Publikationsdatenbank

Improvement and development of methods to propagate Theileria annulata in vitro and to study the T. annulata life cycle based on cell culture techniques and an artificial tick feeding System (2024)

Art

Hochschulschrift

Autor

Elati, Khawla (WE 13)

Quelle

Berlin: Mensch und Buch Verlag, 2024 — VIII, 131 Seiten

Sprache

Englisch

Verweise

URL (Volltext): https://refubium.fu-berlin.de/handle/fub188/45323

Kontakt

Institut für Parasitologie und Tropenveterinärmedizin

Robert-von-Ostertag-Str. 7-13
14163 Berlin
+49 30 838 62310
parasitologie@vetmed.fu-berlin.de

Abstract / Zusammenfassung

Tropical bovine theileriosis (TT, Theileria annulata infection) is a protozoan disease that affects cattle in the Mediterranean, Middle East and Asia. In countries where it occurs, the disease is mainly transmitted by ticks of the genus Hyalomma. Despite the availability of various control strategies, TT is still a major problem for the livestock industry in several countries. Progress in developing and improving control options (mainly vaccination) against T. annulata and its vectors is limited by several factors, including limited knowledge of the attenuation mechanism of the cell lines used as live vaccines, the need for experimental animals to maintain tick colonies, to produce infected tick challenge material and to assess the attenuation status. Another point of ethical concern is the use of Foetal Bovine Serum (FBS) in the production of the T. annulata cell culture vaccine. This reliance on the use of animal models and products, which is associated with high costs and logistical, biosafety and ethical constraints, frames the research approaches described in this thesis. In the four main chapters, different aspects in studying the life cycle of T. annulata in vitro while adhering to the 3Rs principle are described. This includes (i) establishing a cell line using serum-free culture medium, replacing the use of FBS, (ii) comparing virulent and attenuated passages of T. annulata using RNA-seq to improve our understanding of virulence factors and the attenuation process and catalogue potential attenuation markers, (iii) inducing merogony in T. annulata cell lines and obtain piroplasm-containing erythrocytes that could later be used to infect ticks in vitro, and (iv) exploit recent advances in artificial tick feeding methods to artificially feed all life stages of two-host ticks Hyalomma scupense and H. excavatum and the three-host tick Hyalomma dromedarii. The successful feeding of all stages of Hyalomma ticks in vitro combined with the generation of T. annulata infected erythrocytes in vitro, may lead to the closure of the T. annulata life cycle in vitro without the use of experimental animals. The results of these studies are encouraging, although they do require optimization, and are expected to contribute to the production of culture-derived Theileria vaccines, improve our understanding of the attenuation process and provide valuable tools to study the Theileria life cycle, including its interaction with vector ticks in vitro. It will also contribute to the 3Rs principle for humane animal research by providing a viable alternative to the use of laboratory animals in Theileria research. These findings could also be extrapolated to other pathogens with similar life cycles.