FIG 3.

The recombinant virus NDV-polio is stable upon propagation in embryonated eggs. (A) Double immunostaining of NDV-polio-infected cells with a mouse monoclonal antibody recognizing an NDV antigen, HN, and the chimpanzee-human hybrid monoclonal antibody A12, recognizing a conformational epitope in the fully assembled poliovirus capsid. Nuclei are visualized with the DNA stain Hoechst 33342. (B) Quantitation of double-positive cells as shown in panel A, indicative of accumulation of correctly assembled poliovirus capsids in cells infected with the recombinant virus NDV-polio propagated for 10 passages in embryonated chicken eggs. Several fields containing at least 100 cells together were quantified. P, passage. (C) Western blots of lysates from HeLa cells infected at an MOI of 10 PFU/cell with the recombinant virus NDV-polio propagated for 1 or 10 passages in embryonated chicken eggs. Expression of the poliovirus capsid protein VP3 and the NDV protein NP is shown. M, mock infection. Actin was used as a loading control.