Measurement of antiviral activity of solid surface coatings using human coronaviruses 229E (HCoV-229E)

Abstract

ABSTRACT Background The current COVID-19 pandemic and previous MERS and SARS-1 outbreaks mean research into coronaviruses is critical. These mild human coronaviruses can help us learn more about severe coronaviruses and thus be used as a model. The virus may be spread via fomite transmission from surfaces and airborne transmission from aerosols. The HCoV-229E virus can be safely handled at BSL-2, easily found in many laboratories and institutions, providing preclinical screening and antiviral design instead of SARS-CoV-2. Methods It was intended to test the Cu-TiO2 surface coatings for antiviral properties using a plaque assay method, modified to use Mv1Lu cells as a target cell for the virus. Various other modifications were tested, and an optimal method was achieved by substituting formalin for alcohol-fixative, adsorbing the viral inoculum for 1.5 h, then adding the supplemented overlay medium (1% agarose: EMEM supplemented with 2.5% FBS and other supplements) and incubating for five days. Staining was done with 0.2% v/v crystal violet. Findings This study determined a workable and consistent method for the growth and titration of HCoV-229E in Mv1Lu. The final optimised assay produced Mv1Lu cells tolerant of cell-cell contact stress and able to proliferate rapidly. Due to time constraints, the assay was not ultimately used to determine whether the Cu-TiO2 coatings had antiviral properties, but the developed assay will facilitate this as a next step in the research.

Interpretation An inexpensive plaque assay has been developed, which will be a valuable tool for HCoV researchers. Although the solid surface coatings were not tested in this project, and the plaques of 229E were not easily countable, considerable progress was achieved in improving the plaque assay utilising Mv1 LU cells. Further study is needed to allow the method to be utilised to evaluate additional coronavirus and antivirals activity.