Immunogenicity and infectivity of mature and immature plasmodium gallinaceum sporozoites

Krettli, Antoniana U.; Laurente, Katia Elizabeth; Daher, Valquiria R.; Rocha, Eliana Maria Maurício da

doi:10.1590/s0074-02761986000600019

Cited by 4 publications

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“…3), implying that exposure subsequent to the elevation of DHEAS augments resistance. Thus, puberty-related resistance in humans may be an acquired form of immunity, distinguishing it from the innate resistance observed in older chicks (17,24) and rats (18), which are less susceptible than their younger counterparts at first exposure to malaria.…”

Section: Discussionmentioning

confidence: 99%

Human Resistance toPlasmodium falciparumIncreases during Puberty and Is Predicted by Dehydroepiandrosterone Sulfate Levels

et al. 2001

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Immunity to Plasmodium falciparum develops slowly in areas of endemicity, and this is often ascribed to poorly immunogenic or highly variant parasite antigens. However, among populations newly exposed to malaria, adults acquire immunity more rapidly than children. We examined the relationship between pubertal development and resistance to P. falciparum. During two transmission seasons in western Kenya, we treated the same cohort of young males to eradicate P. falciparum and then obtained blood smears each week for 4 months. We determined pubertal development by Tanner staging and by levels of dehydroepiandrosterone sulfate (DHEAS) and testosterone in plasma. In multivariate and age-stratified analyses, we examined the effect of pubertal development on resistance to malaria. In both seasons (n ‫؍‬ 248 and 144 volunteers, respectively), older males were less susceptible than younger males. Age-related decreases in the frequency and density of parasitemia were greatest during puberty (15-to 20-year-olds). DHEAS and testosterone were significant independent predictors of resistance to P. falciparum parasitemia, even after accounting for the effect of age. Fifteen-to 20-year-old males with high DHEAS levels had a 72% lower mean parasite density (P < 0.01) than individuals with low DHEAS levels. Similarly, 21-to 35-year-old males with high DHEAS levels had a 92% lower mean parasite density (P < 0.001) and 48% lower frequency of parasitemia (P < 0.05) than individuals with low DHEAS levels. These data suggest that the long period needed to attain full immunity could be explained as a consequence of host development rather than as the requirement to recognize variant or poorly immunogenic parasite antigens.Plasmodium falciparum malaria is a leading cause of morbidity and mortality in developing countries, infecting hundreds of millions of individuals and killing up to 1 million children in sub-Saharan Africa each year (2). This death toll will rise as drug-resistant parasites spread (35), and meanwhile the promise of a broadly effective malaria vaccine remains unfulfilled despite important technological advances (27). Residents of areas of endemicity develop protective immunity that limits parasitemia and disease, providing a model for vaccine development, but the responses conferring naturally occurring protection have not been elucidated.P. falciparum infection is more frequent and severe in children than in adults (23; reviewed in reference 4), and resistance is acquired over years of exposure. The long period required to develop resistance has supported the widely held views that the parasite is poorly immunogenic or that protective immunity is strain specific and requires exposure to the many parasite variants circulating in a community (10,14). The recent observation that adult migrants to an area of endemicity acquire resistance more rapidly than their younger counterparts implicates host development in decreased susceptibility to P. falciparum (5, 7). In an area of holoendemicity in Kenya, where malaria is ubiqu...

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Section: Discussionmentioning

confidence: 99%

Human Resistance toPlasmodium falciparumIncreases during Puberty and Is Predicted by Dehydroepiandrosterone Sulfate Levels

et al. 2001

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Circumsporozoite protein of Plasmodium gallinaceum characterized by monoclonal antibodies

Krettli

Rocha

Lopes

et al. 1988

Parasite Immunology

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Monoclonal antibodies (MoAb) were produced against both salivary gland sporozoites (SGS) and oocyst sporozoites (OS) of Plasmodium gallinaceum, an avian malaria parasite. By indirect immunofluorescence, all of the MoAbs reacted with both SGS and OS of P. gallinaceum and two of the MoAbs cross-reacted weakly with P. berghei sporozoites. None of the MoAbs reacted with sporozoites of six additional species of mammalian plasmodia. In Western blot analysis of extracts of either SGS or OS of P. gallinaceum, these MoAbs identified two polypeptides with molecular weights of approximately 76,000 and 64,000 D. The results of a MoAb inhibition of binding assay and a two-site one-antibody immunoradiometric assay indicate that the circumsporozoite protein of P. gallinaceum, like those of mammalian malaria parasites, contains a repetitive immunodominant epitope. Two of the anti-P. gallinaceum MoAbs were tested in a sporozoite neutralization assay and decreased, but did not abolish, the infectivity of sporozoites for chickens, indicating that the polypeptide of P. gallinaceum identified by immunoblot is probably the protective antigen.

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Direct lysis of Trypanosoma cruzi: a novel effector mechanism of protection mediated by human anti‐gal antibodies

Gazzinelli

Pereira

Romanha

et al. 1991

Parasite Immunology

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Anti-gal antibodies directed against a carbohydrate epitope present in mouse laminin (galactosyl alpha 1-3 galactose) and detected in high levels in sera from patients in the acute phase of Chagas disease are responsible for the direct lysis (DL) of Trypanosoma cruzi blood forms independent of either the classic or alternative complement pathways. Furthermore, the lectins Euonymus europaeus (EE) specific for the carbohydrates gal alpha 1-3 gal present a similar lytic activity against T. cruzi at the same concentrations of purified anti-gal antibodies. The DL activity was tested with several other lectins but Concanavalin A (Con A) specific for alpha-D-mannose and alpha-D-glucose was the only one also presenting lytic activity. The lectins and anti-gal antibodies lytic activity can be inhibited by specific carbohydrates suggesting that this phenomenon is related to the capability of these lectins or anti-gal antibodies to bind to a crucial surface component of T. cruzi. Moreover, the infectivity of T. cruzi blood forms to mice was clearly inactivated by incubation with acute chagasic sera (ACS) but not by ACS absorbed by immunoaffinity chromatography with mouse laminin, a strong evidence that high levels of anti-gal antibodies participate in the decline of the parasitaemia from the acute to the chronic phase in Chagas disease.

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Immunogenicity and infectivity of mature and immature plasmodium gallinaceum sporozoites

Cited by 4 publications

References 0 publications

Human Resistance toPlasmodium falciparumIncreases during Puberty and Is Predicted by Dehydroepiandrosterone Sulfate Levels

Human Resistance toPlasmodium falciparumIncreases during Puberty and Is Predicted by Dehydroepiandrosterone Sulfate Levels

Circumsporozoite protein of Plasmodium gallinaceum characterized by monoclonal antibodies

Direct lysis of Trypanosoma cruzi: a novel effector mechanism of protection mediated by human anti‐gal antibodies

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