Vaccination against bovine tropical theileriasis (Theileria annulata)

Gill, B. S.; Bhattacharyulu, Y.; Kaur, Devinder; Singh, Avtar

doi:10.1038/264355a0

Cited by 28 publications

(9 citation statements)

References 5 publications

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Section: Immune Response and Protection Conferred By The Schizont Vacmentioning

confidence: 99%

“…A proportion of the vaccinated cattle remained asymptomatic following the challenge infection, but in most instances transient fever and mild parasitemia occurred. 54,102,103 A lesser degree of protection was witnessed when cattle immunized with attenuated schizonts were challenged with sporozoites originating from a relatively remote geographical area 104 or were subjected to heavy tick challenge. 105 Field observations have shown that local, as well as exotic, cattle from theileriosisfree geographical areas, were protected by the schizont vaccine when introduced into theileriosis-infected pastures.…”

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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“…Control of tropical theileriosis is mainly with attenuated cell‐line vaccines ( Pipano & Tsur 1966; Gill et al . 1976 ; Ozkoc & Pipano 1981; Pipano 1981; Singh 1990).…”

Section: Introductionmentioning

confidence: 99%

Mechanism(s) of attenuation of Theileria annulata vaccine cell lines

Hall

Ilhan

Kirvar

et al. 1999

Tropical Med Int Health

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SummaryAttenuated vaccines are an important means of controlling Theileria annulata infection of cattle. Production is by prolonged cultivation of macroschizont-infected cells. The mechanism of attenuation remains unclear. There are three general nonmutually exclusive possibilities: Selection of avirulent subpopulations, genome rearrangements and alterations in gene expression. Several groups, including ours, have provided evidence that the population structure usually tends to simplify during attenuation. Our data on the T. annulata (Ta) Ankara cell line show that attenuation is not necessarily accompanied by the population becoming clonal. We have been unable to detect large DNA rearrangements. Evidence for alterations in host and parasite gene expression during attenuation is available. With respect to the host we have shown that attenuation is accompanied by loss of expression of parasite induced matrix metalloproteinases (MMPs). However, in different lines different protease activities are involved. In the T. annulata Ode line we have shown that 8 activities (including MMP9) are downregulated and that this correlates with a loss of metastatic behaviour. This has previously been shown in vitro using reconstituted basement membrane (Matrigel TM ) and is demonstrated in vivo using scid mice in this study. Thus part of the pathology, namely the ability to disseminate, mediated by host MMPs, is lost upon attenuation. Re-isolation experiments have shown that the reduction/loss of MMP is a stable transferable trait. A logical extension is that loss of MMP activity (and virulence in general) must be at the most fundamental level a genetic trait of the parasite. Evidence for loss of parasite gene expression is implied by the loss of the ability to differentiate into merozoites on attenuation. Specific evidence for loss of parasite gene expression has been obtained using differential RNA display. We view virulence as a multifactorial phenomenon involving interacting subpopulations of cells and attenuation is a threshold effect whereby the number of virulence factors is reduced below a critical level. On this basis there will be many different ways to achieve attenuation.keywords Theileria annulata, attenuation, virulence, vaccine, matrix metalloproteinase, metastasis, microschizont correspondence Roger Hall,

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“…However, the results obtained with T. annulata and T. parva were very different. Administration of 10 5 or fewer T. annulata ‐infected cells resulted in immunity to parasite challenge, although prolonged in vitro passage of the cell lines was required to avoid production of clinical disease by the vaccine . Initial studies in Israel in the early 1970s resulted in a national vaccine programme for T. annulata using cultured cells.…”

Section: Live Vaccinesmentioning

confidence: 99%

“…Administration of 10 5 or fewer T. annulata-infected cells resulted in immunity to parasite challenge, although prolonged in vitro passage of the cell lines was required to avoid production of clinical disease by the vaccine. 5,27,41 Initial studies in Israel in the early 1970s resulted in a national vaccine programme for T. annulata using cultured cells. Similar vaccines were subsequently developed in several other countries using cell lines derived from local parasite isolates.…”

Section: Vaccination With Parasitized Cell Linesmentioning

confidence: 99%

Approaches to vaccination against Theileria parva and Theileria annulata

Nene

Morrison

2016

Parasite Immunology

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SummaryDespite having different cell tropism, the pathogenesis and immunobiology of the diseases caused by Theileria parva and Theileria annulata are remarkably similar. Live vaccines have been available for both parasites for over 40 years, but although they provide strong protection, practical disadvantages have limited their widespread application. Efforts to develop alternative vaccines using defined parasite antigens have focused on the sporozoite and intracellular schizont stages of the parasites. Experimental vaccination studies using viral vectors expressing T. parva schizont antigens and T. parva and T. annulata sporozoite antigens incorporated in adjuvant have, in each case, demonstrated protection against parasite challenge in a proportion of vaccinated animals. Current work is investigating alternative antigen delivery systems in an attempt to improve the levels of protection. The genome architecture and protein‐coding capacity of T. parva and T. annulata are remarkably similar. The major sporozoite surface antigen in both species and most of the schizont antigens are encoded by orthologous genes. The former have been shown to induce species cross‐reactive neutralizing antibodies, and comparison of the schizont antigen orthologues has demonstrated that some of them display high levels of sequence conservation. Hence, advances in development of subunit vaccines against one parasite species are likely to be readily applicable to the other.

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Vaccination against bovine tropical theileriasis (Theileria annulata)

Cited by 28 publications

References 5 publications

Vaccination against Tropical Theileriosis

Vaccination against Tropical Theileriosis

Mechanism(s) of attenuation of Theileria annulata vaccine cell lines

Approaches to vaccination against Theileria parva and Theileria annulata

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