Microsatellite analysis of Toxoplasma gondii shows considerable polymorphism structured into two main clonal groups

Ajzenberg, Daniel; Bañuls, Anne‐Laure; Tibayrenc, Michel; Dardé, Marie Laure

doi:10.1016/s0020-7519(01)00301-0

Cited by 246 publications

(164 citation statements)

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“…Remarkably, these three clonotypes, as well as many of the less common strains, appear to represent the recent merging of two distinct gene pools (8,9), because among these strains there are just two major allelic types for each locus (9,10). The success of Toxoplasma as a parasite belies this genetic simplicity: it can infect almost any warm-blooded vertebrate, and it maintains a high prevalence in many host species, including humans.…”

mentioning

confidence: 99%

Just one cross appears capable of dramatically altering the population biology of a eukaryotic pathogen like Toxoplasma gondii

Boyle

Saeij

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

115

126

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Toxoplasma gondii, an obligate intracellular protozoan of the phylum Apicomplexa, is estimated to infect over a billion people worldwide as well as a great many other mammalian and avian hosts. Despite this ubiquity, the vast majority of human infections in Europe and North America are thought to be due to only three genotypes. Using a genome-wide analysis of single-nucleotide polymorphisms, we have constructed a genealogy for these three lines. The data indicate that types I and III are second-and first-generation offspring, respectively, of a cross between a type II strain and one of two ancestral strains. An extant T. gondii strain (P89) appears to be the modern descendant of the non-type II parent of type III, making the full genealogy of the type III clonotype known. The simplicity of this family tree demonstrates that even a single cross can lead to the emergence and dominance of a new clonal genotype that completely alters the population biology of a sexual pathogen.clonal population structure ͉ genetic recombination ͉ virulence A central question in understanding the biology of parasitic protozoa is the role of sexual reproduction in shaping their population structure (1). In Toxoplasma gondii, the sexual cycle occurs exclusively within felines, but this species is an unusual coccidian parasite in that transmission can also occur between intermediate hosts (e.g., an infected mouse eaten by a hawk) and so propagation does not depend on sexual reproduction (2). When the parasite does enter the sexual cycle in a cat, an individual parasite can give rise to an infection that includes both micro-and macrogametes (3); therefore, self-mating will be the rule unless the cat ingests multiple strains simultaneously or in rapid succession (4).These properties have led to an unusual population structure for Toxoplasma: in North America and Europe, at least, a majority of the isolates obtained from humans and livestock appear to fall into just three clonal lineages (5-7). Remarkably, these three clonotypes, as well as many of the less common strains, appear to represent the recent merging of two distinct gene pools (8, 9), because among these strains there are just two major allelic types for each locus (9, 10). The success of Toxoplasma as a parasite belies this genetic simplicity: it can infect almost any warm-blooded vertebrate, and it maintains a high prevalence in many host species, including humans. It appears, then, that much of the ''success'' of Toxoplasma in certain geographical locales is due to the emergence of only a few lines that have dramatically enhanced fitness when compared to other genotypes (8,9). Similar clonal population structures have been described in other parasitic protozoa (1), and although the mechanisms that led to clonal propagation may differ between species (and the clonal line), identifying the genetic basis for their emergence and eventual dominance in a large geographical area has the potential to shed considerable light on the evolution of eukaryotic pathogens. To do this, a gene...

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mentioning

confidence: 99%

Just one cross appears capable of dramatically altering the population biology of a eukaryotic pathogen like Toxoplasma gondii

Boyle

Saeij

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

115

126

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“…?show "fnote_aff1"$^! "content-markup(./author-grp [1]/aff|./author-grp [1]/dept-list)> Toxoplasma gondii is an obligate intracellular protozoan parasite that can infect virtually any warm-blooded animal, including human beings. Felidae are the only definitive hosts, but they can also act as intermediate hosts.…”

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Isolation and Genotyping ofToxoplasma GondiiCausing Fatal Systemic Toxoplasmosis in an Immunocompetent 10-Year-Old Cat

et al. 2011

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Abstract.A 10-year-old male, neutered domestic shorthair cat was presented with fever, anorexia, vomiting, and diarrhea. Serologic testing for Feline immunodeficiency virus and Feline leukemia virus were negative. Fine-needle aspirates of mesenteric lymph nodes revealed the presence of banana-shaped apicomplexan parasites. The cat died after 4 days of hospitalization. Postmortem polymerase chain reaction (PCR) analysis confirmed the presence of Toxoplasma gondii in all examined organs. Parasites were ex vivo isolated in outbred mice and subsequently transferred into cell culture. Genotyping, using genetic markers for SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, and Apico for PCR-restriction fragment length polymorphism, revealed infection with type II T. gondii displaying type II alleles at all loci except Apico, which exhibited a type I allele. This is the most frequently identified genotype among cats acting as definitive hosts in central Europe, but to the authors' knowledge, it has never been associated with systemic toxoplasmosis in an adult, immunocompetent cat.

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“…Studies over the last two decades have shown that in many regions, a select number of strains dominate in certain host species, especially humans and their domesticated animals/livestock (Darde et al 1988, Sibley & Boothroyd 1992, Howe & Sibley 1995, Ajzenberg et al 2002, Miller et al 2004, Lehmann et al 2006). This appears to have been the result of a clonal expansion of a small number of extremely fit genotypes.…”

Section: Clues From Population Biologymentioning

confidence: 99%

“…The model presented here incorporates data from more global analyses that show the diversity of strains when regions outside of Europe and North America, and/or when hosts beyond livestock and humans, are examined (Ajzenberg et al 2002, Khan et al 2006, Lehmann et al 2006, Sibley & Ajioka 2008. These strains are presumably more "natural" and are existing within the true complexity that exists in less disturbed ecosystems.…”

Section: Clues From Population Biologymentioning

confidence: 99%

Expansion of host range as a driving force in the evolution of Toxoplasma

Boothroyd

2009

Mem. Inst. Oswaldo Cruz

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Microsatellite analysis of Toxoplasma gondii shows considerable polymorphism structured into two main clonal groups

Cited by 246 publications

References 45 publications

Just one cross appears capable of dramatically altering the population biology of a eukaryotic pathogen like Toxoplasma gondii

Just one cross appears capable of dramatically altering the population biology of a eukaryotic pathogen like Toxoplasma gondii

Isolation and Genotyping ofToxoplasma GondiiCausing Fatal Systemic Toxoplasmosis in an Immunocompetent 10-Year-Old Cat

Expansion of host range as a driving force in the evolution of Toxoplasma

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