Zoo InternQuest is a career exploration program for high school students. For more information see the Zoo InternQuest Journals. For more photos see the Zoo InternQuest Photo Journal.

In recent years, one of the polar bears at the San Diego Zoo died mysteriously from an unknown disease. Following that death, a giraffe and some gazelles also died within a short period of time. Researchers and vets at the Zoo needed to discover what caused these possibly related illnesses and how to stop them from spreading to other species. So they turned to the Molecular Diagnostics Lab at the Arnold and Mabel Beckman Center for Conservation Research. Dr. Mark Schrenzel, the head of the lab, explained to us what they found. Through DNA testing, they determined that the virus was a herpes virus, which had spread to these animals from a zebra. This type of herpes virus is a chronic disease in zebras that does not adversely affect them. However, it does affect animals that are not accustomed to it, such as polar bears.

Solving mysteries like this is all a part of Dr. Schrenzel’s job at the Institute for Conservation Research. In the Molecular Diagnostic Lab, he works with a wide variety of animals and the diseases associated with them, so he needs to be able to switch mental tracks quickly, and work to generate critical, new information for the sake of the survival of species.

According to Dr. Schrenzel, his work entails four main steps. First, he needs to characterize the disease outbreak, the most challenging step of all. This means finding out what type of disease the animal has and how that disease spreads between animals. One way to do this is by using PCR, or Polymerase Chain Reaction. PCR is used to make literally billions of copies of a section of the pathogenic DNA that scientists are interested in. Having lots of copies makes it easier for Dr. Schrenzel and his team to look at the different aspects of the disease that they are studying. Once they have these copies, they are able to run the sample through an agarose matrix, a process called gel electrophoresis. This enables them to confirm whether or not a given DNA sample is infected with the disease they are studying. From there, he can develop a genetic diagnostic test, a quick and easy way to test for the disease in future samples.

The last couple of steps in Dr. Schrenzel’s work are arguably the most important when it comes to the big picture. After creating the diagnostic test, he can examine how the disease is spread, and what factors make animals susceptible to it. They can then connect it all into the ecology of infectious disease, examining the many factors that went into the illness, such as the stress level or depressed immune system of the host animal. These steps are crucial in discovering how to stop the spread of diseases, especially at the Wild Animal Park and the Zoo, where so many different kinds of animals are housed, each with their own specific needs. As head of the Molecular Diagnostics Lab, Dr. Schrenzel plays a very important role in the process of saving the planet’s awe-inspiring species. What an amazing job!

Becky, Careers Team

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