Notably, with daily cIFN-a protein injections of up to 40 mg/kg, significant protection was observed; however, survival rates did not exceed 80% in those studies employing the same PICV hamster model system and virus stock [15, 16] . In contrast, DEF201 consistently elicited greater protection (90-100%). The improved efficacy observed with DEF201 may be explained by a combination of factors that includes constitutive expression of fully glycosylated protein and reduced animal stress levels by avoiding daily injections for 7-10 days. We hypothesize that with the appropriate dose of DEF201, therapeutic levels of consensus IFN-a can be maintained, effectively eliminating the daily bolus effect produced by i.p. injections. In addition, because cIFN-a is produced in genetically engineered Escherichia coli, the native glycosylation pattern is lost. Conceivably, enhanced immunotherapeutic activity results from fully glycosylated cIFN-a expressed from cells transduced with DEF201.