Co-administration of chicken IL-7 or NK-lysin peptide 2 enhances the efficacy of Eimeria elongation factor-1a vaccination against Eimeria maxima infection in broiler chickens

Authors: LEE, YOUNGSUB - US Department Of Agriculture (USDA); PARK, INKYUNG - US Department Of Agriculture (USDA); WICKRAMASURIYA, SAMIRU - US Department Of Agriculture (USDA); BEN AROUS, JULIETTE - Seppic, Inc; KOZIOL, MARIE-EVE - Seppic, Inc; Lillehoj, Hyun

Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/13/2022
Publication Date: 9/22/2022
Citation: Lee, Y., Park, I., Wickramasuriya, S., Ben Arous, J., Koziol, M., Lillehoj, H.S. 2022. Co-administration of chicken IL-7 or NK-lysin peptide 2 enhances the efficacy of Eimeria elongation factor-1a vaccination against Eimeria maxima infection in broiler chickens. Poultry Science. 101:102013. https://doi.org/10.1016/j.psj.2022.102013.
DOI: https://doi.org/10.1016/j.psj.2022.102013

Interpretive Summary: Avian coccidiosis is a ubiquitous intestinal disease caused by several distinct Eimeria species with significant economic losses to global poultry industry, but there are no recombinant vaccines yet. In this study, ARS scientists describe a novel recombinant vaccine strategy using subunit of Eimeria parasite (3-1E) that stimulates host protective immunity when mixed in the ISA78 commercial immunostimulatory adjuvant. The results showed that adjuvant combination of chicken cytokine IL-7 in immune stimulating gel in combination with a coccidia protein 3-1E stimulated protective immune response with high serum antibodies and cellular immune response. In summary, these results show the protective effects of the EF-1a recombinant vaccine, which can be further enhanced by co-injection with IL-7 against E. maxima infection. These results will facilitate the development of a novel immune strategy using recombinant antigen against coccidiosis to reduce more than $ 13 billion economic losses due to coccidiosis.

Technical Abstract: This study was conducted to develop a recombinant Eimeria elongation factor-1a (EF-1a)-vaccination strategy against Eimeria maxima (E. maxima) infection by co-administering with chicken IL-7 (chIL-7) or chicken NK-lysin peptide 2 (cNK-2) in commercial broiler chickens. Chickens were divided into the following five groups: control (CON, no Eimeria infection), non-immunized control (NC, PBS plus MontanideTM ISA 78 VG), Vaccination 1 (VAC1, 100 µg of recombinant EF-1a plus MontanideTM ISA 78 VG), Vaccination 2 (VAC2, VAC1 plus 1 µg of chIL-7), and Vaccination 3 (VAC3, VAC2 plus 5 µg of cNK-2 peptide). The secondary immunization was given with the same concentration of components as the primary immunization one week later. All chickens except the CON group were orally inoculated with freshly prepared E. maxima (1.0 × 104 oocysts per chicken) oocysts on Day 19. The results of the in vivo vaccination trial showed that chickens of all groups immunized with recombinant EF-1a antigen (VAC1, VAC2, and VAC3) showed higher serum antibody levels to EF-1a, and co-injection with chIL-7 further increased the serum IL-7 level in the VAC2 and VAC3 groups. Chickens in the VAC2 group showed significantly (P < 0.01) higher body weight gains at 6- and 9-days post-E. maxima challenge infection (dpi) with reduced gut lesions in the jejunum at 6 dpi. The VAC3 group showed reduced fecal oocyst shedding compared to the non-immunized and infected chickens (NC). At 4 dpi, E. maxima infection significantly (P < 0.05) up-regulated the expression levels of proinflammatory cytokines (IL-ß and IL-17F) and type ' cytokines (IFN-' and IL-10) in the jejunum (NC), but the expression of these cytokines was significantly (p < 0.05) down-regulated in the VAC1, VAC2, and VAC3 groups. Furthermore, E. maxima challenge infection significantly (P < 0.05) down-regulated the expressions of jejunal tight junction (TJ) proteins (Jam2 and Occludin) at 4 dpi, but their expression was up-regulated in the VAC2 and VAC3 groups. Collectively, these results show the protective effects of the EF-1a recombinant vaccine, which can be further enhanced by co-injection with chIL-7 or cNK-2 peptide against E. maxima infection.