Figure 4. Mortality of recombinant H7N9 viruses in mice.

Eight- to ten-week-old female C57BL/6 mice (n = 5/group) were inoculated intranasally with 50 μl PBS containing 10¹, 10² (data not shown as no mice died at these two doses), 10³ (a), 10⁴ (b), 10⁵ (c) and 10⁶ TCID₅₀ (d) of the recombinant A/Anhui/1/2013 (H7N9) viruses. During the 14-day period post-inoculation, mice with a body weight loss of over 30% and those that died naturally were recorded as dead. rgAH1-KD (wild type virus carrying PB2-627K and 701D), rgAH1-KN (with PB2-627K and 701N), and rgAH1-EN (with PB2-627E and 701N).