To assess whether γδ T cells could protect against B. abortus in an in vivo adoptive transfer model, Rag-1−/− mice were depleted of NK cells and reconstituted with bovine macrophages, macrophages plus autologous γδ T cells, or macrophages plus autologous CD4+ T cells prior to infection with B. abortus (leukocytes for adoptive transfer were all derived from Calf #1). Here, CD4 is linked to infection.