13 research outputs found
Foldamers in Medicinal Chemistry
International audienc
The Application of Viruses to Biotechnology
Viruses are microscopic agents that exist worldwide and are present in humans, animals, plants, and other living organisms in which they can cause devastating diseases. However, the advances of biotechnology and next-generation sequencing technologies have accelerated novel virus discovery, identification, sequencing, and manipulation, showing that they present unique characteristics that place them as valuable tools for a wide variety of biotechnological applications. Many applications of viruses have been used for agricultural purposes, namely concerning plant breeding and plant protection. Nevertheless, it is interesting to mention that plants have also many advantages to be used in vaccine production, such as the low cost and low risks they entail, showing once more the versatility of the use of viruses in biotechnology. Although it will obviously never be ignored that viruses are responsible for devastating diseases, it is clear that the more they are studied, the more possibilities they offer to us. They are now on the front line of the most revolutionizing techniques in several fields, providing advances that would not be possible without their existence. In this book there are presented studies that demonstrate the work developed using viruses in biotechnology. These studies were brought by experts that focus on the development and applications of many viruses in several fields, such as agriculture, the pharmaceutical industry, and medicine
Zika virus M protein as a viroporin drug target
Zika virus (ZIKV) an arbovirus that became widely known in 2015 due to the
epidemic in Brazil, spreading across South and North America. Whilst previous
Old World ZIKV outbreaks comprised largely mild, or even asymptomatic
infections, the New World epidemic became notorious for its association with
foetal microcephaly following maternal infection, and an increased incidence of
various neurological symptoms, including Guillain-Barré syndrome.
Mature, infectious ZIKV particles comprise three structural proteins, Capsid (C),
small Membrane (M) and the envelope (E) glycoprotein; the latter is responsible
for receptor binding and mediates membrane fusion upon encountering low pH
within the acidifying endosome. However, the function of M within this context is
unknown.
Based upon its structural similarity to “viroporins”, a class of virus-coded ion
channels mediating virus entry and uncoating, we investigated whether M could
form alternative oligomeric forms to the dimeric structure seen within mature
virions, and in so doing exhibit channel activity. Gratifyingly, M peptides adopted
higher order structures within membrane-mimetic environments and displayed
channel activity in vitro, sensitive to the prototypic viroporin inhibitor,
Rimantadine. Accordingly, ZIKV entry was blocked in a dose-dependent fashion
by the drug, which also prevented virus spread in mouse models of ZIKV
infection. Molecular dynamics simulations supported that M protein is able to
oligomerise into a hexameric viroporin channel, opening of which was within
acidified environments via protonation of a conserved histidine residue.
Rimantadine was predicted in silico to interact at a lumenal binding site, against
which we derived improved inhibitors from a library of generic, FDA-approved
and other bio-active small molecules, providing a basis for novel M protein
targeted drug discovery. Significantly, due to its role during virus entry, M targeted drugs might either prevent or reduce the severity of ZIKV infections,
including those crossing the placenta, and may also show activity against
closely related M proteins from other Flaviviruses
Targeted delivery of anti-cancer drugs by MS2 virus-like particles
Problems associated with poor pharmacokinetics and biodistribution, as well as toxic off-target effects, limit the curative potential of most anti-cancer drugs. This has prompted the development of nanoparticulate drug delivery systems to impart both more favourable pharmacological properties and precise tumour targeting. The vast number of formulations, ranging from fully synthetic delivery systems to ones derived from natural sources, currently undergoing clinical trials or preclinical testing underlines the significance of this field. This project is a proof-of-concept investigation into the feasibility and effectiveness of a novel drug delivery system, based on virus-like particles (VLPs) of the MS2 bacteriophage.
Doxorubicin (Dox) and an anti-BCL2 siRNA were used as model drug cargos. They were packaged inside MS2 VLPs either by chemical infusion, or via covalent attachment to an MS2 packaging signal, TR, respectively. An average loading of ~10 molecules of siRNA or ~110 molecules of Dox per VLP was achieved. Packaged cargos remained stably encapsidated; the siRNA was protected from nuclease degradation. VLPs were surface decorated with polyethylene glycol (PEG), and tumour-targeting ligands, human transferrin (Tf) or A9L, an RNA aptamer that targets prostate-specific membrane antigen (PSMA). Extensive PEGylation was achieved (~97% of coat proteins), and each VLP displayed on average ~7 molecules of Tf or ~16 molecules of A9L.
PEGylation significantly reduced the non-specific cellular uptake of VLPs, and antibody binding. Further addition of tumour-targeting ligands facilitated the specific delivery of drug cargos to targeted cancer cells in culture, likely via receptor-mediated endocytosis, and induced significant cytotoxicity with an LC50 of ~10 nM for siRNA and ~800 nM for Dox. Importantly, negligible toxic effects were observed in the presence of excess free targeting ligands, or with non-targeted control cell lines. Furthermore, the cellular uptake of VLPs did not appear to induce any off-target effects.
MS2 VLPs continue to show promise as a robust, flexible and effective drug delivery system. This project highlights the versatility of VLPs for displaying a range of useful ligands on their surface, as well as packaging various therapeutic cargos, and demonstrated their ability to specifically deliver drugs to targeted cancer cells. Though further studies are required, the work presented here is an important step towards fully realising the potential of this drug delivery system
Targets in Gene Therapy
This book aims at providing an up-to-date report to cover key aspects of existing problems in the emerging field of targets in gene therapy. With the contributions in various disciplines of gene therapy, the book brings together major approaches: Target Strategy in Gene Therapy, Gene Therapy of Cancer and Gene Therapy of Other Diseases. This source enables clinicians and researchers to select and effectively utilize new translational approaches in gene therapy and analyze the developments in target strategy in gene therapy