Population structure and mouse-virulence of Toxoplasma gondii in Brazil

Pena, Hilda Fátima de Jesus; Gennari, Solange Maria; Dubey, J. P.; Su, Chunlei

doi:10.1016/j.ijpara.2007.09.004

Cited by 336 publications

(430 citation statements)

References 30 publications

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“…Some of these atypical genotypes are detected in multiple locations. They may correspond to new successful clonal lineages (Pena et al, 2007).…”

Section: Toxoplasma Genotypes the Three Main Clonal Lineagesmentioning

confidence: 99%

“…Genetically distinct isolates are found in different regions of South America (Dubey et al, 2007c). Common clonal lineages, different from the three classical types, may circulate on this continent (Pena et al, 2007).…”

Section: South Americamentioning

confidence: 99%

“…First reports from Asia (Dubey et al, 2007a(Dubey et al, , 2007b(Dubey et al, , 2007d) reveal a more limited genetic diversity than in South America, with some genotypes common to both areas. The few strains isolated from African patients possess a fixed combination of type I and III alleles which can suggest the existence of a clonal African type (Ajzenberg et al, 2004) possibly related to one of the Brazilian types (Pena et al, 2007).…”

Section: South Americamentioning

confidence: 99%

“…They ranged from highly virulent to intermediate or non-virulent phenotype according to the differences in the combination of genes they have inherited (Grigg & Suzuki, 2003). Pena et al (2007) define their virulence at isolation (i.e. without knowledge of infecting dose) on mortality of mice within four weeks of infection and categorize isolates into three groups: virulent (death of 100 % of mice within four weeks), intermediate virulent (30 % to less than 100 % mortality), and non-virulent (< 30 % death within four weeks).…”

Section: Virulence Of Non Clonal Lineagesmentioning

confidence: 99%

“…Other candidate genes has been found on chromosome XII (ROP5, SAG3, Adenosine kinase) (Saeij et al, 2006), and various parasitic secretions from micronemes or dense granules also play additional roles in expression of virulence (review Lebrun et al, 2007) It would be interesting to look for the polymorphism and the expression level of the virulence genes detected by these experimental crosses in naturally recombinant strains to better predict the virulence of a given isolate. A first study detected significant differences in virulence among atypical isolates according to alleles I, II and III of CS3 locus, one of the candidate virulence gene located on chromosome VIIa in close proximity to ROP18 locus (Pena et al, 2007).…”

Section: Genetic Background Of Virulencementioning

confidence: 99%

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Toxoplasma gondii, “new” genotypes and virulence

Dardé¹

2008

Parasite

143

108

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Summary :Toxoplasma gondii has been described as a parasite with a low genetic diversity and a clonal population structure. The three main clonal lineages designated as type I, II or III largely predominate in Europe and North America. But strains not related to these main lineages circulate, notably, in other continents. They possess a shuffled combination of alleles that typify the three clonal types and unique polymorphisms detected by multilocus analysis. The population structure of Toxoplasma in these continents is also characterized by a higher genetic diversity associated with a lower linkage desequilibrium suggesting a role for genetic exchange. Due to their genomic diversity, it is difficult to draw global conclusions about their virulence. However, most of them are virulent in mice at isolation. Several reports also suggest a higher pathogenicity in humans and an association with ocular toxoplasmosis or severe cases of acquired toxoplasmosis in immunocompetent patients. T he three main types respond to the criteria for a clonal population structure of Toxoplasma (isolation of identical multilocus genotypes over large geographic areas and at interval of several years, and a strong linkage disequilibrium) (Tibayrenc et al., 1991). This simple clonal structure is accompanied by a low genetic divergence between the three main lineages (only ≈ 2 % divergence at the DNA sequence level between lineages). A large majority (84 %) of the of the single nucleotide polymorphisms (SNPs) identified among the three types are type I and II SNPs, type III polymorphisms (only 16 %) being located mainly on chromosome IV (Boyle et al., 2006). The assymetrical distribution of SNPs on chromosomes indicates 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. The limited genetic diversity within each of these lineages and the low divergence between lineages strongly suggest that these three clonal lineages have expanded as the dominant strains relatively recently, from a common ancestor 10,000 years ago (Su et al., 2003).

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“…Some of these atypical genotypes are detected in multiple locations. They may correspond to new successful clonal lineages (Pena et al, 2007).…”

Section: Toxoplasma Genotypes the Three Main Clonal Lineagesmentioning

confidence: 99%

Section: South Americamentioning

confidence: 99%

Section: South Americamentioning

confidence: 99%

Section: Virulence Of Non Clonal Lineagesmentioning

confidence: 99%

Section: Genetic Background Of Virulencementioning

confidence: 99%

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Toxoplasma gondii, “new” genotypes and virulence

Dardé¹

2008

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143

108

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Genetic Mapping of Acute Virulence in Toxoplasma Gondii

Sibley¹,

Boothroyd²

2012

Evolution of Virulence in Eukaryotic Microbes

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Toxoplasma gondii clonal type III is the dominant genotype identified in Grenadian pigs

Chikweto

Alhassan

et al. 2022

Veterinary Medicine & Sci

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Background Toxoplasma gondii is a widespread zoonotic protozoan parasite capable of infecting all warm‐blooded animals. Although the genotypes of T. gondii in pigs have been reported worldwide, there is no information on the genotypes and diversity of T. gondii in pigs in Grenada, West Indies. Objectives The aims of the present study were to isolate, genotype and determine the diversity of T. gondii genotypes in pigs. Methods We carried out a modified agglutination test (MAT) on blood from 149 pig hearts collected from a local meat market. Myocardial tissue homogenate from pigs that tested positive for T. gondii was homogenized and inoculated into mice for isolation of the parasite. We collected mouse tissues and extracted DNA for genotyping based on 11 polymerase chain reaction‐restriction fragment length polymorphism markers (SAG1, SAG2, alt. SAG2, SAG 3, BTUB, GRA6, L358, PK1, C22‐8, C 29‐2 and Apico). Results Out of the 149 pig hearts, 31 (20.8%) tested positive for T. gondii on MAT. Bioassays in mice yielded 12 isolates designated TgpgGr1 to TgpgGr12. Molecular characterisation of T. gondii revealed four genotypes as follows: ToxoDB #2‐clonal type III (seven isolates); ToxoDB #7 (three isolates); ToxoDB #13 (one isolate); ToxoDB #30 (1 isolate). Overall, ToxoDB #2 was the most common (58%). Toxo database (DB) # 13, which causes interstitial pneumonia in affected mice, has also been reported. Conclusion The genetic diversity of T. gondii in pigs in Grenada is lower than that in other surrounding Caribbean areas.

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Population structure and mouse-virulence of Toxoplasma gondii in Brazil

Cited by 336 publications

References 30 publications

Toxoplasma gondii, “new” genotypes and virulence

Toxoplasma gondii, “new” genotypes and virulence

Genetic Mapping of Acute Virulence in Toxoplasma Gondii

Toxoplasma gondii clonal type III is the dominant genotype identified in Grenadian pigs

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