Structure and Composition of the Oocyst Wall of Eimeria tenella

Stotish, Ronald L.; Wang, C C; Meyenhofer, Markus F.

doi:10.2307/3279729

Cited by 50 publications

(57 citation statements)

References 14 publications

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“…This antibody, as well as anti-APGA, an antibody that was raised against an enriched fraction of native gametocyte antigens predominating in gam56 and gam82, recognized only a ϳ33-kDa (wp33) protein in oocyst wall preparations; they did not recognize any smaller proteins (10 to 14 kDa) reported previously to be the major components of the oocyst wall in Eimeria (14,20,31). Thus, an investigation was carried out to elucidate the relationship between these smaller 10-to 14-kDa oocyst wall proteins and gam56 in E. maxima.…”

Section: Resultsmentioning

confidence: 80%

“…Mild conditions were deliberately used here to extract proteins from the oocyst wall in an effort to maintain the antigenicity of the proteins. However, under such conditions, it has been estimated that less than 10% of the oocyst wall is solubilized (31), and therefore, the proteins described here might represent only a few of the total number of proteins involved in wall formation.…”

Section: Vol 2 2003 Oocyst Wall Formation In Eimeria 461mentioning

confidence: 96%

“…It is bilayered, composed of a 10-nm-thick lipid outer layer and a 90-nm-thick glycoprotein inner layer arising from the contents of specialized organelles called wall-forming bodies, which are found exclusively in the sexual stage (macrogamete or macrogametocyte) of the parasite (13,26,31). Progress towards understanding the mechanism of oocyst wall formation in Eimeria has been difficult due to the lack of a good culture system for studying the sexual stages of Eimeria and problems associated with isolating large quantities of parasites.…”

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confidence: 99%

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Roles of Tyrosine-Rich Precursor Glycoproteins and Dityrosine- and 3,4-Dihydroxyphenylalanine-Mediated Protein Cross-Linking in Development of the Oocyst Wall in the Coccidian Parasite Eimeria maxima

Belli

Wallach²,

Luxford

et al. 2003

Eukaryot Cell

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The oocyst wall of apicomplexan parasites protects them from the harsh external environment, preserving their survival prior to transmission to the next host. If oocyst wall formation could be disrupted, then logically, the cycle of disease transmission could be stopped, and strategies to control infection by several organisms of medical and veterinary importance such as Eimeria, Plasmodium, Toxoplasma, Cyclospora, and Neospora could be developed. Here, we show that two tyrosine-rich precursor glycoproteins, gam56 and gam82, found in specialized organelles (wall-forming bodies) in the sexual stage (macrogamete) of Eimeria maxima are proteolytically processed into smaller glycoproteins, which are then incorporated into the developing oocyst wall. The identification of high concentrations of dityrosine and 3,4-dihydroxyphenylalanine (DOPA) in oocyst extracts by high-pressure liquid chromatography, together with the detection of a UV autofluorescence in intact oocysts, implicates dityrosine-and possibly DOPA-protein cross-links in oocyst wall hardening. In addition, the identification of peroxidase activity in the wall-forming bodies of macrogametes supports the hypothesis that dityrosine-and DOPA-mediated cross-linking might be an enzyme-catalyzed event. As such, the mechanism of oocyst wall formation in Eimeria, is analogous to the underlying mechanisms involved in the stabilization of extracellular matrices in a number of organisms, widely distributed in nature, including insect resilin, nematode cuticles, yeast cell walls, mussel byssal threads, and sea urchin fertilization membranes.Eimeria maxima is an intestinal parasite of chickens and is one of the causative agents of coccidiosis, contributing to costs on the order of billions of dollars per year to the poultry meat industry (34, 37). The life cycle of Eimeria includes asexual and sexual stages of development that lead to the formation of the infective form of the parasite, the oocyst (23). Prior to excretion, the oocyst is encapsulated by a hard barrier, the oocyst wall, which protects the parasite from the harsh external environment. Once excreted from the host, the oocyst develops further (sporulation) and is passed onto the next host via the fecal-oral route.The oocyst wall is a structure that is vital to the parasite and ensures the organism's survival and transmission to the next host. It is bilayered, composed of a 10-nm-thick lipid outer layer and a 90-nm-thick glycoprotein inner layer arising from the contents of specialized organelles called wall-forming bodies, which are found exclusively in the sexual stage (macrogamete or macrogametocyte) of the parasite (13,26,31). Progress towards understanding the mechanism of oocyst wall formation in Eimeria has been difficult due to the lack of a good culture system for studying the sexual stages of Eimeria and problems associated with isolating large quantities of parasites. However, with the advent of new technologies in proteomics and molecular biology, together with improved methods for the increased ...

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Section: Resultsmentioning

confidence: 80%

Section: Vol 2 2003 Oocyst Wall Formation In Eimeria 461mentioning

confidence: 96%

mentioning

confidence: 99%

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Roles of Tyrosine-Rich Precursor Glycoproteins and Dityrosine- and 3,4-Dihydroxyphenylalanine-Mediated Protein Cross-Linking in Development of the Oocyst Wall in the Coccidian Parasite Eimeria maxima

