Mechanistic Elucidation of Protease–Substrate and Protein–Protein Interactions for Targeting Viral Infections

Viral infections represent an old threat to global health, with multiple epidemics and pandemics in the history of mankind. Despite several advances in the development of antiviral substances and vaccines, many viral species are still not targeted. Additionally, new viral species emerge, posing a menace without precedent to humans and animals and causing fatalities, disabilities, environmental harm, and economic losses. In this thesis, we present rational modeling approaches for targeting specific protease-substrate and protein-protein interactions pivotal for the viral replication cycle. Over the course of this work, antiviral research is supported beginning with the development of small molecular antiviral substances, going through the modeling of a potential immunogenic epitope for vaccine development, towards the establishment of descriptors for susceptibility of animals to a viral infection. Notably, all the research was done under scarce data availability, highlighting the predictive power of computational methods and complementarity between in-silico and in-vitro or in-vivo methods

Descubrimiento de proteínas off target humanas para la proteasa NS3 del virus del dengue y sus implicaciones para el diseño de fármacos basados en estructura

Dengue Virus (DENV) is perhaps the most relevant infectious agent in the tropical and subtropical countries. Nowadays, worldwide efforts to develop new molecules capable to prevent DENV growth have increased...El virus del Dengue (DENV) es probablemente uno de los agentes infecciosos más relevantes para los países en las áreas tropicales y subtropicales. En la actualidad se han incrementado los esfuerzos a nivel mundial para desarrollar moléculas que tengan la capacidad de inhibir el crecimiento de DENV y por ende su infección..

Antiviral activities and applications of ribosomally synthesized and post-translationally modified peptides (RiPPs)

The emergence and re-emergence of viral epidemics and the risks of antiviral drug resistance are a serious threat to global public health. New options to supplement or replace currently used drugs for antiviral therapy are urgently needed. The research in the field of ribosomally synthesized and post-translationally modified peptides (RiPPs) has been booming in the last few decades, in particular in view of their strong antimicrobial activities and high stability. The RiPPs with antiviral activity, especially those against enveloped viruses, are now also gaining more interest. RiPPs have a number of advantages over small molecule drugs in terms of specificity and affinity for targets, and over protein-based drugs in terms of cellular penetrability, stability and size. Moreover, the great engineering potential of RiPPs provides an efficient way to optimize them as potent antiviral drugs candidates. These intrinsic advantages underscore the good therapeutic prospects of RiPPs in viral treatment. With the aim to highlight the underrated antiviral potential of RiPPs and explore their development as antiviral drugs, we review the current literature describing the antiviral activities and mechanisms of action of RiPPs, discussing the ongoing efforts to improve their antiviral potential and demonstrate their suitability as antiviral therapeutics. We propose that antiviral RiPPs may overcome the limits of peptide-based antiviral therapy, providing an innovative option for the treatment of viral disease

Computational methods in drug repurposing and natural product based drug discovery

