FIG 5.
Reassortant H7 viruses containing PH1N1 PB2, NA, or M induce considerable morbidity in mice. (A to C) Groups of male C57BL/6J mice were inoculated intranasally with 104 TCID50 of the indicated viruses, and weight loss was measured for 7 days. Morbidity is displayed as percentages of original body weight remaining for mice inoculated with the indicated virus that showed weight loss that was significantly greater than (A), equal to (B), or significantly less than (C) that seen with the parental H7N3 virus. (D) Male C57BL/6J mice were inoculated intranasally with 103 TCID50 of H7N3, PH1N1, or H7N3 containing the PB2 segment of PH1N1 (H7N3PB2), and weight loss was measured for 14 days. The data represent the averages and standard errors of the means of results determined for at least six animals from two or more independently performed experiments per virus. (*, P < 0.05; **, P < 0.01; ***, P < 0.005; ****, P < 0.001 [compared to H7N3 values]; ##, P < 0.01; ###, P < 0.005; ####, P < 0.001 [compared to PH1N1 values].)