How Do Invertebrates Defend Themselves from Pathogens?
Using Trematodes and Biomphalaria glabrata as a Model System
One of the long-standing interests in our lab is to use trematodes and snails as model systems to better understand how invertebrates (in our case, snails) protect themselves from pathogens and parasites (Abstract) (Abstract). Major long-term collaborators in this work include Dr. Coen Adema and Dr. Si-Ming Zhang.
Our studies focus on how both the cellular and humoral responses of snails are directed towards attacking and destroying the larval stages of digenetic trematodes, and how these parasites overcome and suppress the attacks by their snail host's defense system (Abstract) (Abstract).
The B. glabrata genome has many genes that encode fibrinogen-related proteins, or FREPs (Abstract) (Abstract). FREPs are unusual for having both immunoglobulin superfamily domains and fibrinogen domains. At least some FREPs circulate in the hemolymph of the snail, and one of our hypotheses is that they function in a defensive role, potentially non-self recognition. We have shown that some FREP genes are up-regulated following infection with trematodes, and that the snail is able to produce diversified FREPs through point mutation and recombination processes (Abstract).
Further studies are underway, including the development of techniques to knockdown FREP expression using RNAi in snails.
These studies fit in well with the overall theme of the NIH COBRE Center for Evolutionary and Theoretical Immunology, funded by the National Center for Research Resources. Currently, the participants in CETI investigate immune systems in organisms as diverse as cnidarians, worms, snails and marsupials, and address theoretical aspects of immunology as well. CETI involves scientists from the Departments of Biology and Computer Science at UNM, the Los Alamos National Labs, and the Santa Fe Institute.
We sincerely thank the NIH for grants IP20RR18754 from the Institutional Development Award (IDeA) Program of the National Center for Research Resources and AI24340 that enable many of the studies reported here.
Updated June 2006
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