BALB/c mice (6–8 weeks) were intradermally immunized with mouse-adapted formalin-inactivated PR8 vaccine equivalent to 2ng hemagglutin per mouse in the presence of non-fractional (LVA/ID) or micro-fractional laser illumination (NAFL/ID) or absence of adjuvants (ID). Naive mice (non-immunized) and IM of the same amount of PR8 vaccine served as controls. Four weeks later, serum HAI titers and a ratio of IgG2a to IgG1 were quantified (A & C). Mice were then challenged with 10 × 50% lethal dose (LD50) of PR8 virus and 4 days later lung viral titers were quantified (B).
*, p<0.05; **, p<0.01, n = 4–6.
ID: Intradermal; IM: Intramuscular; LVA: Laser-based vaccine adjuvant; NAFL: Non-ablative fractional laser.