Protective effect of egg-propagated Eimeria tenella (local isolates) gametocytes as vaccine(s) against mixed species of coccidia in chickens.

Egg propagated gametocytes of Eimeria tenella (local isolates) were used to prepare the adjuvanted (Amphigen) and nonadjuvanted vaccine(s) and evaluated on the basis of cellular, humoral, and challenge responses. Modified splenic cell migration inhibition test and enzyme-linked immunosorbant assay were used to assess the cellular and humoral responses, respectively. Chicken in groups A, B, C, and D were given adjuvanted vaccine (orally), adjuvanted vaccine (subcutaneously, s/c), nonadjuvanted vaccine (orally), and nonadjuvanted vaccine s/c, respectively. Control groups E, F, G, and H were given adjuvant (orally), adjuvant (s/c), phosphate-buffered saline (PBS) + adjuvant (orally), and PBS + adjuvant (s/c), respectively. On 5 and 15 days post vaccination after boosting, significantly higher (P<0.05) cell-mediated and humoral responses were detected in vaccinated chicken compared to control. No significant effect of adjuvant and vaccination route on the immune responses was found. Maximum percent protection (survivors after challenge) against mixed species of genus Eimeria was observed in group A (71.42%) followed by group C (63.63%), B (59.09%), and group D (54.54). Significantly higher (P<0.05) oocysts per gram (OPG) of droppings was observed in the control groups compared to the vaccinated chickens. Maximum percent reduction in OPG was also recorded in group A (86) followed by group C (84), group B (83), and group D (82). From these results, it was concluded that egg-propagated gametocytes (E. tenella) that gave protection upon challenge may be due to the control of E. tenella. Further studies on its feasibility as commercial vaccine are underway.