Paired single-cell host profiling with multiplex-tagged bacterial mutants reveals intracellular virulence-immune networks

Summary Encounters between host cells and intracellular bacterial pathogens lead to complex phenotypes that determine the outcome of infection. Single-cell RNA-sequencing (scRNA-seq) are increasingly used to study the host factors underlying diverse cellular phenotypes. But current approaches do not permit the simultaneous unbiased study of both host and bacterial factors during infection. Here, we developed scPAIR-seq, an approach to analyze both host and pathogen factors during infection by combining multiplex-tagged mutant bacterial library with scRNA-seq to identify mutant-specific changes in host transcriptomes. We applied scPAIR-seq to macrophages infected with a library of Salmonella Typhimurium secretion system effector mutants. We developed a pipeline to independently analyze redundancy between effectors and mutant-specific unique fingerprints, and mapped the global virulence network of each individual effector by its impact on host immune pathways. ScPAIR-seq is a powerful tool to untangle bacterial virulence strategies and their complex interplay with host defense strategies that drive infection outcome.