Sadeyen, Jean-RémyWu, ZhiguangDavies, Hollyvan Diemen, Pauline MMilicic, AnitaLa Ragione, Roberto MKaiser, PeteStevens, Mark PDziva, Francis2015-01-222015-01-222015-01-23Veterinary Research. 2015 Jan 23;46(1):5http://dx.doi.org/10.1186/s13567-014-0132-5https://hdl.handle.net/2139/39475Abstract Avian pathogenic Escherichia coli (APEC) infections are a serious impediment to sustainable poultry production worldwide. Licensed vaccines are available, but the immunological basis of protection is ill-defined and a need exists to extend cross-serotype efficacy. Here, we analysed innate and adaptive responses induced by commercial vaccines in turkeys. Both a live-attenuated APEC O78 and#916;aroA vaccine (Poulvacand#174; E. coli) and a formalin-inactivated APEC O78 bacterin conferred significant protection against homologous intra-airsac challenge in a model of acute colibacillosis. Analysis of expression levels of signature cytokine mRNAs indicated that both vaccines induced a predominantly Th2 response in the spleen. Both vaccines resulted in increased levels of serum O78-specific IgY detected by ELISA and significant splenocyte recall responses to soluble APEC antigens at post-vaccination and post-challenge periods. Supplementing a non-adjuvanted inactivated vaccine with Th2-biasing (Titermaxand#174; Gold or aluminium hydroxide) or Th1-biasing (CASAC or CpG motifs) adjuvants, suggested that Th2-biasing adjuvants may give more protection. However, all adjuvants tested augmented humoral responses and protection relative to controls. Our data highlight the importance of both cell-mediated and antibody responses in APEC vaccine-mediated protection toward the control of a key avian endemic disease.Journal Article2015-01-22enJean-Rémy Sadeyen et al.; licensee BioMed Central Ltd.