5D Health Protection Group Ltd

Global Virology and Antiviral Testing Services

5D perform antiviral testing utilising in vitro models only. Virucidal efficacy testing can be carried out in a range of in vitro models. 5D Standard models that are employed to evaluate the efficacy of antimicrobials on viruses include suspension tests and hard surface carrier tests. Methods employed involve using neutral red assays, microscopic cytopathic effects (CPE) assays and virus yield reduction assays to name but a few. These and a variety of further methods are used routinely to evaluate products, such as household and industrial disinfectants and medical devices.

In addition to evaluating the efficacy of actives on viruses 5D also offer viral barrier testing for wound dressing evaluation and for testing materials that are being evaluated during the selection and innovation of new medical devices.

Virucidal Efficacy Testing

The most common methods that are routinely employed by 5D are shown below.

Assessment of Antibacterial Finishes on Textile Materials, Modified for Viruses

This is a standard method for assessing the antimicrobial properties of textiles and can be modified for antiviral testing. It can also be modified to assess the antiviral properties of textiles. The method is now used to evaluate the efficacy of wound dressings. Whilst the AATCC 100 is a standard method there are numerous modifications that can be made.

This standard requires a 24 or 48 hour incubation period some viruses require a 7-10 day time period to show activity against cell lines. In addition to this different antimicrobials may require different neutralising methods.

Standard Practice to Assess the Activity of Microbicides Against Viruses in suspension

ASTM E1052 is a standard used to determine if a substance has the ability to inactivate viruses in a suspension i.e. it is used to determine the virucidal activity of a substance.

Median Tissue Culture Infectious Dose (TCID₅₀)

The media tissue culture infectious does is often called the endpoint dilution assay. Virus infectivity is defined as the number of virus particles that have the ability to invade a host cell. The viral titre can be measured by the TCID₅₀ which indicates the concentration at which 50% of cells have been infected. It can also be defined as the quantity of viruses that that are able to produce a cytopathic effect in 50% of cells that have been inoculated with viruses. At 5D we use 2 methods to determine the TCID₅₀, the Spearman-Karber and the Reed-Muench methods.

Practice to Assess Virucidal Activity of Chemicals Intended for Disinfection of Inanimate, Nonporous Environmental Surfaces

ASTM E1053 is a standard used to evaluate the effectiveness of a liquid, aerosol/foam and spray products against viruses. It is used to evaluate those microbicides which are intended to be used on inanimate, nonporous and environmental surfaces.

Standard Quantitative Disk Carrier Test Method

ASTM E2197 is a standard test used to evaluate the ability of a substance to inactivate viruses, fungi, mycobacteria, bacterial spores and vegetative on disk carriers of brushed stainless steel. The brushed stainless steel is used to represent hard, nonporous surfaces and medical devices.

Quantitative Suspension Test for the Evaluation of Virucidal Activity in the Medical Area

EN 14476 is a standard used to determine the virucidal activity of non-enveloped viruses using a quantitative suspension assay.

Pre-Saturated Towelettes Initial Virucidal Effectiveness Test

This test is used to evaluate the virucidal efficacy of pre-saturated or impregnated towelettes that are being used for hard, non-porous surface disinfectants.

Viral Barrier Testing

Viral barrier testing is used to evaluate if a technology is impermeable to viruses. This method is often appropriate for evaluating the viral barrier property of wound dressings.

Cytopathic Effect (CPE) Inhibition Assay

The CPE is used to indicate if there are morphological changes occurring in cells caused by a cytopathogenic virus. This assay is used to evaluate agents to determine if they are able to inhibit a CPE.

Quantitative Polymerase Chain Reaction (qPCR)

qPCR can be used to detect the presence of virus nucleic acids. This test can be used to evaluate whether a technology has the ability to reduce virus nucleic acid which would indicate the antiviral efficacy of a technology.

Plaque Reduction Assay

Virus particles multiply inside cells which result in plaques which are circular zones of infected regions. A plaque reduction assay is used to measure if a test solution or technology can reduce the number of plaques being developed.