Question

An outbreak of Vibrio vulnificus occurred in people that ate oysters from a local restaurant. The oysters were traced backed to a farm that grows oysters in four separate salt-water ponds. You want to use PCR to determine which ponds are contaminated with V. vulnificus so you can decontaminate them. After collecting water samples from each pond and isolating the DNA from each sample, you perform PCR using V. vulnificus specific primers and obtain the results shown below.

A. What do you need in order to run the PCR besides your primers (things that go in the PCR and the thing that the PCR goes in)?

B. What makes your primers specific to V. vulnificus?

C. Based on the PCR results above, which pond (if any) should be decontaminated?

Answer 1

People who ate oysters from a local restaurant had an infectious outbreak of Vibrio vulnificus which is responsible for causing Cholera. On tracing back, it was found that the oysters came from four separate saltwater ponds. Our aim is to use the polymerase chain reaction (PCR) to identify the pond and decontaminate it. We use primers that are specific to V vulnificus and the DNA is isolated from each sample in the experiment.

A. Apart from the primer, we also need the DNA template, buffers and the DNA polymerase for carrying out PCR properly.

B. Primers play a very important role in the process of PCR. They are ss DNA and their composition is complementary to that of the DNA template. Its function is to flank the DNA template and allow DNA polymerase to carry out the next steps. For making the primers specific to V vulnificus, we first need to study the genetic composition of V vulfinicus and then create the primer with complementary base pairing.

C. There will be four PCR results because there was four setups from four different saltwater ponds. The one that will provide us with maximum DNA copies will be the one where PCR was efficient. So, in this way er can infer our result and decontaminate the pond where PCR was most effective.