Immunological effect of Lactic acid bacteria adjuvant on in ovo injection of Newcastle disease vaccine

Surface Display of Duck Hepatitis A Virus Type 1 VP1 Protein on Bacillus subtilis Spores Elicits Specific Systemic and Mucosal Immune Responses on Mice

Duck viral hepatitis, primarily caused by duck hepatitis A virus type 1 (DHAV-1), poses a significant threat to the global duck industry. Bacillus subtilis is commonly utilized as a safe probiotic in the development of mucosal vaccines. In this study, a recombinant strain of B. subtilis, designated as B. subtilis RV, was constructed to display the DHAV-1 capsid protein VP1 on its spore surface using the outer coat protein B as an anchoring agent. The immunogenicity of this recombinant strain was evaluated in a mouse model through mixed feeding immunization. The results indicated that B. subtilis RV could elicit specific systemic and mucosal immune responses in mice, as evidenced by the high levels of serum IgG, intestinal secretory IgA, and potent virus-neutralizing antibodies produced. Furthermore, the recombinant strain significantly upregulated the expression levels of IL-2, IL-6, IL-10, TNF-α, and IFN-γ in the intestinal mucosa. Thus, the recombinant strain maintained the balance of the Th1/Th2 immune response and demonstrated an excellent mucosal immune adjuvant function. In summary, this study suggests that B. subtilis RV can be a novel alternative for effectively controlling DHAV-1 infection as a vaccine-based feed additive.

Anemoside B4 attenuates necrotic enteritis of laying hens induced by Clostridium perfringens via inhibiting NF-κB and PI3K/Akt/mTOR signalling pathways

Poultry necrotic enteritis is an important enteric disease which might be controlled by antibiotics. However, with the excessive use of antibiotics, the phenomenon of drug resistance of Clostridium perfringens is becoming increasingly prominent. Anemoside B4 exhibits important anti-inflammatory, antioxidant and immunomodulatory effects. This study was performed to estimate the effect of Anemoside B4 on chicken necrotic enteritis induced by C. perfringens in vivo and in vitro. In the in vivo experiment we investigated the efficacy of Anemoside B4 on the growth curve, biofilm formation, haemolytic activity, virulence-related gene expression and NF-κB and PI3K/AKT/mTOR activation in Caco-2 cells induced by C. perfringens. The results showed that 12.5-50 μg/mL Anemoside B4 had no antibacterial activity but could inhibit biofilm formation, attenuate haemolytic activity and virulence-related gene expression of C. perfringens and weaken NF-κB and PI3K/Akt/mTOR activation triggered by C. perfringens in Caco-2 cells. In the in vivo experiment, 60 17-day-old healthy White Leghorns were randomly divided into six groups. The growing laying hens of the control group were fed a basic diet, and those of the five challenged groups were fed a basic diet (infection group), added 0.43 g/kg Anemoside B4 (0.43 g/kg Ane group), 0.86 g/kg Anemoside B4 (0.86 g/kg Ane group), 1.72 g/kg Anemoside B4 (1.72 g/kg Ane group) and 40 mg/kg lincomycin (lincomycin group), respectively. All challenged laying hens were infected with 1 × 109 CFU C. perfringens from day 17-20. Blood and intestinal samples were obtained, and the data demonstrated that Anemoside B4 improved the blood biochemical parameters, attenuated jejunum tissue injury, increased the spleen, thymus, bursa of fabricius index, and decreased lesion scores of the jejunum and the ileum. In the jejunum, Anemoside B4 and lincomycin downregulated the expression of IL-1β, IL-6, IL-10, TNF-α and IFN-γ at mRNA levels. Moreover, Anemoside B4 significantly enhanced both mRNA and protein levels of tight junctions ZO-1, Claudin-1 and MUC-2 in the jejunum. Anemoside B4 weakened p-P65, p-PI3K, p-Akt and p-mTOR protein expression in the jejunum infected by C. perfringens. Diets supplemented with Anemoside B4 alleviated C. perfringens-induced necrotic enteritis in laying hens by inhibiting NF-κB and PI3K/Akt/mTOR signalling pathways and improving intestinal barrier functions.

How to Break through the Bottlenecks of in Ovo Vaccination in Poultry Farming

Poultry farming is one of the pillar industries of global animal husbandry. In order to guarantee production, poultry are frequently vaccinated from the moment they are hatched. Even so, the initial immunity of chicks is still very poor as they are in the "window period" of immune protection. In ovo vaccination pushes the initial immunization time forward to the incubation period, thereby providing earlier immune protection for chicks. In ovo vaccination is currently a research hotspot of poultry disease prevention and control, which is in line with the intensification of poultry production. However, the vaccines currently available for in ovo vaccination are limited and cannot meet the needs of industrial development, so how to efficiently activate the adaptive immune response of chicken embryos becomes the key to restrict product development and technological progress of in ovo vaccination. Its breakthrough, to a large extent, depends on systematic illustration of the mechanism underlying the adaptive immune response post immunization. Clarification of this issue will provide us with theoretical support and potential solutions for the development of novel vaccines for in ovo vaccination, the augmentation of efficacy of current vaccines and the optimization of immune programs.