The University of Georgia College of Veterinary Medicine

Georgia Veterinary Scholar Program

2003 Scholars

Georgia Veterinary Scholar	Faculty Mentor

Brier Bostrom University of Georgia Class of 2005	Dr. David Peterson

**Sequence variability in the ssurRNA internal transcribed spacer region of Babesia gibsoni isolates.**

Babesia gibsoni is a small, tick-transmitted intraerythrocytic protozoan that parasitizes dogs. Canine Babesiosis due to Babesia gibsoni infection is characterized by lethargy, anorexia and regenerative hemolytic anemia. Although babesiacidal drugs are now available in the United States , the clinical outcome of Babesia gibsoni infections is variable, ranging from death to an asymptomatic chronic carrier state. Our hypothesis is that the different clinical outcomes resulting from Babesia gibsoni infection is due to genetically distinguishable strains. Information pertaining to the diversity of Babesia gibsoni could assist in the diagnosis of canine Babesiosis and provide information to guide treatment. To assess the genetic variability and identify strains of Babesia gibsoni isolates we sequenced the small subunit ribosomal RNA internal transcribed spacer region of Babesia gibsoni isolates. The internal transcribed spacer region exhibits a greater degree of variability than most gene loci due to less evolutionary constraint, making the region ideal for studying intraspecific gene polymorphism. We amplified the internal transcribed spacer regions of Babesia gibsoni isolates using polymerase chain reaction. We then used an automated sequencer to obtain the complete sequence of this region. Thus far results are limited to isolates obtained from within Georgia , although we anticipate samples from the rest of the United States and parts of Asia . To date, Babesia gibsoni isolates obtained from Georgia proved to be genetically identical at the first internal transcribed spacer region, although distinctly differing from other Babesia species and closely related apicomplexan species. Although differing from our hypothesis, this information gives us insight into the recent evolutionary history and pathology of Babesia gibsoni within the southeastern United States . Although more investigation is needed, the gradual rise in clinical cases of canine Babesiosis within the Southeast may be due to clonal expansion of a single strain within a susceptible host population. In addition, the differing clinical outcomes may not be due to genetic differences in the parasite population, but rather host factors that affect the course of the disease.