Elucidating the regulatory mechanism of a Brucella-specific small RNA required for virulence

Project Summary Brucella spp. are bacteria that naturally infect a variety of domesticated and wild animals leading to abortions and sterility, and these bacteria are also capable of causing debilitating human infections, which often result from human exposure to infected animals and animal products. Brucella spp. are considered threats as potential biological weapons. Importantly, antibiotic treatment against brucellosis is prone to disease relapse, and there is currently no safe and effective vaccine to protect humans against infection with Brucella. The brucellae are intracellular pathogens that reside within immune cells called macrophages where they replicate in a specialized compartment, and the capacity of Brucella to survive and replicate within macrophages is essential to their ability to cause disease. Over the last few years, our laboratory has characterized genetic pathways that are critical for the intracellular survival and pathogenesis of Brucella strains, and specifically, we have identified small regulatory RNAs (sRNAs) that are essential for Brucella virulence. Preliminary experiments have determined that one sRNA, called MavR, for MurF- and virulence-regulating sRNA is required for full virulence of B. abortus in a mouse model of chronic Brucella infection. Preliminary work has demonstrated that MavR is a negative regulator of MurF, which is an essential enzyme involved in peptidoglycan biosynthesis. Taken together, these data led us to develop a model for the MavR-MurF genetic pathway that is critical for Brucella virulence, and the work outlined in this application will test several independent hypotheses associated with this important genetic circuit. In the end, the information gleaned from these studies may be used to develop new therapeutic and vaccine strategies against human Brucella infection.