Journal: bioRxiv
Article Title: Sec61 translocon inhibitor Flavitransin blocks selectively dengue virus polyprotein insertion into the ER membrane with pan-flavivirus antiviral potency
doi: 10.1101/2025.03.29.646078
Figure Lengend Snippet: A , DENV2 was passaged on Huh7 cells under FT pressure. Compound concentration was gradually increased when viral cytopathic effect on cells was detected. After 75 passages, virus was cultivated in the absence of compounds to generate virus stocks for downstream analysis. At passage 50 and 75, virus was collected and genotyped by nanopore sequencing (see panel C). FT resistance was selected in 2 independent cell cultures. As controls, a culture with FT IN or with control medium was included that underwent the same passaging procedure. Cartoon created with BioRender (2025); www.bioRender.com . B , At end-point, virus stocks were evaluated in Huh7 cells for sensitivity to FT. A virus stock from a low passage (# 3; light blue) was included as reference. Cells were infected with the different virus stocks (MOI ∼ 0.5) and treated with increasing concentrations of FT. After 4-5 days post infection, virus yield in the supernatant was quantified by RT-qPCR detection of the viral 3’UTR. Graph shows the four parameter concentration-response curves of FT for virus release from infected cells. Values (mean ± SD, from two independent experiments; n=2) represent the viral load in FT-treated cells as normalized to the viral copy number of each untreated virus control. C , Summary of the detected AA mutations in the different viral clones as compared to the initial DENV2 control strain (# 3). The numbers in each colored box refer to the residues of the respective viral subunit. The mutations in the medium control (dark blue) and FT IN (grey) are shown at the top; the two FT-resistant viruses (dark and light red) are shown at the bottom. D , Schematic representation of the hydrophobic mutants of the DENV2 C 14 SPs. HEK293T cells were transiently transfected with the VSV-G-tGFP-P2A-BFP constructs and treated with FT for 18 h. GFP and BFP fluorescence (mean fluorescent intensity) was quantified by flow cytometry and relative tGFP:BFP expression ratio (normalized to untreated transfection control) was determined. Graph on the left shows the four parameter concentration response curves of FT for VSV expression for different C14 mutants from three independent experiments. Values are mean ± SD; n=3. Graph at the right shows the relative tGFP:BFP expression ratios at 2 µM FT for additional hydrophobic mutants (A102V/I/L/M/F/Y/W). Values are mean ± SD; n=3.
Article Snippet: For flow cytometry experiments, the VSV-G protein (from VSV-G expressing pMD2.G plasmid, Didier Trono Lab, Addgene) was inserted into a pCAGGS-tGFP-P2A-BFP expression vector after linearization of the vector via EcoRV cleavage (New England Biolabs, Ipswich, Massachusetts, USA).
Techniques: Concentration Assay, Virus, Nanopore Sequencing, Control, Passaging, Infection, Quantitative RT-PCR, Clone Assay, Transfection, Construct, Fluorescence, Flow Cytometry, Expressing