In the challenge experiments, on day 5 post lethal-dose infection with the heterologous HK68 H3N2, the mice from the groups of rtN2/N2P2-KLH(×2) and rtN2/N2P2TP2nano(×2) experienced slight body weight losses comparable to the group of rtN2(×3) (Figure 4), suggesting the peptide boosters are effective in enhancing protective antibody response. The gene discussed is RTN2; the disease is infection.