For a few decades now, computation methods have been widely used in drug discovery or drug repurposing process, especially when saving time and money are important factors. Development of bioinformatics, chemoinformatics, molecular modelling techniques and machine or deep learning tools, as well as availability of various biological and chemical databases, have had a significant impact on improving the process of obtaining successful drug candidates. This dissertation describes the role of natural products in drug discovery, as well as presents several computational methods used in drug discovery and drug repurposing. Application of these methods is presented with the example of searching for potential drug treatment options for the COVID-19 disease. The disease is caused by the novel coronavirus SARS-CoV-2, which was first discovered in December 2019 and has caused the death of more than 5.6 million people worldwide (until January 2022). Findings from two research projects, which aimed to identify potential inhibitors of main protease of SARS-CoV-2, are presented in this work. Moreover, a summary on COVID-19 treatment possibilities has been included. In the first project, a ligand-based virtual screening of around 360,000 compounds from natural products databases, as well as approved and withdrawn drugs databases was conducted, followed by molecular docking and molecular dynamics simulations. Moreover, computational predictions of toxicity and cytochrome activity profiles for selected candidates were provided. Twelve candidates as SARS-CoV-2 main protease inhibitors were identified - among them novel drug candidates, as well as existing drugs. The second project was focused on finding potential inhibitors from plants (Reynoutria japonica and Reynoutria sachalinensis) and was based on molecular docking studies, followed by in vitro studies of the activity of selected compounds, extract, and fractions from those plants against the enzyme. Several natural compounds were identified as promising candidates for SARS-CoV-2 main protease inhibitors. Additionally, butanol fraction of Ryenoutria rhizomes extracts also showed inhibitory activity on the enzyme. Suggested drugs, natural compounds and plant extracts should be further investigated to confirm their potential as COVID-19 therapeutic options. Presented workflow could be used for investigation of compounds for other biological targets and different diseases in the future research projects.Seit einigen Jahrzehnten werden bei der Entwicklung und Repositionierung von Arzneimitteln rechenintensive computergestützte Methoden eingesetzt, insbesondere da Zeit- und Kostenersparnis wichtige Faktoren sind. Die Weiterentwicklung der Bioinformatik und Chemoinformatik und die damit einhergehende Optimierung von molekularen Modellierungstechniken und Tools für maschinelles sowie tiefes Lernen ermöglicht die Verarbeitung von großen biologischen und chemischen Datenbanken und hat einen erheblichen Einfluss auf die Verbesserung des Prozesses zur Gewinnung erfolgreicher Arzneimittelkandidaten. In dieser Dissertation wird die Rolle von Naturstoffen bei der Entwicklung von Arzneimitteln beschrieben, und es werden verschiedene computergestützte Methoden vorgestellt, die bei der Entdeckung von Arzneimitteln und der Repositionierung von Arzneimitteln eingesetzt werden. Die Anwendung dieser Methoden wird am Beispiel der Suche nach potenziellen medikamentösen Behandlungsmöglichkeiten für die Krankheit COVID-19 vorgestellt. Die Krankheit wird durch das neuartige Coronavirus SARS-CoV-2 ausgelöst, das erst im Dezember 2019 entdeckt wurde und bisher (bis Januar 2022) weltweit mehr als 5,6 Millionen Menschen das Leben gekostet hat. In dieser Arbeit werden Ergebnisse aus zwei Forschungsprojekten vorgestellt, die darauf abzielten, potenzielle Hemmstoffe der Hauptprotease von SARS-CoV-2 zu identifizieren. Außerdem wird ein Überblick über die Behandlungsmöglichkeiten von COVID-19 gegeben. Im ersten Projekt wurde ein ligandenbasiertes virtuelles Screening von rund 360.000 Kleinstrukturen aus Naturstoffdatenbanken sowie aus Datenbanken für zugelassene und zurückgezogene Arzneimittel durchgeführt, gefolgt von molekularem Docking und Molekulardynamiksimulationen. Darüber hinaus wurden für ausgewählte Kandidaten rechnerische Vorhersagen zur Toxizität und zu Cytochrom-P450-Aktivitätsprofilen erstellt. Es wurden zwölf Kandidaten als SARS-CoV-2-Hauptproteaseinhibitoren identifiziert - darunter sowohl neuartige als auch bereits vorhandene Arzneimittel. Das zweite Projekt konzentrierte sich auf die Suche nach potenziellen Inhibitoren aus Pflanzen (Reynoutria japonica und Reynoutria sachalinensis) und basierte auf molekularen Docking-Studien, gefolgt von In-vitro-Studien der Aktivität ausgewählter Verbindungen, Extrakte und Fraktionen aus diesen Pflanzen gegen das Enzym. Mehrere Naturstoffe wurden als vielversprechende Kandidaten für SARS-CoV-2- Hauptproteaseinhibitoren identifiziert. Außerdem zeigte die Butanolfraktion von Ryenoutria Rhizomextrakten ebenfalls eine hemmende Wirkung auf das Enzym. Die vorgeschlagenen Arzneimittel, Naturstoffe und Pflanzenextrakte sollten weiter untersucht werden, um ihr Potenzial als COVID-19-Therapieoptionen zu bestätigen. Der vorgestellte Arbeitsablauf könnte in zukünftigen Forschungsprojekten zur Untersuchung von Verbindungen für andere biologische Ziele und verschiedene Krankheiten verwendet werden

Analysis of Zika and Dengue virus proteases

in English Zika and Dengue flaviviruses are transmitted by mosquitoes in human populations living in tropical areas. They cause fevers which in the case of Dengue can lead to life threatening haemorrhagic form. There is a possible relationship between pregnant women being infected by Zika virus and higher risk of microcephaly in new-borns. The infection is currently treated mainly symptomatically. However, there is an effort to develop compounds which block viral life cycle and viral spread through organism. Viral enzymes, such as flaviviral proteases, are regarded as suitable targets for this effort. These serine proteases with chymotrypsin fold are heterodimers which consist of flaviviral non- structural proteins NS2B and NS3. NS3 domain also contains a helicase, which can be removed by gene recombination for study purposes. NS2B is a transmembrane protein, but only a hydrophilic 40 amino acid peptide is important for the interaction with NS3 domain. This peptide has a chaperon function and participates in substrate binding to the active site. In this study, six variants of recombinant proteins containing activating peptide of NS2B and protease domain of NS3 were expressed and purified. Four variants were characterized in enzymologic studies including testing of possible inhibitors. A dipeptide...Zika a Dengue jsou flaviviry šířící se v lidských populacích obývající tropické oblasti skrze komáří mezihostitele. Flaviviry způsobují horečky, které se mohou v případě Dengue rozvinout až do život ohrožující hemorrhagické formy. Existuje možná souvislost mezi těhotnými ženami nakaženými virem Zika a zvýšeným rizikem vzniku mikrocefalie u novorozenců. Flavivirové horečky se v dnešní době léčí hlavně symptomaticky, nicméně je zde snaha o vývoj látek blokující životní cyklus virů a jejich šíření v organismu. Vhodným cílem takových látek jsou specifické virové enzymy, například flavivirová proteasa. Tato serinová proteasa chymotrypsinového typu je tvořena heterodimerem flavivirových nestrukturních proteinů NS2B a NS3. Doména NS3 obsahuje také helikasu, tu je však možné pro studii samotné proteasy rekombinantně odstranit. Protein NS2B je transmembránový, s doménou NS3 však interaguje pouze hydrofilní, 40 aminokyselinový peptid. Ten funguje jako chaperon a podílí se na vazbě substrátu v aktivním místě. V této práci bylo studováno šest variant rekombinantních proteinů obsahující aktivační peptid NS2B a proteasovou doménu NS3. Tyto proteiny byly exprimovány a purifikovány. Čtyři varianty byly charakterizovány v enzymologických studiích, včetně testování možných inhibitorů. Toto testování odhalilo...Katedra biochemieDepartment of BiochemistryFaculty of SciencePřírodovědecká fakult

