Exploring the associations of host genes for viral infection revealed by genome-wide RNAi and virus-host protein interactions.

Genome-wide RNA interference screens have greatly facilitated the identification of essential host factors (EHFs) for viral infections, whose knockdown effects significantly influence virus replication but not host cell viability. However, little has been done to link EHFs with another important host factor type, i.e., virus targeting proteins (VTPs) that viruses directly interact with for intracellular survival, hampering the integrative understanding of virus-host interactions. Using EHFs and VTPs for human immunodeficiency virus type 1 (HIV-1) and influenza A virus (IAV) infections, we found in general that despite limited overlap, EHFs and VTPs are both among the most differentially dysregulated genes in host transcriptional response to HIV and IAV infections, and notably they show consistency in regulation orientation. In the human protein-protein interaction network, both EHFs and VTPs hold topologically important positions at the global center, and importantly their direct interactions are statistically significant. We also identified BRCA1 and TP53 (or SMAD3 and PIK3R1) being the most extensive VTP-interacting EHFs (or EHF-interacting VTPs) for HIV-1 and IAV, which hold great potential in deciphering specific infection features and discovery of host directed antivirals. Further, most EHFs are the upstream regulators of VTPs when mapped in the same signaling pathways, some of which present intensive cross links. Collectively, these results provide insights into functional associations of the identified host gene factors for viral infections and highlight the regulatory significance of EHFs, and the necessity of their selective exploitation in confrontation to viral infections.