The aims of this study were to determine the immune response and the anticoccidial activity induced by Moringa oleifera and Vernonia amygdalina leaves in rabbits infected with Eimeria magna and Eimeria media.
Thirty-five-day-old rabbits, free from coccidia, were infested with 2.103 oocysts of Eimeria magna and Eimeria media, then received the acetone extract of the leaves of Moringa oleifera and Vernonia amygdalina at different doses by oral gavage.
The inhibition of the excretion of oocysts was evaluated by the McMaster technique and the levels of cytokines (IL-4 and IL-12) and immunoglobulin IgG were assayed by the ELISA method. The in vivo efficacy on E. magna and E. media oocysts was 95.43% and 96.53% for Moringa oleifera and Vernonia amygdalina at 1000 mg/kg bw against 98% for the positive control. Interestingly the plant extracts increased the production of interleukin (IL) and immunoglobulins (Ig) compared to controls. Plasma IL-4 levels (pg/ml) in rabbits were 128.94 and 131.38; those of IL-12 (pg/ml) were 395.55 and 426.56, and then for those of IgG (μg/ml) were 14.70 and 13.94 respectively with the acetone extracts of Moringa oleifera and Vernonia amygdalina on D14 PT at 1000 mg/kg bw. This study indicates that Moringa oleifera and Vernonia amygdalina can be used as an alternative to synthetic anticoccidials. These plants could be used to increase the resistance of the immune system of rabbits to infestations of Eimeria species in rabbit farms.

Coccidiosis, caused by the infection of Eimeria parasites, is one of the most common diseases in domestic rabbits. Live anticoccidial vaccine formulated with attenuated precocious lines of pathogenic eimerian parasites is expected to be valuable for the control of rabbit coccidiosis as a similar strategy to produce anticoccidial vaccines against chicken coccidiosis has being used for several decades. Eimeria media, moderate pathogenic, is widespread in China. Therefore, attenuated anticoccidial vaccines against rabbit coccidiosis should contain vaccine strain(s) of E. media. In this study, a precocious line of E. media (Empre) was selected by collecting and propagating the early excreted oocysts with 16 successive generations. The prepatent period of Empre reduced from 108 h of its parental strain (Emwt) to 70 h. The fecundity of Empre was about 1/10 to 1/3 lower than that of Emwt. Each sporocyst of Empre sporulated oocyst contained only one large refractile body instead of two smaller ones seen in the parental strain. When vaccinated with 1 × 103 or 1 × 104 precocious line oocysts, the rabbits were completely protected against homologous challenge with the parental strain 14 days post challenge by terms of body weight gain and oocyst output counting, indicating the efficacy of Empre. Meanwhile, all immunized rabbits showed no clinical sign post immunization, indicating the safety of Empre. For co-immunization, 1 × 103Empre oocysts and 5 × 102 oocysts of a precocious line of E. intestinalis (EIP8) were inoculated to each rabbit in a trial. No diarrhea or mortality was found after vaccination, and the weight gains of the vaccinated group were similar to that of unvaccinated-unchallenged control (UUC) group, while the weight gains of the vaccinated group were similar to that of unvaccinated-unchallenged control (UUC) group (P > 0.05), but significantly higher than that of UCC group (P < 0.01) after challenge, indicating it is safe and effective when using co-immunization. These results together show that Empre, as a precocious line, is a good candidate of precocious line of E. media for anticoccidial vaccine development.