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Title: Mechanisms of virucidal action of alcohol and metallic ions against nonenveloped viruses
Author: Vieira Goncalves, Leonam
ISNI:       0000 0004 7224 1508
Awarding Body: Cardiff University
Current Institution: Cardiff University
Date of Award: 2018
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Studying the mechanism of action (MoA) of biocides against pathogenic microorganisms is crucial to understand their efficacy and limitations, and to develop more efficient microbicidal formulations. Combining alcohol and zinc has been reported to enhance microbicidal activity, but the reasons for such activity are unknown. This study focuses on the impact of combining ethanol and zinc salt at pH 10.5 against nonenveloped viruses. The study is focused on three different aspects: i) virucidal activity screening of ethanol:zinc combinations against bacteriophages and human viruses; ii) impact of ethanol:zinc combinations on virus structure, particularly the viral capsid and nucleic acid, using Transmission Electron Microscopy (TEM); Atomic Force Microscopy (AFM) and agarose gel DNA electrophoresis and iii) chemical speciation and stability of ethanol:zinc combinations over time. The combination of ethanol with zinc salt was found to be more effective against viruses than control formulations containing sole active ingredients and/or excipients only. Activity test of 40%(w/v) ethanol with 0.1% (w/v) zinc salt with excipients (RB- 002 formulation) against F116 and adenovirus type 2 (AdV2) at 60 min contact time yielded 0.68 ± 0.02 and 5.26 ± 0.10 log10 reduction, respectively. In comparison, 0.1% (w/v) zinc salt only with excipient (RB-002G formulation) showed no virucidal activity against bacteriophage F116 (0.14 ± 0.02 log10 reduction) and AdV2 (0.80 ± 0.12 log10 reduction) in suspension. Differences between activities against bacteriophage MS2 and poliovirus type 1 were similar as the ones found between F116 and AdV2. Formulation containing 40%(w/v) ethanol with 0.1% (w/v) zinc salt produced a range of structural damage to F116 and attP AdV5 indicating possible capsid alteration. Effect of the combined formulation on viral capsid was confirmed with AFM with a possible decreased in virus capsid stiffness and significant virus capsid height reduction over 10 min contact time. F116 DNA damage was detected upon exposure to 40%(w/v) ethanol with 0.1% (w/v) zinc salt with excipients, but no damage was detected on AdV2 DNA through electrophoresis analysis. The alcohol/zinc formulation system at pH 10.5 was shown to have promising virucidal activity against non-enveloped viruses at room temperature following an alteration of the viral capsid, and possible damage to the viral nucleic acid. This study also showed the limitations of using bacteriophage as surrogate for mammalian viruses.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: R Medicine (General) ; RM Therapeutics. Pharmacology