Figure 3. Early viral clearance can be introduced by i.n. immunization using a three peptide combination vaccine.

A24Tg mice were immunized i.n. three times at 7 to 9 days intervals with the mixture of PA_130–138, PB1_430–438 and PB2_549–557 peptides in the presence of CpG-ODN, or PBS alone. A week after the final immunization, mice were challenged with A/HK483 (40 PFU/mouse), A/PR8 (1000 PFU/mouse) or A/Aichi (500 PFU/mouse). On day 5 post-infection, lung viral titers were determined by calculating TCID₅₀ using MDCK cells as described in Materials and Methods. *p<0.05. , **p<0.01.