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

Abstract

Background Necrotic enteritis (NE) is caused by type A strains of the bacterium Clostridium perfringens. 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 C. perfringens produce two major toxins, a-toxin and NetB. Immune responses against either toxin can provide partial protection against NE. Methods 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 Nicotiana benthamiana to enable high levels of expression. The 6-His tagged PlcC-NetB fusion protein was synthesized in N. benthamiana using a geminiviral replicon transient expression system, purified by metal affinity chromatography, and used to immunize broiler birds. Results 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 C. perfringens 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.

A triple-sugar regulated Salmonella vaccine protects against Clostridium perfringens-induced necrotic enteritis in broiler chickens

“…Our previous data proved that the operon fusion of nontoxic antigens PlcC and GST-NetB delivered by Salmonella induce protection ( Jiang et al, 2015 ; Wilde et al, 2019 ). The effectiveness of the fusion of PlcC and NetB has also been demonstrate by other researchers ( Hunter et al, 2019 ; Katalani et al, 2020 ). Salmonella delivering fructose-1,6-bisphosphate aldolase, has also been proved to induce protection against C. perfringens challenge ( Wilde et al, 2019 ).…”

“…Vaccination with NetB as toxoid, detoxified subunit, or chimeric protein, could provide protection from the development of NE in chickens ( Mot et al, 2014 ; Rood et al, 2016 ). It has been delivered by Salmonella , plant, non-virulent C. perfringens strain or in nanoparticles ( Jiang et al, 2015 ; Lillehoj et al, 2017 ; Mishra and Smyth, 2017 ; Hunter et al, 2019 ; Wilde et al, 2019 ; Hoseini et al, 2021 ; Mauri et al, 2021 ). We previously showed that a regulated delayed lysis strain χ11802 delivering a plasmid pYA5112 encoding an operon fusion of PlcC and GST-NetB could induce partial protection against C. perfringens challenge immunized with a 2-dose regime in which chickens were immunized at 3- and 17-d of age ( Jiang et al, 2015 ; Wilde et al, 2019 ).…”

An atypical lipoteichoic acid from Clostridium perfringens elicits a broadly cross-reactive and protective immune response

“…The discovery that the major antigen recognized by this immune response was a nonproteinaceous antigen suggests that although vaccines targeting C. perfringens toxins may reduce the risk or severity of disease, these and other vaccines targeting protein antigens are unlikely to induce killing or clearing of C. perfringens cells from the intestinal tract. This may explain why several toxoid vaccines and one pilin-based vaccine show reduction in C. perfringens-induced lesion scores in chickens but are unable to fully eliminate lesions in at least half of vaccinated birds (30,(41)(42)(43).…”

Combating Human Viral Diseases: Will Plant-Based Vaccines Be the Answer?

“…Of great importance among plant expression systems, is the bean yellow dwarf geminivirus (BeYDV) system wherein the target gene of interest replicates highly efficiently within the plant cell nucleus [ 268 , 269 ]. The geminivirus system considerably shortens the product recovery time and generates high yields of the desired antigen or antibody [ 270 , 271 ]. Further, a single given vector based on the BeYDV system can express several multimeric proteins in a non-competing manner whereas RNA virus-based systems require the use of multiple viruses that are non-competing to generate different proteins [ 269 ].…”