M. Brittany Johnson
Ph.D. in Microbiology, May 2014
Thesis: Mechanisms of Neisseria gonorrhoeae intracellular survival inside primary human neutrophils
Research: Brittany’s thesis research focuses on mechanisms of Neisseria gonorrhoeae(Gc) survival inside primary human neutrophils. Gc is the causative agent of the major global health problem, gonorrhea. In response to infection with Gc abundant neutrophils are recruited. However, Gc can be cultured from patient exudates, indicating Gc has developed mechanisms to defend against neutrophil killing. Brittany made the striking observation that Gc phagosomes avoid fusion with neutrophil primary (azurophilic) granules, allowing the bacteria to remain viable intracellularly. Delayed phagosome-primary granule fusion could be overcome by opsonizing Gc with immunoglobulin or by Gc expression of surface-exposed opacity-associated proteins (Opa). Residence in a degradative phagolysosome resulted in decreased Gc viability by exposing the bacteria to proteases found in primary granules. Together these data reveal that Gc avoids clearance by neutrophils in acute gonorrhea by manipulating neutrophil membrane trafficking to prevent the formation of a degradative phagolysosome.