Abstract:
A 3-fold increase in the numbers of Lyt-2⁺ T cells in the circulating blood of mice infected and reinfected with the Welgevonden stock of Cowdria ruminantium, as determined by flow cytometry, is supportive evidence that immunity in heartwater is cell-mediated. The rise in Lyt-2⁺ cells only after reinfection of the mice is further evidence that the development of immunity in heartwater is dependent on the unhindered and adequate replication of C. ruminantium.