Lethal Giardia from a wild-caught sulphur-crested 
cockatoo (Cacatua galerita) established in vitro 
chronically infects mice

Upcroft, Jacqueline; McDonnell, Pauline Ann; Gallagher, A.; Chen, N.; Upcroft, Peter

doi:10.1017/s0031182096008724

Cited by 42 publications

(35 citation statements)

References 25 publications

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“…This strain was genetically similar to human isolates and was infective for mice, in which it established a chronic infection with high parasite burdens; the mice also lost up to 20% of their body weight, mimicking the human failureto-thrive syndrome (204,205). This is the first report of a bird isolate infecting mammals.…”

Section: Giardia Infectionmentioning

confidence: 86%

“…Such a benchmark example was recently described for a Giardia isolate which was found to be lethal for sulfur-crested cockatoos (204). This strain was genetically similar to human isolates and was infective for mice, in which it established a chronic infection with high parasite burdens; the mice also lost up to 20% of their body weight, mimicking the human failureto-thrive syndrome (204,205).…”

Section: Giardia Infectionmentioning

confidence: 93%

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Drug Targets and Mechanisms of Resistance in the Anaerobic Protozoa

2001

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The anaerobic protozoa Giardia duodenalis, Trichomonas vaginalis, and Entamoeba histolytica infect up to a billion people each year. G. duodenalis and E. histolytica are primarily pathogens of the intestinal tract, although E. histolytica can form abscesses and invade other organs, where it can be fatal if left untreated. T. vaginalis infection is a sexually transmitted infection causing vaginitis and acute inflammatory disease of the genital mucosa. T. vaginalis has also been reported in the urinary tract, fallopian tubes, and pelvis and can cause pneumonia, bronchitis, and oral lesions. Respiratory infections can be acquired perinatally. T. vaginalis infections have been associated with preterm delivery, low birth weight, and increased mortality as well as predisposing to human immunodeficiency virus infection, AIDS, and cervical cancer. All three organisms lack mitochondria and are susceptible to the nitroimidazole metronidazole because of similar low-redox-potential anaerobic metabolic pathways. Resistance to metronidazole and other drugs has been observed clinically and in the laboratory. Laboratory studies have identified the enzyme that activates metronidazole, pyruvate:ferredoxin oxidoreductase, to its nitroso form and distinct mechanisms of decreasing drug susceptibility that are induced in each organism. Although the nitroimidazoles have been the drug family of choice for treating the anaerobic protozoa, G. duodenalis is less susceptible to other antiparasitic drugs, such as furazolidone, albendazole, and quinacrine. Resistance has been demonstrated for each agent, and the mechanism of resistance has been investigated. Metronidazole resistance in T. vaginalis is well documented, and the principal mechanisms have been defined. Bypass metabolism, such as alternative oxidoreductases, have been discovered in both organisms. Aerobic versus anaerobic resistance in T. vaginalis is discussed. Mechanisms of metronidazole resistance in E. histolytica have recently been investigated using laboratory-induced resistant isolates. Instead of downregulation of the pyruvate:ferredoxin oxidoreductase and ferredoxin pathway as seen in G. duodenalis and T. vaginalis, E. histolytica induces oxidative stress mechanisms, including superoxide dismutase and peroxiredoxin. The review examines the value of investigating both clinical and laboratory-induced syngeneic drug-resistant isolates and dissection of the complementary data obtained. Comparison of resistance mechanisms in anaerobic bacteria and the parasitic protozoa is discussed as well as the value of studies of the epidemiology of resistance

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Section: Giardia Infectionmentioning

confidence: 86%

Section: Giardia Infectionmentioning

confidence: 93%

Drug Targets and Mechanisms of Resistance in the Anaerobic Protozoa

2001

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“…We have previously described an isolate of Giardia duodenalis (BRIS/95/HEPU/2041), referred to as 2041, established from a bird which died of an overwhelming infection with the parasite (31). Isolate 2041 chronically infects mice and produces higher peak parasite loads than the human Giardia isolate BRIS/83/HEPU/106 (referred to as 106) (31,32).…”

