Our contribution to fighting the Covid-19 pandemic is our antiviral testing, enabling customers with active surfaces, textiles, procedures or antiviral substances to bring their solution into application.
In our S2-lab, classical
antiviral assays according to ISO 21702 (surfaces) and ISO 18184 (textiles) or for substance effects according to the RKI guidelines are done, but also innovative new assays employing a spray-nozzles to produce droplets and aerosols of virus suspension or barrier-function assays for protective agents. This way we focus on meaningful analysis adapted to the clients needs. We use Human Coronavirus 229E or Adenovirus Type 5 with competent cell-lines.
- Testing for antiviral effect, with a special focus on corona virus, for substances or solutions in reference to the RKI-guidelines
- Testing of textiles according to ISO 18184:2019, modified for corona virus
- Testing of surface effects against virus according to ISO 21702:2019, modified for corona virus
- Spray-nozzle assay to test the effect of surfaces, textiles, virus deactivation methods on virus activity in droplets and aerosols
- Barrier function analysis for substances that block of virus entry into model cells
- Adaptation of incubation time, protein or other load, temperature, light to analyse realistic application scenarios
How is antiviral testing done?
Step 1: Inoculation with virus
The samples in infected with a drop or a spray nozzle.
Step 2: Sampling
After a defined time of incubation, the virus is washed of the sample with a nutrient solution.
Step 3: Evaluation
The effect of the virus on competent cells is evaluated either by a plate count or a plaque formation assay. The titer of active virus is calculated.
Corona – what do we test for?
Almost everybody must have heard that the name is derived from the characteristic form of the spike proteins. Coronaviruses, first discovered in 1966 by June Almeida, are an extensive virus family. They are characterized by having their genetic information stored as RNA, which is very large in comparison. It is also very stable, because corona virus have an included mechanism against mutations. Apart from the club-shaped spike protein, a lipid bi-layer membrane is very typical for this group. This detail also makes them especially susceptible for fat-dissolving agents, like soap when washing hands.
The Coronaviruses differ in their composition, especially the spike protein responsible for docking onto cells. Virologists however classify them by their genetic code, which reveals relationships. Within the actual corona viruses (Orthocoronavirinae), there are 4 genera (and maybe soon 5, as research is accelerated). One of them is the Alphacoronaviruses, with 13 subgenera, one of which contains the Human Coronavirus 229E, which has been known for a long time and is our test organism. It usually doesn’t lead to more than a light cold, if at all, and is very widespread. This makes it a much more comfortable test organisms than the “real” Sars viruses. These belong to the genus of Betacoronovirus. Humans have first known them with Sars, the “Severe acute respiratory syndrom”, causing serious illness and death. It was followed by Mers from the same genus, and now we fight against Sars-2, or more precisely “Severe acute respiratory syndrom corona virus 2” – Sars-CoV-2 which causes the “Covid-19” disease, Corona-virus-induced-disease-of-2019.
What does that mean – “antiviral”?
When we label something as antiviral we mean that the substance, the material surface, the textile or a treatment lead to the inactivation of the virus in the sense that it becomes unable to cause an infection. Since this is a very general definition and can be caused by a plethora of different mechanisms, in terms of actual testing antiviral is defined as the reduction of infection in sensitive target cells – a virus can only enter and infect cells that carry certain key proteins on their surface. The reduction is calculated as a concentration.
These are the main mechanisms by which an antiviral effect can be produced:
- the virus is chemically or physically destroyed
- crucial components of the virus are altered:
– the spike protein, making it unable to initiate entry into the cell
– the genetic information, inhibiting virus replication
– other crucial proteins important in the production cycle are inactivated
– only for lipid-containing strains like coronaviruses: the lipid barrier is destroyed so that the RNA or proteins can be significantly altered - retention: viruses are bound or retained, so that they cannot enter the cell and finally decompose
- masking: the key sequences for docking onto cells are blocked
Antiviral testing itself cannot reveal, which mechanism has lead to the reduction of the infectious titer.
The RKI has defined protocols, methods, definitions and conditions on how to test for and document an antiviral effect.