Furthermore, Oral administration of recombinant L. lactis expressing functional influenza NA or M2e proteins elicites effective mucosal and systemic immune responses without the use of adjuvant in the chicken model, and protects MDCK cells against A/PR/8/34 (H1N1) virus challenge [28], however, the cross-protective efficacy of L. lactis/pNZ-NA or L. lactis/pNZ-4xM2e in chickens against virus challenge is not yet investigaged. Here, XK is linked to influenza.