IL4 and Newcastle disease: lactis-AvBD1-2–6-13 as an adjuvant for the Newcastle disease inactivated vaccine, after 1 week of immunization, the recombinant β-defensin rAvBD1-2–6-13 immune adjuvant group and the non-adjuvant vaccine group showed no significant difference in IL-4 concentration (P > 0.05; Fig. 6A).