This study was performed to compare four Clostridium perfringens recombinant proteins as vaccine candidates using the Montanide™ ISA 71 VG adjuvant in an experimental model of necrotic enteritis. Broiler chickens were immunized subcutaneously with purified clostridial recombinant NetB toxin, pyruvate: ferredoxin oxidoreductase (PFO), α-toxin, or elongation factor-Tu (EF-Tu), or with vehicle control, in conjunction with ISA 71 VG, and intestinal lesion scores, body weight gains, NetB toxin and PFO antibody levels, and proinflammatory cytokine and chemokine levels were measured as outcomes of protection following oral co-infection with C. perfringens and Eimeria maxima. Birds immunized with all recombinant proteins plus ISA 71 VG showed significantly reduced gut lesions compared with the ISA 71 VG-only group. Birds immunized with NetB toxin or PFO plus ISA 71 VG exhibited significantly increased body weight gains compared with the ISA 71 VG alone group. Greater NetB toxin antibody titers were observed in the NetB/ISA 71 VG group, and greater PFO antibody titers were evident in the PFO/ISA 71 VG group, each compared with the other three vaccine/adjuvant groups. Finally, decreased levels of gene transcripts encoding interleukin-8, tumor necrosis factor superfamily 15, and LPS-induced TNF-α factor were observed in the intestinal lymphocytes of chickens immunized with NetB toxin, PFO, α-toxin, and/or EF-Tu in the presence of ISA 71 VG compared with ISA 71 VG alone. All parameters evaluated were equal in co-infected chickens given ISA 71 VG alone compared with infected/adjuvant-free birds, indicating that the adjuvant itself did not have a disease protective effect. These results suggest that vaccination with clostridial recombinant proteins, particularly NetB toxin or PFO, in combination with ISA 71 VG enhances protective immunity against experimental necrotic enteritis in broiler chickens.
Published by Elsevier Ltd.