from blood and sputum specimens expressed MID at approximately the same frequency. In addition, no variation was observed between strains of different geographical origins (Australia, Europe, Japan, or the United States). MID and the mid gene were found solely in M. catarrhalis, whereas related Neisseria and Moraxella species did not express MID. Taken together, MID appears to be a conserved protein that can be found in essentially all M. catarrhalis strains. Furthermore, MID is governed by poly(G) tracts when bacteria undergo phase variation.
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| 6. |
- Bengtsson, Torbjörn, et al.
(författare)
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Secreted gingipains from P. gingivalis colonies exert potent immunomodulatory effects on human gingival fibroblasts
- 2015
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Ingår i: Microbiological Research. - 0944-5013. ; 178, s. 18-26
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Tidskriftsartikel (refereegranskat)abstract
- Periodontal pathogens, including Porphyromonas gingivalis, can form biofilms in dental pockets and cause inflammation, which is one of the underlying mechanisms involved in the development of periodontal disease, ultimately leading to tooth loss. Although P. gingivalis is protected in the biofilm, it can still cause damage and modulate inflammatory responses from the host, through secretion of microvesicles containing proteinases. The aim of this study was to evaluate the role of cysteine proteinases in P. gingivalis colony growth and development, and subsequent immunomodulatory effects on human gingival fibroblast. By comparing the wild type W50 with its gingipain deficient strains we show that cysteine proteinases are required by P. gingivalis to form morphologically normal colonies. The lysine-specific proteinase (Kgp), but not arginine-specific proteinases (Rgps), was associated with immunomodulation. P. gingivalis with Kgp affected the viability of gingival fibroblasts and modulated host inflammatory responses, including induction of TGF-β1 and suppression of CXCL8 and IL-6 accumulation. These results suggest that secreted products from P. gingivalis, including proteinases, are able to cause damage and significantly modulate the levels of inflammatory mediators, independent of a physical host-bacterial interaction. This study provides new insight of the pathogenesis of P. gingivalis and suggests gingipains as targets for diagnosis and treatment of periodontitis.
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| 7. |
- Blomqvist, Maria, et al.
(författare)
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Chlamydia psittaci in birds of prey, Sweden
- 2012
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Ingår i: Infection Ecology and Epidemiology. - 2000-8686. ; 2, s. 8435-
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Tidskriftsartikel (refereegranskat)abstract
- Background: Chlamydia psittaci is an intracellular bacterium primarily causing respiratory diseases in birds but may also be transmitted to other animals, including humans. The prevalence of the pathogen in wild birds in Sweden is largely unknown. Methods: DNA was extracted from cloacae swabs and screened for C. psittaci by using a 23S rRNA gene PCR assay. Partial 16S rRNA and ompA gene fragments were sequence determined and phylogenies were analysed by the neighbour-joining method. Results and conclusion: The C. psittaci prevalence was 1.3% in 319 Peregrine Falcons and White-tailed Sea Eagles, vulnerable top-predators in Sweden. 16S rRNA and ompA gene analysis showed that novel Chlamydia species, as well as novel C. psittaci strains, are to be found among wild birds.
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| 8. |
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| 9. |
- Collin, Betty, 1976-
(författare)
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Characterization and persistence of potential human pathogenic vibrios in aquatic environments
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Vibrio spp., natural inhabitants of aquatic environments, are one of the most common causes of bacterial gastroenteritis in the world, being spread to humans via the ingestion of seafood, contaminated drinking water or exposure to seawater. The majority of Vibrio spp. are avirulent, but certain strains may sporadically be human pathogenic. Vibrio cholerae may cause cholera and fatal wound infections, Vibrio parahaemolyticus may cause gastroenteritis and Vibrio vulnificus may cause wound infections and sepsis. To expand current knowledge of the occurrence, ecological niche and persistence of potential human pathogenic Vibrio spp. in aquatic environments, occurrence and laboratory studies were performed. The seasonal variation of Vibrio spp. in clams and mussels from Mozambique and Sweden were studied, with isolated strains characterized and compared with those isolated from water samples collected in India. Results showed that the numbers of Vibrio spp. in Mozambican clams peaked during the warmer rainy season and that the dominating species was V. parahaemolyticus. Biochemical fingerprinting and virulence screened by PCR revealed a high similarity among strains from the different aquatic environments. However, isolate functional hemolytic analyses and antibiotic resistance patterns differed between strains; Swedish and Indian strains were less sensitive to the tested antibiotics and had a lower hemolytic capacity than those from Mozambique. Molecular analysis of bacterial DNA from Swedish mussels showed the presence of the three Vibrio spp. most commonly linked with human illness, as well as their associated virulence genes. The strains isolated from marine and clinical environments were equally and highly harmful to the tested eukaryotic cells. The persistence of clinical V. cholerae in aquatic environments was investigated in vivo. Strains were exposed to mussels, with bacterial uptake and elimination then examined. The mussels were able to avoid the most potent strain by complete closure of shells. The less potent strain was accumulated in mussel tissue in low levels and one marine control strain to a higher degree. Mussels eliminated the pathogenic strain less efficiently than they did the marine strain. One clinical and one marine strain were then exposed to 4°C for 21 days, with the temperature then increased to 20°C. The clinical strain was more prone to lose culturability than the marine strain at 4°C, the former performed significantly better in regaining culturability after the temperature up-shift. Subsequently, the persistence of the clinical strain in natural bottom sediment, incubating as above, was studied and results showed a similar decrease in culturable numbers in the sediment as in the water. As the clinical V. cholerae strains did not carry any of the standard set of virulence genes, the ability to change from non-culturable to culturable may be of great importance to strain pathogenicity. The results also show that natural bottom sediment may be a potential reservoir of human pathogenic Vibrio spp.
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| 10. |
- Collin, Betty, 1976-, et al.
(författare)
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Occurrence and potential pathogenesis of Vibrio cholerae, Vibrio parahaemolyticus and Vibrio vulnificus on the South Coast of Sweden
- 2011
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Ingår i: FEMS Microbiology Ecology. - 0168-6496 .- 1574-6941. ; 78:2, s. 306-313
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Tidskriftsartikel (refereegranskat)abstract
- During the summer of 2006, several wound infections - of which three were fatal caused by Vibrio cholerae were reported from patients who had been exposed to water from the Baltic Sea. Before these reports, we initiated a sampling project investigating the occurrence of potential human pathogenic V. cholerae, Vibrio vulnificus and Vibrio parahaemolyticus in The Sound between Sweden and Denmark. The Blue mussel (Mytilus edulis) was used as an indicator to follow the occurrence of vibrios over time. Molecular analyses showed high frequencies of the most potent human pathogenic Vibrio spp.; 53% of mussel samples were positive for V. cholerae (although none were positive for the cholera toxin gene), 63% for V. vulnificus and 79% for V. parahaemolyticus (of which 47% were tdh(+) and/or trh(+)). Viable vibrios were also isolated from the mussel meat and screened for virulence by PCR. The mortality of eukaryotic cells when exposed to bacteria was tested in vivo, with results showing that the Vibrio strains, independent of species and origin, were harmful to the cells. Despite severe infections and several deaths, no report on potential human pathogenic vibrios in this area had been published before this study.
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