FIG 1.

Characterization of growth properties of viruses expressing cHA. (A) Multicycle growth of chimeric and WT viruses was evaluated in embryonated chicken eggs. Error bars are based on standard deviations of results from three independent samples at each time point. (B) Plaque morphology of chimeric viruses was determined by immunostaining (21) and by measuring the size of plaques formed in ImageJ. Images are representative of results of two plaque assays per virus, and error bars are based on standard deviations of results from comparisons between 20 plaques counted per two wells for each virus. Plaques could not be counted for cH4/1 Cal NA virus.