Figure 3.

Membrane-bound immunomodulators are incorporated during budding and release of virions from influenza virus infected cells. MDCK CYT-IVAC producer cells infected with filamentous influenza virus A/Udorn/72 were stained at 8 hr post-infection with antibodies specific for mGM-CSF (A, green) and hemagglutinin (B, red). Images A and B are overlaid to depict co-localization of mGM-CSF and full-length HA to budding viral filaments (C). Released virus particles collected from supernatants of infected CYT-IVAC producer cells stained for GM-CSF and HA as described above (D). Western blot of gradient purified virus derived from GM-CSF/HA expressing MDCK cells or wild-type MDCK cells (E) and probed for the presence of GM-CSF.