Evan Griffith MCM’17 Describes his Summer Externship with Dr. Skelly and Dr. Shoemaker at the Molecular Helminthology Lab, TCSVM
Dr. Da’darah and I leaned closer to the screen as a fluorescent green oval slowly came into focus. “There it is!” I exclaimed. I looked in appreciation as Dr. Da’darah switched the filter and we saw a group of sparkling blue circles spread throughout the worm body. Another filter switch, and this time we saw streaks of firehouse red interwoven throughout the body. After hours in the lab, carefully following an unfamiliar procedure, my first experiment was a success! During the next four weeks of my externship in the Molecular Helminthology Laboratory (MHL), I found similar success in a series of experiments staining molecules in parasitic worms called schistosomes. I also learned a lot about schistosomiasis and molecular techniques in general.
For the Love of Worms
Schistosomiasis is a neglected tropical disease (NTD) that infects over 250 million people worldwide, with another 800 million at risk. This disease is caused by a parasite that has a complex lifecycle requiring a freshwater snail intermediate host and definitive human host. I first became interested in this disease when I learned about the scale of the problem and the potential role of re-introduced native snail predators, in this case, freshwater prawns, to reduce infection prevalence in sub-Saharan Africa. Although schistosomiasis is a globally important NTD, efforts to develop a vaccine have thus far been unsuccessful. That’s where Dr. Skelly and Dr. Shoemaker in the MHL at the Cummings School of Veterinary Medicine come in.
The Worm Doctors
Dr. Skelly, Dr. Shoemaker, and Dr. Da’darah have worked extensively to understand the surface biochemistry and cell biology of schistosomes and identify molecules accessible to host immune effectors. These molecules are important vaccine candidates as well as novel drug targets. In order to be accessible, molecules need to be located at the parasite surface. One way to determine where molecules are located is through immunofluorescence staining, which I focused on extensively throughout my four-week externship this summer.
Proteins and Protocol
Immunofluorescent (IF) staining is relatively simple to understand—add a primary antibody that will bind to your protein of interest, followed by a secondary antibody that has a fluorescent molecule attached to it that will bind to the primary antibody. Then, when viewed under a fluorescent microscope, a bright green color indicates where the protein of interested is located. I performed this procedure many times over the course of my externship with six primary antibodies in total, using fixed and live parasites, and parasite sections (Figure 1).
Figure 1. Pictures of stained antigens in worm sections from mice, and in schistosomula (larval parasites). Location of surface molecules is shown by bright green. DAPI staining (blue) shows the location of DNA in cells, and Phalloidin (red) stains actin, showing the location of muscles in the worms.
Conservation Medicine and Schistosomiasis
This externship was part of my course requirements in the Master’s in Conservation Medicine (MCM) program. The MCM program focuses on health relationships that occur at the intersection of human health, animal health, and environmental health. I first learned about schistosomiasis, an excellent example of an intersectional health relationship, during the course of the year and became interested in investigating the disease further for my externship. Working with Dr. Skelly and Dr. Da’Darah, I learned a lot about the disease, and also gained proficiency in molecular biology techniques. I’m increasingly interested in NTDs like schistosomiasis that negatively impact over one billion people worldwide. Currently, I’m working toward obtaining my DVM/MPH dual degree at Cummings School and hope to use my expertise in veterinary medicine, public health, and conservation medicine in the future as part of an interdisciplinary team to combat these debilitating diseases. The work I conducted this summer will give me more tools to do that.