Publications by authors named "Martina Köhsler"

16 Publications

  • Page 1 of 1

An unusual thioredoxin system in the facultative parasite Acanthamoeba castellanii.

Cell Mol Life Sci 2021 Apr 18;78(7):3673-3689. Epub 2021 Feb 18.

Institute of Specific Prophylaxis and Tropical Medicine, Medical University of Vienna, Kinderspitalgasse 15, 1090, Vienna, Austria.

The free-living amoeba Acanthamoeba castellanii occurs worldwide in soil and water and feeds on bacteria and other microorganisms. It is, however, also a facultative parasite and can cause serious infections in humans. The annotated genome of A. castellanii (strain Neff) suggests the presence of two different thioredoxin reductases (TrxR), of which one is of the small bacterial type and the other of the large vertebrate type. This combination is highly unusual. Similar to vertebrate TrxRases, the gene coding for the large TrxR in A. castellanii contains a UGA stop codon at the C-terminal active site, suggesting the presence of selenocysteine. We characterized the thioredoxin system in A. castellanii in conjunction with glutathione reductase (GR), to obtain a more complete understanding of the redox system in A. castellanii and the roles of its components in the response to oxidative stress. Both TrxRases localize to the cytoplasm, whereas GR localizes to the cytoplasm and the large organelle fraction. We could only identify one thioredoxin (Trx-1) to be indeed reduced by one of the TrxRases, i.e., by the small TrxR. This thioredoxin, in turn, could reduce one of the two peroxiredoxins tested and also methionine sulfoxide reductase A (MsrA). Upon exposure to hydrogen peroxide and diamide, only the small TrxR was upregulated in expression at the mRNA and protein levels, but not the large TrxR. Our results show that the small TrxR is involved in the A. castellanii's response to oxidative stress. The role of the large TrxR, however, remains elusive.
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http://dx.doi.org/10.1007/s00018-021-03786-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8038987PMC
April 2021

Phlebotomus (Adlerius) simici NITZULESCU, 1931: first record in Austria and phylogenetic relationship with other Adlerius species.

Parasit Vectors 2021 Jan 6;14(1):20. Epub 2021 Jan 6.

Institute of Specific Prophylaxis and Tropical Medicine, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria.

Background: Phlebotomine sand flies are the principal vectors of Leishmania spp. (Kinetoplastida: Trypanosomatidae). Information on sand flies in Central Europe is scarce and, to date, in Austria, only Phlebotomus mascittii has been recorded. In 2018 and 2019, entomological surveys were conducted in Austria with the aim to further clarify sand fly distribution and species composition.

Results: In 2019, a Ph. simici specimen was trapped in Austria for the first time. Analyses of two commonly used marker genes, cytochrome c oxidase I (coxI) and cytochrome b (cytb), revealed high sequence identity with Ph. simici specimens from North Macedonia and Greece. Phylogenetic analyses showed high intraspecific distances within Ph. simici, thereby dividing this species into three lineages: one each from Europe, Turkey and Israel. Low interspecific distances between Ph. simici, Ph. brevis and an as yet unidentified Adlerius sp. from Turkey and Armenia highlight how challenging molecular identification within the Adlerius complex can be, even when standard marker genes are applied.

Conclusion: To our knowledge, this study reports the first finding of Ph. simici in Austria, representing the northernmost recording of this species to date. Moreover, it reveals valuable insights into the phylogenetic relationships among species within the subgenus Adlerius. Phlebotomus simici is a suspected vector of L. infantum and therefore of medical and veterinary importance. Potential sand fly expansion in Central Europe due to climatic change and the increasing import of Leishmania-infected dogs from endemic areas support the need for further studies on sand fly distribution in Austria and Central Europe in general.
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http://dx.doi.org/10.1186/s13071-020-04482-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7788815PMC
January 2021

Integrative Approach to Grassi, 1908: First Record in Vienna with New Morphological and Molecular Insights.

Pathogens 2020 Dec 9;9(12). Epub 2020 Dec 9.

Institute of Specific Prophylaxis and Tropical Medicine, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, 1090 Vienna, Austria.

