Brucella abortus egresses from infected cells exploiting multivesicular bodies

SPERA JM; GUAIMAS, F; CZIBENER, C; UGALDE JE

MEndoza

Workshop; Pathogenic microbes-host interaction: highlights in intracellular traffic; 2022

IHEM

Host cell egress is a critical step in the life cycle of intracellular pathogens, especially in microbes capable of establishingchronic infections. The Gram-negative bacterium Brucella belongs to such group of pathogens. Even though much hasbeen done to understand how Brucella avoids killing and multiplies in its intracellular niche, the mechanism that thisbacterium deploys to egress from the cell to complete its cycle has been poorly studied. In this manuscript we quantifiedthe kinetics of bacterial egress and show that Brucella exploits multivesicular bodies to exit host cells. For the first time,we visualized the process of egress in real time by live video microscopy and showed that some bacteria exit from hostcells in vacuoles containing multivesicular bodies-like features. We observed co-localization of Brucella with twomultivesicular markers, CD63 and LBPA, during both the final stages of the intracellular life cycle and in egressedbacteria. Moreover, drugs that either promote or inhibit multivesicular bodies, increased or decreased the number ofextracellular bacteria, respectively. Our results strongly suggest that Brucella hijacks multivesicular bodies to exit thehost cells to initiate new infection events.