Development of nucleic acid-based diagnostics considering modern signal amplification and rapid prototyping technologies

Die Entwicklung und Optimierung bioanalytischer Testsysteme erfordert zunehmend innovative und effiziente Strategien, um insbesondere den steigenden individuellen Anforderungen der personalisierten Medizin gerecht zu werden. Hierzu müssen stetig moderne Konzepte zur Charakterisierung potenzieller Biomarker untersucht und in schnell anpassbare diagnostische Anwendungen integriert werden. Gerade der sensitive und gleichzeitige Nachweis spezifischer Nukleinsäuren ist dabei von großem Interesse. Mit dieser Dissertation wurde die Entwicklung und Evaluierung spezifischer Hybridisierungssonden zum Nachweis viraler Nukleinsäuresequenzen in Zell- und Gewebemodellen mittels Fluoreszenzmikroskopie dargelegt. Hierbei zeigte sich, dass bei hinreichend großer Viruslast auch sehr kurze Sequenzbereiche effektiv detektiert werden können. Um zur Evaluierung von neuen Zielsubstanzen möglichst sensitive Aussagen treffen zu können, wurden weiterhin innovative Signalverstärkungstechnologien, insbesondere zur Analyse von Biomolekülen in mikropartikelbasierten Assays untersucht. Neben der erfolgreichen Übertragung der bereits für zellbasierte Anwendungen eingesetzten Tyramidsignalverstärkung auf Mikropartikel zeigten neuartige Nukleinsäurekonstrukte, sogenannte Origamis, großes Potential für zukünftige, sensitive Nachweisverfahren. Neben den einzelnen Assaykomponenten selbst sind zudem die Planung und der Aufbau von neuen Versuchssystemen entscheidend für einen erfolgreichen Einsatz in der Bioanalytik. Hier bieten moderne Fabrikationstechnologien, wie der 3D-Druck, enorme Vorteile für individuelle Untersuchungsmethoden. Diese Arbeit zeigte, dass entsprechend thermisch und fluoreszenzspektrometrisch charakterisierte Polymermaterialien gut für den funktionalen Einsatz in mikro-, zell- und molekularbiologischen Anwendungen geeignet sind und dadurch in Zukunft, bei kontinuierlicher Weiterentwicklung solcher maßgeschneiderten Systeme, rasch und wirksam auf neue diagnostische Fragestellungen und Bedürfnisse reagiert werden kann.The development and optimization of bioanalytical test systems requires increasingly innovative and efficient strategies, to meet the growing individual requirements of personalized medicine. For this purpose, modern concepts for the characterization of potential biomarkers must be continuously investigated and integrated into rapidly adaptable diagnostic applications. Especially the sensitive and simultaneous detection of specific nucleic acids is of great interest. This dissertation describes the development and evaluation of specific hybridization probes for the detection of viral nucleic acid sequences in cell and tissue models using fluorescence microscopy. It was shown that even very short sequence ranges can be detected effectively if the virus load is sufficiently high. In order to evaluate new target substances and to be able to make the most sensitive statements possible, innovative signal amplification technologies, especially for the analysis of biomolecules in microparticle-based assays, were also investigated. In addition to the successful transfer of the tyramid signal amplification, already used for cell-based applications, to microparticles, novel nucleic acid constructs, so-called origamis, showed great potential for future, sensitive detection methods. In addition to the individual assay components themselves, the planning and construction of new experimental systems are crucial for successful use in bioanalytics. Here, modern manufacturing technologies such as 3D printing offer enormous advantages for individual test methods. This work showed that appropriately thermally and fluorescence-spetrometrically characterized polymer materials are well suited for functional use in micro-, cell- and molecular biological applications. Thus, in the future, with continuous development of such tailor-made systems, it will be possible to react quickly and effectively to new diagnostic questions and needs

Geno- and Phenotypic Characteristics of a Klebsiella pneumoniae ST20 Isolate with Unusual Colony Morphology

Klebsiella pneumoniae is a common member of the intestinal flora of vertebrates. In addition to opportunistic representatives, hypervirulent (hvKp) and antibiotic-resistant K. pneumoniae (ABR-Kp) occur. While ABR-Kp isolates often cause difficult-to-treat diseases due to limited therapeutic options, hvKp is a pathotype that can infect healthy individuals often leading to recurrent infection. Here, we investigated the clinical K. pneumoniae isolate PBIO3459 obtained from a blood sample, which showed an unusual colony morphology. By combining whole-genome and RNA sequencing with multiple in vitro and in vivo virulence-associated assays, we aimed to define the respective Klebsiella subtype and explore the unusual phenotypic appearance. We demonstrate that PBIO3459 belongs to sequence type (ST)20 and carries no acquired resistance genes, consistent with phenotypic susceptibility tests. In addition, the isolate showed low-level virulence, both at genetic and phenotypic levels. We thus suggest that PBIO3459 is an opportunistic (commensal) K. pneumoniae isolate. Genomic comparison of PBIO3459 with closely related ABR-Kp ST20 isolates revealed that they differed only in resistance genes. Finally, the unusual colony morphology was mainly associated with carbohydrate and amino acid transport and metabolism. In conclusion, our study reveals the characteristics of a Klebsiella sepsis isolate and suggests that opportunistic representatives likely acquire and accumulate antibiotic resistances that subsequently enable their emergence as ABR-Kp pathogens