Immune response of mice to immunization with subunit influenza A vaccine in DTP vaccine

Experiments were carried out to examine the initial feasibility of immunizing infants and children with inactivated influenza virus vaccine combined with diphtheria-tetanus-pertussis (DTP) vaccine. Groups of mice were immunized with saline vaccine or vaccine mixed with DTP: three doses of vaccine were given 3 weeks apart, and the antibody response and resistance to challenge infection were tested 3 weeks after the 1st and 3rd immunizations. The results showed that the antibody response and immunity to challenge virus infection were significantly greater for mice given vaccine in DTP than for mice given saline vaccine alone. Comparison of the response to graded doses of vaccine in saline or DTP indicated that vaccine in DTP was >250-fold more effective in inducing serum antibody and protection than saline vaccine alone. The enhancing activity of DTP was significant for the alum component alone; however, most of the adjuvant effect was from the antigen components of the DTP vaccine. The results suggest that immunization against influenza in infants and young children could be achieved by combining small amounts of influenza antigen with DTP vaccines; however, the present results have been obtained in mice, and, since the responses to vaccines and adjuvants vary from species to species, the present results cannot be used to indicate similar results in human volunteers. The results indicate the potential value of an immunization procedure which should be tested in volunteers and which could provide a simple strategy for the immunization of at-risk infants and children against influenza.