Partial protection against four species of chicken coccidia induced by multivalent subunit vaccine

In this study, a multivalent subunit vaccine was designed to protect chickens against simultaneous infection by several Eimeria species. This vaccine contains recombinant proteins from four Eimeria species - E. tenella, E. necatrix, E. acervulina and E. maxima - and was evaluated for efficacy in animals. To produce this vaccine, candidate antigens from each Eimeria species were first screened in chickens via intramuscular inoculation and subsequent challenge. Antigens tested include recombinant proteins TA4 and SO7 from E. tenella, NA4 and NPmz19 from E. necatrix, LDH, 3-1E and MIF from E. acervulina, and Em6 and Em8 (two portions of EmTFP250) from E. maxima. A homologous challenge was then performed to identify which antigen from each species conferred the best protection. The antigens identified as most protective against its species were then challenged by heterologous species. Finally, the selected recombinant proteins from each of the four respective species were mixed with the final concentration of 400 μg/ml (100 μg of each protein/ml) to form the multivalent subunit vaccine, which was tested for efficacy in animals. The results indicated that TA4 from E. tenella, NA4 from E. necatrix, LDH from E. acervulina, and Em8 from E. maxima each induced the most effective protection from homologous challenge. Cross-protection results showed that TA4 provided partial cross-protection against E. necatrix, NA4 provided partial cross-protection against E. tenella and E. acervulina, LDH provided partial cross-protection against E. tenella and E. necatrix, and Em8 provided partial cross-protection against E. tenella and E. acervulina. The multivalent subunit vaccine provided partial protection against E. tenella, E. necatrix, E. acervulina and E. maxima challenge, and resulted in ACIs of more than 170. These results suggest that our candidate multivalent vaccine could protect chickens against simultaneous infection by several Eimeria species.