Belli

Wallach²,

Luxford

et al. 2003

Eukaryot Cell

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“…After fertilization of macrogametes, a complex, two-layered wall is secreted around the young oocyst by exocytosis of wall-forming body type I and type II (WFBI and WFBII) (35). While the 10-nm-thick outer oocyst wall is built up by the contents of WFBI, the 90-nm inner oocyst wall is composed mainly of glycoproteins that were stored in WFBII (31,37). The oocyst displays a remarkable rigidity and protects the parasite from several physically and chemically adverse influences, such as commonly used disinfectants (34).…”

mentioning

confidence: 99%

Excystation of Eimeria tenella Sporozoites Impaired by Antibody Recognizing Gametocyte/Oocyst Antigens GAM22 and GAM56

et al. 2008

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Eimeria tenella is the causative agent of coccidiosis in poultry. Infection of the chicken intestine begins with ingestion of sporulated oocysts releasing sporocysts, which in turn release invasive sporozoites. The monoclonal antibody E2E5 recognizes wall-forming body type II (WFBII) in gametocytes and the WFBII-derived inner wall of oocysts. Here we describe that this antibody also binds to the stieda body of sporocysts and significantly impairs in vitro excystation of sporozoites. Using affinity chromatography and protein sequence analysis, E2E5 is shown to recognize EtGAM56, the E. tenella ortholog of the Eimeria maxima gametocyte-specific GAM56 protein. In addition, this antibody was used to screen a genomic phage display library presenting E. tenella antigens as fusion proteins with the gene VIII product on the surfaces of phagemid particles and identified the novel 22-kDa histidine-and proline-rich protein EtGAM22. The Etgam22 mRNA is expressed predominantly at the gametocyte stage, as detected by Northern blotting. Southern blot analysis in combination with data from the E. tenella genome project revealed that Etgam22 is an intronless multicopy gene, with approximately 12 to 22 copies in head-to-tail arrangement. Conspicuously, Etgam56 is also intronless and is localized adjacent to another gam56-like gene, Etgam59. Our data suggest that amplification is common for genes encoding oocyst wall proteins.Coccidiosis in poultry is caused by protozoan parasites of the genus Eimeria. Worldwide economic losses due to these parasites have been estimated to exceed 1.2 billion U.S. dollars per annum (41). The most virulent species is Eimeria tenella, causing severe hemorrhagic enteritis by infection of the epithelium and submucosa of the ceca and, eventually, death of infected chickens (24).Eimeria infections occur by ingestion of oocysts (24). In the intestine, oocysts release four sporocysts, each containing two sporozoites. After excystation, motile infective sporozoites actively enter cells in the epithelium of the cecum. Three rounds of asexual multiplication in the epithelium and submucosa are then followed by differentiation to sexual stages of micro-and macrogametocytes (23). After fertilization of macrogametes, a complex, two-layered wall is secreted around the young oocyst by exocytosis of wall-forming body type I and type II (WFBI and WFBII) (35). While the 10-nm-thick outer oocyst wall is built up by the contents of WFBI, the 90-nm inner oocyst wall is composed mainly of glycoproteins that were stored in WFBII (31, 37). The oocyst displays a remarkable rigidity and protects the parasite from several physically and chemically adverse influences, such as commonly used disinfectants (34). A potential use of gametocyte antigens involved in formation of the oocyst wall as protective transmission-blocking vaccines has been described for Eimeria maxima (2,4,25,(38)(39)(40)46).The formation of oocyst and sporocyst walls and sporozoite excystation are rather complex processes that we are just beginning to underst...

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“…The contents of the Eimeria oocyst wall were originally thought to consist of a high proportion of glycoproteins (37), a theory supported by biochemical analyses of EmGam56 and EmGam82 that revealed high concentrations of the amino sugar (glycan) galactosamine. It is unclear why these wallforming proteins require glycosylation; however, the strong conservation of O-glycosylation motifs in both EmGam56 and EtGam56 (19) implies that it is an important process.…”

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confidence: 99%

The Glycosylation Pathway of Eimeria tenella Is Upregulated during Gametocyte Development and May Play a Role in Oocyst Wall Formation

et al. 2010

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Sexual-stage glycoproteins of Eimeria are important components of the oocyst wall, a structure that ensures the efficient transmission of these and related parasites. In this study, the primary enzyme in the glycosylation pathway of Eimeria tenella, glucosamine:fructose-6-phosphate aminotransferase (EtGFAT), has been characterized as a macrogamete-specific protein. Although the transcription of EtGFAT was observed early in macrogamete development, protein expression was restricted to mature macrogametes, prior to their conversion into unsporulated oocysts. Genes coding for three other enzymes required for N-acetylgalactosamine (GalNAc) synthesis were also transcribed during E. tenella macrogamete development. Gene transcription of the enzyme responsible for the O-linked transfer of GalNAc to proteins, EtGalNAc-T, was upregulated primarily in unsporulated oocyst stages, and accordingly, a significant increase in GalNAc levels was observed in E. tenella gametocytes and oocysts. Gam56 and Gam82, two well-characterized glycoproteins of Eimeria macrogametes and the oocyst wall, contain high levels of GalNAc and represent probable targets of GalNAc O linkage. It appears that the glycosylation pathway, specifically relating to the formation of GalNAc O links, is dramatically upregulated in E. tenella sexual stages and may play a role in directing a number of macrogamete proteins to the developing oocyst wall.

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Structure and Composition of the Oocyst Wall of Eimeria tenella

Cited by 50 publications

References 14 publications

Roles of Tyrosine-Rich Precursor Glycoproteins and Dityrosine- and 3,4-Dihydroxyphenylalanine-Mediated Protein Cross-Linking in Development of the Oocyst Wall in the Coccidian Parasite Eimeria maxima

Roles of Tyrosine-Rich Precursor Glycoproteins and Dityrosine- and 3,4-Dihydroxyphenylalanine-Mediated Protein Cross-Linking in Development of the Oocyst Wall in the Coccidian Parasite Eimeria maxima

Excystation of Eimeria tenella Sporozoites Impaired by Antibody Recognizing Gametocyte/Oocyst Antigens GAM22 and GAM56

The Glycosylation Pathway of Eimeria tenella Is Upregulated during Gametocyte Development and May Play a Role in Oocyst Wall Formation

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