Burkholderia pseudomallei is a Gram-negative, facultative, cytosolic bacterial pathogen that is the
causative agent of melioidosis in humans, an often-fatal disease prevalent in Southeast Asia and northern Australia. B. pseudomallei and related species are the only bacterial pathogens known to spread by inducing cell-cell fusion of host cells, however, little is known about the mechanism of B.thailandensis induced cell-cell fusion aside from the requirement of two major features. First, intracellular motility of B. thailandensis is thought to bring the plasma membrane of neighboring cells into proximity, which is required for membrane fusion in general. The second required feature is the fifth type 6 secretion system (T6SS-5) and its tip protein VgrG-5.mUnderstanding the mechanism of cell-cell fusion will elucidate a key aspect of Burkholderia pathogenesis, which may impact our understanding of how to combat melioidosis.

Nora hypothesizes that B. thailandensis induces cell-cell fusion through a series of steps including membrane protrusion formation and membrane fusion pore formation, of which the VgrG-5 functions as the plasma membrane fusogen during this process. The aims of Nora’s project will be to visualize B. thailandensis cell-cell fusion using live cell microscopy using GFP-labeled bacteria to infect A549 (human lung epithelial) cells expressing an RFP-tagged farnesyl plasma membrane marker, followed by characterization of VgrG-5 function in cell-cell fusion.

The results of Nora’s studies will reveal when and where protrusion formation and membrane fusion occur, as well as have the potential to uncover alternative approaches to inhibit growth of this antibiotic-resistant pathogen in vivo, for example by inhibiting VgrG-5-mediated cell-cell fusion. In addition, this investigation into understanding how Burkholderia spp. spread from cell-to-cell will help illucidate the mechanisms used by these pathogens for virulence. Research into their pathogenicity and spread will help in developing new strategies for targeting them.