Novel hyperimmune egg yolk IgY antibodies developed against protective antigens of Eimeria and Clostridium perfringens protect against necrotic enteritis

Authors: GOO, DOYUN - US Department Of Agriculture (USDA); GADDE, U - Us Food & Drug Administration (FDA); KIM, WOO-KYUN - University Of Georgia; Gay, Cyril; PORTIA, E.W. - Arkion Life Sciences; JONES, S.W. - Arkion Life Sciences; WALKER, S - Arkion Life Sciences; Lillehoj, Hyun

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/2023
Publication Date: N/A
Citation: N/A

Interpretive Summary: Necrotic enteritis (NE) is a devastating enteric disease caused by pathogenic Clostridium perfringens type A/G anaerobic bacteria. NE impacts global poultry industry by compromising performance, and health of the chickens. In the absence of effective vaccines against NE, ARS scientists collaborated with scientists in the private industry to develop a novel orally deliverable chicken IgY antibody mixture that reduces gut lesions mediated by NE. To develop NE-specific IgY antibodies that are specific against NE-causing pathogens, broiler hen chickens were hyperimmunized multiple times with 4 immunodominant protein antigens from pathogens causing NE, and the egg yolks from hens were used to isolate antibody-enriched protein fractions to develop novel immunotherapeutics. To prove the disease-mitigating effects of novel immunoglobulins against NE, yolk fraction containing high levels of antibodies against NE antigens were pooled (IgY fraction) and fed to newly hatched chickens. Results showed that oral feeding of newly hatched chickens with hyperimmune IgY antibodies protect chickens against NE infection and mitigated negative effects of NE promoting growth performance of commercial broiler chickens. In young chickens which received hyperimmune IgY antibodies, gut lesion was reduced with better performance in a dose-dependent manner. This is the first study reporting IgY-based protective strategy against NE.

Technical Abstract: The purpose of these studies was to investigate the effect of passive immunization using hyperimmune egg immunoglobulin Y (IgY) on protection against experimental necrotic enteritis (NE) infection in broiler chickens. In Experiment 1, six different-spray dried egg powders were produced by immunizing broiler chickens with recombinant Clostridium perfringens antigens: a-toxin (EA), NE B-like toxin (EB), elongation factor Tu (ET), pyruvate: ferredoxin odixdoreductase (EP), mixed 4 antigens (EM-1), and control egg powder from unimmunized hens (EC). Chickens in NE groups were either fed with different egg powders (EC, EA, EB, ET, EP, and EM-1) at 1% level or no egg powders (EN), and challenged with Eimeria maxima and C. perfringens dual challenge to experimentally induce NE. The chickens in EB, ET, and EM-1 groups showed increased body weight gain (BWG) compared to that of EN and EC groups (P < 0.001). NE lesion score was decreased in EB and ET groups compared to EN group (P < 0.001). In Experiment 2, the reproducibility of treatment groups, EN and ET, was tested. Chickens in both EN and ET groups showed increased BWG upon NE challenge infection compared to EN and EC (P < 0.01). Serum NetB toxin level was significantly decreased in EB and ET groups compared to EN and EC (P < 0.001). In vitro NetB neutralization assay showed that IgY against C. perfringens antigen NetB significantly decreased Leghorn Male Hepatocellular (LMH) cell cytotoxicity from 66% (without IgY) to 12% (P < 0.01). Experiment 3 was conducted with increased number of chickens in different environments to evaluate the protective effects of a new egg powder developed using 5 antigen mixture (EM-2; NetB, EFTu, EF1a, and 3-1E). EM-2 group showed similar body weight, BWG and feed intake from days 7 to 22 compared to the NC group (P < 0.05). In addition, EM-2 group showed similar intestinal permeability, NE lesion score, and jejunal NetB and collagen adhesion protein (CNA) levels measured at day 20 compared to the NC group (P < 0.05). Overall, we conclude that passive immunization against NE using hyperimmune IgY antibodies has significant protective effects against NE challenges in broiler chickens.