Protective Immune Responses toTheileria Annulata of Relevance to Vaccine Development

Preston, Patricia M.; Visser, Astrid E.; Abraham, Ambily; Richardson, Wendy; Richardson, J.; Forsyth, L.M.G.; Bell‐Sakyi, Lesley; Wilkie, Gwen; Entrican, Gary; Boid, R.; Spooner, R. L.; Brown, C.G.D.

doi:10.1007/bf02632954

Cited by 5 publications

(4 citation statements)

References 10 publications

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“…These profiles include interleukins (IL-1α, IL β, IL-6, and IL-10) tumor necrotic factor α (TNFα) and interferon (INF) types α and β. [97][98][99] Macrophages from infected cattle spontaneously produce TNFα 100 and nitric oxide (NO), 101 which are known to be lethal to intracellular protozoa. Both factors inhibit the invasion of sporozoites into bovine cells in vitro.…”

Section: Immune Response and Protection Conferred By The Schizont Vacmentioning

confidence: 99%

“…The innate immune mechanism involves stimulation of macrophages to produce TNFα and NO, production of INFγ by macroschizont-infected cells, and cytotoxic natural killer cells. The adaptive immune response, in cooperation with innate mechanisms, mounts a directional T-helper 1 response, and production of TNFα, INFγ, and cytokines, which activate macrophages to induce NO, which, in turn, inhibit the development of throphozoites to schizonts 99 and cytotoxic T-cell responses.…”

Section: Immune Response and Protection Conferred By The Schizont Vacmentioning

confidence: 99%

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Vaccination against Tropical Theileriosis

Pipano

Shkap

2000

Annals of the New York Academy of Sciences

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Theileria annulata, the cause of tropical theileriosis is propagated in cattle with stage‐to‐stage transmission by Hyalomma ticks. Three stages in the life cycle of the parasite‐tick‐derived sporozoites, intramononuclear schizonts, and erythrocytic merozoites‐infect cattle. When cattle are inoculated with schizont‐infected cells, the parasite is transferred from the donor cell to the recipient. The main pathological damage in cattle is induced by the schizont stage. Each development stage of T. annulata elicits a specific immune response. Schizont‐infected lymphoid cells can be grown indefinitely in culture and prolonged cultivation results in loss of virulence. Blood‐derived schizonts induce stronger immunity than culture‐derived schizonts, which suggests that restrictions on the parasite population or antigenic variation occur during prolonged cultivation. The duration of immunity following sporozoite or schizont infections has not yet been determined, but does not appear to be lifelong. The attenuated, culture‐derived anti‐theileria vaccine proved to be safe and effective in prevention of field theileriosis in large enzootic areas.

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Section: Immune Response and Protection Conferred By The Schizont Vacmentioning

confidence: 99%

Section: Immune Response and Protection Conferred By The Schizont Vacmentioning

confidence: 99%

Vaccination against Tropical Theileriosis

Pipano

Shkap

2000

Annals of the New York Academy of Sciences

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“…Indeed, cytostatic macrophages have been demonstrated in T. annulataimmune cattle (Preston 1981;Preston and Brown 1985;Preston et al 1992b). On the basis of the capacity of such macrophages to produce TNF-a (Preston et al 1993) and NO (Visser et al 1995), it has been suggested that CD4 + cells produce IFN-c, which participates in the activation of such macrophages to produce NO and to kill the schizonts (Preston et al 1997;Richardson et al 1998). This is a very attractive hypothesis, but it needs to be con®rmed, since recently published results indicate that IFN-c may support the pathogenesis of the disease.…”

Section: T-helper Cellsmentioning

confidence: 99%

Review: the cellular basis of the immunity to and immunopathogenesis of tropical theileriosis

