Giardia lamblia: Traffic of a Trophozoite Variant Surface Protein and a Major Cyst Wall Epitope during Growth, Encystation, and Antigenic Switching

McCaffery, J. Michael; Faubert, G M; Gillin, Frances D.

doi:10.1006/expr.1994.1087

Cited by 72 publications

(87 citation statements)

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“…Protein concentrations were determined by the Bradford method, and 6 g protein/lane was electrophoretically size-fractionated on a 10% denaturing, reducing polyacrylamide gel. Proteins were transferred to nitrocellulose, and blots were stained with a mAb (8C5) against CWP2 (29) as described previously (30). As a control, blots were reacted with a mAb against the giardial lectin, taglin (31).…”

Section: Immunoblot Analysis Of Giardial Cyst Wall Protein 2 (Cwp2) Ementioning

confidence: 99%

Nitric Oxide Production by Human Intestinal Epithelial Cells and Competition for Arginine as Potential Determinants of Host Defense Against the Lumen-Dwelling Pathogen Giardia lamblia

Eckmann

Laurent

Langford³

et al. 2000

The Journal of Immunology

220

203

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Giardia lamblia infection of the human small intestine is a common protozoan cause of diarrheal disease worldwide. Although infection is luminal and generally self-limiting, and secretory Abs are thought to be important in host defense, other defense mechanisms probably affect the duration of infection and the severity of symptoms. Because intestinal epithelial cells produce NO, and its stable end products, nitrite and nitrate, are detectable mainly on the apical side, we tested the hypothesis that NO production may constitute a host defense against G. lamblia. Several NO donors, but not their control compounds, inhibited giardial growth without affecting viability, suggesting that NO is cytostatic rather than cytotoxic for G. lamblia. NO donors also inhibited giardial differentiation induced by modeling crucial environmental factors, i.e., encystation induced by bile and alkaline pH, and excystation in response to gastric pH followed by alkaline pH and protease. Despite the potent antigiardial activity of NO, G. lamblia is not simply a passive target for host-produced NO, but has strategies to evade this potential host defense. Thus, in models of human intestinal epithelium, G. lamblia inhibited epithelial NO production by consuming arginine, the crucial substrate used by epithelial NO synthase to form NO. These studies define NO and arginine as central components in a novel cross-talk between a luminal pathogen and host intestinal epithelium.

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Section: Immunoblot Analysis Of Giardial Cyst Wall Protein 2 (Cwp2) Ementioning

confidence: 99%

Nitric Oxide Production by Human Intestinal Epithelial Cells and Competition for Arginine as Potential Determinants of Host Defense Against the Lumen-Dwelling Pathogen Giardia lamblia

Eckmann

Laurent

Langford³

et al. 2000

The Journal of Immunology

220

203

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“…A compartment with functional and structural characteristics of the endoplasmic reticulum (ER) 1 has been identified and characterized as an endomembraneous network, which extends throughout the cell body. Immunoelectron microscopy studies demonstrated the localization of giardial BiP (11), three protein-disulfide isomerase paralogues (12), as well as trophozoite and cyst surface antigens in the Giardia ER (13). Other morphologically recognizable membrane compartments are the peripheral vesicles (PVs, approximately 150 -200 nm in size), which are thought to perform both lysosomal and endosomal activities (14).…”

