Protection againstinfection in rabbits immunized with the recombinant elongation factors EF1α and EFG.

Abstract

is the most pathogenic species of rabbit coccidiosis, causing weight loss, diarrhea, and even acute death. The currently used anticoccidial drugs againstin rabbits are associated with drug resistance and residues. Immunological control might be a potential alternative. We cloned and expressed therecombinant EF1&#x3b1; and EFG (r-EF1&#x3b1; and r-EFG, respectively). Rabbits were immunized subcutaneously every 14 days with 100 &#xb5;g of r-EF1&#x3b1; and r-EFG and followed by 5 &#xd7; 10sporulated oocysts orally challenge. Serum samples were collected every 7 days to measure the levels of specific antibodies and cytokines. On post-challenge day 14, rabbits were sacrificed and the anticoccidial index was evaluated. The rabbits of PBS challenged groups exhibited anorexia, diarrhea, marked intestinal wall thickening, and white nodules that formed patches, while rabbits from the r-EF1&#x3b1; or r-EFG challenged group exhibited milder symptoms. The r-EF1&#x3b1; group showed a 75.18% oocyst reduction and 89.01%wt gain; the r-EFG group had a 60.58% oocyst reduction and 56.04%wt gain. After vaccination, specific IgG levels increased and stayed high (< 0.05). The IL-4 and IL-2 levels of r-EF1&#x3b1; immunized groups showed a significant increase after immunization (< 0.05). Both r-EF1&#x3b1; and r-EFG could induce humoral and cellular immune responses. In contrast, rabbits immunized with r-EF1&#x3b1; were better protected from challenge bythan r-EFG.