Sand flies (Diptera: Psychodidae: Phlebotominae) are blood-feeding insects that transmit the protozoan parasites spp. and various arthropod-borne (arbo) viruses. While in Mediterranean parts of Europe the sand fly fauna is diverse, in Central European countries including Austria mainly is found, an assumed but unproven vector of . To update the currently understudied sand fly distribution in Austria, a sand fly survey was performed and other entomological catches were screened for sand flies. Seven new trapping locations of are reported including the first record in Vienna, representing also one of the first findings of this species in a city. Morphological identification, supported by fluorescence microscopy, was confirmed by two molecular approaches, including sequencing and matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) protein profiling. Sand fly occurrence and activity were evaluated based on surveyed locations, habitat requirements and climatic parameters. Moreover, a first comparison of European populations was made by two marker genes, cytochrome c oxidase subunit 1 (), and cytochrome b (), as well as MALDI-TOF mass spectra. Our study provides new important records of in Austria and valuable data for prospective entomological surveys. MALDI-TOF MS protein profiling was shown to be a reliable tool for differentiation between sand fly species. Rising temperatures and globalization demand for regular entomological surveys to monitor changes in species distribution and composition. This is also important with respect to the possible vector competence of .
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http://dx.doi.org/10.3390/pathogens9121032DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7764109PMC
December 2020

Validation of reference genes for the normalization of RT-qPCR gene expression in Acanthamoeba spp.

Sci Rep 2020 06 25;10(1):10362. Epub 2020 Jun 25.

Institute of Specific Prophylaxis und Tropical Medicine, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria.

Acanthamoebae are potentially pathogenic organisms, with a highly unique, yet still insufficiently investigated metabolism. Many open questions can be addressed by gene expression studies, however, for Acanthamoeba reliable standards have not yet been established. In this study, suitable reference genes (RGs) for RT-qPCR in Acanthamoeba were comprehensively evaluated, comparing different Acanthamoeba strains and employing four different algorithms (NormFinder, GeNorm, BestKeeper and RefFinder). Expression stability was assessed under various conditions and the potentials of the most promising RGs for accurate normalization of target genes were evaluated. Expression stability of RGs varied depending on conditions and employed algorithms, however, the genes for the 18S rRNA and the hypoxanthine phosphoribosyl transferase seem to be widely suitable RGs. Normalization with a combination of two carefully chosen RGs resulted in reliable expression data for target genes, while normalization with unsuitable RGs led to significant misinterpretation of expression profiles. Thus, a careful evaluation of RGs prior to expression studies is essential.
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http://dx.doi.org/10.1038/s41598-020-67035-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7316857PMC
June 2020

Diversity of digenean trematode larvae in snails from Lake Victoria, Kenya: First reports and bioindicative aspects.

Acta Trop 2020 Jun 6;206:105437. Epub 2020 Mar 6.

University of Vienna, Institute of Inorganic Chemistry, Althanstrasse 14, 1090, Vienna, Austria; University of Johannesburg, Department of Zoology, P.O. Box 524, Auckland Park, 2006, South Africa. Electronic address:

This study investigated the occurrence of digenean trematode larvae in snails from the Kenyan part of Lake Victoria. The survey included caenogastropod snails that have received less focus in parasitological studies in Africa: their trematodes are largely unknown. Out of 1145 snail specimens, 149 (13.0%) were infected with Digenea. The highest prevalence (P) was recorded in Melanoides tuberculata (64.5%), followed by Pila ovata (15.4%), Radix natalensis (9.5%), Bulinus ugandae (9.1%), Bellamya unicolor (8.9%), Biomphalaria pfeifferi (7.3%) and Biomphalaria sudanica (4.4%). Morphological and molecular analyses revealed 17 digenean species. Contrary to reports of low diversity of Digenea in caenogastropods, P. ovata harboured 8 species - at least twice as many as in each of the pulmonates. The following taxa are reported for the first time in the Lake Victoria region: Haplorchis pumilio, Thapariella prudhoei, Nudacotyle sp., Renicola sp. and Bolbophorus sp. An unknown cercaria belonging to the genus Haematoloechus is reported from P. ovata: a xiphidiocercaria possessing a long sword-shaped stylet (47-71 µm) which does not match any available literature records. From this study, H. pumilio from M. tuberculata (P = 69.4%), Fasciola gigantica from R. natalensis (P = 1.9%) and Bolbophorus sp. from Bu. ugandae (P = 4.6%) are species of veterinary or medical importance. Snails from the study site with little direct anthropogenic influence had the highest prevalence and diversity of digenean larvae, indicating that environmental conditions influence trematode occurrence.
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http://dx.doi.org/10.1016/j.actatropica.2020.105437DOI Listing
June 2020

Recovery of an Acanthamoeba strain with two group I introns in the nuclear 18S rRNA gene.

