Evaluation of a toxoid fusion protein vaccine produced in plants to protect poultry against necrotic enteritis

• Published in: PeerJ (San Francisco, CA) CA), 2019-03, Vol.7, p.e6600, Article e6600
• Main Authors: Hunter, Joseph G L, Wilde, Shyra, Tafoya, Amanda M, Horsman, Jamie, Yousif, Miranda, Diamos, Andrew G, Roland, Kenneth L, Mason, Hugh S
• Format: Article
• Language: English
• Subjects: Affinity chromatography; Agricultural Science; Analysis; Antibiotic resistance; Antibiotics; Antigens; Base sequence; Biological products; Biological products industry; Biotechnology; Chromatography; Clostridium perfringens; Codons; Contamination; DNA; DNA sequencing; Dogs; Enteritis; Enzymes; Epidemics; Feeds; Fusion protein; Gangrene; Health care; Immune response; Immunotherapy; Infections; Microbial drug resistance; Microbiology; Microbiota; Mortality; Necrotic enteritis vaccine; Nucleotide sequence; Pathogenesis; Pathogenic microorganisms; Plant protection; Plant-based antigen production; Poultry; Poultry industry; Poultry vaccine; Proteins; Salmonella; Strains (organisms); Toxin A; Vaccination; Vaccines; Veterinary Medicine; Wildlife conservation
• ISSN: 2167-8359; 2167-8359
• DOI: 10.7717/peerj.6600

Necrotic enteritis (NE) is caused by type A strains of the bacterium . Total global economic losses to the poultry industry due to NE is estimated to be over two billion dollars annually. Traditionally, NE has been effectively controlled by inclusion of antibiotics in the diet of poultry. However, recent concerns regarding the impact of this practice on increasing antibiotic resistance in human pathogens have led us to consider alternative approaches, such as vaccination, for controlling this disease. NE strains of produce two major toxins, a-toxin and NetB. Immune responses against either toxin can provide partial protection against NE. We have developed a fusion protein combining a non-toxic carboxyl-terminal domain of a-toxin (PlcC) and an attenuated, mutant form of NetB (NetB-W262A) for use as a vaccine antigen to immunize poultry against NE. We utilized a DNA sequence that was codon-optimized for to enable high levels of expression. The 6-His tagged PlcC-NetB fusion protein was synthesized in using a geminiviral replicon transient expression system, purified by metal affinity chromatography, and used to immunize broiler birds. Immunized birds produced a strong serum IgY response against both the plant produced PlcC-NetB protein and against bacterially produced His-PlcC and His-NetB. Immunized birds were significantly protected against a subsequent in-feed challenge with virulent when treated with the fusion protein. These results indicate that a plant-produced PlcC-NetB toxoid is a promising vaccine candidate for controlling NE in poultry.