How do disinfectants kill viruses?

© 2012 EPFL

© 2012 EPFL

We use bleach, pasteurization, and UV radiation to purify water and food, without really understanding how they work. An EPFL laboratory has discovered the effect these common disinfectants have on viruses.

Boiling water, chlorinating a swimming pool, bleaching your bathroom – everyone’s familiar with common disinfection methods. Even though they’re effective and used widely, we still don’t completely understand how these proven methods kill viruses.

Professor Tamar Kohn, head of EPFL’s Environmental Chemistry Laboratory, and her team have shown that disinfectants don’t all work in the same way. She published an article in Environmental Science and Technology. “A virus is a genome and some proteins. We discovered that each disinfectant has totally different effects, attacking one or several of the virus’ functions. Even though the outcome is the same, the eradication methods are different.”

Kohn discovered three important functions that must remain intact for the virus to be infectious: it must be able to attach to the host cell, inject its material into the host cell and then be able to replicate. So how do our viruses react to pasteurization, chlorine disinfection and UV radiation?

Pasteurize, chlorinate…

Pasteurization is used to conserve a food, such as milk, for long periods of time by drastically reducing the number of micro-organisms in it. Heat inhibits the bonding with the host cell. The virus no longer recognizes the host, so it cannot attach to it.

The disinfectant properties of UV radiation have been explored for more than 100 years. Food networks or ventilation and air-conditioning systems were coupled to UV lamps in order to eliminate the propagation of pathogenic agents.

The radiation acts in two ways on a virus. First, it triggers chemical reactions that destroy the genome, so that it can no longer replicate itself in the host. In addition, it breaks the virus’ protein shell, or capsid. Because the virus’ genetic material is held under pressure in the capsid, when this shell is broken, there is no way for the virus to inject the material into the host cell.

Chlorinating drinking water and swimming pools has become commonplace. Chlorine attacks the genome, prevents it from replication and destroys its injection function.

Kohn’s research allows us to better understand how each disinfectant is working and in what quantity it will be effective. Thanks to these methods, it will be possible to more effectively combat viruses that infect water and food, such as viruses responsible for Polio, gastrointestinal disease and Hepatitis A.