Eur J Protistol 2019 Apr 28;68:88-98. Epub 2019 Jan 28.

Institute of Tropical Medicine and Specific Prophylaxis, Centre for Pathophysiology, Infectiology, and Immunology, Medical University of Vienna, Kinderspitalgasse 15, 1090 Vienna, Austria.

Nuclear group I introns are parasitic mobile genetic elements occurring in the ribosomal RNA genes of a large variety of microbial eukaryotes. In Acanthamoeba, group I introns were found occurring in the 18S rDNA at four distinct insertion sites. Introns are present as single elements in various strains belonging to four genotypes, T3 (A. griffini), T4 (A. castellanii complex), T5 (A. lenticulata) and T15 (A. jacobsi). While multiple introns can frequently be found in the rDNA of several algae, fungi and slime moulds, they are usually rare and present as single elements in amoebae. We reported herein the characterization of an A. lenticulata strain containing two introns in its 18S rDNA. They are located to already known sites and show basal relationships with respective homologous introns present in the other T5 strains. This is the first and unique reported case of multiple nuclear introns in Acanthamoeba.
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http://dx.doi.org/10.1016/j.ejop.2019.01.007DOI Listing
April 2019

New insights from molecular phylogenetics of amoebophagous fungi (Zoopagomycota, Zoopagales).

Parasitol Res 2018 Jan 23;117(1):157-167. Epub 2017 Nov 23.

Central Institute of the Federal Armed Forces Medical Services, P.O. Box 7340, D 56070, Koblenz, Germany.

Amoebophagous fungi are represented in all fungal groups: Basidiomycota, Ascomycota, Zygomycota, and Chytridiomycota. The amoebophagous fungi, within the zygomycota (Zoopagales, Zoopagomycota), mainly affect naked amoebae as ectoparasites or endoparasites. It is rather difficult to isolate members of the Zoopagales, because of their parasitic lifestyle, and to bring them into culture. Consequently, gene sequences of this group are undersampled, and its species composition and phylogeny are relatively unknown. In the present study, we were able to isolate amoebophagous fungi together with their amoeba hosts from various habitats (moss, pond, bark, and soil). Altogether, four fungal strains belonging to the genera Acaulopage and Stylopage plus one unidentified isolate were detected. Sequences of the 18S rDNA and the complete ITS region and partial 28S (LSU) rDNA were generated. Subsequent phylogenetic analyses showed that all new isolates diverge at one branch together with two environmental clonal sequences within the Zoopagomycota. Here, we provide the first molecular characterization of the genus Stylopage. Stylopage is closely related to the genus Acaulopage. In addition, taxonomy and phylogeny of amoebophagous fungi and their ecological importance are reviewed based on new sequence data, which includes environmental clonal sequences.
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http://dx.doi.org/10.1007/s00436-017-5685-6DOI Listing
January 2018

'Candidatus Cochliophilus cryoturris' (Coxiellaceae), a symbiont of the testate amoeba Cochliopodium minus.

Sci Rep 2017 06 13;7(1):3394. Epub 2017 Jun 13.

Division of Microbial Ecology, Department of Microbiology and Ecosystem Science, University of Vienna, Vienna, Austria.

Free-living amoebae are well known for their role in controlling microbial community composition through grazing, but some groups, namely Acanthamoeba species, also frequently serve as hosts for bacterial symbionts. Here we report the first identification of a bacterial symbiont in the testate amoeba Cochliopodium. The amoeba was isolated from a cooling tower water sample and identified as C. minus. Fluorescence in situ hybridization and transmission electron microscopy revealed intracellular symbionts located in vacuoles. 16S rRNA-based phylogenetic analysis identified the endosymbiont as member of a monophyletic group within the family Coxiellaceae (Gammaprotebacteria; Legionellales), only moderately related to known amoeba symbionts. We propose to tentatively classify these bacteria as 'Candidatus Cochliophilus cryoturris'. Our findings add both, a novel group of amoeba and a novel group of symbionts, to the growing list of bacteria-amoeba relationships.
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http://dx.doi.org/10.1038/s41598-017-03642-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5469826PMC
June 2017

Update on Acanthamoeba jacobsi genotype T15, including full-length 18S rDNA molecular phylogeny.

