NEW DELHI: With countries looking at lockdown mode to curb the spread of coronavirus that has reached almost every continent, here’s the lowdown on how viruses self-assemble into a functional active menace, and how they can be tackled with something as simple as soap.
A virus is a nano ‘collaboration’
- Most viruses consist of three key building blocks: RNA, proteins and lipids. These three units self-assemble to form a virus.
- The viral self-assembly is based on weak interactions between the proteins, RNA and lipids. The lipids form a protective coat around the virus and help keep its components together. But the lipid outer layer is the weakest link in the virus’ structure.
- Together these act like Velcro to keep the self-assembled viral particle intact. Since there are no strong bonds holding the three units together, the virus can be broken up without the use of harsh chemicals.
How viruses interact with surfaces
- Most viruses, including the coronavirus, are between 50-200 nanometres — truly nanoparticles, which have complex interactions with surfaces they are on.
- The tiny droplets from coughs and sneezes end up on surfaces and often dry out quickly but the viruses remain active .
- Wood, fabric, skin interact strongly with viruses. In contrast are steel, porcelain and plastics like teflon. The flatter the surface, the less the virus will “stick” to it.
- Rougher surfaces pull the virus apart but this does not mean such surfaces are completely safe. The skin is an ideal surface — the proteins and fatty acids in the dead cells on the surface interact with the virus.
- When you touch, say, a steel surface with a virus particle on it, it will stick to your skin and get transferred onto your hands. But you are not (yet) infected — If you touch your face though, the virus can get transferred from your hands and on to your face.
- That makes the virus dangerously close to the airways and the mucus membranes in and around your mouth and eyes, which can lead to a viral infection unless your immune system kills the virus.
- Covid-19 is thought to stay active on favourable surfaces for hours, possibly a day. Moisture, sun light and heat make the virus less stable.
Why soap is saviour
- Most people touch their faces once every 2-5 minutes. Once the virus is on your hands, you are at high risk unless you can wash the active virus off. Washing it off with just water is not enough as the virus is sticky and may not budge.
- Soapy water is totally different. Soap contains fat-like substances known as amphiphiles, some structurally very similar to the lipids in the virus outer membrane. The soap molecules “compete” with the lipids in the virus’ outer layer, effectively “dissolving” the glue that holds the virus together.
- The soap also outcompetes the interactions between the virus and the skin surface. Soon the viruses get detached and fall apart on the combined action of soap and water.
- Skin is quite rough and wrinkly, which is why you do need a fair amount of rubbing and soaking to ensure soap reaches very nook and cranny on the skin surface that could be hiding active viruses.