Hyperimmune egg yolk antibodies developed against Clostridium perfringens antigens protect against necrotic enteritis

Necrotic enteritis (NE) is a widespread infectious disease caused by Clostridium perfringens that 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. perfringens antigens, and their protective effects against NE were evaluated in commercial broilers. Six different spray-dried egg powders were produced using recombinant C. perfringens antigens: 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 maxima and C. perfringens dual 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. perfringens antigens (NetB and EFTu) and Eimeria antigens (elongation factor-1-alpha: EF1α and Eimeria profilin: 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.

Research Note: A novel method for preparation of egg yolk immunoglobulin Y against Porphyromonas gingivalis

Porphyromonas gingivalis (P. gingivalis, P. g) is the main pathogen of periodontal disease, which is treated with egg yolk immunoglobulin Y (IgY) against P. gingivalis. In order to quickly obtain IgY, 30 hens were immunized with inactivated P. gingivalis. The purification of IgY was carried out by the oleic acid (OA) method and the classical method (AS), respectively. The IgY antibody characteristics and antibacterial effects in HPDLF cells were detected by SDS-PAGE, indirect ELISA, Western blot and viability/toxicity assays. SDS-PAGE and Western blot analysis showed that IgY molecules which were rapidly purified by OA method were complete and specific to P. gingivalis. In addition, the results of crystal violet staining and bacterial staining indicated that IgY could agglutinate with P. gingivalis, inhibiting bacterial invasion of host cells. This study is the first to rapidly and efficiently purify IgY by OA method, and the purified IgY is expected to be used in the detection and treatment of P. gingivalis.