Parasitol Res 2017 Apr 11;116(4):1273-1284. Epub 2017 Feb 11.

Molecular Parasitology, Institute of Specific Prophylaxis and Tropical Medicine, Medical University of Vienna, Kinderspitalgasse 15, 1090, Vienna, Austria.

Free-living amoebae of the genus Acanthamoeba are worldwide present in natural and artificial environments, and are also clinically important, as causative agents of diseases in humans and other animals. Acanthamoeba comprises several species, historically assigned to one of the three groups based on their cyst morphology, but presently recognized as at least 20 genotypes (T1-T20) on the basis of their nuclear 18S ribosomal RNA (rRNA) gene (18S rDNA) sequences. While strain identification may usually be achieved targeting short (<500 bp) 18S ribosomal DNA (rDNA) fragments, the use of full-length gene sequences (>2200 bp) is necessary for correct genotype description and reliable molecular phylogenetic inference. The genotype T15, corresponding to Acanthamoeba jacobsi, is the only genotype described on the basis of partial sequences (~1500 bp). While this feature does not prevent the correct identification of the strains, having only partial sequences renders the genotype T15 not completely defined and may furthermore affect its position in the Acanthamoeba molecular tree. Here, we complete this gap, by obtaining full-length 18S rDNA sequences from eight A. jacobsi strains, genotype T15. Morphologies and physiological features of isolated strains are reported. Molecular phylogeny based on full 18S rDNA confirms some previous suggestions for a genetic link between T15 and T13, T16, and T19, with T19 as sister-group to T15.
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http://dx.doi.org/10.1007/s00436-017-5406-1DOI Listing
April 2017

Acanthamoeba misidentification and multiple labels: redefining genotypes T16, T19, and T20 and proposal for Acanthamoeba micheli sp. nov. (genotype T19).

Parasitol Res 2015 Jul 15;114(7):2481-90. Epub 2015 Apr 15.

CHLAREAS Chlamydia Research Association, 12 rue du Maconnais, Vandoeuvre-lès-Nancy, 54500, Nancy, France,

Acanthamoeba species are ubiquitous amoebae able to cause important infections in humans and other vertebrates. The full/near-full sequences (>2000 bp) of the small subunit ribosomal RNA gene (SSU rDNA or 18S rDNA) are used to cluster Acanthamoeba as genotypes, labeled T1 to T20. Genotype T15 remains an exception, being described only partially on a 1500-bp fragment. Strains are thus usually identified based on their 18S identity matches with reference strains, often using shorter (<500 bp) diagnostic fragments of the gene. Nevertheless, short fragments (<1000 bp) have been used to propose genotypes. This has been criticized, and doubts arise therefore on possible confusion leading to classify distinct partial sequences with a same label(s). We demonstrate herein that several partial sequences misassigned either to T16 or to T4, actually belong to at least two separate and distinct genotypes. We obtained the full 18S rDNA of a strain previously typed as T16 on the basis of a small fragment and demonstrated that it actually belongs to the recently described T19. We propose the name Acanthamoeba micheli sp. nov., for this strain. Furthermore, partial molecular phylogenies were performed to show that several other misassigned T16 partial sequences belong to a new genotype. This latter includes also misassigned T4 partial sequences, only recently available as full sequences and labeled as T20. We thus reassign these partial sequences to the genotype T20. Longer sequences, ideally at least 90 % of the total gene length, should be obtained from strains to ensure reliable diagnostic and phylogenetic results.
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http://dx.doi.org/10.1007/s00436-015-4445-8DOI Listing
July 2015

Proteomic aspects of Parachlamydia acanthamoebae infection in Acanthamoeba spp.

ISME J 2010 Nov 20;4(11):1366-74. Epub 2010 May 20.

Department of Specific Prophylaxis and Tropical Medicine at the Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Kinderspitalgasse 15, Vienna A-1090, Austria.

