FIG. 1.

Study design timeline. Study weeks are shown relative to the time of infection (in weeks [w]) under the horizontal line. Groups A, B, and C were treated with CY (50 mg/kg three times per week) for 3 weeks prior to viral challenge; treatment continued until the end of study. Rats in group A received 15 mg of PZ (i.m.)/kg 1 day prior to infection. Rats in groups A, B, and C were challenged intranasally with A2 virus at 0 weeks (3 weeks after beginning CY treatment). Groups A and B received 15 mg of PZ (i.m.)/kg 6 weeks after viral challenge. Group C never received PZ and served as a no-antibody control. Nasal wash samples were obtained weekly from groups A and B and inoculated onto HEp-2 cells to isolate virus. The experiment was terminated at 12 weeks post-first infection; lungs were harvested for RNA extraction and viral isolation.