Growth kinetics of NIBRG-14 and the panel of NIBRG-14 NCR variant viruses.

Embryonated hens’ eggs were infected with a 10−5 dilution of each virus and incubated for various times. Titres at each time point were determined using the haemagglutination assay as described in Materials and Methods. Values are the log2 median HA titres; error bars denote standard deviations.