United States Department of Agriculture, Agricultural Research Service, Animal and Natural Resources Institute, Animal Parasitic Diseases Laboratory, Building 1001, Beltsville, MD 20705-2350, USA.
Infect Genet Evol. 2012 Mar;12(2):359-68. doi: 10.1016/j.meegid.2011.12.010. Epub 2011 Dec 29.
Recent population studies revealed that a few major clonal lineages of Toxoplasma gondii dominate in different geographical regions. The Type II and III lineages are widespread in all continents and dominate in Europe, Africa and North America. In addition, the type 12 lineage is the most common type in wildlife in North America, the Africa 1 and 3 are among the major types in Africa, and ToxoDB PCR-RFLP #9 is the major type in China. Overall the T. gondii strains are more diverse in South America than any other regions. Here, we analyzed 164 T. gondii isolates from three countries in Central America (Guatemala, Nicaragua, Costa Rica), from one country in Caribbean (Grenada) and five countries from South America (Venezuela, Colombia, Peru, Chile, and Argentina). The multilocous polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) based genotyping of 11 polymorphic markers (SAG1, SAG2, alt.SAG2, SAG3, BTUB, GRA6, L358, PK1, C22-8, C29-2 and Apico) were applied to 148 free-range chicken (Gallus domesticus) isolates and 16 isolates from domestic cats (Felis catus) in Colombia; 42 genotypes were identified. Linkage disequilibrium analysis indicated more frequent genetic recombination in populations of Nicaragua and Colombia, and to a lesser degree in populations of Costa Rica and Argentina. Bayesian structural analysis identified at least three genetic clusters, and phylogenetic network analysis identified four major groups. The ToxoDB PCR-RFLP #7, Type III and II were major lineages identified from Central and South America, with high frequencies of the closely related ToxoDB PCR-RFLP #7 and Type III lineages. Taken together, this study revealed high diversity within and between T. gondii populations in Central and South America, and the dominance of Type III and its closely related ToxoDB PCR-RFLP #7 lineages.
最近的人口研究表明，刚地弓形虫的少数几个主要克隆谱系在不同地理区域占主导地位。II 型和 III 型谱系广泛分布于各大洲，在欧洲、非洲和北美洲占主导地位。此外，12 型谱系是北美的野生动物中最常见的类型，非洲 1 型和 3 型是非洲的主要类型之一，而 ToxoDB PCR-RFLP #9 是中国的主要类型。总的来说，南美的刚地弓形虫菌株比其他任何地区都更加多样化。在这里，我们分析了来自中美洲三个国家（危地马拉、尼加拉瓜、哥斯达黎加）、加勒比一个国家（格林纳达）和南美洲五个国家（委内瑞拉、哥伦比亚、秘鲁、智利和阿根廷）的 164 株刚地弓形虫分离株。应用 11 个多态性标记（SAG1、SAG2、alt.SAG2、SAG3、BTUB、GRA6、L358、PK1、C22-8、C29-2 和 Apico）的多基因座聚合酶链反应-限制性片段长度多态性（PCR-RFLP）对 148 株自由放养的鸡（Gallus domesticus）分离株和 16 株哥伦比亚家养猫（Felis catus）分离株进行了基因分型；鉴定出 42 种基因型。连锁不平衡分析表明，尼加拉瓜和哥伦比亚的种群中遗传重组更为频繁，而哥斯达黎加和阿根廷的种群则较少。贝叶斯结构分析确定了至少三个遗传群，而系统发育网络分析确定了四个主要群体。ToxoDB PCR-RFLP #7、III 型和 II 型是从中美洲和南美洲鉴定出的主要谱系，ToxoDB PCR-RFLP #7 和 III 型谱系的密切相关谱系的频率很高。总之，这项研究揭示了中美洲和南美洲刚地弓形虫种群内和种群间的高度多样性，以及 III 型及其密切相关的 ToxoDB PCR-RFLP #7 谱系的主导地位。
