2.3 Immunization and sampling of serum and BALF
Mice were vaccinated intratracheally with 1 or 10 μg of S1 antigen with or without SF-10 twice or thrice every 2 weeks. Mice were vaccinated by intranasal instillation of 30 μL of S1-SF-10 or saline containing S1 antigen using a pipette, the dosage is the amount sufficient covering a mucous membrane from the nasal cavity to the lower respiratory tract.
As a positive control group, mice were immunized intramuscularly (into thigh muscles) with 10 μg S1 in 50 μL of saline or 10 μg S1 mixed with an adjuvant AS03 (AddaS03™, InvivoGen, San Diego, CA) using a 1 mL plastic syringe. S1-AS03 solution was prepared according to the instructions provided by the manufacturer. At 2 weeks after the last immunization, serum and bronchoalveolar lavage fluid (BALF) samples were obtained as described in detail previously.15