FIG. 4.
Membrane-bound NA-chIL-2 bioactivity on MDCK cells and virions is preserved following inactivation with β-propiolactone. (A) Mitomycin C treated NA-chIL-2-MDCK and wild-type MDCK cells were exposed for 20 min to either β-propiolactone or solvent alone prior to testing for IL-2 using T blasts. Samples were run in quadruplicate and soluble recombinant IL-2 (2 × 10−5 mM) served as a positive control. (B) Influenza A/Udorn/72 virus propagated in MDCK/NA-chIL-2 or MDCK/Vec cells was tested for chIL-2 bioactivity after purification, quantitation, and inactivation with β-propiolactone. Samples were run in quadruplicate and soluble recombinant chIL-2 at 10−6 mM served as a positive control.