Question: How do you know if there’s a virus in food

Amy Heather Fitzpatrick answered on 11 Nov 2019:

So hard!!!!
So a lot of the viruses that make humans sick are REALLY REALLY REALLY hard to grow! So we have to look for the DNA/RNA. This means when we find DNA/RNA from a virus in food, we don’t really know if that virus is alive or dead, but its the only test we have. In order to get the DNA/RNA out of the food you have to put the samples in alcohols and soapy washes and beat them with beads and then put them in a big centrifuge. A centrifuge spins the samples at a very fast speed. Because you spin the samples so fast, the heavy parts of the sample go to the bottom of the tube. Viruses are really really really small so you only take the liquid at the top of the tube. This is called size separation. The rest of the method is complicated and involves taking information we know above the sequence of a virus. So a sequence is A T G C. It might 4000 – 130000 bases long. We design tags that read a specific series of A T G C and put these tags in with the sample and heat them up. With the heat the tags attach to the virus. Then we run these samples on a gel. You can see photos on my page on I’m A Scientist. The gel has a ladder that tells us the different sizes. We know from designing the tags how big our sample should be. If the size looks correct we know our sample has the virus in it 😀