Construction of a screening system for key intracellular survival proteins of macrophages of Staphylococcus aureus

To establish a high-throughput screening system to obtain key Staphylococcus aureus (S. aureus) secretory proteins which required for S. aureus survival in macrophages.

Based on our validated eukaryotic expression vector library of S. aureus secretory proteins, DNA transfection was used to obtain an RAW264.7 macrophage array expressing S. aureus secretory proteins. After the RAW264.7 cells were infected with S. aureus, the extracellular bacteria were removed to observe the intracellular surviving situation of S. aureus. Finally, the screening results were validated by the overexpression and knockout S. aureus of corresponding secretory proteins.

The optimal transfection dose (1.0 μg/well) of plasmids for RAW264.7, multiplicity of infection (MOI, 1.0), and infection time (4 h after removing extracellular bacteria of S. aureus) were established respectively. To validate the screening results, the corresponding overexpression and knockout strains were constructed. And hypothetical protein and Serine protease E were found to promote the survival of intracellular S. aureus.

We successfully construct a screening system for key secreted secretory proteins which required for S. aureus surviving in macrophages, which may advance the study of the intracellular surviving mechanism of S. aureus.