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. 2000 Mar 21;97(8):4309–4314. doi: 10.1073/pnas.070525997

Figure 2.

Figure 2

Growth characteristics of wild-type PR8, NS1–99, and delNS1 viruses in embryonated eggs. (A) One hundred pfu of virus was injected into the allantoic cavity of embryonated eggs of varying age and incubated for 48 h at 37°C. Allantoic fluid was harvested and titrated by HA assay as described in Materials and Methods. HA titers were not detected for delNS1 virus at days 8, 10, 12, or 14. NS1–99 infection did not give detectable HA titers at day 14. Graph represents the average reciprocal HA dilution of two to six eggs for each virus. (B) Embryonated eggs were infected with either PR8 or delNS1 virus as in A, and allantoic fluid was titrated on MDCK cells as described in Materials and Methods.