Ten Newzeland white rabbits of 3 months old as well as ten Friesian calves aged between 6-8 months were used to evaluate the immunizing effects of whole adult Rhipicephalus appendiculatus tick antigen under laboratory and field conditions. A soluble extract was obtained from extensively disrupted partially fed male and female ticks and this fraction was used for vaccination of rabbits and calves. Animals used were apparently health and never be infested with ticks. Animals within each species, were allocated randomly into two groups, each consisting of five animals. The first experiment was done under laboratory conditions in which five rabbits administered with two immunizations, the first was given subcutaneously (plus Freund's incomplete adjuvant) at the beginning of the experiment and the second was given 12 days later. At the same time, rabbits of control group were injected with phosphate buffered saline plus adjuvant. All rabbits in the two groups were challenges with starved adult tick Rhipicephalus appendiculatus. 7 days after the second injection. The second experiment was operated under field conditions where five Friesian calves were given two immunizations, the first was administered subcutaneously plus Freund's incomplete adjuvant) and the second dose was injected two weeks later. At the same time, calves of the second were injected with phosphate buffered saline plus adjuvant. Calves in the two groups, were sin tested with the antigen, where they were injected in three different sites with 50 µl of 50, 100 and 200 ng of the antigen. At the same time, control sites were injected PBS and the diameter of the reaction sites was measured . the results of the first experiment, clarified that there was reduction in number and weight of ticks that fed on all immunized rabbits. Also, the number of oviposit female ticks, number of eggs laid per tick and the percentages of egg hatchability were reduced. Regarding, the results of the second experiment, done under field conditions, it was noticed that the vaccination of animals resulted in 69.14$, 39.69%, 64.83% and 75.63% reduction in mean tick burden, tick weight, oviposition and egg hatchability, respectively. Vaccination induced a good immunity that could protect calves during tick season as indicated from skin hypersensitivity reaction with the tick antigen. |
