In the relentless pursuit of sustainable and efficient poultry farming, a groundbreaking study has emerged from the labs of the U.S. Department of Agriculture. Researchers, led by Alfredo Panebra from the Animal Biosciences and Biotechnology Laboratory at the Beltsville Agricultural Research Center, have developed a novel vaccine delivery system using Bacillus subtilis to combat one of the poultry industry’s most persistent foes: coccidiosis.
Coccidiosis, caused by the apicomplexan protozoa of the genus Eimeria, wreaks havoc on chicken intestinal epithelial cells, leading to severe gut damage and significant welfare issues. The economic impact is staggering, with billions of dollars lost annually due to reduced productivity and increased mortality. Panebra and his team have taken a significant step towards mitigating this problem by engineering a Bacillus subtilis-based expression system that delivers the Eimeria acervulina profilin (3-1E) antigen, aiming to induce protective immunity in chickens.
The research, published in Poultry Science, details the construction of a pBE-S-3-1E plasmid library, comprising approximately 900 recombinants, each expressing and secreting the 3-1E antigen but with distinct signal peptides. Through a rigorous screening process, the team isolated 25 high-expressor recombinants, ultimately selecting four top performers for further testing. “The key was to identify the signal peptide that would drive the most efficient expression and secretion of the 3-1E antigen,” Panebra explained.
The selected recombinants (#147, #241, #285-2, and #879) were put through their paces in both in vitro and in vivo assays. All clones sporulated, with clone #241 showing the highest germination rate. The secretion of 3-1E by these germinated recombinant clones was confirmed through western blot, indirect ELISA, and immunofluorescence assays. Moreover, the conditioned media from these recombinants induced significant expression of key cytokines in HD11 macrophage cells, indicating a robust immune response.
In a pilot trial involving 30 broiler chickens, the recombinant spores demonstrated their potential. Chickens immunized with the recombinant spores exhibited significantly higher levels of serum IgY and cecal sIgA, crucial indicators of humoral immunity. Additionally, splenocytes from these chickens showed increased proliferation when stimulated with the recombinant 3-1E protein, suggesting a strong cellular immune response. “The results are promising,” Panebra noted, “and indicate that this Bacillus subtilis-based delivery system could be a game-changer in the fight against coccidiosis.”
The implications of this research are far-reaching. By developing an effective vaccine delivery system, the poultry industry could see a significant reduction in the use of antibiotics, which are often employed to control coccidiosis. This shift would not only improve animal welfare but also address the growing concern of antibiotic resistance. Furthermore, the enhanced productivity and reduced mortality could lead to substantial economic benefits for poultry farmers.
Looking ahead, this research paves the way for further innovations in vaccine development and delivery systems. The use of Bacillus subtilis, a well-studied and safe bacterium, offers a versatile platform that could be adapted for other diseases affecting poultry and potentially other livestock. As Panebra and his team continue to refine their approach, the future of poultry farming looks brighter, with the promise of healthier chickens and more sustainable practices. The study was published in Poultry Science, a journal that translates to ‘Aviculture Science’ in English.