Genetic analyses of atypical Toxoplasma gondii strains reveal a fourth clonal lineage in North America.
Genetic analyses of atypical Toxoplasma gondii strains reveal a fourth clonal lineage in North America.
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DOI：
10.1016/j.ijpara.2011.01.005
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发表时间：
2011-05
影响因子：
4
通讯作者：
Sibley LD
中科院分区：
文献类型：
--
作者：
Khan A;Dubey JP;Su C;Ajioka JW;Rosenthal BM;Sibley LD
弓形虫是一种广泛存在于动物体内的寄生虫，可引起人畜共患病。以前的研究已经揭示了北美和欧洲的强克隆种群结构，而来自南美的菌株在遗传上是分离的，并且更加多样化。然而，最近对来自该地区的遗传变异更大的菌株的描述对北美地区的组成提出了质疑。在这里，我们使用基于序列的系统发育和种群分析来检查一组扩大的分离株，以重新评估T。在北美洲的弓形虫。我们的研究结果表明，以前定义的非典型限制性片段长度多态性模式的菌株分为两个离散的组。在一种情况下，这些新的分离株代表了现有谱系的变体，它们与现有谱系的差异仅在于微小的突变漂移。然而，在第二种情况下，很明显，这些分离物定义了一个在北美常见的全新谱系。支持这一新的谱系是基于遗传学，主成分分析，结构分析，和群体之间的基因流的统计分析。这个新的组，被称为单倍群12，包含分离自海獭的不同基因型，以前被称为A和X。与此相一致的是，第12组主要在野生动物中发现，偶尔也在人类中发现。这个新的谱系也具有高度克隆的种群结构。多位点基因型的遗传分析显示，组12内的不同菌株是2型和独特的亲本谱系之间的单一重组事件的产物。总的来说，原型2型与北方少数谱系的克隆扩张有关，这是与几个不同亲本系单独但不频繁的遗传杂交的结果。
Toxoplasma gondii is a widespread parasite of animals that causes zoonotic infections in humans. Previous studies have revealed a strongly clonal population structure in North America and Europe, while strains from South America are genetically separate and more diverse. However, the composition within North America has been questioned by recent descriptions of genetically more variable strains from this region. Here, we examined an expanded set of isolates using sequenced-based phylogenetic and population analyses to re-evaluate the population structure of T. gondii in North America. Our findings reveal that isolates previously defined by atypical restriction fragment length polymorphism patterns fall into two discrete groups. In one case, these new isolates represent variants of an existing lineage, from which they differ only by minor mutational drift. However, in the second case, it is evident that these isolates define a completely new lineage that is common in North America. Support for this new lineage was based on phylogeny, principle components analysis, STRUCTURE analyses, and statistical analysis of gene flow between groups. This new group, referred to as haplogroup 12, contains divergent genotypes previously referred to as A and X, isolated from sea otters. Consistent with this, group 12 was found primarily in wild animals, as well as occasionally in humans. This new lineage also has a highly clonal population structure. Analysis of the inheritance of multilocus genotypes revealed that different strains within group 12 are the products of a single recombination event between type 2 and a unique parental lineage. Collectively, the archetypal type 2 has been associated with clonal expansion of a small number of lineages in the North, as a consequence of separate but infrequent genetic crosses with several different parental lines.
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影响因子：
56.9
作者：
Saeij, J. P. J.;Boyle, J. P.;Boothroyd, J. C.
通讯作者：
Boothroyd, J. C.
影响因子：
6.4
作者：
Ajzenberg, D;Cogné, N;Dardé, ML
通讯作者：
Dardé, ML
影响因子：
4
作者：
Miller, MA;Grigg, ME;Conrad, PA
通讯作者：
Conrad, PA
影响因子：
64.8
作者：
Saeij, J. P. J.;Coller, S.;Boothroyd, J. C.
通讯作者：
Boothroyd, J. C.
DOI：
10.1046/j.1471-8278.2000.00014.x
发表时间：
2001-03-01
期刊：
MOLECULAR ECOLOGY NOTES
影响因子：
--
作者：
Agapow, PM;Burt, A
通讯作者：
Burt, A