Description: Recombinant Human IFN-alpha 2a produced in E. coli is a single, non-glycosylated, polypeptide chain containing 165 amino acids and having a molecular mass of 19241 Dalton. Quality Control: Biological activity: The specific activity as determined in a viral resistance assay using VSV-WISH cells was found to be greater than 1.0 x 108 IU/ mg.