Molecular Diagnostic Laboratory


Cutting-edge Science in Historical Surroundings

Looking across St. Michael’s bridge, early morning, in Ghent, Belgium.

I stood on the side of Saint Michael’s bridge staring at the stunning city before me: Ghent, Belgium. For four nights I was privileged to live in the beauty of this Central European city and take in all of her cafes, castles, and (my favorite!) chocolate. More importantly, I was there on official San Diego Zoo Global business to join some of the world’s best minds for a short, intensive workshop on molecular epidemiology and attend an influential conference that is held only once every three years: The International Symposium of Veterinary Epidemiology and Economics (ISVEE; endearingly called “iz-v”). It was an amazing opportunity provided by special funds set aside for employee development to meet with, learn from, and establish collaborations with some of the best in the field.

My journey started with the workshop in molecular epidemiology. The course instructors came from distant corners of the globe, including New Zealand, Scotland, and the U.S. to share their expertise with approximately 30 participants. We gathered for 3 days under the dim lights and a vaulted ceiling of wooden beams on the 4th floor (a.k.a. the attic) of a medieval Dominican monastery, Het Pand. This venue was not exactly the white, sterile laboratory from the movies (or the Zoo’s lab!) in which molecular science is usually performed, but I liked the contrast…cutting-edge science in historical surroundings.

Het Pand is the medieval Dominican Monastery where the molecular epidemiology course was held, Ghent, Belgium.

Molecular epidemiology is a specialized subfield of epidemiology (see Epidemi-what?) that requires unique tools and techniques to uncover patterns of disease transmission at the genetic level. My interest in this topic stems from the Zoo’s Molecular Diagnostic Laboratory. The lab was established in 1999 as part of the Wildlife Disease Laboratories to fulfill a need to develop diagnostic tests suitable for our animals and to improve our ability to identify and control important diseases. As one of the only zoo-based molecular diagnostic labs in the world, it has been instrumental in the development of diagnostic tests and animal disease research. For example, in 2007 a generous grant from the Ellen Browning Scripps Foundation allowed us to carry out a large study to describe herpesviruses in hoofed mammals (antelope, deer, goats, sheep, cows, and similar species). These herpesviruses can cause a fatal disease called malignant catarrhal fever when they are passed from animals that naturally carry the virus to new, susceptible hosts. Molecular methods can be used to look at the genetic similarities between viruses found in different animals to determine who is passing them to whom. This is where the epidemiology comes in.

Looking for patterns within molecular data (i.e., patterns across changes in DNA) requires methods that are new to me as an analytical epidemiologist. Thus, my goal in attending the course was to develop a working knowledge of such techniques to further improve the Wildlife Disease Laboratories’ ability to answer some pressing conservation questions. On the second day I was introduced to a new data analysis technique called Analysis of Molecular Variance (or “AMOVA” for short). Such a technique will allow me to extend our valuable data on herpesviruses and ask new or additional questions like: “Are animals in multispecies exhibits more likely to transmit the virus to each other?” Such an analysis could have a big impact on providing information that helps zoos better manage endangered species in the presence of this known disease.

A view of Maastricht, looking over the Meuse river.

Following the workshop, my travels then took me 90 miles east to the Belgium-Netherlands border where I joined 1,000 conference participants in Maastricht, The Netherlands, for 5 days of everything-animal-related epidemiology. Maastricht is a beautiful, historic-yet-modern city on the banks of the Meuse River that is famous for the birthplace of the European Union and the single European currency, the euro. My days in Maastricht consisted of attending talks on the latest work in the field, while the evenings presented opportunities to meet veterinary epidemiologists from around the world and engage in discussions of their research projects and areas of expertise.

I was honored to be a representative of San Diego Zoo Global at this venue and share some of our notable conservation work in epidemiology. Experiences like these provide me with better capabilities for using science to save species.

Carmel Witte is a senior research coordinator at the San Diego Zoo Institute for Conservation Research. Read her previous post, Investigating Primate Malaria in the Amazon.


Invisible Clues

An ashy-headed goose

Working in the Molecular Diagnostic Laboratory is often an adventure. I never know when I am going to get an email or phone call from our Pathology Lab letting me know we have an interesting animal case and they are sending a liver, or a lung, or various other animal parts for testing using our molecular techniques.

When the clinicians and pathologists have a good idea of what disease or pathogen the animal may have, our molecular diagnostic tools can be just the thing they need to confirm and back up their diagnosis. In some unusual instances, our testing may even reveal a pathogen that has never been described in that particular species. One method we use most often is PCR (polymerase chain reaction). With this tool we can use extracted DNA or RNA from the animal sample and amplify it from a few copies to millions of copies. In order to make this technique very sensitive and specific, we use primers that are specifically designed to attach to and amplify certain targeted genes of viruses, or other pathogens.

One interesting case example was a 15-year-old female ashy-headed goose that had died. A thorough review of her health history, as well as a necropsy and histology, was performed. The clinicians and pathologists had an idea as to what organism could be affecting this animal but needed further confirmation so that the lagoon exhibit could be managed in the most appropriate and effective manner. After extracting the DNA from the goose’s cecum and liver, running it on a conventional PCR, cloning (inserting the PCR product into a vector) it, and finally sequencing the PCR products, the clinicians’ and pathologists’ findings in conjunction with the molecular results determined that Avian schistosomiasis, an infestation of trematodes (blood flukes, scientific name Dendritobilharzia pulverulenta) was what made this bird sick.

Having these valuable techniques available is a complement to the management processes that protects and maintains the health of San Diego Zoo Global’s animal collections. Working with such a talented team of clinicians, pathologists, and all the animal care staff is very rewarding and fulfilling!

Jennifer Burchell is a research coordinator for the San Diego Zoo Institute for Conservation Research.