Clostridium perfringens is an opportunistic pathogen. Its main virulence factors are exotoxins, which are the etiological agents of enteritis necroticans and enterotoxemia caused in livestock (cattle, sheep, and rabbits). Here, we demonstrated effective immune protection for rabbits against α, β, and ε exotoxins of C. perfringens provided by an oral tetravalent bait probiotic vaccine delivering α, ε, β1, and β2 toxoids of C. perfringens. Results showed that the recombinant probiotic had good segregational stability and good colonization ability in the rabbit intestinal tract. Oral administration of the probiotic vaccine can effectively elicit significant levels of antigen-specific mucosa sIgA and sera IgG antibodies with exotoxin-neutralizing activity. Additionally, oral immunization with the probiotic vaccine effectively promoted lymphoproliferation and Th1/Th2-associated cytokine production. The protection rate of immunized rabbits with the probiotic vaccine was 80% after challenging rabbits with a combination of C. perfringens (toxinotypes A, C, and D) and exotoxin mixture, which was better than the 60% provided by a commercial inactivated C. perfringens A, C, and D trivalent vaccine. Moreover, obvious histopathological changes were observed in the intestinal tissues of rabbits in the commercial vaccine and PBS groups. The bait probiotic vaccine can provide effective protection against C. perfringens exotoxins, suggesting a promising C. perfringens vaccination strategy.

The spread of drug-resistant Staphylococcus aureus(S.aureus) in cattle herds not only threatens livestock production but also becomes an important route fo

Porcine rotavirus is a major threat to the swine industry, yet effective vaccines are still lacking. Lactobacillus casei bacterial ghosts ( L. casei BGs) as DNA vaccine delivery vehicles represent a promising approach, providing a safe and structurally intact platform that enhances antigen presentation and elicits intestinal mucosal immunity. To elucidate how L. casei BGs regulate macrophage function and amplify mucosal immune responses, we investigated the response of macrophages and the intestinal mucosal immune system to an L. casei BG-based DNA vaccine encoding VP7. Using genetically engineered L. casei BGs, we performed in vitro macrophage stimulation and in vivo oral/intramuscular immunization in murine models, assessing phagocytic efficiency, TLR/MyD88/NF-κB pathway activation, M1 polarization, antigen presentation, serum IgG, fecal IgA, T cell proliferation, intestinal viral load, virus neutralization, and intestinal histopathology. Compared with a naked DNA vaccine, the L. casei BG-based vaccine significantly enhanced phagocytosis and antigen presentation and promoted M1 polarization via the TLR/MyD88/NF-κB pathway. Furthermore, oral administration of the vaccine proved superior to intramuscular injection in inducing mucosal immunity, preserving intestinal villus integrity, and enhancing antiviral protection. Collectively, this study establishes L. casei BGs as an effective DNA vaccine delivery system that enhances immunogenicity by modulating macrophage function and activating mucosal immunity, and offers a promising strategy for the control of porcine rotavirus infection.

Salmonella pullorum (S. pullorum) remains a major enteric pathogen in young chicks, causing high mortality and severe economic losses in poultry production. This study evaluated a prophylactic strategy using engineered Bacillus subtilis (B. subtilis) expressing gallus trefoil factor 2 (gTFF2) and epidermal growth factor (gEGF) to protect chicks against S. pullorum infection. In vitro, gEGF significantly promoted UMNSAH/DF-1 (DF-1) cell proliferation, whereas both gTFF2 and gEGF enhanced epithelial cell migration. In vivo, oral administration of recombinant B. subtilis significantly reduced mortality from 75.0% and 66.7% in the PBS and pHT43 groups to 50%, 33.3%, and 25.0% in the gTFF2, gEGF, and gTFF2+gEGF groups, respectively. Cecal colonization of S. pullorum was reduced by 2–4 log₁₀ CFU/g, accompanied by improved average daily gain and immune organ indices. Treatment also significantly decreased serum IL-6 levels and increased TGF-β levels (p < 0.05), indicating attenuation of the inflammatory response. Histological analysis showed significantly increased villus height (0.94–1.58-fold) and villus height-to-crypt depth ratio (1.47–3.25-fold) compared with the infected controls, together with markedly alleviated hepatic and intestinal lesions. The combined administration of gTFF2- and gEGF-expressing strains consistently exhibited the greatest protective efficacy. Collectively, these findings demonstrate that engineered probiotic-mediated delivery of mucosal repair factors represents a promising antibiotic-alternative strategy for preventing pullorum disease and improving intestinal health in poultry production.