The free-living but facultatively pathogenic amoebae of the genus Acanthamoeba are frequently infected with bacterial endosymbionts that can have a profound influence on the physiology and viability of their host. Parachlamydia acanthamoebae, a chlamydial endosymbiont in acanthamoebae, is known to be either symbiotic or lytic to its host, depending on the ambient conditions, for example, temperature. Moreover, parachlamydiae can also inhibit the encystment process in Acanthamoeba, an essential survival strategy of their host for the evasion of chemotherapeutic agents, heat, desiccation and radiation. To obtain a more detailed picture of the intracellular interactions of parachlamydiae and acanthamoebae, we studied parachlamydial infection in several Acanthamoeba isolates at the proteomic level by means of two-dimensional gel electrophoresis (2DE) and mass spectrometry. We observed that P. acanthamoebae can infect all three morphological subtypes of the genus Acanthamoeba and that the proteome pattern of released P. acanthamoebae elementary bodies was always practically identical regardless of the Acanthamoeba strain infected. Moreover, by comparing proteome patterns of encysting cells from infected and uninfected Acanthamoeba cultures, it was shown that encystment is blocked by P. acanthamoebae at a very early stage. Finally, on 2D-gels of purified P. acanthamoebae from culture supernatants, a subunit of the NADH-ubiquinone oxidoreductase complex, that is, an enzyme that has been described as an indicator for bacterial virulence was identified by a mass spectrometric and bioinformatic approach.
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http://dx.doi.org/10.1038/ismej.2010.68DOI Listing
November 2010

Major role for cysteine proteases during the early phase of Acanthamoeba castellanii encystment.

Eukaryot Cell 2010 Apr 26;9(4):611-8. Epub 2010 Feb 26.

Department of Specific Prophylaxis and Tropical Medicine, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria.

Acanthamoeba castellanii is a facultative pathogen that has a two-stage life cycle comprising the vegetatively growing trophozoite stage and the dormant cyst stage. Cysts are formed when the cell encounters unfavorable conditions, such as environmental stress or food deprivation. Due to their rigid double-layered wall, Acanthamoeba cysts are highly resistant to antiamoebic drugs. This is problematic as cysts can survive initially successful chemotherapeutic treatment and cause relapse of the disease. We studied the Acanthamoeba encystment process by using two-dimensional gel electrophoresis (2DE) and found that most changes in the protein content occur early in the process. Truncated actin isoforms were found to abound in the encysting cell, and the levels of translation elongation factor 2 (EF2) were sharply decreased, indicating that the rate of protein synthesis must be low at this stage. In the advanced stage of encystment, however, EF2 levels and the trophozoite proteome were partly restored. The protease inhibitors PMSF (phenylmethylsulfonyl fluoride) and E64d [(2S,3S)-trans-epoxysuccinyl-L-leucylamido-3-methylbutane ethyl ester] inhibited the onset of encystment, whereas the protein synthesis inhibitor cycloheximide was ineffective. Changes in the protein profile, similar to those of encysting cells, could be observed with trophozoite homogenates incubated at room temperature for several hours. Interestingly, these changes could be inhibited significantly by cysteine protease inhibitors but not by inhibitors against other proteases. Taken together, we conclude that the encystment process in A. castellanii is of a bipartite nature consisting of an initial phase of autolysis and protein degradation and an advanced stage of restoration accompanied by the expression of encystment-specific genes.
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http://dx.doi.org/10.1128/EC.00300-09DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2863413PMC
April 2010

Acanthamoeba strains lose their abilities to encyst synchronously upon prolonged axenic culture.

Parasitol Res 2008 Apr 5;102(5):1069-72. Epub 2008 Feb 5.

Department of Medical Parasitology, Clinical Institute of Hygiene and Medical Microbiology, Medical University of Vienna, Vienna, Austria.

To evaluate the influence of prolonged axenic culture on the encystment capacity of Acanthamoeba spp., the encystment potential of four closely related Acanthamoeba strains, subcultured axenically for different periods of time, was evaluated comparing five encystment media. Media with more alkaline pH values were slightly more effective; however, the composition of the respective encystment medium had only limited influence on the encystment potential, while a strong correlation of losses in encystment potential and times strains had been cultured axenically was demonstrated. Furthermore, our results indicate that losses in encystment potential occur shortly after transfer into axenic culture to remain constant over many years.
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http://dx.doi.org/10.1007/s00436-008-0885-8DOI Listing
April 2008

Cytotoxic activity of N-chlorotaurine on Acanthamoeba spp.

Antimicrob Agents Chemother 2008 Feb 26;52(2):470-6. Epub 2007 Nov 26.

Department of Medical Parasitology, Clinical Institute of Hygiene and Medical Microbiology, Medical University of Vienna, Kinderspitalgasse 15, Vienna A-1095, Austria.

