The Role of FTL_1228 in Erythrocyte Invasion by Francisella tularensis

Abstract

Francisella tularensis is a gram-negative bacterium and is the causative agent of tularemia – a disease commonly referred to as ‘rabbit fever’.  This microbe is extremely virulent as inhalation of fewer than ten bacteria can lead to a lethal infection.  During infection, F. tularensis replicates in cells of the immune system, such as macrophages, as well as other non-phagocytes such as epithelial cells and hepatocytes.  Moreover, this bacterium has been shown to invade erythrocytes – a process that enhances colonization of ticks (a major disease vector).  Our laboratory previously showed that a locus encoding a hypothetical gene, FTL_1228, was induced in the presence of erythrocytes.  Therefore, we hypothesized that this gene may be responsible for invasion of these host cells.  In this study, we mutated FTL_1228 of F. tularensis LVS. Studies are ongoing to determine the role of this gene in erythrocyte invasion.  Preliminary data shows that a strain containing a disruption mutation of FTL_1228 invades erythrocytes at a higher rate than the wild-type F. tularensis LVS.  This may suggest that FTL_1228 suppresses red blood cell invasion.