Development Of Database And Computational Methods For Disease Detection And Drug Discovery

Ph.DDOCTOR OF PHILOSOPH

Drug Repurposing

This book focuses on various aspects and applications of drug repurposing, the understanding of which is important for treating diseases. Due to the high costs and time associated with the new drug discovery process, the inclination toward drug repurposing is increasing for common as well as rare diseases. A major focus of this book is understanding the role of drug repurposing to develop drugs for infectious diseases, including antivirals, antibacterial and anticancer drugs, as well as immunotherapeutics

Gastrointestinal viruses and beyond: antiviral development and molecular epidemiology

With over 27 viral families known to infect humans, viral pathogens impose a significant global public health and economic burden. Despite this, only a small fraction of human viruses possess antiviral treatments or vaccines. Whilst antiviral development efforts are crucial to the host-pathogen arms race, so too is the molecular surveillance of these viruses to identify prevalent and virulent strains for vaccine development. This thesis begins, in chapter four, with the development of broad-spectrum non-nucleoside inhibitor compounds using a complex-based pharmacophore and virtual screening approach. This virtual screen identified one compound, NCS-013, which demonstrated broad-spectrum inhibition of the transcriptional activity of human norovirus and feline calicivirus from the Caliciviridae, Zika virus and hepatitis C virus from the Flaviviridae and hepatitis A virus from the Picornaviridae. The second half of the thesis focuses on molecular epidemiology of norovirus and adenovirus, two of the leading causes of viral gastroenteritis worldwide. In chapter five, we observed an interesting dynamic of GII.4 Sydney 2012 [P16] co-dominance in clinical samples throughout the study period. We also enhanced our sewage surveillance capabilities through the addition of partial ORF1 sequencing enabling the identification of recombinant strains. The role of non-group F adenoviruses in gastroenteritis although often reported, remains an area of controversy. In chapter six, we analysed sewage to complement clinical samples and better understand the diversity of adenovirus within the population, including from healthy individuals. In summary, this thesis approached the problem of viral pathogens from both the angle of antiviral development and through understanding of population-level molecular epidemiology, which can contribute to future vaccine development efforts

Identification and characterisation of small molecule inhibitors targeted to the hepatitis C virus NS2 autoprotease.

Hepatitis C virus (HCV) is a positive-strand RNA virus present in 2-3% of the global population and commonly establishing a chronic infection, leading to long term diseases such as liver cirrhosis and hepatocellular carcinoma. Recent advances have led to the development of a range of direct-acting anti-viral drugs (DAAs), some of which are already improving outcomes in the clinic. It is clear however, that effective therapy for the treatment of HCV will most likely require a combination of DAAs to overcome the rapid onset of viral resistance. In this regard additional inhibitors of the virus lifecycle, which act through a novel molecular target, are required. The autoprotease activity encoded within the C-terminus of the non-structural 2 (NS2) protein is essential for processing of a precursor to the mature viral proteins, and as a consequence is also required for the onset of viral genome replication and the establishment of HCV infection. Despite representing an attractive target for anti-virals, no inhibitors of the NS2 autoprotease have been reported. In order to identify small molecule inhibitors of the NS2 autoprotease, two independent assays were optimised as a measure of NS2-mediated proteolysis. These assays were employed to demonstrate that inhibitors of the NS2 autoprotease were able to block HCV genome replication. The assays were subsequently used to identify a lead-like small molecule inhibitor by screening an in silico enriched library. This compound was further characterised in the context of NS2 activity in vitro and cell culture models of the virus lifecycle. The resultant series represent the first documented inhibitors capable of exerting an anti-viral effect by targeting the NS2 autoprotease

Computational Approaches: Drug Discovery and Design in Medicinal Chemistry and Bioinformatics

This book is a collection of original research articles in the field of computer-aided drug design. It reports the use of current and validated computational approaches applied to drug discovery as well as the development of new computational tools to identify new and more potent drugs