Biology subjects

Fragkoudis, R.

Publications and source records attributed to Fragkoudis, R..

6 recordsLinked to original sources

bioRxiv2023

Biofoundry-scale DNA assembly validation using cost-effective high-throughput long read sequencing

Biofoundries are automated high-throughput facilities specialising in the design, construction and testing of engineered/synthetic DNA constructs (plasmids), often from genetic parts. A critical step of this process is assessing the fidelity of the assembled DNA construct to the desired design. Current methods utilised for this purpose are restriction digest or PCR followed by fragment analysis, and sequencing. The Edinburgh Genome Foundry (EGF) has recently established a single-molecule sequencing quality control step using the Oxford Nanopore sequencing technology, along with a companion Nextflow pipeline and a Python package to perform in-depth analysis and generate a detailed report. Our software enables biofoundry scientists and end-users to rapidly analyse sequencing data, without specialised bioinformatics knowledge. In conclusion, we have created a laboratory and software protocol that validates assembled, cloned or edited plasmids, using Nanopore long reads, which can serve as a useful resource for the genetics, synthetic biology and sequencing communities. Author informationAll authors contributed to the design of the sequencing quality control step and pipeline, and the preparation of the manuscript. P.V. wrote the manuscript, designed and implemented the bioinformatics pipeline and interpreted results. S.D. wrote the manuscript, implemented the laboratory protocol and interpreted results. G.S. designed the bioinformatics pipeline. R.F. wrote the manuscript and contributed to the design of the laboratory protocol and pipeline. Address: Edinburgh Genome Foundry (University of Edinburgh), Michael Swann Building, Max Born Crescent, Edinburgh, EH9 3BF, United Kingdom Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=108 SRC="FIGDIR/small/558498v1_ufig1.gif" ALT="Figure 1"> View larger version (21K): org.highwire.dtl.DTLVardef@a819e5org.highwire.dtl.DTLVardef@3c34ceorg.highwire.dtl.DTLVardef@aef5d8org.highwire.dtl.DTLVardef@8e5d2f_HPS_FORMAT_FIGEXP M_FIG C_FIG

synthetic biology↗

bioRxiv2023

A synthetic biology approach to transgene expression

The ability to control gene expression is pivotal in genetic engineering and synthetic biology. However, in most non-model and pest insect species, empirical evidence for predictable modulation of gene expression levels is lacking. This knowledge gap is critical for genetic control systems, particularly in mosquitoes, where transgenic methods offer novel routes for pest control. Commonly, the choice of RNA polymerase II promoter (Pol II) is the primary method for controlling gene expression, but the options are limited. To address this, we developed a systematic approach to characterize modifications in translation initiation sequences (TIS) and 3 untranslated regions (UTR) of transgenes, enabling the creation of a toolbox for gene expression modulation in mosquitoes and potentially other insects. The approach demonstrated highly predictable gene expression changes across various cell lines and promoter sequences, representing a significant advancement in mosquito synthetic biology gene expression. tools. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=100 SRC="FIGDIR/small/555539v1_ufig1.gif" ALT="Figure 1"> View larger version (31K): org.highwire.dtl.DTLVardef@1db954forg.highwire.dtl.DTLVardef@1279543org.highwire.dtl.DTLVardef@1b86fa2org.highwire.dtl.DTLVardef@1a9176a_HPS_FORMAT_FIGEXP M_FIG C_FIG

synthetic biology↗

bioRxiv2023

Inhibition of potassium ion channels reduces Semliki Forest virus genome replication

IntroductionSemliki forest virus (SFV) is a model virus used to investigate the Alphavirus genus, which includes human pathogens Chikungunya virus and Ross River virus. Viruses harness cellular machinery to facilitate various steps of their replicative cycles. Ion channels are one group of cellular proteins required for the efficient replication of some viruses, including Influenza A viruses, Ebola virus and members of the Betacoronavirus genus. This study focussed on understanding SFVs requirement for functional ion channels during replication. MethodsThe effect of ion channel inhibitors on in vitro SFV infections was measured to investigate the contribution of ion channels in its replication cycle. ResultsIn vitro SFV infections carried out in the presence or absence of different ion channel inhibitors showed broad-range K+ channel inhibitors reproducibly attenuated virus replication and reduced its cytotoxicity in two mammalian cell lines. These broad-range K+ channel inhibitors disrupted an early, post-entry step causing a delay or reduction in SFV protein and RNA synthesis. Screens using inhibitors of specific K+ channel families showed that two-pore domain K+ channel (2pK) inhibitors attenuated SFV replication. Confocal microscopy revealed decreased detection of dsRNA and SFV protein in the presence of inhibitor but no change in RNA and protein colocalisation, which would indicate disruption of replication complexes. Broad-range K+ and 2pK inhibitors decreased viral RNA replication and transcription from the subgenomic promoter. ConclusionsK+ channel inhibitors attenuate in vitro SFV replication by inhibiting an early, post-entry step of virus replication, potentially RNA synthesis. ImportanceNo antiviral therapies have been approved for clinical use against diseases caused by members of the Alphavirus genus. Work presented in this manuscript shows for the first time that SFV genome replication and virus induced cytotoxicity can be reduced in vitro by treating infected cells with K+ channel inhibitors. This work provides the basis for investigating the effectiveness of K+ channel inhibitors against other alphaviruses both in vitro and in vivo and, because many ion channel inhibiting drugs are already in clinical use, rapid repurposing against alphavirus infections would be possible.

