Seminário do Grupo de Biofísica - "Biophysical assessment of the mechanism of action of broad-spectrun antivirals against viral fusion"

Palestrante: 
Prof. Nuno Santos - Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Portugal
Data do Seminário: 
25/09/2018 - 15:00
Local: 
Ed. Principal Ala I sala 201 (sala de seminários)
Resumo: 
Effective antivirals have been developed against specific viruses, such as HIV, hepatitis C virus and influenza virus. This “one bug–one drug” approach to antiviral drug development can be successful, but it may be inadequate for responding to an increasing diversity of viruses that cause significant diseases in humans. The majority of viral pathogens that cause emerging and re‑emerging infectious diseases are membrane-enveloped viruses, which require the fusion of viral and cell membranes for virus entry. Therefore, antivirals that target the membrane fusion process represent recent paradigms for broad-spectrum antiviral discovery. An aryl methyldiene rhodanine derivative, LJ001, and oxazolidine-2,4-dithione, JL103, act on the viral membrane, inhibiting its fusion with a target cell membrane. We investigated the interactions of these two active compounds and an inactive analogue used as a negative control, LJ025, with biological membrane models, in order to clarify the mechanism of action at the molecular level of these new broad-spectrum enveloped virus entry inhibitors. Fluorescence spectroscopy was used to quantify the partition and determine the location of the molecules on membranes. The ability of the compounds to produce reactive oxygen molecules in the membrane was tested using 9,10-dimethylanthracene, which reacts selectively with singlet oxygen (1O2). Changes on membrane properties were assessed by fluorescence anisotropy and generalized polarization measurements, and the ability to inhibit membrane fusion was evaluated using FRET. Our results indicate that 1O2 production by LJ001 and JL103 is able to specially target the unsaturated phospholipids C=C double bonds. Using atomic force microscopy (AFM), we aimed at unraveling the effects that JL103 is able to induce in the lipid membrane architecture at the nanoscale. Our results show that the 1O2 produced by JL103 decreases membrane thickness, with an expansion of the area per phospholipid, by attacking the unsaturated phospholipids. This membrane reorganization prevents the fusion between enveloped viruses and target cell membranes, resulting in viral entry inhibition.

Desenvolvido por IFUSP