ABSTRACT
The relapsing fever group Borrelia miyamotoi is an emerging tick-borne pathogen. Diagnosis of infection is currently mainly based on serological methods detecting antibodies against B. miyamotoi glycerophosphodiester phosphodiesterase (GlpQ). Here, we scrutinized the reliability of GlpQ as a diagnostic marker and compared the seroprevalence in different study populations and by applying various immunoblotting methods. Antibodies were detected in the sera of 7/53 hunters and in 1/11 sera of Lyme neuroborreliosis patients. Furthermore, 17/74 sera of persons with high concentrations of anti-Borrelia burgdorferi sensu lato (α-Bbsl) antibodies reacted strongly with B. miyamotoi GlpQ in immunoblots. The B. miyamotoi GlpQ seroprevalence was 7/50 in α-Bbsl negative persons. In healthy blood donors from commercial suppliers and from the Austrian Red Cross, seroprevalences were 5/14 and 10/35, respectively. Strikingly, two B. miyamotoi PCR-positive cases from Austria had negative GlpQ serology, indicating poor sensitivity. Finally, when we analyzed sera of dogs, we found α-B. miyamotoi GlpQ antibody seroprevalence in tick-free dogs (n = 10) and in tick-exposed dogs (n = 19) with 2/10 and 8/19, respectively. Thus, our results indicate that GlpQ-based B. miyamotoi serology holds neither specificity nor sensitivity.
ABSTRACT
A long one-dimensional single-stranded DNA (ssDNA) molecule with a periodic sequence motif is an attractive building block for DNA nanotechnology because it allows the positioning of oligonucleotide-labeled particles or molecules with high spatial resolution via molecular self-assembly simply by hybridization reactions. In vitro enzymatic isothermal rolling circle amplification (RCA) produces such long concatemeric ssDNA molecules. These are complementary in sequence to their circular template. In this chapter, the preparation of stretched and surface-attached RCA products at the single molecule level is described. The methods presented comprise the enzymatic circularization of a ssDNA oligonucleotide, the covalent coupling of amino-modified primers to carboxylated fluorescence beads, the preparation of a hydrophobic glass substrate, the RCA in a flow-through system, the postsynthetic staining and stretching of the RCA products as well as the microscopic observation of individual ssDNA molecules.
Subject(s)
DNA, Circular/chemistry , DNA, Single-Stranded/chemistry , Nanostructures/chemistry , Nanotechnology/methods , Nucleic Acid Amplification Techniques/methods , Bacillus Phages/enzymology , DNA, Circular/metabolism , DNA, Single-Stranded/metabolism , DNA-Directed DNA Polymerase/metabolism , Microscopy, Fluorescence , Nucleic Acid Hybridization , Organic ChemicalsABSTRACT
Enzymatic isothermal rolling circle amplification (RCA) produces long concatemeric single-stranded DNA (ssDNA) molecules if a small circular ssDNA molecule is applied as the template. A method is presented here in which the RCA reaction is carried out in a flow-through system, starting from isolated surface-tethered DNA primers. This approach combines gentle fluidic handling of the single-stranded RCA products, such as staining or stretching via a receding meniscus, with the option of simultaneous (fluorescence) microscopic observation. It is shown that the stretched and surface-attached RCA products are accessible for hybridization of complementary oligonucleotides, which demonstrates their addressability by complementary base pairing. The long RCA products should be well suited to bridge the gap between biomolecular nanoscale building-blocks and structures at the micro- and macroscale, especially at the single-molecule level presented here.
Subject(s)
DNA/chemical synthesis , Nanostructures/chemistry , Nucleic Acid Amplification Techniques/instrumentation , Microscopy, Fluorescence , NanotechnologyABSTRACT
Microarray technology provides new analytical devices that allow the parallel and simultaneous detection of several thousands of probes within one sample. Microarrays, sometimes called DNA chips, are widely used in gene-expression analysis, genotyping of individuals, analysis of point mutations and single nucleotide polymorphisms (SNP) as well as other genomic or transcriptomic variations. In this chapter we give a survey of common microarray manufacturing, the selection of support material, immobilisation and hybridisation and the detection with labelled complementary strands. However, DNA arrays may also serve as the basis for more complex analysis based on the action of enzymes on the immobilized templates. This property gives DNA microarrays the potential for being the template for whole PCR and transcription experiments with high parallelism, as will be discussed in the last section of this chapter.
Subject(s)
Oligonucleotide Array Sequence Analysis/methods , DNA Mutational Analysis/instrumentation , DNA Mutational Analysis/methods , Oligonucleotide Array Sequence Analysis/instrumentation , Point Mutation , Polymerase Chain Reaction/instrumentation , Polymerase Chain Reaction/methods , Polymorphism, Single Nucleotide , Transcription, GeneticABSTRACT
We developed a DNA microarray for identification of Bacillus anthracis and other phylogenetic groupings within the "Bacillus cereus group". Nucleotide sequences of 16S-23S ribosomal DNA internal transcribed spacers containing genes for tRNA(Ile) from 52 B. anthracis strains were found to be identical to sequences from seven strains published previously and different from all other bacteria. When 42 oligonucleotide probes targeting polymorphic sites were immobilized on glass slides and hybridized to fluorescently labeled PCR amplification products, one or more mismatches could be discriminated in all but one cases. Hence, hybridization events were highly specific and identification of B. anthracis was straightforward.
