Exposure of Immunized Cattle to Prolonged Natural Challenge of Theileria Lawrencei Derived From African Buffalo (Syncerus Caffer)

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Young A.S
Radley D.E
Cunningham M.P
Musisi F.L
Payne R.C
Purnell R.E
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Cattle were immunized with Theileria lawrencei stabilates either by fortuitous recovery or intentionally by chemoprophylaxis with oxytetracycline. The immunized cattle were exposed together with susceptible control cattle in a paddock where a lethal T. lawrencei challenge derived from two African buffaloes had been established. Theileria lawrencei stabilates used for immunization were of two types: one batch was prepared from Rhipicephalus appendiculatus fed on a buffalo in the paddock, and the other was from a number of tick batches fed on the two buffaloes over a period of 3 months. All the susceptible control cattle exposed in the paddock died of acute Theileria lawrencei infections. Cattle immunized with the composite stabilates survived T. lawrencei challenge for a prolonged period without showing clinical disease. The protection to the T. lawrencei challenge persisted for at least 1.5 years after the composite stabilates had been prepared. The stabilate prepared from ticks fed on a buffalo on one occasion failed to give effective protection since half of these immunized cattle died of T. lawrencei infection when exposed. These results suggest that different immunogenic types of T. lawrencei occur in buffalo which may hinder the effectiveness of a vaccine for T. lawrencei.
Veterinary Parasitology: An International Journal Of Veterinary Helminthology, Entomology And Protozoology, 3, p. 283-290