Our results demonstrated an influenza-specific recall response in the CD4+CD8− (naïve), the CD4−CD8+ (CTL) and the CD4+CD8+ (Thelper) cells of pigs vaccinated with the adjuvanted split vaccine, but only in the CD4+CD8+ (Thelper) cells of pigs vaccinated with the non-adjuvanted whole vaccine. Here, CD4 is linked to influenza.