Identification of cellular partners of Influenza A virus (H5N1) non-structural protein NS1 by yeast two-hybrid system

Influenza A virus (IAV) subtype H5N1 is associated with the re-emergence of severe human influenza. The virus is highly virulent and viral non-structural protein I (NS1) is believed to play a crucial role in the viral pathogenesis. A screening for human proteins interacting with NS1 was performed by a yeast two-hybrid system (Y2H). Two bait plasmids that expressed DNA binding domain (BD) fused to either RNA binding domain or to effector domain of NS1 were constructed and transformed into yeast. The bait yeast was mated with a prey yeast containing human macrophage cDNA library fused to DNA activation domain. Obtained clones were interacting with interleukin-6 receptor (IL-6R), MHC class I HLA-B, cathepsin B, ubiquitin, and adenosine deaminase acting on RNA (ADAR1). These proteins play important role in the immune response, targeting for proteosomal degradation, and RNA editing. Thus, IAV H5N1 may use NS1 to manipulate these host proteins for its own benefit and in that way confer an unusual severity to the infection.