Cellular immune responses of mice to influenza virus vaccines

Parenteral sensitization of mice with equivalent amounts of untreated, gradient-purified or UV-inactivated influenza A/PR/8/34 virus (PR8 virus) results in the stimulation of maximal serum antibody titers, greatest numbers of antibody-forming cells (AFC), and strong virus-specific cytotoxic T lymphocyte (CTL) activity. In contrast, inoculation of formalin-inactivated virus, which induced antibody titers of equivalent magnitude, did not elicit a measurable primary CTL response nor prime for a secondary response. However, in mice previously exposed to untreated virus, challenge with formalin-inactivated virus evoked a secondary CTL response. Immunization of unprimed mice with aggregated viral glycoproteins or detergent-disrupted virus vaccine was much less immunogenic for antibody and AFC responses and did not evoke measurable primary, secondary, or memory cytotoxic effector cells in vivo.