The complete small subunit ribosomal RNA (srRNA) gene of Theileria parva was cloned and sequenced. Two primers were designed which permitted the specific amplification of part of the Theileria srRNA gene from Theileria-infected cell line samples which were predominantly (> 95%) bovine DNA. The sequence of the central (variable) region of the srRNA genes of T. annulata, T. taurotragi, T. mutants and two unidentified parasites referred to as Theileria sp. (buffalo) and Theileria sp. (Marula) were obtained. An alignment of the sequences was generated from which 6 oligonucleotide probes, corresponding to species-specific regions, were designed. These probes were demonstrated to provide unequivocal identification of each of the 6 species either by direct detection of parasite srRNA or by hybridization to amplified parasite srRNA genes. The probes were not able to distinguish buffalo-derived T. parva, the causal agent of Corridor disease, from cattle-derived T. parva, the causal agent of East Coast fever.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0031182000067263

Discrimination between six species of Theileria using oligonucleotide probes which detect small subunit ribosomal RNA sequences.

Publisher Summary Parasites of the genus Theileria are tick transmitted intracellular protozoa, which are important causes of disease in domestic livestock in the tropical and subtropical regions of the world. This chapter focuses on Theileria parva , Theileriu annulata , and other species, which infect cattle because of their economic importance. It also discusses the different ways that theilerial parasites can be characterized, both at species and strain level, and considers the implications of the improved methods of characterization in the development and application of immunization against theileriosis in the field. A variety of methods is now available for characterizing species and strains of Theileria . The current methods of immunization against theileriosis involve the use of live parasite populations, which are generally poorly defined and, in addition, have the capacity to undergo biological change within hosts and vectors. The methods of characterizing Theileria range from Giemsa's staining to DNA hybridization; all have a role to play, and by a judicious selection of appropriate methods for particular circumstances, it is becoming possible to characterize theilerial parasites very precisely. Improved methods of characterization can, in turn, lead to a better understanding of parasite biology and to the development of improved methods of immunization and control.

Characterization of species and strains of Theileria.

Theileria annulata is an important pathogen of domestic Bovidae across a broad region of the world with some 250 million cattle at risk. Our basic knowledge of the incidence and mortality is reviewed together with an outline of current control measures, including the use of acaricides, chemotherapy and attenuated cell line vaccines. The limitations and potential problems of these control measures are discussed and considered in relation to the use of a subunit vaccine. Research over the last ten years on the protective immune response to the disease in both laboratory and field studies suggests that a humoral immune response to the sporozoite could be protective although the primary protective response appears to be mediated by cytotoxic T-cells recognising the macroschizont-infected lymphocyte stage. Recent work on the study of protective antigens using recombinant DNA and hybridoma technologies is discussed together with the potential advantages and problems of such approaches. Possible future developments in our understanding of the immune response and the identification of the relevant antigens are considered in addition to the use of new techniques for diagnosis and the analysis of parasite diversity.

C.G.D. Brown

Papers

Fine structure and invasive behaviour of the early developmental stages of Theileria annulata in vitro