Acanthamoeba spp. are the causative agents of Acanthamoeba keratitis (AK), which mainly occurs in contact lens wearers, and of skin lesions, granulomatous amoebic encephalitis (GAE), and disseminating diseases in the immunocompromised host. AK therapy is complex and irritating for the eye, skin lesions are difficult to treat, and there is no effective treatment for GAE. Therefore, new anti-Acanthamoeba drugs are needed. We investigated the anti-Acanthamoeba activity of N-chlorotaurine (NCT), an endogenous mild antiseptic. It was shown that NCT has amoebicidal qualities, both in phosphate-buffered saline (PBS) and in amoebic culture medium. After 6 h of treatment with 10 mM NCT in PBS, the levels of trophozoites of all strains investigated already showed at least a 2-log reduction. When the trophozoites were treated with 20 mM NCT in culture medium, they showed a 2-log reduction after 24 h. The addition of NH(4)Cl to NCT led to a faster decrease in the numbers of living cells, if tests were carried out in PBS. A delay of excystation was observed when cysts were treated with 55 mM (1%) NCT in culture medium. A complete failure of excystment was the result of treatment with 1% NCT plus 1% NH(4)Cl in PBS. Altogether, NCT clearly demonstrated amoebicidal activity at concentrations well tolerated by human tissues and might be useful as a topical drug for the treatment of Acanthamoeba infections. The addition of ammonium chloride can be considered to enhance the activity.
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http://dx.doi.org/10.1128/AAC.00715-07DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2224745PMC
February 2008

Detection of a serine proteinase gene in Acanthamoeba genotype T6 (Amoebozoa: Lobosea).

Exp Parasitol 2006 Sep 20;114(1):26-33. Epub 2006 Mar 20.

Department of Medical Parasitology, Clinical Institute of Hygiene and Medical Microbiology, Medical University of Vienna, Kinderspitalgasse 15, 1095 Vienna, Austria.

Cytopathic proteins are assumed to contribute to the pathogenicity of Acanthamoeba spp. due to their degrading capacity that is required for tissue invasion. In this study, a serine proteinase gene was demonstrated in a highly virulent Acanthamoeba keratitis causing strain with genotype T6. This gene was detected in both, the genomic DNA and the cDNA by PCR and subsequent sequencing. The gene fragment comprises about 500 bp and exhibits high sequence similarity to the serine proteinases of Acanthamoeba strains with genotype T4 and T12. The detection of a serine proteinase in this Acanthamoeba T6 strain is significant, because while T4 is the most common genotype among pathogenic Acanthamoeba strains and also T12 is known to be associated with disease, this is the only virulent Acanthamoeba T6 strain known to date. Obviously, this serine proteinase represents a common tool in pathogenic processes during Acanthamoeba infection.
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http://dx.doi.org/10.1016/j.exppara.2006.02.004DOI Listing
September 2006

ITS1 sequence variabilities correlate with 18S rDNA sequence types in the genus Acanthamoeba (Protozoa: Amoebozoa).

Parasitol Res 2006 Jan 1;98(2):86-93. Epub 2005 Nov 1.

Department of Medical Parasitology, Clinical Institute of Hygiene and Medical Microbiology, Medical University of Vienna, Kinderspitalgasse 15, 1095 Vienna, Austria.

The subgenus classification of the ubiquitously spread and potentially pathogenic acanthamoebae still poses a great challenge. Fifteen 18S rDNA sequence types (T1-T15) have been established, but the vast majority of isolates fall into sequence type T4, and so far, there is no means to reliably differentiate within T4. In this study, the first internal transcribed spacer (ITS1), a more variable region than the 18S rRNA gene, was sequenced, and the sequences of 15 different Acanthamoeba isolates were compared to reveal if ITS1 sequence variability correlates with 18S rDNA sequence typing and if the ITS1 sequencing allows a differentiation within T4. It was shown that the variability in ITS1 is tenfold higher than in the 18S rDNA, and that ITS1 clusters correlate with the 18S rDNA clusters and thus corroborate the Acanthamoeba sequence type system. Moreover, high sequence dissimilarities and distinctive microsatellite patterns could enable a more detailed differentiation within T4.
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http://dx.doi.org/10.1007/s00436-005-0022-xDOI Listing
January 2006