Goo, D., Gadde, U.D., Kim, W.K., Gay, C.G., Porta, E.W., Jones, S.W., Walker, S., and Lillehoj, H.S.
Necrotic enteritis (NE) is a widespread infectious disease caused by Clostridium perfringensthat inflicts major economic losses on the global poultry industry. Due to regulations on antibiotic use in poultry production, there is an urgent need for alternative strategies to mitigate the negative effects of NE. This paper presents a passive immunization technology that utilizes hyperimmune egg yolk immunoglobulin Y (IgY) specific to the major immunodominant antigens of C. perfringens. Egg yolk IgYs were generated by immunizing hens with 4 different recombinant C. perfringensantigens, and their protective effects against NE were evaluated in commercial broilers. Six different spray-dried egg powders were produced using recombinant C. perfringensantigens: α-toxin, NE B-like toxin (NetB; EB), elongation factor-Tu (ET), pyruvate:ferredoxin oxidoreductase, a mixture of 4 antigens (EM-1), and a nonimmunized control (EC). The challenged groups were either provided with different egg powders at a 1% level or no egg powders (EN). The NE challenge model based on Eimeria maximaand C. perfringensdual infection was used. In Experiments 1 and 2, the EB and ET groups exhibited increased body weight gain (BWG; P< 0.01), decreased NE lesion scores (P< 0.001), and reduced serum NetB levels (P< 0.01) compared to the EN and EC groups. IgY against NetB significantly reduced Leghorn male hepatocellular cytotoxicity in an in vitro test (P< 0.01). In Experiment 3, the protective effect of the IgYs mixture (EM-2) against C. perfringensantigens (NetB and EFTu) and Eimeriaantigens (elongation factor-1-alpha: EF1αand Eimeriaprofilin: 3-1E) was tested. The EM-2 group showed similar body weight, BWG, and feed intake from d 7 to 22 compared to the NC group (P< 0.05). On d 20, the EM-2 group showed comparable intestinal permeability, NE lesion scores, and jejunal NetB and collagen adhesion protein levels to the NC group (P< 0.05). In conclusion, dietary mixture containing antibodies to NetB and EFTu provides protection against experimental NE in chickens through passive immunization.