Ahmed

Mehlhorn

1999

Parasitol Res

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The intracellular protozoan parasite Theileria annulata causes a severe and often fatal disease of pure and crossbred cattle in tropical and subtropical countries. Animals that recover from the infection are immune against challenge with homologous parasite strains. In the present review we refer to the role of immunocompetent cells and their products in containing the infection or in facilitating the progress of the disease. Parasite-infected host cells produce cytokines, which, depending on their concentration and timing of production, may enhance the establishment of the infection. Thus, cell lines producing high levels of proinflammatory cytokines cause severe postvaccinal reactions when inoculated into cattle. This may be supported by an aberrant non-specific activation of naive T-cells, leading to the production of high levels of gamma-interferon (IFN-y). Under these circumstances development of the specific immune response may be inhibited. At this stage, innate immune reactions are operating to contain the infection. Natural killer cells and macrophages may represent the most important part of this immunity. Antibodies and specific T-lymphocytes, CD4+ T-cells and cytotoxic T-lymphocytes (CTLs), play the most important role in a challenge infection. In this context, CD4+ T-cells produce cytokines required for the clonal expansion of CTLs that kill their target cells in a major histocompatibility complex (MHC) class I-restricted manner. In addition, CD4+ T-cells produce macrophage-activating cytokines such as IFN-gamma. Such activated macrophages produce mediators such as NO, which destroy the intracellular schizonts. Attempts have been directed toward the identification of parasite antigens involved in the induction of immunity. To date, only a limited number of sporozoite and merozoite antigens have been identified and examined for their immunogenicity, and the protection achieved is partial. An effective vaccine must include schizont proteins, notably, those proteins that are secreted into the host cell cytoplasm because these may have access to the MHC class I and II compartments to be presented to CTLs and CD4+ T-cells, respectively. Several schizont proteins have been identified and these are now under investigation.

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“…Antibody production in vaccinated cattle, even at a high level, does not prove that the cattle have acquired resistance to reinfection; calves with antibody titers of 1:16 and 1:64 were resistant to tick challenge, whereas others with titers of 1:4000 and 1:16000 succumbed to the same challenge. 17,35 It has been suggested 36, 37 that cooperation between innate and adoptive immune systems could be involved in protective immune responses to T. annulata infection. The innate immune system directs the adaptive T‐cell responses toward T helper (Th1) responses and promotes activation of macrophage‐dependent responses.…”

Section: Culture‐grown T Annulata and T Parvamentioning

confidence: 99%

Culture‐Derived Parasites in Vaccination of Cattle against Tick‐Borne Diseases

Shkap¹,

Pipano²

2000

Annals of the New York Academy of Sciences

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The major economically important tick‐borne diseases of cattle are theileriosis, babesiosis, anaplasmosis, and cowdriosis. Culture‐derived attenuated schizonts of Theileria annulata have proved to be safe for all types of cattle and they protect against tick‐borne theileriosis. T. parva was also successfully grown in vitro; however, inoculation of cattle with allogeneic schizont‐infected cells resulted in rejection and destruction of the parasites together with the host cells. The number of schizont‐infected cells needed for immunization is greater than for T. annulata theileriosis. Culture‐propagated Babesia bovis and B. bigemina were used for large scale vaccination in the field. An avirulent population of Babesia spp. was obtained by in vitro cloning; inoculation of cattle did not induce clinical babesiosis, but produced specific antibodies. Culture‐derived exoantigens of Babesia spp. proved to be completely safe for cattle, however, they conferred less protection than live parasites. Cell‐cultured Cowdria ruminantium was highly infective for susceptible animals but, attenuated in vitro, could offer a potential source for vaccination. Anaplasma marginale, successfully grown in tick cell culture, may be developed for vaccines. Factors that should be considered in the developing of vaccines against tick‐borne diseases include: the protective immune response to the pathogenic parasite developmental stages, virulence, immunological strain differences, and antigenic variations in cattle and in culture.

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Protective Immune Responses toTheileria Annulata of Relevance to Vaccine Development

Cited by 5 publications

References 10 publications

Vaccination against Tropical Theileriosis

Vaccination against Tropical Theileriosis

Review: the cellular basis of the immunity to and immunopathogenesis of tropical theileriosis

Culture‐Derived Parasites in Vaccination of Cattle against Tick‐Borne Diseases

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