Efficacy of microbicides for inactivation of Ebola–Makona virus on a non-porous surface: a targeted hygiene intervention for reducing virus spread

Abstract

Microbicides play critical roles in infection prevention and control of Ebola virus by decontaminating high-touch environmental surfaces (HITES), interrupting the virus-HITES-hands nexus. We evaluated the efficacy of formulations containing different microbicidal actives for inactivating Ebola virus–Makona strain (EBOV/Mak) on stainless-steel carriers per ASTM E2197-11. Formulations of sodium hypochlorite (NaOCl) (0.05–1%), ethanol (70%), chloroxylenol (PCMX) (0.12–0.48% by weight) in hard water, and a ready-to-use disinfectant spray with 58% ethanol (EDS), were tested at contact times of 0, or 0.5 to 10 min at ambient temperature. EBOV/Mak was inactivated (> 6 log10) by 70% ethanol after contact times ≥ 2.5 min, by 0.5% and 1% NaOCl or EDS (> 4 log10) at contact times ≥ 5 min, and by 0.12–0.48% PCMX (> 4.2 log10) at contact times ≥ 5 min. Residual infectious virus in neutralized samples was assessed by passage on cells and evaluation for viral cytopathic effect. No infectious virus was detected in cells inoculated with EBOV/Mak exposed to NaOCl (0.5% or 1%), PCMX (0.12% to 0.48%), or EDS for ≥ 5 min. These results demonstrate ≥ 6 log10 inactivation of EBOV/Mak dried on prototypic surfaces by EDS or formulations of NaOCl (≥ 0.5%), PCMX (≥ 0.12%), or 70% ethanol at contact times ≥ 5 min.

Efficacy of microbicidal actives and formulations for inactivation of Lassa virus in suspension

“…For disinfectants that are non-cytotoxic to the cellular infectivity assays used for demonstrating efficacy, a 4-log 10 reduction in viral titer is typically considered to be effective. However, as we have previously done when dealing with especially lethal viruses, such as Ebola virus 23,24 , we extended the stringency of the assay for detecting residual infectious virus post-exposure to the microbicides by conducting the plate safety test. The latter enabled any infectious virus remaining post-exposure/neutralization to amplify in Vero cells in a six-well plate format, with up to two passages onto fresh cells performed for negative wells.…”

Hand hygiene: virucidal efficacy of a liquid hand wash product against Ebola virus

“…It is likely that the susceptibility of enveloped viruses such as Ebola virus to microbicides such as salicylic acid is attributed to disruption/lysis of the lipid envelope, which is derived from the host cell during the viral maturation and release process (termed budding) [ 32 , 33 ]. This proposed mechanism is supported by the known efficacy of alcohol hand rubs against Ebola virus [ 34 ] and by the efficacy of a commercial antiseptic liquid for inactivating EBOV/Mak in suspensions containing a tripartite soil load [ 35 , 36 ]. Additional mechanisms of viral inactivation may play roles in the case of this particular LHW.…”

Virucidal activity of three standard chemical disinfectants against Ebola virus suspended in tripartite soil and whole blood

“…To ensure experimental reproducibility, water of standardized hardness (WSH) was prepared as previously described 13 . Brie y, 2.1 g MgCl 2 and 2.3 g CaCl 2 were diluted in 50 ml of ddH 2 O and designated as solution A.…”

“…Virucidal activity of these decontamination solutions was assessed in two different biological soil types. Tripartite soil containing 100 µl 5% bovine serum albumin (BSA), 400 µl 0.4% mucin, and 140 µl 5% tryptone (all sourced from Sigma Aldrich, Buchs, Switzerland) representing a medium soil load as a mucus substitute as previously described [13][14][15] . For a heavier soil load, whole blood was drawn with informed consent from a healthy 24-year-old donor never exposed to Ebola virus using BD Vacutainer K2E (EDTA) Plus Blood Collection Tubes (BD Switzerland Sàrl, Eysins, Switzerland) and used within 72 hours.…”