FIGURE 2.
H7N9-derived HA was not able to enhance the pathogenicity and replication of H9N2 virus in mouse. Mice were intranasally inoculated with a single dose of 106 EID50 of either the parental H9N2 CK/F98 virus or the CK/F98-4664HA hybrid virus with HA gene being replaced by its counterpart from H7N9 SH/4664 virus. (A) Weight loss during a 14-day observation period. (B) Virus titers in animal lungs, as determined by EID50 using MDCK cells. (C) Virus titers in animal nasal turbinates, as determined by EID50 using MDCK cells. n = 3 for each group. Data are expressed as mean ± SEM. *P < 0.05 by one-way ANOVA.