Immunoprotective effect of recombinant ubiquitin-conjugating enzyme (UCE) and elongation factor 1-alpha (EF1α) in rabbits against Eimeria media.

Eimeria media, one of the primary rabbit coccidia, causes rabbits diarrhea, dehydration, and hindered growth, leading to economic losses. Anticoccidial drugs are the current primary ways of preventing and controlling rabbit coccidiosis. However, increasing drug resistance has become a serious concern, and vaccine research and application for E. media remain limited, with current efforts mainly focused on precocious strains. To screen candidate antigens for a recombinant subunit vaccine against E. media, this study expressed ubiquitin-conjugating enzyme (UCE) and elongation factor 1-alpha (EF1α) from E. media. Experimental rabbits were divided into six groups for an immunization and challenge trial: the negative group, the challenge control group, the adjuvant + vector protein group, the rEiEF1α immunization group, the rEmeUCE immunization group, and the combined rEiEF1α + rEmeUCE immunization group. Following the second immunization, an oral challenge with sporulated oocysts was administered to the rabbits. The results showed that the relative body weight gain rates of rEmeUCE immunization group, rEiEF1α immunization group, and the combined immunization group all exhibited significant increases (P < 0.05), which were 87.27%, 75.42%, and 78.41%. The oocysts per gram of feces (OPG) reduction rates were 68.55%, 71.14%, and 67.30%. Intestinal lesion scores were significantly decreased (P < 0.05), compared with the challenge control group which were 1.04, 0.61 and 0.58, and the anticoccidial indices reached 171.17, 155.02, and 162.61, respectively. In conclusion, both rEmeUCE and rEiEF1α represent promising candidate antigens for developing an E. media recombinant subunit vaccine.