Cytokine production/T-cell-stimulatory ability of Theileria annulata-infected cells and post-vaccinal reactions

The interplay of cytokines in bovine tropical theileriosis: a mini review

Studying cytokine profiling in Theleria annulata infection enhances our understanding of how the immune response unfolds, the intricate interactions between the host and the parasite, the strategies employed by the parasite to evade the immune system, and potential avenues for developing treatments. The generation of pro-inflammatory cytokines plays a pivotal role in the immune response against T. annulata infection. Elevated concentrations of these cytokines potentially contribute to the manifestation of clinical symptoms associated with the disease, such as fever, anemia, exophthalmia, and weight loss. The production of anti-inflammatory cytokines potentially serves as a regulatory mechanism for the immune response, preventing the development of severe disease. Nevertheless, in animals afflicted by T. annulata infection, there is often a notable decrease in the levels of these cytokines, suggesting that they may not be as effective in mitigating the disease as they are in uninfected animals. This knowledge can be harnessed to develop improved diagnostic methods, treatments, and vaccines for tropical theileriosis. The objective of this current mini review is to achieve the same goal by consolidating the available knowledge of cytokine interactions in Bovine Tropical Theileriosis (BTT).

Lymphocyte stimulatory capacity of Theileria annulata-infected ovine lymphoblastoid cells

T. annulata, the causative agent of tropical theileriosis in cattle, is transmitted by ticks of the genus Hyalomma. Sporozoites of this parasite invade their target cells, where they differentiate to macroschizonts. T. annulata additionally invades and transforms ovine and caprine leukocytes. T. annulata infection in the ovine system is poorly studied, thus we used a mixed lymphocyte culture (MLC) to analyze the capacity of these cells to activate naïve uninfected ovine cells. The peak response was observed on day three or four and the response could not be induced by lysates of infected cells or their supernatants. The stimulated cells expressed IL-2 and secreted an IL-2-like growth factor.

Proliferation and cytokine profile of T. annulata-infected ovine, caprine, and bovine lymphoblastoid cells

T. annulata, the causative agent of tropical theileriosis in cattle, can also infect ovine and caprine leukocytes in vitro. In vivo studies showed that this parasite causes a mild infection in both these animal species, and in sheep merozoite stage development seems to be inhibited. Since the nature of T. annulata infected caprine and ovine cells is not known, all three cell lines were karyotyped and phenotypically characterized by flow cytometry. They all express mRNA of cytokines IL-1 alpha, IL-1 beta, IL-8, and TNF-alpha, but not of IFN-gamma, IL-2, and IL-4. In contrast, IL-6 mRNA was expressed in the cattle cell line only, while mRNA of IL-10 was exclusively produced by the sheep cell line. The observed differences in cytokine mRNA expression may be responsible for the different pathogenesis of T. annulata infection in cattle and sheep.