ABSTRACT
This paper presents results of a study of a new cationic oligomer that contains end groups and a chromophore affording inactivation of SARS-Cov-2 by visible light irradiation in solution or as a solid coating on wipes paper and glass fiber filtration substrates. A key finding of this study is that the cationic oligomer with a central thiophene ring and imidazolium charged groups give outstanding performance in both killing of E. coli bacterial cells and inactivation of the virus at very short times. Our introduction of cationic N-Methyl Imidazolium groups enhances the light-activation process for both E. coli and SARS-Cov-2 but dampens the dark killing of the bacteria and eliminates the dark inactivation of the virus. For the studies with this oligomer in solution at concentration of 1 g/mL and E. coli we obtain 3 log killing of the bacteria with 10 min irradiation with LuzChem cool white lights (mimicking indoor illumination). With the oligomer in solution at a concentration of 10 g/mL, we observe 4 logs inactivation (99.99 %) in 5 minutes of irradiation and total inactivation after 10 min. The oligomer is quite active against E. coli on oligomer-coated wipes papers and glass fiber filter supports. The SARS-Cov-2 is also inactivated by the oligomer coated glass fiber filter papers. This study indicates that these oligomer-coated materials may be very useful as wipes and filtration materials.
ABSTRACT
Cellular entry of coronaviruses depends on binding of the viral spike (S) protein to a specific cellular receptor, the angiotensin-converting enzyme 2 (ACE2). Furthermore, the viral spike protein expresses an RGD motif, suggesting that cell surface integrins may be attachment co-receptors. However, using infectious SARS-CoV-2 requires a biosafety level 3 laboratory (BSL-3), which limits the techniques that can be used to study the mechanism of cell entry. Here, we UV-inactivated SARS-CoV-2 and fluorescently labeled the envelope membrane with octadecyl rhodamine B (R18) to explore the role of integrin activation in mediating both cell entry and productive infection. We used flow cytometry and confocal fluorescence microscopy to show that fluorescently labeled SARS-CoV-2R18 particles engage basal-state integrins. Furthermore, we demonstrate that Mn2+, which activates integrins and induces integrin extension, enhances cell binding and entry of SARS-CoV-2R18 in proportion to the fraction of integrins activated. We also show that one class of integrin antagonist, which binds to the I MIDAS site and stabilizes the inactive, closed conformation, selectively inhibits the engagement of SARS-CoV-2R18 with basal state integrins, but is ineffective against Mn2+-activated integrins. At the same time, RGD-integrin antagonists inhibited SARS-CoV-2R18 binding regardless of integrin activity state. Integrins transmit signals bidirectionally: 'inside-out' signaling primes the ligand binding function of integrins via a talin dependent mechanism and 'outside-in' signaling occurs downstream of integrin binding to macromolecular ligands. Outside-in signaling is mediated by G13 and induces cell spreading, retraction, migration, and proliferation. Using cell-permeable peptide inhibitors of talin, and G13 binding to the cytoplasmic tail of an integrin's {beta} subunit, we further demonstrate that talin-mediated signaling is essential for productive infection by SARS-CoV-2.
Subject(s)
COVID-19ABSTRACT
The current Covid-19 Pandemic caused by the highly contagious SARS-CoV-2 virus has proven extremely difficult to prevent or control. Currently there are few treatment options and very few long-lasting disinfectants available to prevent the spread. While masks and protective clothing and social distancing may offer some protection, their use has not always halted or slowed the spread. Several vaccines are currently undergoing testing; however there is still a critical need to provide new methods for inactivating the virus before it can spread and infect humans. In the present study we examined the inactivation of SARS-CoV-2 by synthetic conjugated polymers and oligomers developed in our laboratories as antimicrobials for bacteria, fungi and non-enveloped viruses. Our results show that we can obtain highly effective light induced inactivation with several of these oligomers and polymers including irradiation with near-UV and visible light. With both the oligomers and polymers, we can reach several logs of inactivation with relatively short irradiation times. Our results suggest several applications involving the incorporation of these materials in wipes, sprays, masks and clothing and other Personal Protection Equipment (PPE) that can be useful in preventing infections and the spreading of this deadly virus and future outbreaks from similar viruses.