[Immunologic relations between cattle and ticks, specifically between cattle and Boophilus microplus]

In the present investigation, it has been demonstrated that cattle become resistant to ticks after several heavy infestations, particularly with B. microplus. During development of the infestations, antibodies against salivary glands of B. microplus were detected using 2 techniques: indirect immunofluorescence and immunoelectrophoresis. There is a positive causal relationship between antibody titer and resistance development. Two precipitating systems against B. microplus in infested cattle and 7 systems in immunized rabbits were studied. The systems 1 and 2 are similar in cattle and rabbits, but system 2 does not show any specificity, as it has been detected in cattle completely lacking tick infestations. Two one-day calves were treated with the antigen of B. microplus by injection of salivary glands and repeated infestations with a small number of larvae. They developed a pronounced resistance to the usual subsequent infestations by the ticks of the same species. Specific antibodies were found before the first usual infestation. This suggests that they might be responsible for resistance.