Development of a subunit vaccine targeting Clostridium perfringens enzymes for the control of necrotic enteritis in broilers

Necrotic enteritis (NE) is a pervasive enteric disease responsible for large scale economic losses within the global poultry industry. The etiologic agent of NE is Clostridium perfringens (CP), an opportunistic pathogen that utilizes numerous extracellular toxins and glycoside hydrolases (GH) as key virulence and nutrient acquisition factors. Notably, some GH, mucinases, degrade components of mucin in the gastrointestinal tract as an energy source. Targeting this mechanism may serve to reduce the incidence of disease associated with CP. Two experiments were completed that evaluated mucinase vaccine targets sourced from conserved peptide sequences of carbohydrate binding module 32 (CBM32) of CP mucinases. In experiment 1, 37 antigen peptides were synthetically generated and used to produce hyperimmune sera which was then evaluated for ability to obstruct CP growth in vitro. Total CFU of CP were measured at 4h, 6h, and 8h incubation to determine growth rate. Peptides 4, 5, 22, 24, and 30 were selected for further in vivo testing based on conservation or the ability to inhibit CP growth by over 50% at 6h and 8h. In experiment 2, the aforementioned peptides were conjugated to an agonistic, CD40-targetting antibody and evaluated in vivo. Broilers were given an Eimeria maxima (EM) and CP in order to induce NE and assess vaccine efficacy. Treatments included a non-vaccinated non-inoculated control (NVNC), nonvaccinated inoculated control (NVIC), vaccination with peptide 4, 5, 22, 24, or 30 (VP4-VP30), or a combination of all five peptides (MC). There was a significant increase (p<0.05) in the percent change in BWG (%ChangeBWG) relative to NVIC for VP22 and MC of 18.54% and 17.43%, respectively. MC vaccinated group had the lowest lesions with a mean score of 0.63±0.18. These results suggest the MC combination was the most successful in alleviating overall performance losses associated with NE-infected broilers and encourage future testing of MC in the development of an NE vaccine.  
 
Keywords: vaccine, Clostridium, necrotic enteritis, Eimeria, subunit vaccine.

Abstract presented at the 3rd International Symposium on Alternatives to Antibiotics 2019.