mentioning

confidence: 99%

An Ancestral Secretory Apparatus in the Protozoan Parasite Giardia intestinalis

Marti

Regös

et al. 2003

Journal of Biological Chemistry

104

137

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The protozoan parasite Giardia intestinalis belongs to one of the earliest diverged eukaryotic lineages. This is also reflected in a simple intracellular organization, as Giardia lacks common subcellular compartments such as mitochondria, peroxisomes, and apparently also a Golgi apparatus. During encystation, developmentally regulated formation of large secretory compartments containing cyst wall material occurs. Despite the lack of any morphological similarities, these encystation-specific vesicles (ESVs) show several biochemical characteristics of maturing Golgi cisternae. Previous studies suggested that Golgi structure and function are induced only during encystation in Giardia, giving rise to the hypothesis that ESVs, as a Giardia Golgi equivalent, are generated de novo. Alternatively, ESV compartments could be built on the template structure of a cryptic Golgi in trophozoites in response to ER export of cyst wall material during encystation. We addressed this question by defining the molecular framework of the Giardia secretory apparatus using a comparative genomic approach. Analysis of the corresponding transcriptome during growth and encystation revealed surprisingly little stage-specific regulation. A panel of antibodies was generated against selected marker proteins to investigate the developmental dynamics of the endomembrane system. We show evidence that Giardia accommodates the export of large amounts of cyst wall material through re-organization of membrane compartment(s) in trophozoites with biochemical similarities to ESVs. This suggests that ESVs are selectively stabilized Golgi-like compartments in a unique and archetypical secretory system, which arise from a structural template in trophozoites rather than being generated de novo.

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“…The development of specific antibodies to cyst wall proteins (CWPs) has contributed significantly to the understanding of the encystation phenomenon (7). Using immunofluorescence and immunogold staining, McCaffery et al (16) have reported that cyst antigens are found in perinuclear and cytoplasmic endoplasmic reticulum cisternae which appear to be the site of cyst antigen synthesis. Encystation begins with the appearance of CWPs on small protusions of the trophozoite membrane, which enlarge to form cap-like structures with progression to formation of the cyst wall.…”

mentioning

confidence: 99%

“…CWP2 contains five tandem copies of a 24-residue leucine-rich repeat. MAb 8C5.C11, which has been used to study the transport of a major cyst epitope during encystation in vitro (6,16), also reacts with recombinant CWP2 (rCWP2) (T. E. Nash personal communication).…”

mentioning

confidence: 99%

Oral Immunization of BALB/c Mice with Giardia duodenalis Recombinant Cyst Wall Protein Inhibits Shedding of Cysts

Larocque

Nakagaki²,

Lee

et al. 2003

Infect Immun

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The process of encystation is a key step in the Giardia duodenalis life cycle that allows this intestinal protozoan to survive between hosts during person-to-person, animal-to-person, waterborne, or food-borne transmission. The release of cysts from infected persons and animals is the main contributing factor to contamination of the environment. Genes coding for cyst wall proteins (CWPs), which could be used for developing a transmission-blocking vaccine, have been cloned. Since the immunogenicity of recombinant Giardia CWP is unknown, we have investigated the immunogenicity of recombinant CWP2 (rCWP2) and its efficacy in interfering with the phenomenon of encystation taking place in the small bowels of BALB/c mice vaccinated with the recombinant protein. Here we report that the immunization of BALB/c mice with rCWP2 stimulated the immune system in a manner comparable to that for a live infection with Giardia muris cysts. Fecal and serum anti-rCWP2 immunoglobulin A (IgA) antibodies were detected in the immunized mice. In addition, anti-rCWP2 IgG1 and IgG2a antibodies were detected in the serum. mRNAs coding for Th1 and Th2 types of cytokines were detected in spleen and Peyer's patch cells from immunized mice. When the vaccinated mice were challenged with live cysts, the animals shed fewer cysts. We conclude that rCWP2 is a possible candidate antigen for the development of a transmission-blocking vaccine.

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Giardia lamblia: Traffic of a Trophozoite Variant Surface Protein and a Major Cyst Wall Epitope during Growth, Encystation, and Antigenic Switching

Cited by 72 publications

References 0 publications

Nitric Oxide Production by Human Intestinal Epithelial Cells and Competition for Arginine as Potential Determinants of Host Defense Against the Lumen-Dwelling Pathogen Giardia lamblia

Nitric Oxide Production by Human Intestinal Epithelial Cells and Competition for Arginine as Potential Determinants of Host Defense Against the Lumen-Dwelling Pathogen Giardia lamblia

An Ancestral Secretory Apparatus in the Protozoan Parasite Giardia intestinalis

Oral Immunization of BALB/c Mice with Giardia duodenalis Recombinant Cyst Wall Protein Inhibits Shedding of Cysts

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