mentioning

confidence: 99%

“…Isolate 2041 chronically infects mice and produces higher peak parasite loads than the human Giardia isolate BRIS/83/HEPU/106 (referred to as 106) (31,32). Mice infected with 2041 suffer weight gain impairment, with the most severe weight deficit occurring at the time of maximum parasite load (32).…”

mentioning

confidence: 99%

Orally AdministeredGiardia duodenalisExtracts Enhance an Antigen-Specific Antibody Response

et al. 2001

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We have identified novel adjuvant activity in specific cytosol fractions from trophozoites of Giardia isolate BRIS/95/HEPU/2041 (J. A. Upcroft, P. A. McDonnell, and P. Upcroft, Parasitol. Today, 14:281-284, 1998). Adjuvant activity was demonstrated in the systemic and mucosal compartments when Giardia extract was coadministered orally with antigen to mice. Enhanced antigen-specific serum antibody responses were demonstrated by enzyme-linked immunosorbent assay to be comparable to those generated by the "gold standard," mucosal adjuvant cholera toxin. A source of adjuvant activity was localized to the cytosolic component of the parasite. Fractionation of the cytosol produced fraction pools, some of which, when coadministered with antigen, stimulated an enhanced antigen-specific serum response. The toxic component of conventional mucosal adjuvants is associated with adjuvant activity; therefore, in a similar way, the toxin-like attributes of BRIS/95/HEPU/2041 may be responsible for its adjuvanticity. Complete characterization of the adjuvant is under way.

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“…5,7 In the wild, a wide variety of aquatic and semiaquatic mammals and birds 8 can be a source of waterborne Giardia cysts. 5,9,10 Studies on giardiasis in a variety of birds suggest they may be zoonotic reservoirs; 7,[9][10][11][12] however, these indications have not been proven. 13 As reviewed by Hopkins and others, 14 numerous studies demonstrated genetic and antigenic similarities among Giardia cyst isolates from humans and other mammalian hosts.…”

mentioning

confidence: 99%

Giardia duodenalis cysts of genotype A recovered from clams in the Chesapeake Bay subestuary, Rhode River.

Graczyk¹,

Thompson²,

Fayer³

et al. 1999

The American Journal of Tropical Medicine and Hygiene

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Abstract. Filter-feeding molluscan shellfish can concentrate zoonotic and anthroponotic waterborne pathogens. Cysts of Giardia sp. were detected by immunofluorescent antibodies in tissues of the clams Macoma balthica and M. mitchelli from Rhode River, a Chesapeake Bay (Maryland) subestuary. Molecular tests identified the cysts as Giardia duodenalis Genotype A, the most common genotype recovered from humans. Macoma clams are burrowers in mud or sandy-mud substrata and preferentially feed on the surface sediment layer. Waterborne Giardia cysts settle rapidly to the bottom in slow-moving waters and contaminate the sediment. Macoma clams do not have economic value, but can serve as biologic indicators of sediment contamination with Giardia sp. cysts of public health importance. These clams can be used for sanitary assessment of water quality.Bivalves can harbor environmentally derived pathogenic microorganisms as a result of filtering large volumes of water and concentrating the recovered particles. 1 Examination of bivalves can demonstrate water pollution even when water testing produces negative results. 2 For example, Cryptosporidium parvum oocysts had never been reported in Chesapeake Bay (Maryland) water until oysters (Crassostrea virginica) collected from that water were found to harbor this zoonotic parasite. 3 Similarly, C. parvum oocysts have been repeatedly recovered from the tissue of feral blue mussels (Mytilus edulis) from Sligo Bay (Ireland), but most of the water samples from the mussel collection sites were oocystnegative. 4

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Lethal Giardia from a wild-caught sulphur-crested cockatoo (Cacatua galerita) established in vitro chronically infects mice

Cited by 42 publications

References 25 publications

Drug Targets and Mechanisms of Resistance in the Anaerobic Protozoa

Drug Targets and Mechanisms of Resistance in the Anaerobic Protozoa

Orally AdministeredGiardia duodenalisExtracts Enhance an Antigen-Specific Antibody Response

Giardia duodenalis cysts of genotype A recovered from clams in the Chesapeake Bay subestuary, Rhode River.

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