Student Presenter(s): Luke D'Cunha
Faculty Mentor: Joseph Horzempa, Ph.D.
Department: Biological Sciences
School/College: College of Osteopathic Medicine, Jonesboro

Francisella tularensis, the causative agent of tularemia, is a pathogenic gram-negative bacterium that enters human red blood cells (RBCs). Previous investigations suggest that invasion of RBCs helps F. tularensis survive in the gut of arthropods – a transmission vector of this bacterium leading to colonization. Since tularemia is a zoonotic infection, humans are not the primary host of F. tularensis. Therefore, we sought to investigate whether F. tularensis was capable of invading RBCs of other animals. Using gentamicin protection assay, we discovered that while F. tularensis could enter sheep and chicken erythrocytes, bovine RBCs did not support invasion. Because of previous studies published by our lab, and due to intrinsic differences between human and bovine erythrocyte surface protein Band 3, we hypothesized that RBC membrane protein Band 3 is required for invasion. We used anti-band 3 Fab fragments to physically block the Band 3 RBC surface protein, and investigated how this impacted F. tularensis invasion, as qualified by gentamicin protection assay. Here, we provide preliminary evidence suggesting that F. tularensis uses Band 3 to enter human RBCs. Using fluorescent microscopy, we observed that F. tularensis bacteria congregate in peculiar clusters during interaction with erythrocytes, and that this interaction appears to be dependent upon erythrocyte surface proteins and the Type VI secretion system.