In Vitro Neutralization of Theilerial Sporozoite Infectivity With Immune Serum

Gray, M.A.; Brown, C.G.D.

doi:10.1007/978-94-009-8346-5_22

Cited by 16 publications

(7 citation statements)

References 4 publications

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“…Sera from cattle recovering from ECF or tropical theileriosis exhibit a neutralizing eect on sporozoites, thus preventing in vitro infection of lymphocytes by sporozoites (Gray and Brown 1981;Preston and Brown 1985;Ahmed et al 1988;Musoke et al 1992). Induction of neutralizing antibodies can be achieved even by immunization of cattle with attenuated schizont cultures (Ahmed et al 1988), indicating that common antigenic determinants do exist between different stages of the parasite.…”

Section: Humoral Immune Responsementioning

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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Section: Humoral Immune Responsementioning

confidence: 99%

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

Ahmed

Mehlhorn

1999

Parasitol Res

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“…In their study, RPMI and MEM stabilates showed similar infectivity when compared to L-15. Gray & Brown (1981) showed that neat serum could have inhibitory effects on sporozoite infectivity and this could explain why the ED of FCS was lower than that of MEM. However, the effect may not be very pronounced as the confidence interval is wide.…”

Section: Discussionmentioning

confidence: 99%

Infectivity of <i>Theileria parva</i> sporozoites following cryopreservation in four suspension media and multiple refreezing : evaluation by <i>in vitro</i> titration

Mwanakasale¹,

Berkvens²,

Dolan³

et al. 2006

Onderstepoort J Vet Res

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Theileria parva sporozoite stabilates are used for immunizing cattle against East Coast fever and in in vitro sporozoite neutralization assays. In this study, we attempted to identify a cheaper freezing medium and quantified the infectivity loss of sporozoites due to refreezing of stabilates, using an in vitro technique. Pools of stabilates prepared using Minimum Essential Medium (MEM), Roswell Park Memorial Institute (RPMI 1640), foetal calf serum (FCS) and phosphate-buffered saline (PBS) were compared. All were supplemented with bovine serum albumin except the FCS. RPMI 1640 was as effective as MEM in maintaining sporozoite infectivity while the infectivity in PBS and FCS reached only 59 % and 67 %, respectively. In a second experiment, a stabilate based on MEM was subjected to several freeze-thaw cycles including various holding times on ice between thawing and refreezing. Refrozen stabilate gave an average sporozoite infectivity loss of 35 % per cycle. The results indicate that RPMI can be used as a cheaper freezing medium for T. parva stabilates and that refrozen stabilate doses need to be adjusted for the 35 % loss of infectivity.

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“…Although infections with T. parva or T. annulata induce only low levels of antibody against sporozoite antigens, antibodies capable of fully neutralizing the infectivity of sporozoites in vitro have been detected in animals subjected to repeated sporozoite challenge. Moreover, monoclonal antibodies with neutralizing activity (nmAbs) have been produced for both parasites by immunizing mice with sporozoites .…”

Section: Approaches To Development Of Subunit Vaccinesmentioning

confidence: 99%

“…Although infections with T. parva 77 or T. annulata 78 induce only low levels of antibody against sporozoite antigens, antibodies capable of fully neutralizing the infectivity of sporozoites in vitro have been detected in animals subjected to repeated sporozoite challenge.…”

Section: Protective Immune Responses To Sporozoitesmentioning

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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In Vitro Neutralization of Theilerial Sporozoite Infectivity With Immune Serum

Cited by 16 publications

References 4 publications

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

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

Infectivity of <i>Theileria parva</i> sporozoites following cryopreservation in four suspension media and multiple refreezing : evaluation by <i>in vitro</i> titration

Approaches to vaccination against Theileria parva and Theileria annulata

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