While we did not directly measure CD4+ specific influenza responses, and the ELISPOT results presented in this study may be CD4+ T cell specific (Fig. 5), previous studies from our group demonstrated that our influenza VLP vaccines elicit a predominately IgG2a and IgG2b anti-HA antibodies, indicative of a T-helper type 1 biased CD4+ response [10]–[12]. This evidence concerns the gene CD4 and influenza.