A comprehensive review of experimental models and induction protocols for avian necrotic enteritis over the past 2 decades.

Necrotic enteritis (NE) is a severe gastrointestinal disease that poses a significant threat to the poultry industry. It leads to progressive damage to the small intestine, reduced performance, increased mortality rates, and substantial economic losses. With the removal of antimicrobial agents from chicken feed, there is an urgent need to find alternative approaches for NE control. Various approaches, including vaccination, prebiotics, probiotics, and plant-derived products, have been utilized to address NE in poultry management. To evaluate the efficacy of these preventive measures against NE, successful induction of NE is crucial to observe effects of these approaches in related studies. This study presents a comprehensive overview of the methods and approaches utilized for NE reproduction in related studies from 2004 to 2023. These considerations are the careful selection of a virulent Clostridium perfringens strain, preparation of challenge inoculum, choice of time and the route for challenge inoculum administration, and utilization of one or more predisposing factors to increase the rate of NE occurrence in birds under experiment. We also reviewed the different systems used for lesion scoring of NE-challenged birds. By gaining clarity on these fundamental parameters, researchers can make informed decisions regarding the selection of the most appropriate NE experimental design in their respective studies.

Necrotic enteritis in chickens: a comprehensive review of vaccine advancements over the last two decades.

Necrotic enteritis (NE) is a severe gastrointestinal disease that poses a significant threat to poultry, leading to progressive deterioration of the small intestine, reduced performance, and increased mortality rates, causing economic losses in the poultry industry. The elimination of antimicrobial agents from chicken feed has imposed a need to explore alternative approaches for NE control, with vaccination emerging as a promising strategy to counteract the detrimental consequences associated with NE. This comprehensive study presents an overview of the extensive efforts made in NE vaccination from 2004 to2023. The study focuses on the development and evaluation of vaccine candidates designed to combat NE. Rigorous evaluations were conducted in both laboratory animals and broiler chickens, the target population, to assess the vaccines' capacity to elicit an immune response and provide substantial protection against toxin challenges and experimental NE infections. The review encompasses the design of vaccine candidates, the antigens employed, in vivo immune responses, and the efficacy of these vaccines in protecting birds from experimental NE infection. This review contributes to the existing knowledge of NE vaccination strategies, offering valuable insights for future research and development in this field.

Evaluation the efficacy of oral immunization of broiler chickens with a recombinant Lactobacillus casei vaccine vector expressing the Carboxy-terminal fragment of α-toxin from Clostridium perfringens.

BACKGROUND: Clostridium perfringens (C. perfringens) is a serious anaerobic enteric pathogen causing necrotic enteritis (NE) in broiler chickens. Following the ban on antibiotics as growth promoters in animal feedstuffs, there has been a remarkable rise in occurrence of NE which resulted in considering alternative approaches, particularly vaccination. The objective of this work was to evaluate the recombinant Lactobacillus casei (L. casei) expressing the C-terminal domain of α-toxin from C. perfringens as a potential probiotic-based vaccine candidate to immunize the broiler chickens against NE. RESULTS: The broiler chickens immunized orally with recombinant vaccine strain were significantly protected against experimental NE challenge, and developed specific serum anti-α antibodies. Additionally, the immunized birds showed higher body weight gains compared with control groups during the challenge experiment. CONCLUSIONS: The current study showed that oral immunization of broiler chickens with a safe probiotic-based vector vaccine expressing α-toxin from C. perfringens could provide protective immunity against NE in birds.

Lactobacillus casei displaying Clostridium perfringens NetB antigen protects chickens against necrotic enteritis.

Necrotic enteritis is a serious economical disease of poultry caused by Clostridium perfringens. NetB toxin of Clostridium perfringens is considered the causative agent of necrotic enteritis. Following the withdrawal of in-feed antibiotic growth promoters, there has been an urgent need to develop alternative approaches such as vaccination. Currently, there are no commercially available vaccines to control necrotic enteritis especially in broiler chickens as the target population. In the present study, we constructed a recombinant Lactobacillus casei strain expressing NetB protein of C. perfringens on the cell surface and used this probiotic-based vaccine strain to immunize broiler chickens orally against experimental induction of necrotic enteritis. The birds immunized with the oral vaccine strain were significantly protected against necrotic enteritis challenge and developed strong serum anti-NetB antibody responses to NetB protein. Furthermore, the immunized birds showed higher body weight gains during the challenge experiment compared with control birds. This study showed, for the first time, that a probiotic-based vector vaccine could be a promising vaccine candidate to provide protection against necrotic enteritis in broiler chickens. KEYPOINTS: • The probiotic L. casei carrying pT1NX-netB plasmid displayed NetB antigen on the cell surface. • The LC-NetB vaccine strain induced high anti-toxin antibody response in broiler chickens. • The LC-NetB vector vaccine provided significant protection against experimental NE challenge.