Submitted to: Annals of the New York Academy of Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/28/2001
Publication Date: N/A
Interpretive Summary: Young calves have a strong innate immunity to infection with the protozoan parasite, Babesia bovis, a tick-borne disease agent. There is concern that the disease may be reintroduced into the United States. It is thus important to understand the complexities of a successful immune response in order to assess the efficacy of experimental vaccines. Products from cells involved in the immune response called cytokines, have the ability to interact with, and orchestrate the various activities of these cells. In this way, the response is modulated to either increase or decrease activities at the appropriate time. In this study, we determined which cytokine patterns were associated with the innate immunity in calves, versus that of adults. It was determined that a delicate balance exists between cytokines that enhance the response and those that inhibit the response. In calves, the balance was shifted toward enhanced activity and in adults the balance was shifted toward inhibition of activity, thus offering an explanation for protection in calves and severe disease in adults. In addition, the type of immune cell that proliferated in the spleen of cattle during infection was identified. The cytokine and proliferative cell profile will benefit immunization trials by offering a means of monitoring which cytokines are induced by a vaccine.
Technical Abstract: There is a strong innate immunity in calves to infection with Babesia bovis 12 and IL-10 have been shown in vitro, to be important immunoregulatory cyt s influencing the fate of T-cells during B. bovis antigen priming. Here we strate in vivo, that the protective innate response in young calves to infe with virulent B. bovis involves the early appearance of IL-12 and IFN-? tr ripts, and a nitric oxide burst in the spleen. In contrast, IL-12 and IFN-? expression in the spleens of adult cattle that succumbed to the infection, elayed and depressed and occurred within the context of IL-10 expression. A n contrast with calves, there was no detectable antibody response before de n adults. A vigorous CD8+ T-cell expansion occurred in the spleen of both c and adults. These results demonstrate the importance of a type-1 immune re e to initial B. bovis infection, and suggest that IL-12 may be an important vant with immunization.