ELISA was performed and values calculated as in Figure 1 showing average and SEM. Serum samples (A) were taken on days 1, 71, 86, 127, 155, 183, 211, 239, 281, and 288 shown by gradually darker bars. Immunizations were given on days 4, 60, 74, and 270 and challenge on day 284. The white bar is thus from pre-immunization sample and the last black bar from 4 days after challenge. Comparison of titers from pre-immunization (day 1) and the last before V4 (day 239) gives p-values of 0.0002, 0.0001, 0.010, 0.014, and 0.0001 for the five antigens. Nasal wash samples (B) were taken on days 1, 127, 239 and 281 (white, light grey, dark grey and black bars respectively). Comparison of titers from pre-immunization (day 1) and before V4 (day 239) gives p-values of 0.08, 0.01, 0.036, 0.001, and 0.0006 for the five antigens.