Genome-wide RNAi screen reveals host factors involved in "Brucella" infection

Abstract

Brucella is an intracellular zoonotic pathogen that causes animal and human brucellosis worldwide. As natural hosts, Brucella infects various animal species including cows, goats, and pigs, causing abortion and birth of weak offspring. Humans are infected as incidental hosts, causing a febrile disease known as Malta fever that can develop into chronic infections with more severe symptoms such as endocarditis or meningitis. Therefore, brucellosis is a significant threat to the economy and general health in endemic areas. Brucella is able to invade phagocytic and non-phagocytic cells and replicates in an intracellular compartment known as the Brucella-containing vacuole (BCV). Following entry into a host cell, the BCV traffics along the endocytic pathway and despite interacting with endo-lysosomal compartments, degradation in these compartments are avoided. At later stages of infection when intracellular proliferation occurs, the BCV is found in close association with the endoplasmic reticulum (ER). Despite many advances in the field, the molecular mechanisms on how Brucella enters cells, avoids lysosomal degradation, and finally establishes an intracellular niche remain largely unknown. To study Brucella entry and replication in human cells, we performed a genome-wide, high-throughput microscopy-based RNA interference (RNAi) screen in HeLa cells. This allowed us to unravel known and novel host signaling pathways involved in Brucella infection. To dissect the stage of infection that is regulated by these signaling pathways, a high-throughput entry assay was developed to study early stages of Brucella infection. Follow up studies allow a deeper understanding of the role of the host signaling pathway of interest during Brucella infection.