Fig 5.

Contrasting SOCS3 protein profiles between human and pig respiratory epithelial cells and macrophages. (A) Primary epithelial cells were infected (I) with HPAI H5N1 virus at an MOI of 1.0 for 3 h and 24 h, whereupon protein lysates were generated for SOCS3 detection. C, uninfected control. The strong upper band (∼38 kDa) found in each pig sample was likely to be highly phosphorylated SOCS3 but was absent in all human samples. The native SOCS3 protein (∼28 kDa) was weakly expressed (3 h) or absent. Comparable protein loading in each lane was demonstrated by β-actin detection (3 h). (B) The SOCS3 protein was highly expressed in pig macrophages regardless of infection (USSR H1N1 virus at an MOI of 1.0 for 24 h) but was undetected in human macrophages. Protein loading in each lane was exemplified by β-actin detection. In relation to SOCS3 RNA profiles, the detection of high constitutive SOCS3 protein levels in pig cells suggests further differences in posttranscriptional or translational SOCS3 regulation between pig and human cells.