microbiology↗

bioRxiv2023

A Zika virus-responsive sensor-effector system in Aedes aegypti

Zika virus (ZIKV) is a recently re-emerged flavivirus transmitted primarily through the bite of an infected mosquito, Aedes aegypti being the main vector. ZIKV infection is associated with a range of adverse effects; infection during pregnancy can lead to foetal abnormalities, including microcephaly. Lacking a licensed vaccine, or specific therapeutics, control of ZIKV transmission focuses on vector control. However, in most transmission settings, current methods are insufficient to successfully control ZIKV, or other similarly-transmitted arboviruses such as dengue and chikungunya viruses. This has stimulated interest in genetics-based methods, either to reduce the number of mosquitoes ("population suppression"), or to make mosquitoes less able to transmit ("population modification"). Here, we describe a method to selectively eliminate infected mosquitoes, using a virus sensor inserted into the mosquito genome and coupled to a quorum-counting lethal effector. In mosquitoes, ZIKV normally establishes persistent, lifelong infection; survival of these infected mosquitoes is crucial to transmission potential. Correspondingly, removal of infected mosquitoes can reduce vectorial capacity of a mosquito population, i.e. ability to transmit. Since relatively few mosquitoes become infected, typically <2%, engineered hypersensitivity to ZIKV would have only a modest population-level fitness cost, and lower still if transmission were successfully reduced by such means.

bioengineering↗

bioRxiv2022

Fake it to break it: mimicking superinfection exclusion disrupts alphavirus infection and transmission in the yellow fever mosquito Aedes aegypti

Multiple viruses cause a phenomenon termed superinfection exclusion whereby a currently infected cell is resistant to secondary infection by the same or a closely related virus. In alphaviruses, this process is thought to be mediated, at least in part, by the viral protease (nsP2) which is responsible for processing the non-structural polyproteins (P123 and P1234) into individual proteins (nsP1-nsP4), forming the viral replication complex. Taking a synthetic-biology approach, we mimicked this naturally occurring phenomenon by generating a superinfection exclusion-like state in Aedes aegypti mosquitoes, rendering them refractory to alphavirus infection. By artificially expressing Sindbis virus (SINV) and chikungunya virus (CHIKV) nsP2 in mosquito cells and transgenic mosquitoes, we demonstrated a reduction in both SINV and CHIKV viral replication rates in cells following viral infection as well as reduced infection prevalence, viral titres and transmission potential in mosquitoes.

microbiology↗

bioRxiv2021

Mosquito saliva sialokinin-dependent enhancement of arbovirus infection through endothelial barrier leakage

Viruses transmitted by Aedes mosquitoes constitute an increasingly important global health burden. Defining common determinants of host susceptibility to this large group of heterogenous pathogens are key for informing the rational design of new pan-viral medicines. Infection of the vertebrate host with these viruses is enhanced by the presence of mosquito saliva, a complex mixture of salivary gland-derived factors and microbiota. We show that enhancement of infection by saliva was dependent on vascular function and was independent of most anti-saliva immune responses, including to salivary microbiota. Instead, the Aedes gene product sialokinin mediated enhancement of virus infection through a rapid reduction in endothelial barrier integrity. Sialokinin is unique within the insect world as having vertebrate-like tachykinin sequence and is absent from non-vector competent Anopheles mosquitoes, whose saliva was not pro-viral and did not induce similar vascular permeability. Therapeutic strategies targeting sialokinin have potential to limit disease severity following infection with Aedes mosquito-borne viruses.

microbiology↗