Variation in Giardia: towards a taxonomic revision of the genus

Monis, Paul; Cacciò, Simone M.; Thompson, R.C.A.

doi:10.1016/j.pt.2008.11.006

Cited by 257 publications

(231 citation statements)

References 51 publications

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“…(reviewed by Thompson and Monis, 2004). We now know these observations largely reflect genetic data indicating that certain genetic groups (assemblages) only appear to occur in certain species of host, and more correctly should be recognized as distinct host adapted species thus validating the observations of taxonomists in the early part of the 1900s Caccio et al 2005 ;Wielinga and Thompson, 2007 ;Monis et al 2009). Thus, the failure of isolates from dogs and livestock to grow in culture is now considered to reflect differences in host specificity, since the media used for growing Giardia in in vitro culture was principally developed to support growth of Giardia from humans.…”

Section: Giardiamentioning

confidence: 74%

Echinococcus,GiardiaandCryptosporidium: observational studies challenging accepted dogma

Thompson

2009

Parasitology

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in vitro culture systems that allow the maintenance, and support the development of Echinococcus, Giardia and Cryptosporidium in the laboratory have had a significant impact on their biology and taxonomy and the epidemiology of infections they cause. This short retrospective review demonstrates how radical shifts in our understanding have occurred as a result of being able to grow these organisms in culture, and how molecular tools have helped in the interpretation of such research that often reflects the observations of earlier workers.

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Section: Giardiamentioning

confidence: 74%

Echinococcus,GiardiaandCryptosporidium: observational studies challenging accepted dogma

Thompson

2009

Parasitology

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“…Nevertheless, a correlation between assemblage and disease, drug susceptibility or proliferation has yielded conflicting results (Monis et al. 2009; Benere et al. 2011).…”

Section: Discussionmentioning

confidence: 99%

Constitutive aneuploidy and genomic instability in the single‐celled eukaryote Giardia intestinalis

et al. 2016

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Giardia intestinalis is an important single‐celled human pathogen. Interestingly, this organism has two equal‐sized transcriptionally active nuclei, each considered diploid. By evaluating condensed chromosome numbers and visualizing homologous chromosomes by fluorescent in situ hybridization, we determined that the Giardia cells are constitutively aneuploid. We observed karyotype inter‐and intra‐population heterogeneity in eight cell lines from two clinical isolates, suggesting constant karyotype evolution during in vitro cultivation. High levels of chromosomal instability and frequent mitotic missegregations observed in four cell lines correlated with a proliferative disadvantage and growth retardation. Other cell lines, although derived from the same clinical isolate, revealed a stable yet aneuploid karyotype. We suggest that both chromatid missegregations and structural rearrangements contribute to shaping the Giardia genome, leading to whole‐chromosome aneuploidy, unequal gene distribution, and a genomic divergence of the two nuclei within one cell. Aneuploidy in Giardia is further propagated without p53‐mediated cell cycle arrest and might have been a key mechanism in generating the genetic diversity of this human pathogen.

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“…However, they all have three characteristics in common: a wide host range and questions of host specificity; an early taxonomy poorly supported by limited and/or questionable morphological discrimination and based largely on host occurrence; and uncertainty about their zoonotic and public health significance [102]. With Echinococcus, Giardia and to some extent Cryptosporidium, molecular tools have helped to resolve taxonomic issues and have supported the proposals of early taxonomists [22,103,104]. Evidence of morphological differences between isolates of Echinococcus from different hosts can now be supported by extensive molecular evidence of genetic variation and as such can be used as reliable and cost effective diagnostic markers in field studies, particularly in developing countries where costs and lack of equipment is an issue.…”

Section: Echinococcus Giardia and Cryptosporidiummentioning

confidence: 99%

“…Frequent reports of infection in companion animals, livestock and aquatic mammals have led to much discussion and controversy over their role as zoonotic reservoirs of infection (104,109). The lack of any significant morphological variability, but considerable evidence of phenotypic differences between isolates, fuelled this debate over many years.…”

Section: Echinococcus Giardia and Cryptosporidiummentioning

confidence: 99%

“…The lack of any significant morphological variability, but considerable evidence of phenotypic differences between isolates, fuelled this debate over many years. The subsequent application of PCR-based molecular tools has resolved questions of host specificity, taxonomy and zoonotic potential, but not the frequency of zoonotic transmission [104,109]. The application of multilocus genotyping to isolates of Giardia from human and other mammalian hosts in different parts of the world has clearly demonstrated the occurrence of zoonotic species in the same geographic areas, supporting the potential for zoonotic transmission [110,111].…”

Section: Echinococcus Giardia and Cryptosporidiummentioning

confidence: 99%

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The molecular epidemiology of parasite infections: Tools and applications

Lymbery

Thompson

2012

Molecular and Biochemical Parasitology

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Molecular epidemiology, broadly defined, is the application of molecular genetic techniques to the dynamics of disease in a population. In this review, we briefly describe molecular and analytical tools available for molecular epidemiological studies and then provide an overview of how they can be applied to better understand parasitic disease. A range of new molecular tools have been developed in recent years, allowing for the direct examination of parasites from clinical or environmental samples, and providing access to relatively cheap, rapid, high throughput molecular assays. At the same time, new analytical approaches, in particular those derived from coalescent theory, have been developed to provide more robust estimates of evolutionary processes and demographic parameters from multilocus, genotypic data. To date, the primary application of molecular epidemiology has been to provide specific and sensitive identification of parasites and to resolve taxonomic issues, particularly at the species level and below. Population genetic studies have also been used to determine the extent of genetic diversity among populations of parasites and the degree to which this diversity is associated with different host cycles or epidemiologically important phenotypes. Many of these studies have also shed new light on transmission cycles of parasites, particularly the extent to which zoonotic transmission occurs, and on the prevalence and importance of mixed infections with different parasite species or intraspecific variants (polyparasitism). A major challenge, and one which is now being addressed by an increasing number of studies, is to find and utilise genetic markers for complex traits of epidemiological significance, such as drug resistance, zoonotic potential and virulence.

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Variation in Giardia: towards a taxonomic revision of the genus

Cited by 257 publications

References 51 publications

Echinococcus,GiardiaandCryptosporidium: observational studies challenging accepted dogma

Echinococcus,GiardiaandCryptosporidium: observational studies challenging accepted dogma

Constitutive aneuploidy and genomic instability in the single‐celled eukaryote Giardia intestinalis

The molecular epidemiology of parasite infections: Tools and applications

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