Brucella abortus S19

The genus Brucella is comprised mostly of mammalian pathogens, which due to their low infectious does, aerosol transmission and treatment difficulty are classified as potential bioterrorism agents. Brucella abortus (strain S19) is a spontaneously attenuated strain discovered by Dr. John Buck in 1923. However, the underlying molecular or physiological mechanisms causing the loss of virulence is not well understood. B. abortus is the primary cause of bovine brucellosis, which results in enormous (billions of dollars) economic losses due primarily to reproductive failure and food losses. It is highly infectious, and can be spread through contact with infected animal products or through the air, making them a potential bioterrorism agent. In man, it causes undulant fever, a long debilitating disease that is treated by protracted administration of antibiotics. Since early 1930s, this strain has been used worldwide as an effective vaccine to prevent brucellosis in cattle until it was replaced by strain RB51 during the 1990s. Once the organism has entered the body, it can become intracellular, and enter the blood and lymphatic regions, multiplying inside phagocytes before eventually causing bacteremia (spread of bacteria through the blood). Virulence may depend on a type IV secretion system which may promote intracellular growth by secreting important effector molecules. (EBI Integr8)