Geographical patterns of Toxoplasma gondii genetic diversity revealed by multilocus PCR-RFLP genotyping

Abstract

In recent years, an extensive collection of Toxoplasma gondii samples have been typed using a set of 10 PCR-RFLP genetic markers. Here we summarize the data reported until the end of 2012. A total of 1457 samples were typed into 189 genotypes. Overall, only a few genotypes dominate in the northern hemisphere, which is in stark contrast to the southern hemisphere where hundreds of genotypes coexist with none being notably dominant. PCR-RFLP genotype #1 (Type II clonal), #2 (Type III), #3 (Type II variant) and #10 (Type I) are identified globally. Genotypes #2 and #3 dominate in Africa, genotypes #9 (Chinese 1) and #10 are prevalent in Asia, genotypes #1, #2 and #3 are prevalent in Europe, genotypes #1, #2, #3, #4 and #5 dominate in North America (#4 and #5 are collectively known as Type 12). In Central and South America, there is no clear dominance of any genotype even though a few have relatively higher frequencies. Statistical analysis indicates significant differences among populations in Africa, Asia, Europe, North America, and Central and South America, with only Europe and North America exhibiting similar diversity. Collectively, the results revealed distinct population structures and geographical patterns of diversity in T. gondii.

Epidemiological aspects of Toxoplasma gondii infection in riverside communities in the Southern Brazilian Amazon

“…However, although all the isolates were virulent and lethal to the infected mice, conclusions regarding the virulence of these isolates cannot be made without knowing the dosage of the inoculum (18) . Nevertheless, the pathogenic profi le observed here is indicative of a high virulence, as observed with the majority of Brazilian isolates (2) (8) .…”

“…Cavalcante et al (3) ( 4) found a prevalence of 73.3% in humans, 87.3% in cats and 37.5% in pigs on 71 farms in the municipality of Monte Negro, Rondônia, in the western Amazon region. From the same area, T. gondii was isolated in free-range chickens and, based on restriction fragment length polymorphism (RFLP), 24 isolates were genotyped (5) , and seven different genotypes were found (6) , thus confi rming the high diversity of T. gondii isolates in Brazil (7) (8) . Furthermore, the pathogenicity of Brazilian strains, based on mouse bioassays, suggested that they carry a higher virulence than isolates from other regions of the world (7) .…”

Fatal toxoplasmosis in an immunosuppressed domestic cat from Brazil caused by Toxoplasma gondii clonal type I

“…This region of Brazil is one of the regions with fewer strains genotyped, most studies have been conducted in the southeastern region, where the non-archetypal Brazilian clonal genotypes BrI, BrII and BrIII predominate (PENA et al, 2008;SHWAB et al, 2014). There is no information on T. gondii genotypes circulating in the state of Santa Catarina, but genotyping of T. gondii strains in the states of Rio Grande do Sul and Paraná, which are in the same southern region, have shown the predominance of non-archetypal genotypes and the great diversity that is characteristic of mainland areas of Brazil (SHWAB et al, 2014). Shwab et al (2014) reviewed the geographical patterns of T. gondii diversity by means of PCR-RFLP based on almost 1,500 samples that had already reported from Africa, Asia, Europe, Central/South America and North America.…”

“…In South American countries, including Brazil, the T. gondii population has high genetic diversity (AJZENBERG et al, 2004;LEHMANN et al, 2006;PENA et al, 2008) and the globally distributed archetypal clonal genotypes types I, II and III (HOWE & SIBLEY, 1995) occur at low frequencies, particularly types I and II (SHWAB et al, 2014). From 106 previously identified genotypes, corresponding to 385 Brazilian strains, which were included in the geographical patterns of T. gondii studied by Shwab et al (2014), two were type I clonal, one was type II clonal, five were type II variant, six were type III clonal (ToxoDB RFLP #10, #1, #3 and #2) and 92 were non-archetypal genotypes.…”

“…From 106 previously identified genotypes, corresponding to 385 Brazilian strains, which were included in the geographical patterns of T. gondii studied by Shwab et al (2014), two were type I clonal, one was type II clonal, five were type II variant, six were type III clonal (ToxoDB RFLP #10, #1, #3 and #2) and 92 were non-archetypal genotypes. Besides being highly diverse, most of the strains isolated in Brazil are virulent towards mice, thus differing from those in North America and Europe (PENA et al, 2008).…”